The Rice Mealy Bug (Ripersia oryzae Green)

 

The Rice Mealy Bug (Ripersia oryzae Green)

Scientific Name:

    Brevennia rehi (Lindinger)

Common name:

    The Rice Mealy Bug

Order:

    Hemiptera

Family:

    Coccidae

Distribution:

    India (Andhra Pradesh, Mysore, Orissa, Madhya Pradesh and West Bengal), Bangladesh and Thailand.

Host:

    Rice and various graminaccous weeds.

    The nymphs and the adult females, being wingless, look alike. They are plump, oblong, reddish-white, soft bodied and are covered with a waxy powder coating. The young nymphs measure 0.4 mm in length. The males are uncommon and have a single pair of wings.

Life-cycle:

    The reproduction is parthenogenetic and the females lay eggs as well as deposit nymphs simultaneously in the outer leaf sheath. A single female may lay 126-319 eggs or nymphs during a life span of 5 days. In Thailand, the number varies from 60-280. The eggs measure 0.3 mm in length. The nymphs hatch within 24 hours. The freshly emerged nymphs remain within the egg sac or under the body of the mother for about 2 days. Then, they move between the leaf sheath and stem and start feeding there. The entire nymphal period is completed in 15 to 34 days. After last moulting, the female nymphs become sessile and start depositing eggs or nymphs at the same spot. The nymphs which are intended to become males transformed into winged adults. Some of them mate with females and other fly off without feeding Asexual and sexual reproduction takes place side by side.

Damage:

    Both nymphs and adults cause damage by sucking the cell sap from the rice stem. This results in stunted plant growth and yellowish curled leaves. In case of severe infestation, the ear heads become smothered and are unable to grow out of their sheaths and drying of the plants appear. The damage occurs in patches and is generally called 'Chakdhora' or 'Soorai' disease.

Control:

    Spray 625 ml of diazinon 20 EC after mixing in 250 litres of water/ha.