Life stages of two-spotted mite
Jasmine is a genus of shrubs and vines in the olive family (Oleaceae). Jasminum sambac, Jasminum auriculatum, Jasminum grandiflorum and Jasminum nitidum are the four cultivable species of Jasminum. The two-spotted mite, Tetranychus urticae, is a key pest of Jasminum sp. To compare the lifecycle of the notorious mite in all the cultivable Jasminum species, a detailed laboratory study was conducted at the Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, India. The observations on lifecycle parameters of two-spotted mite, T. urticae, revealed that the life cycle consists of egg, larva, protochrysalis, protonymph, deutochrysalis, deutonymph, teleochrysalis and adult. The lifecycle and duration of each stage are found to be the shortest in J. nitidum and the longest in J. sambac.
- Jasminum sambac
- Jasminum auriculatum
- Jasminum grandiflorum
- Jasminum nitidum
- two-spotted mite
Flowers are inseparable from the social fabric of human life. Flowers, being adorable creation of god, befit all occasions. Jasmine is an important traditional flower, cultivated nearly throughout the tropical and subtropical parts of the world for its fragrant flowers .
This twinning climber has slender stems and forms a dense habit. The dark glossy green leaves are lanced-shaped and the fragrant white star-shaped flowers appear throughout summer in clusters. The angel wing jasmine is grown for its flowers and glossy foliage. It is planted in small or large gardens for its fragrance or to grow over lattice or a pergola. It is suitable for coastal subtropical regions and establishes in 1–2 years. It is also used in containers and grown under glass in cold climates. Once established, it has a high-water requirement, and responds to occasional deep watering particularly during dry periods  (Figure 4).
The production of jasmine is affected by various factors, among which, insect pests are the most devasting factor. The major pests affecting jasmine are jasmine bud worm (
In case of severe infestation, the whole plant becomes pale in colour, and affects production and size of the flower buds. Damage to the leaves inhibits photosynthesis, and severe infestations can result in premature leaf fall, shoot dieback, and decreased plant vigor. Although the individual lesions are very small, attack by hundreds or thousands of spider mites can cause thousands of lesions and thus can significantly reduce the photosynthetic capability of plants . Such buds fetch a low market price. Silk webbing on the undersides of leaves is a characteristic sign of spider mites. Under high population densities, the mites move to the tip of the leaf or top of the plant and congregate using strands of silk to form a ball-like mass, which will be blown by winds to new leaves or plants, in a process known as “ballooning’ (Figure 5).
As the infestation by the two-spotted mite,
Management of this pest has become a menace for the jasmine growers. The knowledge on life history of the pest as well as the life-table on different varieties is essential for developing IPM in better management of any pests. The knowledge of the sequence of developmental stages, their duration, and number of generations and method of overwintering is essential to know the ‘weakest link’ in the lifecycle. This would help to aim control measures effectively at the most vulnerable stage of the pest. The biology of jasmine two-spotted mite is attempted in the four cultivable jasmine species, that is,
2. Materials and methods
The life history of red spider mite was studied under laboratory conditions at the Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, India with the prevailing weather parameters. Pure culture of red spider mite,
About 20 mated females were released on a fresh leaf in the petridish and allowed overnight, in order to obtain the eggs. Next morning, the eggs were carefully lifted with the help of a moistened 00 size camel hairbrush and transferred to previously prepared leaf discs at the rate of one egg per leaf disc per Petri plate. Such 35 plants were maintained to study the biology. The development of various stages of the mite was observed twice a day with the help of stereoscopic binocular microscope. The observation on life history included incubation period (days), duration of larva, (days) protonymph, deutonymph, quiescent stages, preoviposition, oviposition and post oviposition periods, fecundity and longevity of adults, sex ratio and the viability of eggs. The midpoint between two observations was considered as the time of moulting whenever a change to next stage was observed. But, if moulting was just taking place at the time of observation, then it was taken as the time of moulting. When the mites reached the adult stage, the other sex of the mite that developed on the leaf disc was released on to the leaf disc to observe mating, pre-oviposition, oviposition and post-oviposition and also fecundity and longevity of the mite.
To study the biology in different
2.1 Fecundity rate
The female deutonymphs and male adults were collected from the respective cultures and released at one pair per Petri dish. They were allowed to oviposit, and observations on the number of eggs laid per day, egg period and total number of eggs laid throughout the oviposition period were recorded.
2.2 Duration of life stages
One pair of matured female and male mites was released per Petri dish. After a few hours of oviposition, the mites were removed using a camel hair brush retaining only five eggs in each petri dish. Hatching was observed, and the duration of different immature stages followed by adult longevity was recorded.
2.3 Percentage of larvae becoming adult
The female deutonymphs and adult males were collected from the respective cultures and released at three pairs per petri dish. Two days after oviposition, mites were removed leaving only the eggs. The numbers of larvae successfully reaching the adult stage were counted in each petri dish and the percentage was worked out.
