Integrated Pest Management (IPM) in Oil Palm, Elaeis guineensis Jacq.

Abstract

The edible oil of Elaeis guineensis Jacq., oil palm, is crucial in filling the demand gap and meet the growing need for edible oil worldwide. Although all precautions have been taken to minimize the introduction of pest populations along with seed sprouts from importing countries, some pests are still found to invade crops and cause production losses. Most of these populations have been found to come from other Arecaceae palms such as coconut, palmyrah and betel nut that may be commonly found around oil palm fields. It has been estimated that the above pests reduced oil palm yield by 20–30%, persisted for several years after attack, depending on cultivation methods, and returned to previous yield levels within a few years of attack. The minor pests of coconut, palmyrah, and maize, psychid and slug caterpillar were discovered to be very invasive on oil palm, resulting in output losses of up to 50%. The presence of favorable conditions such as low temperature and high humidity within oil palm plantations may possibly be the reason for migration. The production losses caused by these migratory pests affect the sustainability of the produce and thus agriculture, so it is important to apply the good management practices.

1. Introduction

Oil palm (Elaeis guineensis Jacq.), is a rich source of edible oil and is a perennial crop cultivated in large areas to beat the edible oil shortage. Upon cultivation, a farmer can draw the yield for 25–30 years, stabilising his economy over its other oil seed crops. Oil palm is cultivated in tropical areas of Asia, Africa, and South America. The productivity of the crop is challenged by the availability of water and nutrient stress, abiotic stress like drought, biotic stresses like pests and diseases, etc. As oil palm requires nearly 300 litres of water per day, irrigation should be continuous at regular intervals, therefore, the micro-climate so formed with high humidity and cold makes pleasant conditions for the event of pests and diseases. The age of the palms will dictate the incidence of pests. The pest infestation from foreign sources may be due to the strict quarantine measures being followed at various ports important for seed sprouts. The sole chance for the pest outbreak is that the migration of pests from other crops grown in the nearby locations of the oil palm plantations is because of the availability of food material continuously. The perennial nature of palms and the monocropping system as practiced in many locations provide ample opportunities for the buildup of the pest. The spread of the problems is slow in new areas. Of the insect pests, the most important is the rhinoceros beetle and defoliators, causing heavy yield losses. The insect pests which are reported as minor and secondary pests on other crops got the pest status as the damage was noticed in both nursery and field palms of oil palm. Oil palm, as it is a perennial crop, is gorgeous to several pests such as the defoliators (leaf-eating caterpillars) such as bagworms, nettle, and hairy caterpillars feed on the palm fonds, causing damage by defoliating the oil palm tree thereby resulting in yield loss because of the reduction of photosynthetic activity and fruit production. High population levels can result in the whole skeletonization and death of the fronds. Damage of 50% will cause a yield decline of around 43% over the following 2 years. Even lower damage like 10–13% also can cause an analogous loss [1]. Natural enemies including predatory or parasitic insects and diseases caused by viruses and fungi, caterpillars are effectively kept below the economic damage threshold under normal conditions. Heavy pest attack is usually the results of a breakdown within the balance of nature. Generalist predators might not totally feed on the oil palm caterpillars and instead take advantage of other insects available within the ecosystem. In search of hosts, dust under dry conditions interferes with predators and parasites. The parasitoids number may be reduced which are commonly attacked by hyperparasitoids. Outbreaks of the caterpillars are sporadic and localised, thereby; parasites and predators do not fully control the caterpillar populations’ altogether years and locations. A monitoring and closed-circuit television for oil palm is in practice for several years. By monitoring a pestilence, the world within which damage is happening is delineated [2]. Chemical intervention is merely used when populations reach threatening levels by injecting the trunk with a systemic insecticide that is translocated within the sap and carried into the leaf tissue. This implies that only the leaf-feeding caterpillars are killed, but not their natural enemies. Overall insecticide use is low, with no quite 5% of the whole area of oil palms receiving application in anyone year. Insecticide application averages about once in an exceedingly planting generation (around 25 years). In many instances, smallholders do not regularly manage the caterpillar populations with trunk injections and high uncontrolled outbreaks occur [3]. Chemical control typically takes place too late to prevent large production losses due to complex application techniques, subpar monitoring mechanisms, and therefore the challenging environment. Chemical application is also expensive and bad for the environment. There’s enormous potential to boost the present pest management practices, and a number of other biological control agents may well be utilised in integrated pest management (IPM) systems [4]. Agronomic practices directed toward developing biodiversity within the oil palm cropping system, and improved pest monitoring and surveying could even be components of this IPM. The practice of Integrated Pest Management (IPM) against several pests and diseases (P&D) of oil palm includes holistic approaches designed for a P&D control program to cut back pest populations below the brink level with minimal environmental impact [5].

2. Pollinating Weevil, Elaedobius kamerunicus

2The pollinating weevil, Elaedobius kamerunicus (Coleoptera: Curculionidae) has been known to be the foremost efficient insect pollinator of oil palm and has successfully improved the pollination and increased the yield. Its introduction has greatly reduced the requirement for assisted pollination. Elaeidobius kamerunicus was introduced into Malaysia during the late 1980s to spice up the assembly of oil palm fruit bunches. Almost 40 years since the introduction of E. kamerunicus, significant improvements are witnessed within the increase of yield of oil palm. Nevertheless, the present concern within the oil palm sector is regarding the decreasing of fruit sets that will be plugged by E. kamerunicus [6]. Through their subsequent visits to the female inflorescences, when the stigmas are receptive, the female flower emits short pulses of an analogous but sharper and more penetrating odour that attracts Elaeidobius species apart from the male flowers and the pollen grains. The weevils chew the anther filaments of opened male flowers, during anthesis when a robust aniseed-like scent is emitted; they crawl or move about on the spikelets [7]. When the weevils crawl over the male inflorescences an outsized number of pollen grains are dispersed which are carried by wind [8]. The weevils enter the female inflorescence but quickly leave after finding no food there, returning to the male flowers. When Elaeidobius species crawl around the female inflorescence, pollen is discharged, which causes them to become covered in it. Over 5000 beetles are thought to visit each female inflorescence during receptivity, and each one can carry up to 600 pollen grains. The development of the larvae occurs on tissue that has served its role and has no utility for the palm because oviposition occurs after anthesis, hence Elaeidobius species do not significantly harm the palm [9]. The most ideal insect for introduction into Malaysia and other regions with poor oil palm pollination is E. kamerunicus. E. kamerunicus, one of the many species of this genus investigated in Cameroon, was the most prevalent in the country’s coastal regions throughout both the wet and dry seasons, transported more pollen than other species, and had a respectable ability to search (Figure 1) [10].

Figure 1.

Pollinating Weevil, Elaeidobius kamerunicus. (A) Female inflorescence, (B) male inflorescence, (C) pollinating Weevil, Elaeidobius kamerunicus, (D) pollinating weevils on male inflorescence, (E) weevil at a spiklet of oil palm male flower.

The weevils are quite useful, and man has introduced them to palm farms to use them for pollinating those trees. In regions where palms and weevils were not native, hand pollination was used, which was exceedingly expensive for the growers. The inadequate pollination has been a significant issue in these nations. In addition to the slow pace of fruit establishment, inadequate pollination can occasionally cause bunch failure [11].

