Learn about how to control pests of vegetables!
1. Red Pumpkin Beetle:
Aulacophora Foveicollis Lucas (Coleoptera- Chrysomelidae):
It is a serious pest of cucurbitaceous plants like melon, pumpkin, cucumber etc. The attack caused by the feeding of adult insect or its larva on leaves, is indicated by the formation of irregular holes in the leaves. The larvae also damage the shoots, roots of the plants which ultimately wither and die. The chief damage however is done to the fruits which are rendered useless for human consumption.
The adult is a brilliant orange coloured beetle, with the body surface shiny and smooth. The underside is entirely black and is covered over with short, wide, soft hair like setae.
The female lay about 60-300 orange or yellowish-brown eggs within a period of slightly more than a month, either singly or in clusters on the moist soil underneath the plants. These eggs under optimal humidity and temperature conditions, hatch in about 6-15 days into young larvae. Right from the start the larvae attack the roots of the plants and moult 4-times before changing into pupa.
For every moult the larva goes into the soil and casts off its cuticle. After a larval period of 13-23 days, they penetrate into the soil to a depth of 1 cm to 25 cm. where they construct an oval waterproof creamy white cocoon.
The pupal period lasts for 7-17 days after which the adult escapes out of the soil. The entire life cycle ranges from 30-55 days. Normally there are 3-5 broods in a year. These pests are extremely active from March to October although occasionally they are found damaging plants in winter months also.
Control:
Besides certain precautionary measures such as adjustment in the time of sowing of plants, ploughing after harvest etc. it is the chemical control mostly which has been found to be effective. Using the carbaryl dust is very effective. Spraying the crop with dimethoate 0.02% or malathion 0.05% also controls the pest.
2. Milon Fruit Fly:
Dacus Cucurbitae Coqu. (Diptera- Tephritidae):
This is the most destructive pest of melons and other cucurbits like ribbed gourd and bitter gourd, etc. Tomato is also attacked occasionally. It is distributed throughout India. The damage is caused by the maggots which bore into the fruits and feed on the pulp. The infested fruits can be easily recognized due to deformation or rotting area round the seat of oviposition.
The female fly lays 5-27 eggs singly or in batches underneath the rind (skin of young fruits) which is punctured by the ovipositor. The eggs hatch in 2-5 days liberating small dirty white apodous larvae. The larvae are typical dipterous maggots, 10-12 mm. when fully mature. These feed continuously on the pulp of the fruit resulting in its complete destruction. They can jump to a height of 30 cm. which helps them in dispersal.
They become fully grown within 8-15 days and then leave the fruit; after falling down to the ground, they burrow in the soil to a depth of 2-8 cm. and pupate there. In about 5-10 days adult flies emerge and infest the whole crop. Complete life cycle takes about 3 weeks. The adult fly is reddish brown measuring about 5 mm. with black and white spots. The wings are transparent with brown bands and grey spots at the apex and with a wing-span of 12-15 mm. There are several generations in a year.
Control:
All infested fruits should be collected and destroyed as soon as they have fallen to kill the maturing maggots inside. In addition, use of 0.03% dimethoate, 0.05% malathion and 0.15% trichlorphon in a sugar solution form of spray, on the foliage, is also very effective.
A poison bait (20 gm malathion 50% W.P. or 50 ml of diazinon + 200 gm of gur or molasses in 2 litres of water) kept in flat containers attracts and kill flies.
3. Diamond Back Moth:
Plutella Xylostella (Linn.) (Lepidoptera- Plutellidae):
This insect is worldwide in distribution and is a serious pest of cauliflower and cabbage. It also feeds on other cruciferous, solanaceous and liliaceous plants. The damage is caused by the caterpillars which in earlier stages feed in mines on the underside of the cabbage leaves and in the later stages feed on exposed leaves.
The diamond-back moth is active throughout the year. The tiny yellowish eggs are laid singly or in clusters of 2-40 on the lower side of the leaves. A female lays about 18-356 eggs in her life time. The eggs hatch in about 3-10 days depending on the climatic conditions. They mature in about 9-17 days under different temperatures and measure about 8 mm. in length. They are yellowish green in colour with black hairs distributed all over the body.
Before pupation, the larva constructs a barrel shaped silken cocoon which is open at both the ends. The pupal stage lasts 4-5 days. The moths measure about 8-12 mm. in length, brown or grey in colour with distinct white spots on the fore wings and appear like diamond patterns while the wings lie flat over the body. The moths may live for about 20 days. The life cycles is completed in about 15-18 days during September-October and there are several generations in a year.
The pest can be controlled by spraying the crop repeatedly at weekly intervals with a number of insecticides viz. malathion 0.05% or endosulfan 0.05% or carbaryl 0.15% etc.
