What are Biopesticides?
What are Biopesticides?
Biopesticides are certain natural plant products that belong to the so called secondary metabolites that include thousands of alkaloids, terpenoids, phenolics and minor secondary chemicals.
Biopesticides have usually no known function in photosynthesis, growth or other basic aspects of plant physiology; however, their biological activity against insect pests, nematodes, fungi and other organisms is well documented. Every plant species has developed an inbuilt unique chemical complex structure that protects it from pests. The plant kingdom offers us a diverse array of complex chemical structures and almost every imaginable biological activity. These biodegradable, economical and renewable alternatives are used especially under organic farming systems.
Biopesticides for insect-pest and disease management: Neem (Azadirachta indica) has emerged as the single most important source of insecticides made form isolates form different parts of the neem tree. These compounds and neem extracts exhibits almost every type of biological activity conceivable against a wide range of insects. More than 300 species of insects are reportedly affect the behaviour and physiology of insects rather than killing them. Among the botanical pesticides investigated, neem has justifiably received the maximum attention during the last three decades. All parts of the neem tree possess insecticidal property but seed kernel is the most active. Neem bark, leaf, fruit and oil as well as extracts with various solvents especially ethanol have been found to exhibit activity against insect-pests. Neem product appears to be quite promising against such Nefarous pests Spodoptera litura, Helicoverpa armigera, S. gredaria and others. Most of the stored grain pests have also been found to be responsive to neem products.
Crop losses due to insect pests and diseases are estimated to be Rs. 6000 crores annually in terms of agricultural crop produce. Though the crop productivity increases significantly due to use of mostly chemical pesticides, their continuous use contributed to increasing environmental threat to natural resources, wildlife, non-target beneficial species, the development of pest resistance/resurgence etc. Mounting concern for environment has, therefore, led to evolve an alternate coherent pest management programme which is eco-friendly, self sustaining and yet provide effective management of pests and diseases. In this context the use of biopesticides or pesticides of microbial origin are becoming increasingly important. These biological products are
- eco-friendly,
- possess higher degree of host specificity,
- genetically stable and do not pose the risk of resistance development,
- compatible with biofertilizers and many agrochemicals,
and can be exploited under the ambit of Integrates Pest Management (IPM). At present, more than 21,500 naturally occurring microbes of their metabolites are known to possess pesticidal properties. The work agrochemical market is currently estimated to be $ 26,800 million, whereas biopesticide sales are around $ 120 million. Biopesticides sales, however, are estimated to increase at 10-25% per annum in contrast to static or shrinking world agrochemical market.
Perhaps it is high time to view agriculture without chemicals/synthetic pesticides. It can only be possible by discovering/formulating highly active biopesticides and popularizing them among farmers for their use. Undoubtedly, biopesticides will be the focus of main attention for plant protection practices to save agro-environment and humanity in 21st century. Due to higher potential of microbes in sustainable agriculture, they are currently being developed at large scale in the laboratory and pilot production units for commercial use in field.
Viral biopesticides: Viral biopesticides of baculovirus group namely Nuclear Polyhedrosis Viruses (NPVs) and Granulosis Viruses (GVs) offer great scope as crop protection agents on high value crops such as cotton and vegetables against lepidopteran pests like Helicoverpa armigera Hbn. and Spodoptera litura Fabr. More than 500 baculovisurses (BVs) have been reported so far. Some of the insect pests from which occlusion viruses have been reported in India have great potential in IPM.
Nuclear Polyhedrosis Virus (NPV): Nuclear polyhedrosis viruses kill the insets when they are ingested. The viruses rapidly multiply and spread into cell nuclei. Diseased larvae move frequently to the periphery of the plant and die showing symptoms by hanging from the plant upside down in the form of ‘V’ called Wipfelkrankit (top diseases) by German workers. The mass multiplication technique of virus has been well demonstrated using 4th instars larvae of Helicoverpa and Spodoptera. Fully infected larvae shield on an average 2x10 poly occlusion bodies (POB) per larva. Two well timed application of NPV @ 1.5 x10 POB (250 LE ha) in the evening hours (to avoid ultraviolet inactivation) coinciding with early stages of the larvae successfully control the pests on chickpea, pigeon pea and sunflower. Similarly, this could be managed on several crop hosts by applying NPV @ 250 500 LE ha depending upon crop canopy.