The Tenera palm variety demonstrated larger yield improvement as a result of E. kamerunicus introduction to Malaysia than the Dura variety. Larger, heavier, and more compact bunches were assembled as a result of weevil pollination, which also increased the oil to bunch ratio from under 19 to 23–25%, especially on trees that were 4–10 years old. Thrips hawaiiensis, an older, less effective pollinator, was not ostensibly replaced by E. kamerunicus. In terms of pollinating oil palms, the weevil population is crucial. Weevil populations have been found to be reduced by a number of factors, including climate, pesticides, interactions with other insects in the area, and male inflorescence [12]. The pollinator force of the weevil was sustained at a spread between 3095.2 and 19126.1 weevils per ha. The mean of weevils per spikelet shows that the range of weevils was between 13.51 and 54.06 per spikelet. There was no correlation between rainfall and population density of EK. However, a correlation was obtained between weevil density and therefore the number of anthesis female inflorescence of oil palm (r = 0.938, p < 0.05). Results of the t-test show that the 6-year-old oil palm stands had a significantly different population density than that of an 8-year-old oil palm stand. The data of this study should be useful as baseline data to analyse why there’s such a large range of weevils per ha or spikelet [13].

The natural enemies of the pollinating weevil, E. kamerunicus are the parasitoid nematodes Aphelenchoides bicaudatus and Cylindrocorpus inevectus attacking during pupal stage [14]. The pupae were found to be severely infested with A. bicaudatus then were treated until nematode-free before being released [15]. The nematode Elaeolenchus parthenonema is harmful to the weevil [16], but the Bacillus thuringiensis products Lepcon-1, Bafog-1 (S), and Ecobac-1 (EC) are proven innocuous to the weevil [17].

In order to search out the impact of bio-agents together with chemical insecticides on the expansion and survival of the pollinating weevils of oil palm, the study was distributed. Newly emerging inflorescences in 24 palms were selected and tagged for applying pesticides and bio-agents. Conventional insecticides quinalphos (0.05%), monocrotophos (0.072%), lambda cyahalothrin (0.02%), and microbial agents namely Metarhizium anisopliae (6.4 × 10⁵ spores/ml) and Beauveria bassiana (3.5 × 10⁵ spores/ml) at normal concentrations were tested as treatments by applying on the inflorescence as a liquid spray. The concentrations of these selected chemical insecticides were proved lethal to the target pests of oil palm. The population count of the weevils (egg to adult stages) was recorded employing a sampling technique. Daily weather data was also recorded during the observation period to correlate the population fluctuation if any with the abiotic factors. Observations recorded on the weevil population showed significant results. Analysis of the obtained data was met out using the chi-square test. The chi-square test results clearly indicate that the difference within the weevil population in untreated and insecticide-treated palms is very significant and contrarywise in untreated and microbial agents viz. Metarhizium anisopliae and Beauveria bassiana. The chemical pesticide quinalphos had a major impact in reducing the weevil population whereas the microbial agents did not cause a major reduction. However, Metarhizium anisopliae, which may be a good microbial agent against many coleopteran pests, was observed to cause less impact on the pollinating weevils which are coleopterans. This means that the microbial agents are safer for pollinating weevils compared to the standard pesticide and hence, can safely be included within the oil palm pest management practices [18].

3. Pests of oil palm

Prior to field planting, oil palm is usually passed through single or double stage nursery system. Oil palm seedlings are maintained for 12–14 months in nursery and culled and planted within the field. Preventive measures such as insecticide application at frequent intervals protect the nurseries and are almost free from pest incidence. However, when within the neglected conditions, few pests are observed causing damage to the seedlings. A number of them are listed below (Tables 1 and 2).

Pests		Common name	Scientific name
Insects	Lepidoptera	Tussock caterpillar	Dasychira mendosa Hb.
	Lepidoptera	Psychid	Metisa plana Walker
	Lepidoptera	Leaf webworm	Acria meyricki
	Lepidoptera	Tobacco caterpillar	Spodoptera litura Fb.
	Hemiptera	Spindle bug	Carvalhoia arecae Miller
	Homoptera	Leaf hopper	Proutista moesta Westwood
	Homoptera	Aphids	Cerataphis brasiliensis
	Coleoptera	Cockchafer beetles (Root grub)	Apogonia/Adoretus spp.
Molluscan pests		Black slug	Laevicaulis alte
Vertebrate pests		Black rat	Rattus rattus Wroughtoni
		Wild boar	Sus scrofa

Table 1.

Pests of oil palm nursery.

Pests		Common name	Scientific name
Insects	Coleoptera	Rhinoceros beetle	Oryctes rhinoceros L.
	Lepidoptera	Tussock caterpillar	Dasychira mendosa Hb.
	Lepidoptera	Slug caterpillar	Darna catenatus
	Lepidoptera	Psychid	Metisa plana Walker
	Lepidoptera	Leaf webworm	Acria meyricki
	Hemiptera	Coccoids (scales and mealy bugs)	Hemiberlesia lataniae, Chrysomphalus aonidum, Pinnapsis aspidistrae, Dysmicoccus brevipes
	Isoptera	Termites	Coptotermes curvignathus
Vertebrates	Avian pests	Crows	Convus splendens protegatus; Corvus macrorhynchus cuiminatus
		Mynah	Acridotheres tristis
		Babbler	Turdoides affinis affinis
		Parrots	Psitticula krameri manillensis
	Mammalian pests	Black rat	Ratus rattus wroughtoni
		House rat	Rattus rattus rufescens
		Western Ghat squirrel	Funambulus tristriatus
		Procupines	Hystrix indica

Table 2.

Pests of oil palm plantations.

4. Insect pests

Insect pests are the most limiting factor for crop production in tropical Asia, among which Lepidopteran pests cause a major amount of injury. Oil yielding and vegetables are the foremost profitable crops and farmers everywhere feel the requirement to shield such high value crops from any style of damage caused by insect pests.

4.1 Lepidopteran pests

4.1.1 Tussock caterpillar: Dasychira mendosa Hb. (Lymantridae)

It is a polyphagous insect, which is mostly found on edible seeds, citrus, guava, banana, etc. Significant damage to nursery seedlings is due to the larvae which occasionally feed voraciously on the leaves. They’re found to cause damage in oil palm plantations also [19]. This pest was observed in oil palm nurseries. The pest is found round the year with the peak incidence during June–July, with the onset of heavy rains [20]. Incidence is seen only in those nurseries which are overgrown and not lifted for transplantation at the proper time (Figure 2).

Figure 2.

Tussock caterpillar.

4.1.1.1 Biology and nature of injury

About 302.9 eggs are laid by a female moth in its lifetime within a period of about 5.5 days. After hatching, the larvae withstand 9–10 instars in 43.1 days. The larvae are found defoliating the oil palm severely at the secondary nursery stage. Initially the leaves are scraped by the young larvae within the congregation and later disperse and begin feeding on the tender leaves severely. The complete life cycle from egg to adult is 65.1 days. Caterpillars possess dense tufts of hair on the body. They are capable of causing minor irritation and sometimes rash on the material body.

4.1.1.2 Management

Under the field conditions, tachinid flies parasitizes the larvae to 10.2% and pupae by are parasitized by Brachymeria albotibialis to 40.0%. The pest can managed with 1–2 sprays of 0.05% quinalphos. The larvae of D. mendosa are parasitized by a tachinid fly (Diptera: Tachinidae) and the pupae of D. mendosa are parasitized by Brachymeria albotibialis (Ashmead) (Hymenoptera: Chalcididae). The fly injects an egg into the caterpillar. The fly maggots burrow inside the host and feed from inside the body upon hatching. The affected caterpillar becomes sluggish reduces in size and fails to pupate and eventually dies. The mean parasitism is generally about 10.2% during the pest activity period. The parasitized pupa turns dark brown or black in colour and only one parasitoid individual emerges out per host pupa. Once the parasitoid emerged, the empty pupal case remained with a circular hole at the pinnacle region. The extent of parasitism under field conditions is often recorded as 40.0%. This information on biology, the character of the damage, seasonal activity, and natural enemies of D. mendosa can be used for planning and developing effective pest management strategies in oil palm nurseries.