3. Results and discussion
The biology of two-spotted mite,
|Life stages of two-spotted mite||Duration of different life stages of |
Mean ± SD (in days)
|Incubation period||2.2 ± 0.91||2.0 ± 0.81||1.5 ± 0.84||1.5 ± 0.84|
|Larval period||2.5 ± 0.52||2.2 ± 0.42||1.9 ± 0.31||1.7 ± 0.483|
|Duration of protochrysalis||2.2 ± 0.42||1.9 ± 0.32||1.6 ± 0.52||1.20 ± 0.42|
|Duration of protonymph||2.4 ± 0.52||1.7 ± 0.48||1.5 ± 0.53||1.1 ± 0.32|
|Duration of deutochrysalis||2.5 ± 0.53||2.0 ± 0.47||1.7 ± 0.48||1.4 ± 0.52|
|Duration of deutonymph||2.7 ± 0.48||2.3 ± 0.48||2.0 ± 0.67||1.0 ± 0.48|
|Duration of teleochrysalis||2.9 ± 0.32||2.2 ± 0.63||1.5 ± 0.71||1.1 ± 0.32|
|Adult longevity||21.7 ± 1.64||21.3 ± 1.64||21.1 ± 2.23||19.9 ± 1.37|
|Total developmental period (egg-adult)||24.9 ± 1.37||24.0 ± 1.83||23.9 ± 1.37||22.8 ± 1.55|
The freshly laid eggs were brown or translucent white in colour, which gradually turned to deep brown and then creamy pinkish as they approach hatching. The spherical-shaped eggs were laid singly. The incubation period ranged from 1 to 3 days. The average incubation period was 2.2, 2.0, 1.5 and 1.5 days in
The newly hatched larvae were almost spherical in shape and creamy white in colour. Two bright and prominent red spots (simple eyes) were present on the dorsal sides of the propodosomal region. The larva possessed only three pairs of legs. The larval period ranged from 2 to 3 days. The average larval period was 2.5, 2.2, 1.9 and 1.7 days in
The dark green matured larva entered into the quiescent stage by anchoring itself to the leaf surface. The stage was dark green. The average period of protochrysalis was 2.2, 1.9, 1.6 and 1.2 days in
The protochrysalis moulted into protonymph. The body was oval in shape with four pairs of legs and dark green in colour in the beginning, which later turned into amber colour. The average period of protonymph was 2.4, 1.7, 1.5 and 1.1 days in
The matured protonymph entered into quiescent, a stage which is known as deutochrysalis. The body also shrinked and decreased in size and attained a dark green colour. The average period of protochrysalis was 2.5, 2.0, 1.7 and 1.4 days in
The deutonymph emerged from deutochrysalis. The body was red coloured, larger and broader than protonymph. The average period of deutonymph was 2.7, 2.3, 2.0 and 1.0 days in
The deutonymph at its maturity enters into a quiescent stage known as teleochrysalis. In this stage, the body shrinks and decreases in size. The colour of this stage is light red to creamy. The average larval period of protochrysalis was 2.9, 2.2, 1.5 and 1.1 days in
The body of the adult male was narrow with a distinct abdomen, greenish in colour which later turned pinkish. The first pair of legs was longer than the rest of the pairs. Males were smaller than females and lived for 11–12 days. The newly emerged females looked dull red which later turned to deep brick red. The simple eyes were seen as two red spots on the sides of the dorsal propodosomal region. The adult female survived for 19–24 days. The pre-oviposition period varied from 2 to 3 days with an average of 2.7 days. The oviposition period lasted for 11–14 days with an average of 12.0 days. Each female laid about 123–160 eggs with an average of 146.6 eggs. The mean number of eggs laid was 10–12 eggs per day. The maximum number of eggs laid by a female was 11–12 eggs per day. The average adult longevity is 21.7, 21.3, 21.1 and 19.9 in
3.8 Total developmental period
The total developmental period (egg to adult) ranged from 24.9, 24.0, 23.9 and 22.8 days in
The biology of the two-spotted mite, comprising egg, larva, protochrysalis, protonymph, deutochrysalis, deutonymph, teleochrysalis and adult stages was completed in 24.9 days. The results are in agreement with Rajakumar et al. , who reported that the total developmental period of mites in jasmine was 22.80 days for ♂ and 31.08 days for ♀. The outcome of the study was also in conformity with Vinoth Kumar et al.  who also suggested that the developmental period ranges from 26 to 27 days in brinjal and Premalatha  who stated that the total developmental period of two-spotted mites lasted from 24.71 to 25.71 days. But the egg-to-adult developmental period was lesser
The observations on life cycle parameters of two-spotted mite,
The use of moderately resistant varieties as a part of the IPM strategy can enhance the biological and chemical tools of insect pest management. One of the techniques to decrease the pest damage is use of the cultivars or species which show higher resistance to insect pests such as