Bio- Intensive Pest Management
H.S.Singh and G.Sangeetha
Central Horticultural Experiment Station (ICAR-IIHR)
PO Aiginia, Bhubaneswar- 751019, Odisha
singhhs21@rediffmail.com
Food production process in India during the green revolution period has been based on the use of more chemical fertilizers and pesticides. The challenge before the crop protection scientists is to boost the yield from the available land without harming the environment. Incorporating ecological and economic factors into decision making and addressing public concerns about environmental quality and food safety is the need of the hour. There is now wide array of techniques available to replace the use of conventional chemical insecticides in IPM programmes. These issues can be sorted out by adopting eco-friendly Bio-intensive Integrated Pest Management strategy.
Bio-intensive IPM is defined as a systems approach to pest management based on an understanding of pest ecology. It begins with steps to accurately diagnose the nature and source of pest problems, and then relies on a range of preventive tactics and biological controls to keep pest populations within acceptable limits. Reduced-risk pesticides are used if other tactics have not been adequately effective, as a last resort, and with care to minimize risks (Benbrook, 1996). An important difference between conventional and bio-intensive IPM is that the emphasis of the latter is on proactive measures to redesign the agricultural ecosystem to the disadvantage of insect pest and to the advantage of its parasite and predator complex but at the same time, bio-intensive IPM shares many of the same components as conventional IPM. BIPM options can be classified into proactive or reactive. In simple terms the proactive measure includes biodiversity, cultural control, host plant resistance and transgenic crops and reactive measures include mechanical control, biological control and use of reduced risk pesticides. The most recent bio-intensive integrated approaches for pest management utilizes components such as cultural methods viz., crop rotation, summer ploughing, fallowing, intercropping, pruning, mulching, spacing, planting date, trap cropping, etc and use of resistant cultivars; bio-agents viz., predators, parasitoids and bio-control agents, mycorrhizal fungi, botanicals including bio-fumigation, oil cakes, FYM, crop residues, green manuring and other organic amendments, physical methods viz., hot water treatment of planting material, soil solarization and bio-rational chemicals like pheromones.
Cultural practices for minimising pest incidence: With the awareness of environmental problems, exploitation of different cultural and mechanical practices has been advocated as a vital approach to curb pest populations. Altering the planting time, increasing the plant diversity, use of trap, barrier and inter crops, crop sanitation, fertilizer as well as water management and crop rotation etc., have been advocated. For example early sown crop rape seed and mustard suffers lower incidence of mustard aphid and planting marigold as trap crop for managing fruit borer in tomato (Srinivasan and Krishnamoorthy 1993). To make the environment uncongenial for pest and also to enhance the activity of natural enemies, the new cultural practices may be evolved. Pests of sucking nature can be managed to a greater extent with the adoption of resistant varieties. Further synchronization of susceptible stage of the crop with the inactive period of insect pest reduces the infestation and chemical intervention. For fruit fly management, growing of trap crop, setting pheromone traps, protein bait spray with permitted insecticide and good sanitation are required. Single line trellis system yields good result by the way of reduced borer incidence and downy mildew infestation in bitter gourd (Singh et al., 2007). Use of nylon net as a barrier for control of brinjal shoot and fruit borer along with shoot clipping could reduce the borer incidence.
Pheromones for monitoring and management of pests: Semio-chemicals that control the communication of insects both interspecific (allelochemicals) and intra-specific (pheromones) and can be used in pest management either alone for pest monitoring and decision-making, for mass trapping or mating disruption, or in combination with insecticides, sterilants, or insect pathogens. Additionally, semio-chemicals released by plants can repel insect pests from the crop (‘push’) and attract them into trap crops (‘pull’). The potential use of semio-chemicals for pest management on small-scale farms remains underexploited. Fruit fly in cucurbits and fruit crops are well managed by use of pheromones. In rice, maize, cotton and vegetables the pheromone technology has been in practice, however, still improvement is needed.
Use of Allelochemicals : There are numerous avenues for use of allelo-chemicals in IPM programs either directly against the insect pests or through enhancement of natural enemies . Volatiles from herbivorous insects and their host plants may serve as reliable cues for bio-control agents in search of suitable hosts. (Hilker and Mcneil, 2008). The aphid parasitoid Diaeretiella rapae, prefers host insects feeding on Brassicae and are attracted by Isothiocynataes that are typical for these plants (Baer et al., 2004)
Entomopathogens: Like other organisms, insects also suffer from diseases caused by bacteria, viruses, fungi, microsporidia, rickettsia and nematodes. So far over 3000 species of microorganisms have been reported to cause diseases in insects but many more remain undiscovered or unidentified. Microbial control agents have shown annual growth rate of more than 10 per cent during the last decade due to their safety, specificity and self-perpetuating action (Glare et al., 2012). For example the target pests of the entomopathogenic fungus Metarhizium anisopliae is Coleoptera, Lepidoptera, Hemiptera and Orthoptera.
Biological control in Bio-intensive IPM: Biological control is often most effective when coupled with other pest control tactics in an integrated pest management (IPM) program. Many practices are often compatible with biological control such as cultural controls, crop rotation, planting pest-resistant varieties, using insecticides with selective modes of action, or spot treatments. Although more than 100 families of insects contain predaceous species, about 12 of these contain the major biological control agents of crop pests. Among the parasitoids, the egg parasitoids, Trichogramma spp. has been utilized to some extent for control of tomato fruit borer. Similarly, spraying of Ha NPV at 250 larval equivalents/ha, has been found to be effective in controlling fruit borer. Chrysoperla zastrowi arabica is an effective predator for control of white fly, aphids, jassids and eggs for some lepidopterous borers. Similarly the larval parasitoids of diamond back moth, Cotesia plutellae and Diadegma semiclausum can be incorporated into biological pest management because of their potential in suppressing the pests larvae and will helpful in areas where diamond back moth is a serious problems because of insecticide resistance.
