Papaya mealy bug – a new threat to sericulture

Papaya mealy bug – a new threat to sericulture

Papaya mealy bug is a polyphagous sucking insect pest and has been recorded on more than sixty host plants in India.

But its serious attack was recorded only in a few economically important crops such as papaya, mango, pomegranate, citrus, beans, tomato, potato, pepper and cotton. In other plants it exists as a minor pest.

However sudden outbreak of any minor pest is common owing to various reasons.

The recent trend in the population built-up of papaya mealy bug on mulberry, the sole food plant of silkworm, indicates its emerging pest status especially in South India where mulberry is cultivated intensively.

Infestation

Papaya mealy bug infestation is typically observed as clusters of cotton like masses on tender stem and veins of mulberry leaves as the insect secretes a white waxy coat over its body.

The adult female lays 100-600 eggs which hatch into nymphs in about ten days. The nymphs crawl actively to search for feeding sites and settle in clusters on leaves and stems.

One generation

The pest completes one generation in a month. The symptoms appear on the leaves as chlorosis (yellowing), deformation and premature drop. Hence, feeding with papaya mealy bug infested mulberry leaves adversely affects the growth of silkworm and silk production.

Cultural method

Planting of highly susceptible host plants such as papaya or hibiscus in the vicinity of mulberry garden should be avoided.

Plugging of the infested twigs and leaves and their burning during early stage of infestation is the best method of eradication of the pest.

Indiscriminate use of insecticides in mulberry fields should also be avoided as they induce resistance in the pests and destroy its natural enemy population.

Biological control

Release of Cryptolaemus montrouzieri, an effective predatory ladybird beetle at 125 adults per acre twice a year at the interval of six months keeps the pest population suppressed.

Spraying dimethoate (0.05 per cent) controls the pest effectively. Leaves can be fed to silkworms 15 days after spraying the insecticide.

N.Sakthivel

Regional Sericultural

Research Station

Central Silk Board, Salem

Tamil Nadu: 636 003