4.1.2 Slug caterpillar Darna catenatus Snellen, (Limacodidae)

The pest was reported as a significant problem in both Malaysia and Indonesia where large hectares of oil palm was infested with it causing heavy defoliation [21]. The incidence of slug caterpillar was first reported on oil palm in 2002 was sporadic and erratic in very few plantations of West Godavari and Krishna districts of Andhra Pradesh, India. The pest was also observed feeding on the adjacent coconut plants but at low levels and doubtless migrated to the oil palm thanks to the provision of lush green leaves. However, it was shown that high summer temperatures had little effect on insect build-up and that a high ratio was a key element in natural suppression (Figure 3).

Figure 3.

Slug caterpillar infecting oil palm.

4.1.2.1 Biology and nature of harm

Every female lays between 250 and 350 eggs. On the abaxial surfaces of the more developed fronds, frequently close to the edges of leaflets, the eggs are placed in rows. These eggs will eventually hatch. The caterpillars have urticating spines and are green. Caterpillars in the first instar solely eat the epidermis, which results in translucent patches that resemble windows. Later-stage caterpillars eat from the lamina’s margin toward the interior, leaving the midvein. The larva develops during a period of 3–7 weeks. To spin cocoons and pupate, caterpillars scurry way down to the tree trunk’s base or amid herbaceous plants. The pupal stage is for 2–4 weeks. The destructive stage, caterpillars, are observed feeding on the leaf lamina, severely defoliating the leaf and leaving just the midribs. The lower whorl leaves have totally dried due to the heavy incidence. Faecal droppings on the bottom level or cover and the sound of gnawing during a significant outbreak can both be used to gauge the pest’s severity. The larvae are found to own setae on the dorsal side of the body causing irritation to handle. The presence of a bluish tinge on the dorsal side of the caterpillar is the conspicuous identification mark of the pest. Except for oil palm, the incidence was also observed in cocoa and maize that are grown within or adjacent to oil palm plantations. The caterpillars are characterised by their stinging spines which may cause a rash on contact with the skin. Young caterpillars scrape strips of the epidermis and as they become mature, generally commence feeding near the information of pinnae, leaving only the midrib [19]. The fronds are severely defoliated during a severe epidemic, leaving the midrib alone.

4.1.2.2 Management

1. At the beginning of the pest activity period, lower fronds with pest stages should be pruned and burned.

2. Natural suppression of the pest is observed in very few plantations thanks to virus infections. Virus infection to the caterpillars arresting the moulting process is observed in severely infested gardens.

3. Application of microorganism, Beauveria bassiana (10⁻¹) that caused white muscardine disease to the caterpillar proved effective but time taking compared to chemical insecticides.

4. Under natural conditions, an oversized number of parasitoids of Eulophidae, Chalcididae, Braconidae, Tachinidae, and Bombyliidae and predators of Hemiptera and Pentatomidae families regulate the host populations [22].

5. For the control, carbaryl 50% WP is advised to be sprayed at 0.1% [23].

6. The pest can be successfully controlled by two aerial applications of quinolphos 0.05% or lambda-cyhalothrin 0.05% spaced 15 days apart throughout the period of pest activity.

7. When the palms have reached their full height, stem injection with monocrotophos 25/100 ml of water per palm is also useful.

4.1.3 Bag worm, Metisa plana (Psychidae)

Bag worm, Metista plana is observed in moderate levels with quite six case worms per leaflet in Andhra Pradesh state all the year round. However in Karnataka the incidence is heavy during the monsoon and winter months. Cocoa (Theobroma cacao), coconut (Cocos nucifera), edible seed (Areca catechu) and areca palm (Dypsis lutescens) are observed as collateral hosts for the pest. There are nine different species of caseworms known to infest oil palm in India. Metisa plana, Manatha albipes, and Crematopsyche pendula were the most often seen species. In almost all the gardens, the pest is observed endemic with the presence of all the stages at any date of observation. Psychid incidence is observed during of July to March leaving the summer months with a percent incidence varying 0.39–8.8 in several palms. Young gardens of but 5 years recorded less incidence compared to middle aged ones. The fundamental cause of the higher prevalence compared to young gardens where such conditions are absent is the observed overlapping and intermixing of leaves of neighbouring palms, which prevents sunlight from penetrating into the older gardens. Unfavourable abiotic conditions, such as high temperatures during the pre-monsoon period, a delay in the monsoon, and heavy rains throughout the monsoon season, may be linked to the natural death of psychids that was seen over the summer and rainy period. Although the pest maintains congenial conditions suited to its growth and development within the bag by regulating the desired temperature and humidity, during this time of year it could not maintain dryness and through hot summers, it’s unable to take care of the specified humidity resulting in mortality of the pest (Figure 4).

Figure 4.

Psychids feeding on oil palm.

4.1.3.1 Biology and nature of harm

The pupal cocoons, which are hidden in sacks, contain 60–80 eggs laid by wingless female adults. The fecundity can occasionally be quite high. The egg cycle lasts 16 days. Before pupating, the larva typically needs 100–125 days. Just five larval instars are seen in males and seven instars in the case of females. The larvae and adults possess black pectinate antennae. Because the caterpillars mature, they turn within the bag, changing from a feeding position with their heads oriented toward the plant surface. It takes 26 days to reach the pupal stage. The primary instar larvae after hatching from eggs are naked with no bag. They start feeding on the mother’s bag as soon as they hatch, eventually forming their own bag. Caterpillars live in a case while they are developing. Each species’ case/bag has a specific form and outward appearance. The pupae are found within the luggage and are just plain cocoons. The males have wings and are able to fly.

The abaxial surfaces of the fronds are scarified by caterpillars in their early stages. The full leaf tissue is chewed by caterpillars in later instars, which also create holes and notches in the leaf tissue by feeding at the leaf margins. When bagworms feed, the surface develops holes and grooves as well as dry necrotic areas where the surface has been destroyed. Bagworms attack the center and older fronds of the palms, with younger fronds usually remaining free from damage. Damage by psychids is severe only the population is incredibly high. The yield of the palm suffers from gradual necrosis and ultimately skeletonization. Defoliation by the bug results in a loss of 3.88% of each palm’s photosynthetic area.

4.1.3.2 Management

1. Regular cutting and burning of the severely damaged and dried leaves that contain insect stages reduces the population.

2. Three species of parasitoids namely Goriphous bunoh infesting pupal stages and Brachymeria spp. and Dolichogenidea metesae infesting larval stages of the pest are recorded in the majority of the plantations [24, 25]. The impact of parasitism on the pest population is observed more within the later stages of the pest. Brachymeria spp. is observed because the main parasitoid causes over 40% parasitism to larval stages. The typical percent parasitism is observed at 33.15% with maximum parasitization (65.23%) during the month of November while minimum (15.83%) during December.

3. Aerial spraying of lambda cyhalothrin 0.05% is typically advised in cases of severe infestation. Since immature larvae are more susceptible to pesticides, spraying should be timed to coincide with their most frequent occurrences. If the palms grow too tall and cannot be sprayed, systemic insecticides like monocrotophos or imidacloprid may be be applied via stem injection or root feeding. If sprayed correctly and irrigated, granular pesticides like phorate or carbofuran applied at a rate of 100–150 g per palm in a basin may also be beneficial.