4. Cabbage Butterfly:
Pieris Brassicae Linn. (Lepidoptera- Pieridae):
The cabbage butterfly is a serious pest of almost all the vegetable plants of the family Cruciferae. It is worldwide in distribution. The damage is caused only by the larvae which are known as “cabbage caterpillars”. The butterflies are pale white with a smoky shade on the dorsal side of the body. The wings are pale white with a black patch on the apical angle of each fore wing and a black spot on the costal margin of each hind wing.
The females measure 6.5 cm. across the spread wings and have two conspicuous black circular dots on the dorsal side of each fore wing. The males are smaller than the females and have black spot on the underside of each fore wing.
The butterflies are very active in the field and lay about 164 yellowish conical eggs in clusters of 50-90 on the upper or lower side of a leaf. The eggs hatch in about 11-17 days in November-February and 3 – 7 days in March – May. The caterpillars feed gregariously during early instars. The mature caterpillars measure 40 – 50 mm. in length. The larvae are pale yellow when young and turn greenish yellow later on.
The head is black and the whole body is marked with black spots. They pass through 5 stages and are full fed in 15 – 22 days during March – April and in 30 – 40 days during November – February. Then they pupate in barns or on the trees. The pupal stage lasts 8-15 days in March – April and 20 – 28 days in November – February. The butterflies live for 3 – 13 days and breeds 4 times in a year.
The pest can be controlled by spraying the crop with malathion 0.05%, diazinon 0.02% up to three weeks, before harvest. During the later stages of growth of the plants 0.2% carbaryl is very useful and safe.
5. Cabbage Semilooper:
Plusia Orichalcea (Fabr.) (Lepidoptera- Noctuidae):
The cabbage semilooper is widely distributed in India. It is a minor pest of cabbage, cauliflower and other winter vegetables. The semiloopers are yellowish-green in colour and are polyphagous. The damage is caused by the semiloopers, which by biting mouth parts, make circular or irregular holes of different sizes into the leaves of cabbage, cauliflower and other vegetables of the winter season. The adults are yellowish brown, with a large golden patch on each forewing. They measure about 42 mm. across the spread wings.
Life History:
The cabbage semiloopers are active during winter (November- March). During active period they lay eggs on the leaves of cabbage, cauliflower and other cruciferous plants. The semiloopers feed individually, making holes on the leaves, the size of which varies considerably depending on the larval instar. The full grown larvae pupate in the debris or rubbish lying on the ground. Similar to many other moths, the moths of cabbage semiloopers are also very active at dusk i.e. crepuscular.
The pest can be controlled by spraying the crop with malathion 0.05% or diazinon 0.02% upto three weeks before harvest.
6. Tobacco Caterpillar:
Spodoptera Litura (Fabr.) (Lepidoptera- Noctuidae):
The tobacco caterpillar is worldwide in distribution. In addition to tobacco, it feeds on castor, groundnut, tomato, cabbage, pulses, solanaceous and cruciferous crops. The damage is caused by the caterpillars which feed on leaves and are nocturnal.
The pest breeds throughout the year. Each female moth lays about 100-300 spherical eggs in groups or batches at night. Hatching takes place in about 3-5 days but in winter it can be upto 26 or more days. The newly hatched larvae are gregarious feeder for the first few days but later they disperse and feed individually. They pass through 6 stages and are full fed in about 15-30 days.
The mature larvae measure 35-40 mm. in length. They are velvety black with yellowish green colour on the dorsal side and white bands on the lateral side. Pupation takes place in the soil in an earthen cell or under fallen leaves. The pupal stage lasts about 7-15 days. The moths are about 22 mm. long and measure 40 mm. across the spread wings.
The fore wings have golden and greyish brown patterns. The hind wings are white and margins of the wings are brown. The moths after emergence live for 7-10 days. The entire life cycle is completed in about 35-60 days depending on the climatic conditions. There are about 8 generations in a year.
Cultural methods of control such as ploughing and burning of crop stubbles, flooding the infested fields and removal of weeds, all helps to lower the pest population. The pest can be controlled by spraying the crop with diazinon 0.02% or phosphamidon 0.03% or endosulfan 0.05%. Dusting the crop with carbaryl is also very effective. The infested crop should be sprayed with malathion 0.05% or carbaryl 0.15%.
7. Epilachna Beetles:
Epilachna Species. (Coleoptera- Coccinellidae):
The Epilachna beetles mostly attack different solanaceous and cucurbitaceous vegetables, as well as some other crops. Their feeding habit is quite characteristic and both the adult and larval stages skeletonize the leaves which present a lace like appearance as green matter in between the veins is eaten away leaving the skeleton of anastomosing veins.