In India, NPVs of H. armigera and S. litura have been formulated as basic formulations (talc based) like dust, wet table powder (WP) and ultra-low volume (ULV) product and have been found effective against these pests on several crops. ULV application of virus in 10% whole egg homogentate @ 250 LE ha have proved effective against Helicoverpa on pigeon pea Jayaraj et al. (1992). Eclar is the first commercial viral insecticide based on NPV developed in 1961. Recently some commercial liquid formulations like H-NPV, Helivax; Biovirus, Heloionil and S-NPV have appeared in the market for bio-control of notorious pests like Helicoverpa and Spodoptera.
Granulosis Virus (GV): Next important to NPVs is granulosis viruses. The GV of sugarcane internode borer has been extensively studied in India. A spray of 109 occlusion bodies (OBs) ml-1 or combination of 105 OB ml-1 + 0.05% Endosulfan effectively controls the pests. It is reported to be safe to natural enemies occurring in sugarcane ecosystem.
Bacterial biopesticides: Many spore former and non-spore forming bacteria are known to be effective against a wide spectrum of insects and pests. The crystalliferous Bacillus thuringiensis (Bt) has been found to be effective against several species of lepidopteran pests. Its insecticidal activity is primarily caused by parasporal crystal (delta endotoxin) produced during sporulation. The discovery of isolate capable of acting against coleopterans (B. thuringiensis tenebrionis and B. sphaericus against mosquito and B. moritai against dipteran insects has further extended the scope of bacterial insecticides (Tanweer et al. 1998). Bt (300g ha-1) has further been used in the management of several pests notably diamond black moth Plutella xylostella on cruciferous vegetables (Jayaraj et al 1992). Certain adjuvant, like whole egg homogenate 1% and whole milk (0.5%) and Catherebthus roseus. Bt @ 0.5-1.0 kg formulation ha-1 has been found quite effective against important pests like S. Litura, E. vitella, H. armigera and P. xylostella. The work on B. Popillae is limited. It causes disease in white grubs. It is reported from several parts of the country and dispersed by birds feeding on grubs and also through irrigation water. If established, it maintains itself in the area for many years.
Several bacteria, like, Pseudomonas fluorescens, Bacillus subtilis, Streptomyces nigrifaciens, Agrobacterium radiobacter and Azotobacter sp are known to be potential bio-agents against several plant pathogen. Most of these bio-control bacteria are, however, in the stage of empirical application, either in the green house or in the field with a few exceptions. There are reports of bacterial bio-agents in enhancing the growth and greater root volumes of crop plants when applied as seed treatment or soil application. This envisages that the responses may be as biofertilizer or by the control of some undiagnosed plant pathogens. Recently, Pseudomonas sp. Are being promoted as plant growth promoting rhizobacteria (PGPR). The mechanism of pathogen suppression by these bacteria includes substrate competition, niche exclusion, and production of siderophores, antibiosis and induced resistance (Rai, 2003).
Fungal biopesticides: Fungi unlike bacteria or virus do not require ingestion for infection; so sucking pests are also targeted by primary contact or by secondary uptake from sprayed vegetation. The pathogenesis begins with germination of conidia on the cuticle and penetration and development inside the host leading to death of host essentially under high humid condition.
