Other
Gram Pod Borer
Helicoverpa armigera
Insect
In a Nutshell
- Feeding damage on flowers and pods.
- Pods with round holes.
- Can cause defoliation.
Can also be found in
Other
Symptoms
The larvae feed on all parts of the plant, but they prefer flowers and pods. Feeding holes are visible on the pods. Sometimes larvae can be observed hanging out of the pods while feeding. If no flowers or pods are available, larvae may also feed on leaves and shoots which can cause defoliation.
Recommendations
Organic Control
Try to keep up a population of beneficials insects parasitizing or attacking Helicoverpa in and around your field. Trichogramma wasps, Microplitis, Heteropelma, Netelia sp., predatory bugs like the big-eyed bug, glossy shield bug and spined predatory shield bug limit its development. Ants and spiders attack the larvae. Bio-insecticides based on NPV (Nucleopolyhedrovirus), Metarhizium anisopliae, Beauveria bassiana and Bacillus Thuringiensis can also be used. Botanical products, such as neem extract and chili or garlic extract can be sprayed on the foliage to control the pest.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments. Monitor population levels to ascertain the necessity of a chemical approach. The economic threshold level is set to 8 moths per night @4 traps/acre in three following nights. The insect has developed a certain degree of resistance to insecticides based on pyrethroid.
What caused it?
Adults are about 1.5 cm long and have a wingspan of nearly 4.0 cm. Their grey, brownish body has a hairy thorax and light-brown forewings with a dark brown band lined with blackish spots on the margins. The hindwings are white with a yellowish outline and a broad black band with a paler patch along the margin. Females lay yellowish white eggs on flowering plants or plants that are about to flower. The larvae's aspects vary depending on their development stages, but they all have a uniformly pale belly. As they mature, they develop little black spots and two bright white or yellow stripes along their flanks. The duration of the different life stages is closely linked to environmental conditions, mostly temperature and the availability of food.
Preventive Measures
- Choose a tolerant variety (e.g Co-6 or Co-7).
- Keep a minimum distance between your plants at sowing.
- Try to keep up a population of beneficial insects by planting border crops like pigeonpea, cowpea or gram.
- Use trap crops (castor or chrysanthemum Marigold) around your field to attract the pest.
- Set up bird perches 10/acre.
- Monitor your plants frequently and check for the presence of larvae.
- Use light traps (1/5 acre) and observe during the evening hours.
- Set up para-pheromone traps (5/1 acre).
- Try to grow large and vital plants with a good fertilization scheme.
- Avoid to over-irrigate the fields as this would favor the pest.
- Plow at least 10 cm deep after harvest to expose larvae to predators.
- Intercrop with non-host species to stop the progression of the pest.
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