2. BIOPESTICIDE

 

Pest problem is one of the major constraints for achieving higher production in agriculture crops. India loses about 30% of its crops due to pests and diseases each year. The damage due to these is estimated to be Rs.60,000 crores annually. The use of pesticides in crop protection has certainly contributed for minimising yield losses. However, quite often the indiscriminate and unscientific use of pesticides lead to many problems, such as pests developing resistance, resurgence of once minor pest into a major problem besides environmental and food safety hazards. Moreover, excessive use of pesticides has adverse effects on the non-target organisms such as pollinators, parasitoids, predators and wild animals. This has adversely affected the ecological balance resulting in pest resurgence, development of resistance in the pest species and environmental pollution. Development of pest resurgence and resistance has resulted in high cost of production and low income especially to cotton farmers in AP, Maharashtra.

In view of the aforesaid problems with the unscientific use of pesticides in agriculture, there is an urgent need for minimising the use of chemical pesticides in the management of insect pests. Growing public concern over potential health hazards of synthetic pesticides and also steep increase in cost of cultivation/low profit making by farmers has led to the exploration of eco-friendly pest management tactics such as Integrated Pest Management (IPM). IPM aims at suppressing the pest species by combining more than one method of pest control in a harmonious way with least emphasis on the use of insecticides. In simple terms "IPM is the right combination of cultural, biological and chemical measures which provides the most effective, environmentally sound and socially acceptable methods of managing diseases, pests and weeds". The success of IPM largely depends upon conservation of naturally occuring bio control agents.

 

 


Why should we go for Biopesticides

 

In nature every ecosystem exists in a balance. Growth and multiplication of each organism depends on the food chain, its predetors, parasites etc. In biological control system, these interrelations are exploited. Among the alternatives, biological control of pests is one of the important means for checking pest problems in almost all agro-ecological situations. Bio pesticides are living organisms, which can intervene the life cycle of insect pests in such a way that the crop damage is minimized. The agents employed as biopesticides, include parasites, predetors and disease causing fungi, bacteria and viruses, which are the natural enemies of pests. Further, they complement and supplement other methods of pest control. Utilisation of naturally occurring parasites, predators and pathogens for pest control is a classical biological control. On the other hand, these bio agents can be conserved, preserved and multiplied under Laboratory condition for field release. Once these bio-agents are introduced in the field to build their population considerably, they are capable of bringing down the targeted pest' population below economic threshold level (ETL). However, the crux lies in their mass production and application at the appropriate time. As they are based on natural principles, they do not leave any residue, act target specifically, does not interfere the activities of natural enemies of pests and thus are regarded as safe and economical.

 

 


Commercial prospects

 

Last decade has witnessed a tremendous breakthrough in this aspect, especially on standardization of production techniques of Trichoderma, Gliocladium, Paecilomyces, Pseudomonas, Trichogramma, NPV and Bacillus to use them against many insect pests and diseases. The popularity of biopesticides has increased in recent years, as extensive and systematic research has greatly enhanced their effectiveness. Also, techniques for the mass production, storage, transport and application of biopesticides have been improved in recent years.
Though there are about 140 biopesticide production units existing in the country, as on today they are able to meet the demand of only less than 1% of cropped area. There exists a wide gap, which can only be bridged by setting up of more and more units for production of biopesticides. This requires large-scale investment and private participation.

Some of the local small-scale industries have already started production and marketing of Trichoderma viride (against few fungal diseases) and Trichogramma (against sugarcane early shoot borer). There is a scope to enhance production and use of biological control agents in the days to come as the demand is on the increase every year.

 

 


Description of A few commercially used Biopesticides

 


TRICHOGRAMMA EGG PARASITE

 

Trichogramma spp. belongs to the category of egg parasitoid of biological agents. Trichogramma spp., the most widely used bio-control agent in the world and is effective against bollworms of cotton, stem borers of sugarcane, fruit borers of fruits and vegetables. It attacks the pest at the egg stage itself and hence damage done by larvae is avoided. It offers a lower cost but more effective plant protection option in comparison to insecticides. Two species i.e., T. chilonis and T. japonicum are predominantly used in India.