Of the several fungi infecting insects, the green muscardine fungus, Metarhizium anisopliae has shown promise against several insect pests. M. anisopliae major @ 5 x 10/mu23 effectively controls rhinoceros beetle in manure pits. Whereas, M. anisopliae anisopliae has been found very effective against BPH, WBH and leaf folder in rice. Fusarium oxysporum @ 6.25 x 106 spores ml-1 caused 100% WP (Pandora delphacis based) applied at 30 and 50 DAT effectively checks BPH population (87.8% mortality). The white muscardine fungus, Beauvaria bassiana has also great potential in the control of rice pests like, BPH, WBPH and rice ear head bug as well as sweet potato weevil Cylas formicarlus (Jayaraj et al. 1992, Moore and Prior 1993). A few mycoinsecticides have recently come in market to thwart the pest problem. Biological control of plant diseases is mainly limited to soil borne diseases. However, studies on seed borne and air borne diseases are underway in India. The successful use of bio-control fungi Trichoderma Viride, T. harzianum. T. virens and Trichoderma sp. are well documented against soil borne diseases of various crops like, rice, groundnut pea, grams, ginger horticultural crops and vegetables in India and abroad. Recently some other fungi like, Aspergillus niger, A terreus, A. nidulans and vesicular- arbusular mycorrhizae (VAM) have also shown promise against soil borne diseases. Broad spectrum activity of A. niger AN-27 against Pythium, Fusarium, Mocrophomina, Rhizoctonia and Sclerotinia is also suggesting their use as potential bio-control agents (Rai, 2003).
Why Biopesticides?
- Human and environmental safety
- Alternatives to conventional pesticides
25 million cases of acute occupational pesticide poisoning in developing countries each year (WHO, 1990)
14% of all known occupational injuries and 10% of all fatal injuries are caused by pesticides (ILO, 1996)
Obsolete pesticides stored in developing counties 20,000 tones in Africa alone
- Amenable to small-scale, local production in developing countries
- Address increased public awareness of environmental and food safety
- Fundamental component of Integrated Pest Management
Natural enemies protected
Controls pests resistant to conventional pesticides
Products available in small, niche markets that are typically in-addressed by large agrochemical companies
Biopesticides are pest management tolls that are based on beneficial microorganisms (bacteria, viruses, fungi and protozoa), beneficial nematodes or other safe, biologically based active ingredients. Benefits of biopesticides include effective control of insects, plant diseases and weeds, as well as human and environmental safety. Biopesticides also play an important role in providing pest management tools in areas where pesticide resistance, niche markets, and environmental concerns limit the use of chemical pesticide products.
| Type of control | Examples |
| Insect Control | |
| Bacteria | Bacillus thuringiensis, B. sphaericus, Paenibacillus popilliae, Serratia entomophila |
| Viruses | Nuclear polyhedrosis viruses, granulosis viruses, non-occluded baculoviruses |
| Fungi | Beauveria spp., Metarhizium, Entomphaga, Zoopthora, Paecilomyces fumosoroseus, Normurae, Lecanicillium lecanii |
| Protozoa | Nosema, Thelohania, Vairimorpha |
| Entomopathogenic nematodes | Steinernema spp. Heterorhabditis spp |
| Other (not strictly biopesticides) | Pheromones, parasitoids, predators, microbial by-products |
| Weed control | |
| Fungi Bacteria |
Colletotrichum gloeosporioides, Chondrostereum purpureum , Cylindrobasidium laeve Xanthomona campestris pv. poannua |
| Plant Diseases Control | |