The eggs are laid in clusters, varying in number, usually on the underside of the leaves and placed vertically. The eggs are pale yellow, elongate or oval with comb like hexagonal sculpturing and they measure about 0.5 mm. in length. Incubation takes about 4-5 days. The larvae are pale yellow, covered with delicate spines when first hatched.
The young larvae start feeding soon after hatching making rows of small windows in the leaves. Full grown larvae are dark yellow, broad with a dark head and strong branched spines and 6-7 mm. long. Larval development takes about 16 days. Pupation takes place on the leaves of the host plant and the pupa is dark yellow.
The adult beetles are oval, 6-9 mm. long reddish to brownish yellow but colour is variable. Each elytra is marked with a series of black spots. Epilachna beetles are the only phytophagous representatives of the family Coccinellidae. The whole life cycle takes about 30-35 days under suitable conditions.
The Epilachna beetles can be controlled by spraying them with diazinon 0.02% or malathion 0.05% or 0.1% carbaryl. On cucurbitaceous vegetables, only malathion 0.05% or methyl parathion 0.02% should be sprayed as the other insecticides are phytotoxic.
8. Brinjal Fruit Borer:
Leucinodes Orbonalis Guen. (Lepidoptera- Pyraustidae):
This is commonly known as “brinjal fruit borer”. The pest is widely distributed in several countries. The young caterpillars are creamy white the mature larvae are pinkish in colour. The moths are white having brown or black spots on the dorsal side of the thorax as well as abdomen. The wing margins are provided with fine bristles and the fore wings have numerous black or brown spots.
The damage is caused mainly by the caterpillars which attack the terminal part of the shoots, thus destroying the growing point. Fruit-buds and fruits are also badly damaged by borers specially in autumn. Further, different varieties of brinjal have been reported to show differential susceptibility to this pest. According to some workers, the varieties of long, narrow fruits to be less infested than those with spherical fruits.
Life History:
Moths of the brinjal borer appear in the beginning of summer i.e. in late March. Each female lays about 100 or 120 eggs singly or in groups of 3 to 4 on almost all the parts of the plant i.e. leaves, stem, flowers and tender fruits. Hatching occurs in about 4 to 6 days. The newly emerged larvae bore into the terminal part of the shoot, flowers, fruits etc. where the eggs are laid.
There are 5 instars and the larval stage lasts 1 to 4 weeks. The mature larvae pupate in silken cocoons among the fallen dry leaves. Pupal duration is about 1 to 2 weeks. The whole life cycle is completed in 3 to 6 weeks. There are several overlapping generations in a year.
The borers can be controlled by spraying, malathion, 0.04% or diazinon 0.02% or 0.1% carbaryl. The borers can be destroyed by removing the infected fruits and leaves.
9. Brinjal Lace Bug:
Urentius Sentis Distant (Heteroptera- Tingidae):
This bug is commonly known as the brinjal lace bug and is distributed throughout the country but very common in plains. The damage is caused by the adults and the nymphs which suck the sap from the leaves. When the attack is severe more than 50% of the crop may be destroyed.
The bugs live for about 30-40 days and lay 35-44 shining white nipple-shaped eggs singly in the tissues on the underside of the leaves. The eggs hatch in 3-12 days and the nymphs feed gregariously on both the lower as well as upper surface of the leaves. They grow through 5 stages and transform into adults in about 10-23 days. The insect passes through 8- overlapping generations in a year.
The pest can be controlled by spraying the crop with diazinon 0.02% or dimethoate 0.05%.
10. Potato Tuber Moth:
Gnorimoschema Operculella (Zeller) (Lepidoptera: Gelechiidae):
It is a destructive pest of potato, tobacco, tomato, brinjal, and several other vegetable plants. The damage is caused only by the larvae, which are pinkish white or greenish in colour. The head of the caterpillar is dark brown.
In favourable conditions the insect may breed throughout the year. As with several other insects, in cold weather the life cycle is much prolonged and in warm and moist weather, it is much shorter. A female moth lays about 150-200 eggs, singly on the underside of the leaves as well as on the exposed potato tubers.
The caterpillars first produce blotch mines on the leaves and then they work their way into the stems. The larvae are about 20 mm. in length. The larval stage in summer lasts 2-3 weeks and the mature larvae pupate in a greyish silken cocoon which is about 13 mm. in length. The moths emerge in 7- 10 days and are very small in size about 13 mm. across the wings when spread. It is greyish brown in appearance. The life cycle is completed in about a month and there are about 5 or 6 generations in a year.
Dusting the potatoes meant for seed with malathion 2% is very effective to control the pest. If potato tubers in the stores are infested, fumigation with carbon disulphide @2-3 litres/100 cubic meters is recommended to control this pest.