Commercial products based on
The diamondback moth,
In the first instar, the larvae enter into the leaf parenchyma and feed between the upper and lower surfaces of leaves creating mines. In the second instar, the larvae leave the mines, and from the second to the third instar, they feed on the leaves, destroying the leaf tissue except for the upper epidermis, leaving transparent “windows” in the leaves. Fourth-instar larvae feed on both sides of the leaves . This insect has a short life cycle, around 18 days, and its population may increase up to 60-fold from one generation to the next . Studies indicate that the moths can remain in continuous flight for several days while covering distances up to 1000 km per day, but how the moths survive at such low temperatures and high altitude is not known . In eastern Canada, annual populations of diamondback moths originate from adult migrants from the United States .
This has prompted increased efforts worldwide to develop IPM programs for
2. Tactics for integrated pest management
2.1. Biological control
Biological control can be defined as the use of one type of organism to reduce the population density of another. Biological control has been used for approximately two millennia, and has been widely used in pest management since the end of the nineteenth century . The following types of biological control can be distinguished: natural, conservative, inoculative (or classical), and augmentative. Natural biological control involves the reduction of pest organisms by their natural enemies and has been occurring since the evolution of the first terrestrial ecosystems, 500 million of years ago . It takes place in all of the world’s ecosystems without any human intervention, and, in economic terms, is the greatest contribution of biological control to agriculture . Conservation biological control consists of human actions that protect and stimulate the performance of naturally occurring enemies . In inoculative biological control, natural enemies are collected in an exploration area (usually the area of origin of the pest) and then released in new areas where the pest was accidentally introduced. In augmentative biological natural control, natural enemies are mass-reared in biofactories for release in large numbers to obtain immediate pest control .
2.1.1. Entomophagous agents: parasitoids and predators
Parasitoids can be defined as insects that are only parasitic in their immature stages, kill their host in the process of development, and have free-living adults that do not move their hosts to nests or hideouts .
All stages of the diamondback moth are attacked by numerous parasitoids and predators, with parasitoids being the more widely studied. Over 90 parasitoid species attack the diamondback moth . Egg parasitoids belonging to the polyphagous genera
Seven species of parasitoids were observed in a
In organically farmed kale in Pernambuco, Brazil, seven natural enemies of
Several studies have been conducted in Brazil to examine whether these entomophagous agents of the diamondback moth could be used as a biological control for this pest in crucifer crops.
Parasitoids of the genus
The impact on non-target species, particularly
Another parasitoid of
Another larval parasitoid studied in Brazil for
Among the stink bug predators,
2.1.2. Entomopathogens: Bacteria
The occurrence of
Recent studies on control strategies and population reduction of
This entomopathogen can be easily found in different environments [52,53], and it is characterized by a variety of strains, each forming one or more protein crystals (Cry) and cytolytic toxins  that have insecticidal activity and determined its efficiency as a control on certain agricultural pests. Another type of insecticidal protein that can be synthesized by some strains of
A long history of intensive research has established that their toxic effect is due primarily to their ability to form pores in the plasma membrane of the midgut epithelial cells of susceptible insects [56,57]. The presently available information still supports the notion that
Among the different protein crystals identified in insect control, 59 toxins were tested against 71 Lepidoptera species . The broadest range of toxins was tested against
However, the low variability in the number of toxins related to formulated biological products, combined with a high number of applications in the field, puts selection pressure on the population of
According to , mixed formulations of different bacteria or isolates of
To improve the biological control of
In pathogenicity tests, the strains behave in different ways, and few of them are able to cause total mortality in the insects analyzed. In research conducted by , approximately 19% of the strains tested caused total mortality to second-instar larvae of
In this case, in addition to pathogenicity and virulence tests, researchers should analyze the sublethal effects of these strains on the remaining individuals, an important parameter in the toxicological evaluation of
Many biological characteristics of
According to  and , the most pronounced biological changes observed between phytosanitary applications with strains and commercial products based on
The behavior of strains or commercial products based on
The Integrated Management of
2.1.3. Entomopathogens: Fungi
There is no fungus-based bioinsecticide registered for crucifer crops in Brazil; however, some entomopathogenic fungi have been studied to determine their potential as a biological control agent for
The most active crude protein extract, isolated from the CNZH strain of
In addition to the species already mentioned, the fungi
2.1.4. Entomopathogens: Nematodes
Research on the control of Lepidoptera with entomopathogenic nematodes has focused on the diamondback moth . Field studies on cabbage in Java (Indonesia) confirmed that
2.2. Chemical control
The chemical control method, recommended as one of the tools or tactics of Integrated Pest Management, is still the main strategy for reducing pest populations among crucifer producers. This preference is due to the practicality, speed, and efficiency of controlling insects considered agricultural pests, particularly
The chemical groups used to control this pest have great variability in terms of the active ingredient, formulation, and toxicological and environmental classes (Table 2).