Trichogramma are dark coloured tiny wasps and the female wasp lays 20-40 eggs into the host's eggs. The entire cycle is completed within 8-12 days. The tiny adult wasps search for the host (pest) eggs in the field and lay their eggs into the eggs of the pests. The parasitised host's eggs turn uniformly black in 3-4 days. A single Trichogramma, while multiplying itself, can thus destroy over 100 eggs of the pest.

 

 


CHRYSOPID PREDETORS

 

Chrysopid predators are important for the management of bollworms and aphids in cotton and tobacco and several sucking pests in fruit crops. They are capable of bringing down the population of the pest drastically. Chrysoperla (Chrysoperla carnea) is a potential chrysopid, which is also amenable to mass multiplication.

Chrysoperla are generally green in colour, varying in length from 1.0-1.3 cm. The pre-oviposition period lasts 3 to 7 days. The green lacewing is being mass released in the field for the control of aphids, white flies, mealy bugs and eggs and young larvae of lepidepteron pests. The Chrysoperla predetors may be used on cotton, groundnut, pulses, vegetables, ornamentals and several other crops. They also feed on the eggs and freshly hatched larvae of Helicoverpa armigera and such other caterpillar pests.

 

 


AUSTRALIAN LADYBIRD BEETLE (Cryptolaemus montrouzieri)

 

Mealybugs are serious pests on fruits, vegetables, ornamentals and plantation crops. Besides causing direct loss to the plants they also reduce market value of infested fruits. The extent of damage may go upto 70 percent in severe infestation. Ladybird beetle, Cryptolaemus montrouzieri introduced from Australia is a potential bio control agent and is being utilized on many crops in Southern India.

Mealybugs or scale insects constitute the natural food of certain ladybird beetles. The adult beetles as well as their larvae (grubs) seek the pests and feed voraciously on all stages. They often wipe out the entire pest colonies. The ladybird beetles are being used for suppression of mealy bugs in citrus, coffee, grapes, guava, ornamental and a variety of other crops.

 


Ha NPV and SI NPV

 

Baculovirus group has a very narrow host range and generally infests the larvae of crop pests. The research aimed at insect pest control is, therefore, confined to nuclear polyhedrosis viruses (NPVs) and granular viruses (GVs).
NPV is a nucleic acid (double standard, circular DNA) enclosed in protein matrix, hence it is called polyhedral occlusion body (POB). NPV infects the nucleus of the cell and multiplies within the nucleus.

In India, extensive research has been conducted on the use of NPVs for tackling two major pests namely Nuclear Polyhedrosis viruses like Ha NPV, SINPV are increasingly being used as alternatives to chemicals. These viruses have distinct advantages over other methods of pest control. NPVs are virulent pathogens of insect characterised by the polyhedral occlusion bodies (POB). These viruses are highly specific and do not affect beneficial insects like parasitoids and predetors and are safe to fish, birds, animals and man.

 

 

A few specific types of NPVs are as follows:

 

1.  Spodoptera litura (Tobacco Caterpillar) ;

2. SI NPV

3. Gram pod borer (Helicoverpa armigera) ;

4. Ha NPV

 


Trichoderma fungi

 

Fungal plant pathogens like Pythium spp., Furarium oxysporum, sclerotium rolfsii, Rhizoctonia solani and Phytophthora spp. generally cause wilt disease in many crops. Trichoderma, is a saprophytic fungi, capable of growing in neutral and acid soils, have proved as an effective biocontrol agent of wilt diseases. Trichoderma spp. are commonly found in almost any soil and other natural habitats consisting of organic matter such as decaying bark, plant material, etc. They grow trophically towards hyphae of other pathogenic fungi, coil them and degrade their cell walls. This process is called "mycoparasitism", which limits the growth and activity of plant pathogenic fungi. In addition, they produce toxic metabolites which protect the seeds from soil borne pathogenic fungi, by forming a protective coating on them.

 

 

The important species available for mass production are Trichoderma viride and Trichoderma harzianum

 

 



SEX PHEROMONE TRAPS OF Helicoverpa armigera AND Spodoptera litura

 

Sex pheromones are single or complex blend of different chemicals released by one insect to attract the opposite sex of the same species. In general, females (especially the moths) emit sex attractants to attract males for mating. Sex pheromones are artificially synthesized in the laboratories and supplied as sex pheromone lures. Such pheromones are placed in the field to attract trap and kill the males, thus matting is not allowed. Hence, sex pheromone traps can be considered as a key component in Integrated Pest Management (IPM).