4.1.4 Leaf web worm, Acria meyricki (Depressaridae)

The pest was first recorded during the winter months of 1995–1996 [26]. The occurrence was erratic for a decade and later confined to few gardens in alternate years. From 2005 onwards, it’s become an everyday pest occurring each year in Krishna, East, and West Godavari districts of the state. In some regions where palm trees have grown to a certain height and where the leaves of nearby palm trees combine, the pest has become endemic. This has created an ideal environment for the insect’s growth. In those orchards where the palms received more basin irrigation due to flood irrigation with more water than necessary, the infestation was made worse. The leaf webworm, A. meyricki, has been linked to yield losses of up to 34%. It was only occasionally and sporadically seen as a pest during the winter. The bug disappears as the temperature rises. Typically, the incidence is seen between October and April. It was discovered that the larval population had a substantial negative correlation with weather variables including maximum and lowest temperatures, and that the relationship between the mean temperature and ratio and rainfall was insignificant (Figure 5) [27, 28].

Figure 5.

Leaf web worm on oil palm.

4.1.4.1 Biology and nature of injury

About 62.5 eggs are laid by a female moth in clusters (in confined conditions). The time span is 4–6 days, with 4.7 days serving as the median. Egg hatchability is 95.6%, ranging from 92.8 to 100%. The larval stage has 6–7 instars, which it goes through in an incredibly long 20.7 days. The larva reaches the pre-pupal stage, which lasts 1 day, when it has reached maturity, stops feeding, shrinks in size, and ceases growing. Pupa stage duration is 5.8 days. A typical adult lives for 5.4 days. From egg to adult stage, the entire life span begins in 30–44 days [29]. The larval stage that remains inside and is active on the underside of the leaves is the caterpillar. The early instars scrape the leaves, and the later instars cause defoliation.

They first cause significant defoliation by nibbling on the elder leaves. The caterpillars go to the following top leaves once the lower leaves have completely been destroyed. Due of a bad infestation, the leaflets were dried out and gave off the appearance of being burned. When disturbed, the larvae dangle from silken threads and either go to nearby palm trees or are pulled back and pursue the same leaves. The infection can easily spread due to the intermixing of palm fronds in the garden. The larvae are discovered eating on cocoa, Theobroma cocoa, coconut, Cocos nusifera and decorative edible seed, Areca catechu, banana, and a few different kinds of grass in the gardens during a serious infestation. When oil palm and cocoa are intercropped, cocoa is frequently infested.

4.1.4.2 Management

1. At the beginning of the pest activity period, lower fronds with pest stages should be pruned and burned.

2. Under field conditions, two biocontrol agents, Apanteles hyposidrae Wilkinson (Hymenoptera: Ichneumonoidea: Braconidae) and Elasmus brevicornis Gahan, are found parasitizing larvae (Hymenoptera: Chalcidoidea: Eulophidae). Elasmid and braconid parasitism rates on larvae range from 21.41 to 36.58%, while Brachymeria albotibialis (Ashmead) (Hymenoptera: Chalcidoidea: Chalcididae) parasitizes pupa, the percent parasitism varies from 21.21 to 79.75.

3. The use of microbial organisms such Beauveria bassiana, Metarhizium anisopliae, and Verticillium lecanii, of which Beauveria bassiana effectively checks the pest population, is an effective method of pest management.

4. It has been shown to be efficient in suppressing the pest to use lambda-cyhalothrin or quinalphos 0.05 or 0.05% twice during the pest activity period at intervals of 15 days.

5. Injection of the stem with monocrotophos 25/100 ml of water per palm is additionally effective within the case of tall palms.

4.1.5 Tobacco caterpillar, Spodoptera litura Fb. (Noctuidae)

During the months of February and March, sporadic instances of the bug feeding on the oil palm nursery leaves are noted. This is particularly typical in nurseries that are built close to tobacco or corn fields. After harvesting the nearby corn fields, the insect may migrate to the oil palm plantations (Figure 6).

Figure 6.

Life cycle of Tobacco caterpillar.

4.1.5.1 Nature and symptoms of damage

The destructive signs include defoliation of young leaves and feeding symptoms on the primordial region.

4.1.5.2 Management

With the application of contact pesticides like quinalphos (0.05%), the pest can be controlled.

4.1.6 Shoot borer: Sesamia inferens walker (Noctuidae)

All of the southern states of India, including Andhra Pradesh, Karnataka, and Kerala, have primary and secondary nurseries with oil palm seedlings where the shoot borer is present (Figure 7).

Figure 7.

Life cycle of shoot borer.

4.1.6.1 Nature and symptoms of damage

Caterpillars enter the stem by the spindle leaf rachis, eat on the meristematic tissues, which result in symptoms like a dead heart and undersized leaves, and therefore hinder the growth. Pink caterpillars develop inside the rachis of the leaf. It has been noted that severe infestation kills secondary nursery plants of the oil palm, necessitating management actions. Nurseries that are poorly run have been proven to be more vulnerable to a shoot borer infestation.

4.1.6.2 Management

A bimonthly application of Carbaryl 50% WP 0.01% will reduce the occurrence of shoot borer [30].

4.2 Coleopteran pests

4.2.1 Rhinoceros beetle, Oryctes rhinoceros L. (Scarabaeidae)

It is a standard pest of the many palms including coconut, oil palm, edible seed and palmyra palms all through the states of India. It became a major pest in all the Indian states that grow oil palm [31]. It’s found throughout South-East Asia and plenty of oil palm-growing countries. Pest incidence is found throughout the year but its incidence where adult emergence is at its peak during South-West Monsoon (June to September). This means that pest emergence synchronises with the monsoon showers. Infestation is severe in plantations where field hygiene and sanitation are neglected. Palmyrah palm (Borasses flabellifer), coconut, arecanut are collateral hosts of this pest (Figure 8) [24, 32, 33].

Figure 8.

A. Life cycle of Rhinoceros Beetle; B. Symptoms of Rhinoceros Beetle infestation on oil palm.

This Rhonoceros beetle was found migrated from other palms such as coconut and palmyra during the initial periods of crop establishment. But within the recent period, it’s found to reject the oil palm. This is often particularly seen when coconut plants are adjacent to these palms. The presence of more lignin at the place of feeding (leaf petiole) in oil palm compared to leaf tips within the case of other Arecaceae palms is that the prime reason for low pest incidence of the pest [34]. This also indicates the pest preference for a specific place of the crop. Costa Rican material, Deli X Ghana is found to be the smallest amount at risk of scarabaeid beetle attack followed by Deli X Nigerian cross. The Malaysian variety Gutherie is found more vulnerable to the beetle followed by Palode material [27].

