Insect Pests and Their Management

The main insect pests of cucurbits are: Cucurbit Fruit Fly, Red Pumpkin Beetle and Epilachna Beetle. Their damage symptoms and control measures are described as follows.

Cucurbit Fruit Fly

Cucurbit Fruit Fly

Fruit flies are most damaging for cucurbitaceous crops.

Nature of damage:

Infected Fruit

·         Adult female flies select soft and young fruits for oviposition by puncturing the rind with the ovipositor. Such damaged fruits show signs of raised and brown resinous encrustation at the sites of ovipositional punctures due to discharge and drain out fruit juice through punctures

·         Infested fruits are either rotten or deformed in shape due to the microbial infection. Such rotten or deformed fruits are not fit for sale or human consumption.

·         Infested fruits with apparent firmness and growth show internal decay and foul smell when cut open.

Control measures:

• Growing of resistant or early maturing varieties and infested fruits should be collected and destroyed.
• Use of sex pheromone like “Cuelure”.
• Fruit flies can be controlled by using poison bait (100g smashed ripened pumpkin + 0.5g Dipterex + 100ml water).
• Apply carbaryl 10% DP in pit before sowing of seeds to destroy the pupae.

Red Pumpkin Beetle

Red Pumpkin Beetle

The red pumpkin beetle is a serious pest of cucurbitaceous plants, except bitter gourd.

Nature of damage:

Infested Leaf

·         Adult beetles feed voraciously on the leaf lamina by making irregular holes.

·         The maximum damage is done when the crop is in the cotyledon stage. The first generation is therefore more injurious than the subsequent generations.

·         The adult insect also feed on the leaves of grown up plant by scrapping off their chlorophyll and make the leaves net like appearance.

·         The attacked plants may wither away and re-sowing of the crop may become necessary in certain cases.

·         The larvae cause damage in various ways by boring into the roots and the underground stem portion and by feeding on the leaves and fruits line in contact with the soil.

·         The damaged roots and the underground roots and the underground stems portion may rot due to infection by the saprophytic fungi.

·         The young and smaller fruits of the infested creepers may dry up, whereas the bigger and mature fruits become unfit for human consumption.

Control measures:

·         Spraying of contact insecticides like carbaryl 10% DP has been effective in controlling beetles, but repeated application at an interval of 7 days are necessary.

·         Using neem oil cake in the soil has been reported to kill the pest larvae.

·         Sown early that the plant passes the cotyledon stage by the time the beetles become active.

Epilachna Beetle

Epilachna beetle:

Epilachna beetle are major insect pest of teasle gourd, cucumber, bitter gourd, watermelon, muskmelon and other cucurbitaceous crops.

Nature of damage:

Infected Leaf

·         Many grubs and adults can be seen on the ventral surface of the leaves.

·         Both the adult and grub stages feed on the leaf surfaces and skeletonize the leaves which present a lace like appearance.

·         The attacked leaves turn brown, dry up and fall off.

·         In case of severe infestation the crop presents a very unhealthy look.

·         The vigour of the plant and thereby its yield is adversely affected.

Control measures:

·         The pest population can be suppressed effectively and its infestation can be squeeze in the bud, by regular killing and picking of eggs, grubs and adults, if the cropped area is small.

·         Also the larvae and adults can be shaken down in container of kerosinized water early in the morning.

·         The pest can be killed by spraying Malathion/ Fyfanon/ Zythiol 50 EC @2 ml of water. The treatment should be applied as soon as the pest appears and repeated at 15 days interval.