The pod fly is a major pest in pigeon pea.
Its attack remains unnoticed by most farmers owing to the hidden lifestyle of the insect and thus it may become difficult to manage.
Identification
Egg
Eggs measure about 0.95-1 mm in length and 0.15-2 mm wide.
They are laid in the walls of the immature pods.
Larva
The freshly hatched maggots are transparent. Mature larvae are white and up to about 3-3.5 mm long. They are legless and feed on the developing grain and pupate inside the pod.
Pupa
Pupal cases are orange-brown, about 3 mm long, with a pair of closely spaced anterior spiracles projecting forward, and a pair of prominently projecting posterior spiracles on tubercles that are joined basally.
The pupae bore the grains and make tunnels in them for the exit of the adults.
Adult
Both sexes are 2-5 mm long, and may appear black to the naked eye, but the thorax and abdomen have a distinct, green metallic sheen if examined under magnification. The head has a prominent ocellar triangle, also metallic green that extends to the lunule (recessed crescent above the antennae). The wings are clear.
The female has an unusually long, black ovipositor sheath.
Damage Symptoms
The maggot/larva feeds on the developing grain.
Infested pods do not show any external evidence of damage until the fully grow larvae chew holes in the pod walls. They bore the grains and make the tunnel in them.
The holes provide emergence “windows” through which the adults exit the pods.
Damaged grains do not mature and due to the larvae excreta, fungus may develop in the grain.
The infested grains become shriveled and lose viability. They are unfit for human consumption.
Dry pods show pin head sized holes.
Management Strategy
Chemical method
The following insecticides are recommended for use against pod flies.
- KINGCODE ELITE 50EC 10ml/20l
- LEXUS 247SC 8ml/20l
- SINOPHATE 750SP 20g/20l
- PRESENTO 200SP 5g/20l
- PROFILE 440EC 30ml/20l
- EPITOME ELITE500SP 10g/20l
- LEGACY 50EC 20ml/20l
- PENTAGON 50EC 10ml/20l
- EMERALD 200SL 10ml/20l
- LOYALTY 700WDG 5g/20l
NOTE
- Whenever doing foliar sprays, it is advisable to mix the insecticide with INTEGRA 3ml/20l, which is a sticker, spreader and penetrant. It improves the efficacy of the product.
- To prevent resistance build-up by the insect, several insecticides should be alternated in a crop’s season, instead of using a single one.
- Timely application of the insecticide(s) is very important for effective control.
Non- chemical methods
- Sow the crop early in the season
- Use resistant varieties
- Intercrop with other crops like sorghum, maize and groundnut to reduce insect population
- Crop rotation with non-host crops
- Conservation of natural enemies/predators like spiders, robber fly
- Use of sticky traps to catch the adults
- Proper weed control
- Maintenance of field sanitation