4.2.1.1 Biology and nature of damage

The oval, white eggs are placed at a depth of 5–10 cm in the surface of decomposing organic waste. The earliest stages of the beetle typically occur in manure pits, compost piles, rotting palm logs and stumps, decomposing organic materials like animal dung, and manure pits. Additionally, the oil palm leaf axils, decaying inflorescences, and mounds of mesocarp on the plantation are all places where the beetles can breed [35, 36]. A female lays between 100 and 150 eggs, which take 8–18 days to hatch. Once they do, the grubs begin to feed on the decomposing materials. The larvae endure three instars and reach maturity in 100–180 days depending on the conditions. The beetle pupates in a deep chamber at a depth of around 30 cm, and it emerges after 10–25 days. They remain in the pupal stage for another 10–20 days. After 20–60 days, they begin to lay eggs. In the dark hours, beetles are busy and drawn to sources of light. A grownup can live for more than 200 days. Typically, one generation is finished each year. When the spear cluster is closed, adult beetles penetrate into the palms at the base to eat the sap and delicate sections of the leaves. The beetles enter the spear cluster’s inner petiole through its outermost petiole, causing a hole that will remain there forever. The frequent symptoms include a hole in the petiole and a wedge-shaped gap in the leaf profile. Compared to adult palms, young palms show much more severe damage near the bottom of the spears. Expanded fronds may break off or become truncated, or the damaged spindle may collapse. Even before anthesis, while the inflorescences are still inside the spathe, adult rhinoceros beetles have been observed digging and devouring the male and female inflorescences [37]. Beetles can be identified by their entry holes because they leave behind chewed-up fibrous fibres [19]. Because of the infiltration of fungi and bacteria through the injuries the insect caused to the palm’s internal organs, secondary rotting of the bud is typically observed. The red palm weevil’s functional birthing sites are wounds formed on petioles and female inflorescences.

4.2.1.2 Management

An integrated pest management approach by incorporating mechanical, sanitation, chemical, and biological aspects is required to combat the pest menace. Identifying all potential pest breeding locations and keeping an eye on the beetle population on the palm’s crown are crucial parts of pest management technology.

1. A hooked, pointed metal rod must be used to extricate the insects from the crowns of immature palm trees because they dig there deeply (beetle hook). The leaf axils around the injured spindle or leaf are to be filled with a mixture of Mancozeb and sterilised fine sand at a ratio of 3 g:1 kg once the beetle has been removed.

2. Leaf axil filling should be done as a preventative measure to protect young palm trees from beetle attack. During April–May, September–October, and December–January, a mixture of Sevidol 8 G (25 g) + fine sand (200 g) is additionally packed into the innermost 2–3 leaf axils of each palm. Care should be used when using the sand, though, as it may contain organisms that reproduce to cause disease.

3. The plantation must be cleared of any potential breeding locations. Carbaryl 50% WP 0.01% is to be sprayed on any breeding grounds that cannot be eradicated or destroyed.

4. Due to the oil palm’s monthly production of two leaves, the granules given to the crown section have proven ineffectual unless they are removed and applied to a fresh spindle each month. It is difficult and time-consuming since the bases of the leaves have spines. In recent years, it has been discovered that the use of lambda-cyhalothrin, a second-generation synthetic pyrethroid, is particularly efficient in lowering the number of pests on Earth.

5. Indigenous predators like Santalus parallelus, Harpalus sp., Scarites sp., Pteropsophus occipitalis, Agrypnus sp. nr. Bifoveatus, etc. suppress the immature stages of scarabaean. The entomopathogen, Metarhizium anisopliae produces epizootics within the natural population of scarabaeid beetle when the moisture levels of the breeding medium are 50% and also the temperature is 29oC and below (conditions ideal for mycosis) [38].

6. Application of Metarhizium anisopliae on the dead coconut logs is additionally proved effective in controlling the pest. The spores of the microbial organism are found viable till 9 months after preparation at room temperatures causing identical mortality to grub stages [39].

7. One of the most effective microbial control agents used to combat rhinoceros beetle infestation of coconut is the Baculovirus of Oryctes. The virus infection reduces the beetles’ lifespan by 40% and completely eliminates their ability to reproduce. Wherever the virus was introduced into the pest’s environment, an early epizootic wiped out populations of larvae and beetles, drastically reducing pest incidence and crop loss [40]. The most affordable, efficient, and simple way to spread the viral inoculum among the beetle population in its natural habitat is to release the infected insects [41].

8. Pheromone traps have a great deal of effectiveness capturing the floating population. Keeping rhinolure/oryctalurte sachets at a height of 10 feet per trap per 2 hectares inside the oil palm plantation using bucket vane traps. However, low humidity and high temperatures negate the pheromone’s potential to attract bugs [42].

4.2.2 Cockchafer beetles (root grub): Apogonia/Adoretus spp. (Scarabaeidae)

Because grubs are visible throughout the year, preferably in the first two to few months after planting, the incidence of adults is seen during the start of monsoon season (Figure 9).

Figure 9.

Cockchafer beetles (root grub).

4.2.2.1 Nature and symptoms of harm

The oil palm is harmed by adults as well as grubs. Young seedlings that are 1–2 months old have their roots killed by grubs, which causes seedling mortality. Defoliation is caused by adults killing the leaves. It is a problem in Karnataka’s red soils and to a little extent in the entire state.

4.2.2.2 Management

The incidence of the grub stage is decreased by adding 20 g of phorate 10 g granules to each nursery bag, however the incidence of adults is effectively decreased by adding contact insecticides like quinalphos (0.05%).

4.3 Hemipteran pests

4.3.1 Spindle bug: Carvalhoia arecae Miller (Miridae)

It is primarily a significant pest of arecanut palms but also attained pest status on oil palms in Karnataka and Kerala states where arecanut is commercially grown. Spindle bug incidence and infestation were noticed very low in nursery seedlings and young plants. Throughout the year, infestation is observed, with June seeing the highest prevalence and, consequently, February seeing the lowest. When the palms got older, the percentage of infestation decreased, and 30 months after field planting, there was no sign of it [20]. The incidence is not reported aside from the above-mentioned states. The existence of low temperatures is also a critical factor for pest incidence (Figure 10).

Figure 10.

Spindle bug on oil palm.

4.3.1.1 Nature and symptoms of harm

As the nymphs and adults sip the sap from the fragile spear leaves, they are able to see the typical linear brown lesions. The spear leaves do not fully open when the infestation is bad. On the infected areas, necrotic patches form, which later turn brown and eventually dry up. Due to severe infestation, the leaves are torn apart by the necrotic patches, creating multiple holes in the leaves, which causes the palms to become stunted [23].

4.3.1.2 Management

Suppression of the bugs happens by an entomopathogenic fungus, Aspergillus candidus Link during the time of year, coinciding with the height period of its incidence [43]. An effective management technique is to apply phorate 10 g granules at 20 g each sachet inside the innermost two leaf axils [44]. With the appearance of new spindles, the phorate sachets are repeatedly relocated to the deepest leaf axils. The sachet lasts for roughly 8–10 months.

4.4 Homopteran pests

4.4.1 Leaf hopper, Proutista moesta Westwood (Derbidae)

On 10–14 month-old nursery plants in Kerala province, low leaf hopper incidence is seen in the months of September–October and once more in the months of January–February. Despite being harmless to seedlings, this has been shown to be a carrier of numerous viral and MLO diseases, most notably Spear rot (Figure 11) [45].

Figure 11.

Leaf hopper, Proutista moesta.

4.4.2 Aphids (Homoptera: Aphididae)

Schizaphis rotundiventris (Signoret) and Mysteropneura setariae (Thomas) infest the oil palm seedlings in state, particularly in area wherever the nurseries are encircled by sugarcane fields. Astegopteryx rhaphides (Van der Goot) has been found encrusting the oil palm leaves in very little Andamans. The spears twist and warp due to the feeding on nursery plants. Jet-black mildew is developed because of honeydew melon secretion.

4.4.2.1 Management

Spraying of dimethoate zero.04% or monocrotophos zero.05% or insect powder zero.05% on the underside of the leaves is suggested for the management of aphids [23].

