It is a polyphagous pest found mostly in chickpea and other pulse crops. It is a gregarious pest of tomato crops and causes nearly 50-60% crop losses in the tomato field. Warm weather conditions, light rain are favorable for multiplication of gram pod borers. Gram pod borer attack in tomato crops is seen mostly during August to September months whereas other generations feed and complete life cycle on chickpea and red gram.
Identification of gram pod borer-
Eggs- The eggs are creamy-white to yellow in color, spherical shaped and laid singly on the leaves of tomato plants. The egg period is 2-4 days.
Larvae- The larvae of gram pod borer vary in color from green to brown. The body of the larvae has brown to grey lines along with the lateral white lines and dark bands along the length. The body is covered with fine hairs. Larvae measure 37-50 mm in length. The larval period is 20-25 days.
Pupa- Gram pod borer's pupa are found in the soil, crop debris as well as also on leaves and sometimes in the pods. The people are brown in color. The pupal stage is of one to two weeks.
Adult- Adult females are generally larger in size than males. Females possess pale brownish-yellow bodies. The forewings are olive-green to pale brown in color having dark brown circular spots in the center with a wingspan of nearly 350-370 mm whereas the hindwings are smoky white with blackish outer margin.
Host plants- Gram pod borer feeds on a wide variety of crops. It feeds widely on chickpea and red gram and pulse crops and therefore is known as gram pod borer. Gram pod borer also feeds on cotton, sorghum, chili, tomato, soybean, maize, okra etc.
Damage caused by gram pod borer-
Larvae- young larvae feed on new leaves, buds, shoots and tender parts of the plant and then migrate towards fruits to attack them. Whereas mature larvae bore circular holes into the fruit and feed on to them. The larvae remain half outside and thrust its other half body in the fruit.
Management and control of gram pod borer-
- Infested fruits and plants must be collected and destroyed thereby killing the larvae.
- Marigold can be planted in between the rows as a trap crop in the ratio 1 is to 16. The larvae are attracted towards marigold and then these plants must be collected and destroyed.
- Pheromone traps can be installed in the field at the rate of 12 per hectare to trap male moths thereby preventing mating.
- Trichogramma species can be released at an interval of 7 days @ 1 lakh for per hectare.
- Helicoverpa armigera Nucleopolyhedrosis Virus can be sprayed in the field to kill larvae.
- Poison bait can be made and kept in the field. For poison bait preparation Carbaryl 50WP @1.25 kg, rice bran @12.5 kg and jaggery @1.25 kg and water 7.5 liters must be mixed to prepare poison bait for 1-hectare area.
- Spray Bacillus thuringiensis @ 2g per liter.