Agrotis ypsilon (Gram cutworm)
- Class– Insecta
- Order– Lepidoptera
- Family– Noctuidae
- Genus– Agrotis
- Species– ypsilon
This pest is distributed throughout the world and damages the crops in America, Africa, Australia, Myanmar, China, Taiwan, Europe, Hawaii, India, Indonesia, Japan, New Zealand, Sri Lanka and Syria, In India it causes damage to various crops in Punjab, Uttar Pradesh, Bihar, Madhya Pradesh and Bengal.
Food (Host) plants :
Gram cutworms damage gram, peas, potato, lentil, mustard, wheat, maize, sugarcane, lucerne, ground-nut, barley, cotton, opium, tobacco etc.
General appearance :
It is a stout medium-sized moth measuring about 25 mm in length. The moth is dirty or black coloured having some greyish patches on the back and dark lines on the forewings. This cutworm has small prothorax, hairs on the under side of the femur and setae on the middle and hind tarsi. Another allied species Agrotis flammatra Schiff causes severe damage to chick pea in northern India. It also feeds on potato, cucurbits, okra, wheat, opium, tobacco, poppy etc. Its adult is heavy bodied greyish or wheat coloured measuring 5-6 cm in wing expanse.
Life history :
The female moth after fertilization oviposits very small, creamy white, dome-shaped eggs singly or in clusters of about 30 eggs each. The eggs are laid at night on the under-surface of the leaves of the host plant, grasses or in the soil beneath the plants. The process of oviposition continues for 5-11 days and total number of eggs laid per female are as many as 350. After incubation period of two days in summer and 8-13 days in winter the eggs are hatched into caterpillars feeding on their own egg-shell and move like a semilooper. The caterpillars are dark coloured having greasy body. They are extremely active at night in cutting down much more foliage than they can devour. During the day time they hide in cracks and crevices (10-15 cm deep) in the soil. After about 30 days the larvae attain the maximum size of about 2 cm length, make earthen chambers in the soil and pupate underground. The pupal period varies from 10 days (summer) to 30 days (winter) after which moth emerges out usually at night. The life cycle is completed in 48-77 days. Three generations have been reported to be completed in a year. Being a cold weather pest, it is found active from October to March in plains and migrates to hills for breeding during summer.
Only larval stage damages the standing crops at night. In India and other warm countries it is a severe pest of Rabi crops particularly of gram and potato. The younger caterpillars feed on the epidermis of leaves. The feeding habit changes with the growing stages of larval period. They damage the crops by cutting the stem either above or below the ground resulting in felling of the plants. The cut branches of host plants are dragged into the holes where the leaves are ingested by the caterpillars.
Prevention and control :
- Clean cultivation should be adopted.
- The caterpillars should be hand-picked from small area.
- Field should be often flooded moderately.
- The application of 2% lindane after the sowing of crops can control the pest.
- Heptachlor, aldrin @ 2.25 kg active ingredient per hectare should be applied to the soil before planting potato tubers.
- Various natural enemies viz., mice, moles, grubs, wasps predaceous and parasitic flies destroy this insect.
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