4.5 Coccoids (scales and mealy bugs)

Palmicultor palmarum (Ehrhorn) and Nipaecoccus nipae (Maskell) were observed on Elaeis in Ecuador. Two species of mealybugs, Dysmicoccus brevipes Cockerell and Rhizoecus americanus Hambleton, are found to cause damage to oil palms in Colombian nurseries. Some species live on the roots of Elaeis, such as D. brevipes Cockerell in Ecuador (Figure 12) [46].

Figure 12.

Scales and Mealy bugs on oil palm.

In India, the spear leaves of oil palm seedlings in the nursery and field planted young oil palm seedlings are infested by Pseudococus citricutus Green, Palmicultor sp. and Margarodids, Icerya aegyptiaca (Douglas). D. brevipes infest the pre-anthesising male and female inflorescences and also unripe and ripe oil palm fruits [47, 48, 49]. Mealybugs on oil palm plants are migrants from other palmaeceae palms. Mealybugs are found in moist, warm climates. Mealy bugs are sporadic pests that are frequent in plantations, although they rarely cause outbreaks, which may be because of the work of natural enemies like coccinellid beetles whereas the primary indicators of endemic infestation are unsanitary circumstances and sanitation measures used in the gardens.

4.5.1 Nature and symptoms of damage

Coccids (soft scales) are noticed on the leaves of oil palms at all ages. Diaspids (armoured scales) are commonly found on the fruit bunches and leaves of oil palms. Sap from the tender spear leaves, inflorescence, and fruits is sucked by both nymphs and adult females. Attack by Diaspids results in the appearance of chlorotic spots on leaf tissues. These pests secrete a waxy cover, which hardens to form tough armour. The shape of the armour varies, being circular as in Aspidiotus, elongated/coma shaped/thread-like as in Pinnaspis. All the females live together and are protected by ants. Infestations of Pseudococus citricutus Green, Palrnicultor sp., Margarodids, and Icerya aegyptiaca (Douglas) have been found on the spear leaves of young oil palm seedlings that have been planted in the field and in nurseries. Both Pseudococus and Palmicultor species attack on spindle leaves of young plants resulting in the yellowing of unfolding leaves and stunted growth of the palm. Ring spots were not observed so far because continuous feeding causes a mottling appearance on leaves. Oil palm fruits of Fresh Fruit Bunches (FFB) are infested by Dysmicoccus spp. and they suck the mesocarp sap. These pests feed on plant sap and excrete honeydew which will attract ants and sooty mould development. The pest feeds only on ripe FFB and when the harvest is delayed, yield loss is more. It is also observed that the pest attack leads to the loosening of the fruits which leads to premature fruit drop.

4.5.2 Management

1. Since ants frequently carry mealy bugs, the pest can be easily eliminated by suppressing ants and maintaining hygienic conditions in the garden. Endemic infestation is caused by unhygienic surroundings and sanitation procedures. Regular weeding and leaf cutting are found to keep pests from attacking the plantation.

2. Ladybird beetles are the most important predators of mealy bugs.

3. Mealybug infestations can be treated by spraying phosphamidon, dimethoate, or methyldemeton at concentrations of 0.025 or 0.05%, respectively. Malathion 0.1% can be sprayed to suppress scale insects.

4.6 Isopteran pests

4.6.1 Termites (Termitidae)

Seedlings kept in polybags, spear leaves, male and female inflorescences, and a field of newly planted seedlings have all been found to have termite infestations. Red soils make up the bulk of the soil types in locations where oil palms are grown, and termite incidence is also more common there. The breakdown of oil palm leftovers such clipped leaves, empty and decaying fruit bunches, and male inflorescences is observed to be accelerated by these good decomposers (Figure 13).

Figure 13.

Mound of Pericapritermes on the palm roots, (b) Hypotermes mound beside oil palm tree, (c) Pericapritermes nest dug from the peat ground, (d) Nasutitermes sp. Nesting inside frond, (e) Nasutitermes sp. consuming the dead frond that laid on the ground and (f) Odontotermes devouring the decaying wood log.

Two termite species, Pericapritermes sp. and Hypotermes sp., destroy the roots of seedlings kept in polybags in Karnataka, resulting in the seedlings’ stunted growth. The infestation is most noticeable in oil palm fields with inadequate irrigation [20]. In the province’s plantations, where the majority of the palm trees were exhibiting indications of clay sheathing over the stem position, this was frequently observed as severe. Due to the industry’s rapid expansion, termite infestation in oil palm trees, particularly in peat soil, has become a serious issue in Malaysia. Odontotermes spp. are the most prevalent pest species in India’s oil palm growing regions overall [32, 50, 51].

4.6.1.1 Nature and symptoms of injury

The pest was identified to be feeding on the trunk in addition to the opposite dried material, such as leaf butts, male inflorescence, dried/bunch rot, bunch failure, and infected FFBs. The infestation was first seen over the winter, and by the end of March or beginning of April, it had reached its peak. Though they are found feeding only on the dried and useless things and causing no death blow to the palms, however, it makes the palms seem ugly and indicates the poor maintenance of the orchards. The earthen sheathings that are formed over the foraging areas are made from subsoil containing high amounts of potash and are beneficial in enhancing soil fertility [52, 53, 54]. By eating on the plant’s collar section, which has distinctive clay wrapping on the stem portion, termites have been discovered to kill young nursery seedlings. Plants that are yielding and poorly managed nurseries are more vulnerable to termite attack. Due to termite occurrence in entirely abandoned plantations, adult producing palms are also discovered dead. Termite activity in irrigated oil palm plantations does not reduce yields, but it gives the plantation an unsightly appearance. In addition, the termite mounds on the plantation may develop into reptile nests, alarming the worker force.

4.6.1.2 Management

1. The use of entomopathogenic fungi, such as Beauveria bassiana and Metarhizium anisopliae, has shown considerable promise for the control of a variety of insect pests [55].

2. Chlorpyriphos 0.05% is typically advised for drenching [23].

4.7 Molluscan pests

Laevicaulis alte, a black slug, is a sporadic pest that feeds on oil palm nursery plants that are one day old. The pest is observed feeding on nursery plants that are put within the main bags and are still in their embryonic stages. It is observed travelling from the neighbouring remnants and debris of harvested crops, such as bananas. After the crop is removed, several bugs are discovered hiding beneath the banana stumps that are dumped. It occurs frequently during the season. It can be seen travelling during this time along with the water. They enter the nursery when it is already dark and feed on the newly planted sprouts. The most common methods used to control this pest include blocking pest entry sites within the greenhouse, applying salt pellets to raised bunds on all sides of the greenhouse, keeping the lights on at night inside the greenhouse, etc. (Figure 14) [56].

Figure 14.

Black slug.

4.8 Vertebrate pests

4.8.1 Avian pests

Birds and rodents are the key pests of oil palm within the oil palm-growing countries of the planet. Both of them go after the mesocarp of Fresh Fruit Bunches (FFB) and cause direct losses in yield. Several species of birds cause extensive damage to oil palm fruits. Birds like crows, Corvus species; Mynah, Acridotheres tristis; Babbler, Turdoides affinis; Parrots, Psitticula krameri take advantage of the mesocarp of fruits causing an estimated fruit loss up to 2.8 t/ha/year. Of these, Indian mynah bird, Jungle crow, house crow, and parakeets cause significant fruit loss. The attack is observed throughout the year round and no seasonal variation in damage intensity is clear [57]. The great pied wagtail, coucal, pariah kite, white-headed babbler, and other birds occasionally eat oil palm fruits. Infestation is higher in ripe bunches (76%) compared to unripe bunches (5.6%). In comparison to Teneras (63%), Duras (84%) are more sensitive among the ripe bunches. However, Pisifera bunch damage is uncommon due to the low palm population and poor fruit setting brought on by sterility. In Madras, the districts of Trichy and Karur, where oil palm is grown in sparse areas, have significant incidences (>20–30%) of bird pests. When compared to crows, the incidence of myna was found to be higher (20–30%). Even when the bunches were covered with oil palm leaves, there was a high incidence of bird damage in the solitary oil palm gardens, with 100% damage. Since there is no alternative food source available to birds throughout the wet and summer seasons, they are more active in oil palm gardens during those times.