Use of Botanicals: Botanical pesticides in general possess low mammalian toxicity thus constitute least or no health hazards and environmental pollution. A number of compounds found in neem seeds, notably azadirachtin, have proven useful as insecticides. Neem is most effective against actively growing immature insects. Use of neem and pongamia cakes in the pest management in brinjal, cucurbits and okra are the new strategies devised. NSKE sprays are recommended on a variety of crops such as crucifers, tomato and cucurbits against all pests, on tomato and cucurbits against serpentine leaf miner, and on beans against stem fly. The use of neem seed cakes is well known for controlling nematodes. These also reduce soil-borne insects like termites, grubs, etc. The use of cakes for the management of many insect pests of brinjal, okra, cucurbits, etc. has been demonstrated recently at IIHR, Bangalore. Sprays of neem and pongamia soaps were found to be highly effective in controlling insecticide resistant DBM in cabbage. The studies conducted at IIHR have shown that soaps were also effective in reducing Helicoverpa armigera in tomato and to a limited extent shoot and fruit borer in brinjal (Krishnamoorty and Kumar, 2004).
Insect growth regulator (IGR) : New approach to insect pest control is the use of substances that adversely affect insect growth and development. These substances are classified as insect hormone mimics or insect growth regulators (IGRs) owing to their effects on certain physiological regulatory processes essential for normal development of insects or their progeny. IGRs may belong to this type of (selective) insecticides and can be grouped according to their mode of action, as chitin synthesis inhibitors (i.e. of cuticle formation) and substances that interfere with the action of insect hormones (i.e. JHs, ecdysteroids) are newest of all approaches to operational and commercial insect control. For example diflubenzuron and its derivatives were effective against insect pests and mites infesting field crops, and were relatively harmless to beneficial insect species. On the other hand, buprofezin, a chitin synthesis inhibitor, was used against homopteran pests including nymphs of brown plant hoppers, Nilaparvata lugens (Stal.), leafhoppers, Nephotettix cincticeps (Uhler), whiteflies, Bemisia tabaci (Gennadius), and scale insects attacking fruit crops and certain species of Coleoptera and Acarina.
Plant-incorporated protectants (PIPs)- GM crops : PIPs/ Genetically Modified Plants have foreign genes causing the plants to produce a pesticide inside its own tissues. Genetic manipulation of seed varieties for pest resistance is an important constituent of plant protection strategy. Examples are virus resistant varieties producing the virus coat protein, which covers virus particles after infection preventing their replication. Genetically modified varieties of some crops, such as cotton and rapeseed-mustard, have been developed but these are surrounded by controversies regarding their long-term effect on the environment and human beings. All of the genetically engineered insect-resistant crop varieties produced so far use specific genes taken from Bacillus thuringiensis, a common soil bacterium, to produce proteins that are toxic to certain groups of insects that feed on them. Regarding insect pest control so far only Bt corn and Bt cotton varieties are being grown. Work in this sector is in progress and it is expected that some directives for field use of such crops in horticulture will come sooner or later.
Similarly the breeding and production of crop plants with heritable arthropod resistant traits has been recognized for more than 100 years even though it is not available for all pests. Host plant resistance (HPR) Inhibit pest attack through toxic or repellent compounds or through physical factors such as color or toughness. Moreover it has the advantage of cumulative effect, specificity, eco-friendly, ease of adoption, compatibility with BIPM components and eliminates or reduces use of pesticides. The benefits of implementing BIPM can include reduced chemical input costs, reduced environmental impacts, and more effective and sustainable pest management and such reductions will benefit the grower and in turn the society. Hence, bio-intensive IPM is considered the desirable path for achieving sustainability in agriculture. The challenge before applied entomologists is to develop, validate and disseminate the site-specific bio-intensive IPM technologies to the farmers.
Conclusion
The concept of bio-intensive pest maangement proposes effective balance of pests and beneficial organisms in an ecological context. Needless to say that the natural balance is disturbed in the crop ecology due to regular cultivation practices. However the crops are meant to yield economic levels of quality produce. Hence there is a need to strike a balance appropriation of various interventions for suppression of insect pests, which can be achieved through various methods as described in previous text. However, detailed scientific scrutiny or models on this aspect are yet to be proposed in Indian context. Bio-intensive IPM requires a shift in research focus and approach with a knowledge base far more different than conventional IPM. Additionally, this concept envisages habitat modification for beneficial organisms, development of healthy and biologically active soils, maintaining uncultivated lands for diversity of flora and fauna, developing entomophage parks for food and shelter to diverse beneficial insects, weed strips, hedge rows, wind breaks, inter crops and conservation of insect bio diversity. Mass emergence devices for in situ and laboratory reared natural enemies, reduced direct mortality or interference to natural enemies, botanicals and laboratory reared /mass cultured bio-agents may have added advantage in BIPM. This may be most useful in situations where the potentially effective natural enemies have become ineffective due to biotic or abiotic factors and the pests cannot be satisfactorily (economically and/or environmentally) controlled by other methods. This bio-intensive approach needs building the knowledge and information infrastructure by making changes in research and education priorities in order to emphasize ecology-based pest management and redesign management programs to promote bio-intensive IPM.
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