Among the pesticides recommended for different brassicas, the chemical group of pyrethroids represents one of the most important for
This may be due to the biological characteristics of this species, the life cycle of which is short when compared to that of other insects, and to the cultural practice of constantly applying pesticides with the same active ingredients in more concentrated doses, without providing a chemical molecule rotation or an appropriate dosage as listed on the label of the phytosanitary product used .
In the context of Integrated Pest Management, cultural, physical, plant resistance, biological, and chemical control methods may be important strategies in the success of the
After a rational application of chemical controls, the first response observed in the field is the high larval mortality of
Among the types of insecticides recommended for the control of
Insecticides of plant origin are also a very important group for the population management of this pest. Among these, neem extract (
In this context, managing the population of
2.3. Plant resistance
The crop forms a template for various interactions between pests and their environment, and varietal resistance to pests is a key component for stabilizing an IPM system .
Plants have a bewildering array of responses to herbivory, broadly categorized as direct and indirect defenses and tolerance . Some primary wax components, including specific long-chain alkyl components, have allelochemical activity that influences the host acceptance behavior of
Among various cultivars of crucifers observed, the cabbage 'chato de quintal' showed a high level of the substance glucobrassicin, and was classified as moderately resistant to
Several studies have been conducted in Brazil to determine the crucifer cultivars resistant to
The use of silicon in the integrated management of diamondback moths may help to reduce the use of pesticides. Silicon damages the jaws of larvae, limiting ingestion and causing high mortality .
2.4. Cultural control
The current pest management tactics pursued by growers focus on the protection of crucifer seedlings, using both cultural and chemical means, in some seasons in the established crops . Because of the failure of insecticides to control the diamondback moth, interest is growing in the use of cultural controls in commercial crucifer production. Some of the classical control measures that have been tried with some success are intercropping, use of sprinkler irrigation, trap cropping, crop cover rotation, and clean cultivation .
The mortality of
A study investigating the impact of irrigation systems on diamondback moth infestation in cabbage noted that when irrigation water was applied by sprinkler-irrigation, diamondback moth infestations were reduced by 37.5–63.9% compared with a drip-irrigated control .
Glucosinolates are biologically active natural products characteristic of crucifers, and crucifer-specialist insect herbivores, such as
With regard to crop cover for crucifers, a broccoli cover-cropping system (cereal rye) resulted in fewer leaves, smaller plants, and a slightly reduced yield when compared to the other systems. Strip-cropping broccoli with potatoes did not convey any agronomic advantages. Gross margin analysis revealed that on a total system basis, a 2.2% yield improvement or a 7% price premium was required to make the cover crop system perform as well as conventional practice .
Another study looked at the effect of two diversification strategies, one a broccoli/potato (
2.5. Sex pheromones
The potential for using synthetic sex pheromone traps as a simple and practical method of monitoring population densities of insect pests has been investigated in many crop systems. Sex pheromones of
Currently, pheromone-baited traps in the Prairie Pest Monitoring Network are used to detect and survey  the arrival of migrating moths. Recent research has shown that capture of male moths in pheromone-baited traps in the Prairie Pest Monitoring Network is correlated with moderate, but not low, densities of the immature stages of the diamondback moth sampled in the same fields . Then exists the potential to develop commercially available pheromone-baited traps as tools that can predict the ephemeral nature of diamondback moth population densities in the prairies and inform producers of key thresholds and timing for control efforts .
When placed on Delta sticky traps, the artificial sex pheromone Bioplutella, marketed in Brazil, efficiently captured males of the diamondback moth and could be used for monitoring this pest .
3. Final remarks
As shown above, the management of pests on crucifers in Brazil has largely been dependent on synthetic pesticides, used prophylactically or in response to