4.8.1.1 Nature and symptoms of injury

Birds deliberately cause harm by primarily eating mesocarp, leaving just fibres on the seeds. Birds may cause partial or total damage. Birds consume 40–50% of the weight of each fruit in fruit that is partially damaged. Weight loss of 68–73% may be seen in bunches with entire fruit destruction. All the fruits in many ripe fruit bunches are lost, resulting in a 100% loss in fruit weight. When fruit is first starting to ripen (130–150 days old), partial fruit damage is more prevalent, however complete fruit damage is found as fruit ripening progresses. Fruit loss in fully developed bunches of 160–180 days is incredibly high.

Bird damage to palm trees is worse in border areas (24.8%) compared to inside plantations (11.4%). Bird damage was estimated to cause an average loss of fruits per bunch of 2.3 kg in border palms and 1.3 kg in interior palms. A mean of 1.8 kg, or 4% of the mesocarp, was lost due to bird damage in each harvested bunch. In Malaysia, it is estimated that these bugs have caused a 30% loss. According to estimates, India loses two.8 tonnes of fresh fruit bundles (FFB) per hectare per year, equivalent to 420 kg of oil [58].

4.8.1.2 Management

1. A wire net with a 1.25 cm mesh (60 × 90 cm size), reed baskets, baskets made of plaited coconut leaves, or oil palm leaves should be used to cover ripe fruit bunches after 150 days of fruit set to prevent bird damage [47].

2. It is discovered to be efficient and affordable to cover the bunches with oil palm leaf tips and tie them with a piece of rope to keep them solid and impenetrable by the bird’s beak.

3. It has been discovered that the easiest way to control the threat is to tie nylon fishnets measuring 9 by 1 metre between two palms. The best type of net to use to capture all birds has 5 sq. cm-sized holes. Nylon. A median of 5 nets per ha could provide the greatest benefit and are discovered to be ideal to rid the plantation of bird infestation. Within a month of being put into use, green and violet-coloured fishnets are easier to use and trap more birds, lowering the % infestation to zero [58].

4. The use of glue traps and sticky glue has not been demonstrated to be useful in reducing the incidence [56].

5. Tying the dead eagles within the periphery of the orchard to scare the birds entering the garden may be a commonly seen practice that’s unique. However, it’s not effective.

4.8.2 Mammalian pests

Rat (Ratus rattus wroughtoni), House rat (Rattus rattus rufescens) Lesser bandicoot (Bandicota bengalensis), Larger bandicoot (Bandicota indica), Indian gerbil (Tatera indica cuvieri), Western Ghat squirrel (Funambulus tristriatus) and Procupines (Hystrix indica) attack oil palm at various stages of its development.

4.8.2.1 Nature and symptoms of injury

Burrowing rat, T. indica (Hardwicke) was found attacking the young oil palm plants by migrating from the adjacent maize fields further because the forest plants. They burrow all the way down to the bole region by making cavities to feed the cabbage tissue leading to the wilting of leaves and mortality of the palms. The immature fruit bunches that were between 2 and 3 months old were the principal food sources for the roof rat, R. rattus Linn. They were discovered drawn, taking use of the semi-solid apical mesocarp and kernel region of the fruit. Because the fruits were only partially chopped, the symptoms of an attack are visible. Rats consume both ripe and unripe bunches of fruit as well as the exposed pericarp of ripe and unripe fruits in mature palm trees [32]. Rodents use their incisors to attack the pericarp, creating distinctive gnawing imprints on fruits. Rats consume the grub and pupae of pollinating weevils while destroying the spikelets of the male inflorescences. Newly planted seedlings are dug up by a boar (Sus scrofa), who then eats them. If they are available, they also consume the fruits from the tree’s bunches.

4.8.2.2 Management

1. By erecting barriers made of 1.25 cm mesh (Chickenwire mesh) collars around the base of young plants, damage can be avoided. To stop the rats from going inside or beneath the bottom, they must be tied tightly around the palm and all the way down.

2. As part of an integrated strategy, traps such as iron live traps, death fall traps, bow traps, etc. are also utilised to lessen rodent damage to oil palms.

3. Zinc phosphide and bromadiolone baiting are proven to be efficient against the rat threat. Comparing the effectiveness of zinc phosphide baiting with newspaper without hand protection, it was shown to be 33% more feasible to use banana leaves as packages.

4. A local method of preventing pigs from entering nurseries and young oil palm crops has been created. The plantation border is delineated by two lines of 20 cm-high, parallel-to-the-bottom 18-gauge G.I. wire fencing that is supported by poles and held in place by guide hooks. Depending on the land’s topography, the poles are spaced anywhere between 3 and 10 m apart. With the aid of four poles, two crushing slabs, two oval plays, and a cracker, junction boxes can be constructed. Depending on the geographical limits, roads, etc., this might be spaced anywhere from 5 to 15 m apart. The aid of a crushing slab suspended from a third play kept on the primary two plays is used to join the two fence lines that arrive at the junction boxes from different sides onto the oval plays, pull them closer, and hold them in place. Under this crushing slab, crackers are maintained. When the animal strikes the fence, it will force the initial play to fall apart, causing the cracker to fall into the second crushing slab that is kept directly underneath and burst. The strategy has been found very effective in scaring away the animals [23, 59].

4.8.2.3 Wild boar, Sus scrofa

Wild boar is reported as a very important mammal causing heavy damage to the nursery in Andhra Pradesh, Karnataka, and Kerala states of India. The damage is seen mostly on the boll region of 18–24 months old seedlings. They are available in groups during the dusk period and go after the seedlings. The damage is found more because of their disturbance compared to their eating. Boar scaring devices like putting electric fencing and other smoking devices are found futile (Figure 15).

Figure 15.

Wild boar Sus scrofa in oil palm garden.

4.8.2.4 Black rat, Rattus rattus Wroughtoni.

Rat incidence on oil palm seedlings is recorded in all the nurseries. It is more serious in poorly managed nurseries. They’re found feeding on the kernel portion of the nuts causing mortality to the seedlings. Incidence is so severe when the spreading of primary seedlings is not done even after 6 months and where the soil is drained therefore the roots are exposed due to poor irrigation practices. In Mizoram, Boi (bamboo rat Cannomys badius) could be a common pest feeding on the roots of the newly planted oil palms (Figure 16).

Figure 16.

Black rat furrowing in oil palm garden.

5. Integrated pest management (IPM) practices

The following are the most significant IPM additives, listed in increasing order of complexity:

5.1 Cultural practices

To eliminate pests or stop them from causing financial harm is one way cultural pest management systems incorporate routine farm tasks. Here is a list of the numerous cultural traditions.

• Methods used to get nursery or main fields free of pest infestation include removing plant debris, pruning bunds, treating soil, and deep midsummer ploughing (which kills a number of pests).

• Vitamin deficiency in the soil is tested to determine which fertilisers should be used.

• Choosing clean, authorised seeds and treating them with fungicides or bio-insecticides prior to sowing to control seed-borne disease.

• Proper plant spacing, which increases plant health and reduces pest risk.

