The Paddy Root Weevil (Echinocnemus oryzae Marshall)
Scientific Name:
Echinocnemus oryzae Marshall
Others Name:
Rice Root Weevil
Order:
Coleoptera
Family:
Curculionidae
Distribution:
In India, it was for the first time reported in 1924 in Guntur in Andhra Pradesh. It also occurs in Tamil Nadu and Kerala. In northern parts of India, it was first recorded in 1953 at Sirsa (Haryana) and recently from Punjab also.
Host:
Rice and roots of certain grasses.
The grubs are translucent white and measure about 6 mm in length. There are six pairs of prominent tubercles on the dorsal side of the abdomen. The adults weer small and brown in color.
Life-cycle:
The adult weevils emerge from cocoons in the soil with the first monsoon showers. The maximum emergence takes place at the end of July and are seen sitting in large numbers in rice fields. The females lay eggs on the soil near the roots of grasses. The grubs hatch within 3-4 days. The grubs lead an aquatic life and feed on the root hairs. Tubercles on the abdomen help them in respiration and they obtain oxygen from the air-spaces inside the roots of the host plants. The larval period lasts for 11 months. After September, they leave the root zone and burrow into a deeper layer of soil upto 25-30 cm from the surface and spend the all winter months resting in the soil. They pupate sometime in May, Pupal period lasts for 10-12 days. Only one generation in a year is completed.
Damage:
The grubs cling to and feed on the rootlets of the newly planted rice, thereby, preventing their proper establishment and growth. The infested crop remains stunted and a large number of plants are killed. The crop transplanted in July is more heavily attacked than the one planted in August. The damage is generally in patchy areas. The old plants with well developed roots can tolerate the damage caused by the grubs
Control:
Apply 10 kg phorate 10 Gor 25 kg carbofuran 3G or 20 kg of lindane 6 Gor 12.5 kg of diazinon 5 G, granules /ha in standing water.
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