Insect pests of soyabean and their management

Insect pests of soyabean and their management

1. Insect pests of S oyabean and their management Course N o . AENT – 5312 Course Title – Pests of crop and stored grain and their management Prepared by, Navneet Mahant Dept. of Agril . Entomology BHARTIYA COLLEGE OF AGRICULTURE, PULGAON, DURG (C.G) – 491001 Affiliated to Indira Gandhi Krishi Vishwavidyalaya , Raipur (C.G)

2. Soybean (Glycine max L. Merril ) is the world’s most important seed legume, which contributes to 25 % of the global edible oil. In the past, there were few pests that caused significant damage to soybean. In resent years, several pests have mad their presence felt throughout the soybean growing region . Soyabean :- Glycine max, leguminaceae

3. Girdle beetle   S.N. :- Oberea ( Obereopsis ) brevis Family:- Cerambycidae Order:- Coleoptera Distribution:- This is more common in M.P, Rajasthan and West Bengal. Its first occurrence was seen in M.P . Host ranges:- Soyabean , pigeon pea, black gram, green gram, sunflower, etc

4. Marks of identification Larva:  White, soft-bodied worm with a dark head. Adult: The freshly emerged adult is yellow, red, brown on the head, thorax and bases of elytra . The adult beetle is characterized by its yellow-red head and chest coloration, and brown colored bases of elytra (wing covers ). The eggs are laid in between girdles by the females. Larvae will bore into stem and feed on the inside, forming a tunnel in the stem.

5. Nature of damage The incidence of girdle beetles is observed at the seedling stage. The presence of 2 circular cuts on the branch or stem is a characteristic symptom. Larvae bore into the stem of soybean. The inside of the stem is eaten by the larvae, forming tunnels within the stem. The infected portion above the circular cut is unable to get any nutrition so it dries up. In the later stages of infestation, the plant is severed at about 15 to 25 cm above the ground . The main damage is caused by the larvae of the insect. The attack of the insect initially begins in the last week of July to the first fortnight of August. The insect remains active from July to October, damaging the crop most severely during August and September. Heavy incidence may reduce the yield by up to 40%.

6. Symptoms of damage Girdling of  stems and petioles The inside of the stem is eaten by the larvae and a tunnel is formed inside the stem. The leaves of plant of infected portion are unable to get the nutrient and are dried up. In later stages the plant is cut at about 15 to 25 cm above the ground.

7. Management Practice deep summer ploughing Sow the crop at the proper time i.e. at the onset of monsoon, with the recommended seed rate of 75 kg/ha. The crop should not be overcrowded Sow tolerant varieties such as NRC-12 or NRC-7 Avoid excess nitrogenous fertilizers Destroy crop residues Collect and destroy infested plant parts at least once every 10 days Apply pesticides if pest population crosses the Economic Threshold Level (5 per cent damaged plants) Spray NSKE 5% or azadirachtin 10,000 ppm @1 ml per 1 litre of water to avoid the pest laying eggs Apply Cartap hydrochloride 4 G @ 4 kg/acre at the time of sowing Spray lambda cyhalothrin 5% EC @ 10 ml or dimethoate 25% EC @ 2 ml per liter of water 30-35 days after sowing and repeat 15-20 days after the first spraying if infestation is observed Always use a hollow cone spray nozzle for spraying

8. S.N. Melanagromyza sojae Family :- Agromyzidae Order :- Diptera Distribution:- Host ranges:- It is a major pest of blackgram , greengram and soybean. Stem Fly  

9. Maggot : White in colour and remains inside the stem. Adult :  Flies are shining black and about 1.60- 1.88mm long, 4.45mm wing span, metallic black colour with a metallic shiny abdomen . Antennae, legs, and bristles on head and thorax are all black .  The wings are transparent. Marks of identification

10. Life cycle Total life cycle completed in 25-30 days

11. Nature of damage and symptoms Symptoms of damage The eggs are laid on leaves. After hatching from the egg yellowish maggots bore the nearest vein of the leaf. The maggot then reach the stem through petiole and bore down the stem. If the infected stem is opened by splitting, distinct zig zag reddish tunnel can be seen with maggot or pupae inside it. The maggots feed on cortical layers of the stem, may extend to tap root, killing of the plant.

12. Deep summer ploughing . Avoid pre monsoon sowing. Use optimum seed rate and plant spacing. Proper crop rotation with dissimilar crops should be followed. Remove and destroy the damaged plant parts. Soil application of phorate 10 G @ 10 kg/ha or carbofuran 3 G @ 30 kg/ha at the time of sowing will prevent early infestation by stem fly. One or two sprays of 0.03% dimethoate 30 EC or 0.05% quinalphos 25 EC can stop the damage . Management

13. White fly S.N. :- Bemisia tabaci Family:- Aleurodidae Order :- Hemiptera

14. Small insects. Most species with a wingspan of less than 3 mm and a body length of 1 mm to 2mm. Adults have well-developed antennae, which in most species in this family are seven- segmented.

15. There are two ocelli, which generally in the Aleyrodidae are placed at the anterior margins of the compound eyes. Both sexes have functional mouthparts and two pairs of membranous, functional wings. The wing venation is reduced.

16. White appearance of adults due to deposition of wax on the body and wings.

17. The adult female lays eggs which are provided with a stalk or pedicel at one end with which they are attached to the leaf. The first instar is called crawler . The legs and antennae of the second, third, and fourth nymphal instars are atrophied and these instars are sessile . The adult develop within the quiescent fourth instars.

18. Whiteflies feed by tapping into the phloem of plants, introducing toxic saliva and decreasing the plants' overall turgor pressure. Since whiteflies congregate in large numbers, susceptible plants can be quickly overwhelmed. Further harm is done by mold growth encouraged by the honeydew whiteflies secrete.

19. Whitefly control is difficult and complex, as whiteflies rapidly develop resistance to chemical pesticides.

20. Several predators and parasitoids may be effective in controlling whitefly infestations, including green lacewings , ladybirds , minute pirate bugs , big-eyed bugs, damsel bugs, and phytoseiid mites. Pirate bug feeding on whitefly larvae

21. A number of plants can be intercropped with vegetables, in a garden setting, serving as companion plants to protect against whiteflies. EXAMPLES Nasturtiums are thought to provide a defense to tomatoes .

22. Zinnias , attract predators that consume whiteflies, including hummingbirds and predatory wasps and flies.