| Fungi | Ampelomyces quisqualis, Candida spp. Clonostachys rosea f. sp. catenulate, Coniothyrium minitans, Pseudozyma flocculosa, Trichoderma spp. |
| Competitive inoculants Composts, soil inoculants | Bacillus pumilus, B. subtilis, Pseudomonas pp, Streptomyces griseoviridis Bacillus pumilus, B. subtilis, Pseudomonas pp, Streptomyces griseoviridis Burkholderia cepacia |
| Nematicides etc. | |
| Nematode trapping fungi Bacteria Mollusc parasitic nematode | Myrothecium verrucaria, Paecilomyces lilacinus Bacillus firmus, Pasteuria penetrans Phasmarhabditis hermaphrodita |
Popular biopesticides
| Product | Microorganism | Target pest/disease | Manufacturer |
| Dipel | Bacillus thuringensis | Caterpillar, larvae | Abott Labs. |
| Acrobe | B. thuringensis isrealensis | Mosquito, Black files, fungus gnats | American Cynamid |
| Novodor | B. thuringenis tenebrionis | Colorado potato beetle | Nova Nordies |
| Certain | B. thuringensis aizawai | Wax moth, Diamond black moth | Novartis |
| Spic biomass | B. Spharicus | Dipteran insects | Tuticorin Alkali Chemicals and Fertilizers |
| Doom | B. popillae | Coleopteran insects | New chemicals Mumbai |
| Labillus | B. moritai | Dipeteran insects | |
| Disease Management | |||
| Pseudomonas flurescens | Rhizoctonia solani, Scleritium rolfsii, Fusarium oxysporum, Legaeumannoyces graminis var. tritici | ||
| Streptomyees nigrifaciens | Tilletia caries, T. facticida, Drechslevsteres, Microdochium nivale | ||
| Agrobacterium radiobacter | Agrobacterium tumefacience | ||
| Bacillus subtilis | Fusarium udum, Fruit Rot of avocado, Xanthomonas malvacearum, Rhizoctonia solani | ||
| Azotobacter sp. | Alternaria, Venturia, Ustilago tritici, Helminthosporium tritici, Erysiphe, Xanthomonas phaseoli, Phytopthora infestans, streptomyces scabies, Sclerotinia, Rhizotonia, Pythium and Fusarium moniliforme | ||
Source: Rai, A.B. 2003
| Product | Microorganism | Target pest/disease | Manufacture/country |
| Insect-pest management | |||
| Vertalee/Bioline | Verticillium lacanii | Aphids, scale insects, mite, thrips | UK, India |
| Entomopthors | Aphids, mites | USA | |
| Numurea releyi | Lepidopteran larvae | USA | |
| Mycar | Hirsutella thompsonii | Citrus rust mite | USA |
| Bovarin/Blorin | Beauveria bassiana | Colorado potato beetle, Codling moth, Coffee berry borer | Russia |
| Asohersonia aleyrodis | Citrus scale insect | ||
| Metaquine | Metarhizium anisopilae | Spittle bug | Brazil |
| Bicon | Paeciliomyces lilacinus | Nematodes | Philippines |
| Metarhizium flavovride | Locust, grasshopper | USA | |
| Mycoinsectide 70 WP, 10D | Pandora delohacis | BPH | India (TNAU) |
| Disease management | |||
| BINAB-T | Trichoderma sp. | Chondrostereaum purpureum | Bio-Innovation, Sweden |
| F-stop | T. harxianum | Pythium sp. | Eastman Kodak co., USA |
| Trichodermin | Trichoderma sp. | Botrytis, Pythjium, Sclerotinia, Verticillium sp. | Bulgarian and Russian Govt. |
| Trichodox | T. harzianum 9T-39) | Botrytis cinerea | Markhteshim, Isreal |
| Tricho dowels | T. harzianum | Rhizoctonia solani,Pythium sp. | Grimm Technologies Ltd. |
| Antagon TV | T. viride | R. Solani, Macrophomina phaseolina | Green Tech, Agro products, Coimbatore |
| Sun-Derma | Tt. viride | -do- | Cun Agro-chemicals, Chennai |
| Ecofit | Trichoderma sp. | -do- | Agro Evo., Mumbai |
| Gliogard | T. virens | Pythium ultimum | WR Grace and Co., USA |
| Soilgard 12 G | T. virens | Pythium sp. | Termo Trilogy Corp., USA |
| Amphelomyces quisqulais | Saphaerotjeca fuliginea | Ecogen, Israel | |
| Pichia quiliermondii | Penicillium sp. | Ecogen Israel | |
| Kalisena | Aspergillus niger AN-27 | Pythium, Fusarium, Macrophomina, Rhizoctonia, Sclerotinia sp. | Cadila Pharma ceuticals Lt., India |