• It is important to encourage the use of biofertilizers, FYM, and effective fertilisers.

• Appropriate water management since excessive wetness in the soil over an extended period of time encourages the growth of pests, particularly those that spread diseases through the soil.

• Effective weed control as it is a well-known undisputed fact that almost all weeds not only compete with crops for micronutrients but also house a variety of pests.

• Placing area yellow pan sticky traps for aphids and white flies a few inches above the ground.

• Synchronised sowing- Here, a network strategy is required to sow the plant simultaneously over a very big area so that pests will not be able to acquire distinctively staged vegetation suitable for increasing their population. If there are too many pests, the procedure is frequently correctly carried out throughout the entire area.

• Vegetation that is enticingly growing along field edges. It goes without saying that a certain pest species favours some plants over others, and these plants are known to attract that insect. Pest populations rise as a result of the vegetation that is grown around the fields’ edges; these populations can be reduced either by employing pesticides or by promoting the growth of their natural enemies for herbal management.

• Intercropping or several crops whenever possible. Every pest species does not appear to be attracted to any particular vegetation, and since desirable vegetation serves as repellents to keep pest species away from it, the incidence of pests is reduced.

• Harvesting as close to the stage of the floor. This is because insect pests and diseases with favourable developmental stages remain on plant components, serving as the primary inoculum for the following crop season. Therefore, cutting down on pests in the following season by picking plants at the floor stage.

• To protect nursery plants from soil-borne diseases, nursery plants are sprayed with copper fungicide or biopesticide solutions before planting.

• Throw away crowded, dead, damaged, or diseased branches and destroy them when pruning fruit trees. Avoid piling them inside orchards because this could serve as a source of pest infestation.

• To shield plants from pest and disease attacks, apply Bordeaux paste or paint to big pruning wounds.

• •Bee hives and floral arrangements designed to attract pollinators promote increased pollination and the subsequent fruit set.

• The choice of high-yielding pest resistant/tolerant varieties.

5.2 Mechanical practices

It is feasible to remove and destroy hundreds of insect pests’ eggs, larvae, pupae, and adults as well as disease-related components of plant life from any location.

• Putting hundreds of parasitized eggs within bamboo cages with hen perchers installed inside the sphere to preserve natural enemies and, whenever feasible, keep pest species away.

• The use of light traps and the eradication of captured insects.

• Installing the necessary hen scarer inside the sphere and adding hen perches inside the sphere to allow birds to perch there while navigating bugs and their juvenile stages, such as eggs, larvae, and pupae.

• The use of pheromones to create new areas and stop mating and pheromone traps to monitor and control the population of pests by mass capturing using.

5.3 Regulatory practices

In this procedure, governmental regulations are put into effect that prevent seeds and plant materials that have been infected from entering the country or moving from one region to another. These are referred to as quarantine techniques and come in two flavours: domestic and international.

5.4 Biological practices

The most important aspect of IPM is biological control of diseases and insect pests through biological methods. Biocontrol, in a more general meaning, is the use of living things to control other living things (pests). In other words, the deliberate use of parasitoids, predators, and diseases to control pest populations at a level below those resulting in economic loss, either by introducing a new bioagent into the environment of pests or by increasing the effectiveness of those already present in the field.

5.4.1 Parasitoids

These are the organisms that deposit their eggs in or on their hosts’ bodies and then finish their life cycles there, killing their hosts in the process. A parasitoid can also come in a variety of forms depending on where it is in the host’s development or how far along it is in its life cycle. As examples, consider Apanteles, Bracon, Chelonus, Brachemeria, and different Trichogramma species, among others.

5.4.2 Predators

These are free-living organisms that feed on the other living things. Examples include several spider species, dragonfly and damsel species, ladybird beetles, Chrysopa species, and birds, among others.

5.4.3 Bio-pesticides

These are microorganisms that attack and infect their hosts, resulting in diseases that kill the hosts. Pathogens can be divided into three primary groups: bacteria, viruses, and fungi. Some nematodes can also transmit diseases to pest insects. Species of Hirsutella, Beauveria, Nomuria, and Metarhizium are important examples of fungi because they are known to infest and kill a lot of insects in fields (up to 90%). The nuclear polyhedrosis virus (NPV) and granulosis viruses are the two most significant instances of viruses. There have been numerous reports of an outbreak of viruses in armyworms, cutworms, leaf folders, hairy caterpillars, and plant hoppers. Bacillus thuringiensis (Bt) and B. papillae are two typical examples of bacteria.

Sometimes, with the use of liquid or powdered formulations that can be sprayed like conventional chemical pesticides, pest diseases can be mass-produced in laboratories at a cost. Bio-pesticides are the name given to these mixtures. The several types of biocontrol techniques are categorised as follows:

Introduction: A replacement species of bio-agent is dispersed into the area during this phase in order to establish itself against its host. This is frequently done only after careful laboratory analysis and field tests to determine its efficacy.

Augmentation: By releasing identical species bio-agents from the field or from a lab in sufficient numbers to suppress the pest population in the area, the population of natural enemies already present in the area is boosted throughout this process.

Conservation: This is frequently the most crucial element of biological management and is crucial in the control of pests. Natural adversaries that exist in nature are protected from being killed during this process. Below are the numerous precautions that must be taken to protect against natural adversaries.

• Collecting parasitized egg masses and putting them in bamboo cages with bird perches to let parasitoids develop and keep pest larvae at bay.

• Using field days, radio shows, and television to teach farmers how to tell the difference between pests and defenders in order to prevent spraying defenders.

• Following observation of the pest defender ratio, chemical spray should be used as a last option as well.

• It is best to avoid using broad-spectrum pesticides. Only selective and comparatively eco-friendly (REF) pesticides should be used, where appropriate. Pesticides should always be used in spot or strip treatments. Use insecticides according to the recommended dose and concentration.

• Changing planting and harvesting times to prevent the insect attack’s peak period.

• Planting trap crops on the edges of main fields before a specific crop is sown in order to trap pests and foster the growth of natural enemies.

• Intercropping and crop rotation both aid in the conservation of defenders.

5.5 Chemical practices

Chemical pesticides are only used as a last resort if all other efforts have failed to reduce the insect population below the point of economic loss. Due to the complexity of insect problems, pesticides would still be necessary for crop protection despite substantial advancements in pest control research. Therefore, to limit both the cost and issues they create, pesticide use should be need-based, judicious, and supported by pest surveillance. When employing chemicals to control an area, we must have a complete understanding of what to spray, when to spray, where to spray, and how to spray.

• The pest defender ratio must be kept in mind.

• If the pest is only present in strips or isolated patches, the entire field should not be sprayed; instead, choose relatively safer pesticides, such as neem-based and biopesticides.

Due of the distinct way that vegetables and fruits are consumed by people, IPM approaches are especially pertinent to these crops. For the recommended crops, only pesticides that have been certified by the CIB&RC should be used. After the primary pesticide’s waiting period is through, farmers should not use any additional pesticides, and the crops should be harvested. Applying pest management techniques to field crops must be done with the utmost care and caution.

6. Conclusion

The sustainability of oil palm cultivation is the need of the hour for both farmers as well as processors and finally the enrichment of the economy. To minimise losses, it is crucial to control the insect population below economic threshold levels. In order to achieve this, integrated management techniques that improve the sustainability of the oil palm industry as a whole must be established employing the most recent low-cost technologies.

Acknowledgments

My due acknowledgments are to the Management, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh-522302, India for their immense support and encouragement in promoting research.

Conflict of interest

“The authors declare no conflict of interest.”