Pests of Peas

1 Gram pod borer

Helicoverpa armigera
Family: - Noctuidea
Order: - Lepidoptera

• Economic importance

Pod borer, aphids and pulse beetle are the important pests of this crop. Besides, cutworms and leaf eating caterpillars also damage this crop.

• Marks of Identification

The moths are light yellowish-brown about 25mm in length and 37mm in wing expanse. Forewings are pale brown with black. Hindwings are lighter in colour having smoky dark margins. Full-grown caterpillars are greenish with dark broken grey along the sides of body, measuring 31 to 50mm in length.

• Nature of damage

Caterpillars feed on tender foliage and young pods. They make holes in the pods and feed on developing seeds by inserting anterior half portion of their body inside the pods.

• Host plants

It is a polyhagous species gram, cotton, tomato, peas, tobacco, ganja and sunflower are some of the important host plants.

• Life history

Shinning greenish yellow sperical eggs are laid singly on the tender parts of plants. They hatch in about 6-7 days. On hatching the caterpillars start feeding on tender leaves and shoots. After pod formation they bore into them and feed on developing grains. Larvae become full-grown in 14 to 15 days. Pupation takes place in earthen cocoons in soil near the plants. Pupal period lasts for about 1 to 4 weeks. A generation is completed in 4 weeks. The pest is active from November to March and hibernates in the pupal stage till next season.

• Control measures

In early stage of attack handpicking of the caterpillars and their destruction, help in reducing the intensity of infestation. Ploughing fields after the harvest of crop would expose the pupae, which would be destroyed by birds. The pest can be successfully controlled by spraying the crop with 0.05% quinalphos or fenitrohion. Spray with HaNPV @ 250 LE/ha.

2 Pulse beetle

Callosbruchus chinesis
Family: -Bruchidae
Order: - Coleoptera

• Economic importance

Though it is an important pest of pulses in storage, minor incidence is noticed in the field on pods from which the infestation is brought to the storage.

• Marks of identification

The adult beetle is more or less tapering at the anterior end; measuring about 6mm in length. There are two ivory coloured spots in the middle of the dorsal side of its body. The beetles are dark brown in colour. The grub is white, cylindrical, and fleshy and wrinkled with brownish month-parts. It is always found inside the grain.

• Nature of damage

It is a major pest of pulses in store. However, field infestation is also common. The young grubs burrow into the pod or grain and continue to develop inside the grain. The holes seen on pulses are the exit holes from where the adults have emerged. Such grains are unsuitable for sowing.

• Host plants

Mug, gram, tur, bean, masur, udid etc.

• Life history

The eggs are deposited mostly singly but sometimes in-groups on the surface of seeds and pods. In the fields, eggs are even laid on green pods, which carry infestation to the store. A female can lay from 60 to 95 eggs. Egg stage lasts for 4-5 days. On hatching, larva enters the grain and becomes full-grown in 2 to 3 weeks. Pupation takes place inside the grain. After 4 to 8 days the adults come out of the grain. It can fly and spread the infestation from store to the field. Adults live for 10 days or more.

• Control measures

It is difficult to control the pest in the field. In storage however, fumigation with carbon-di-sulphid at the rate of 1 lb/100 cu.ft. or 2.5 1b EDCT/100 cu.ft. or methyl bromide at 1 lb/1000cu.ft. would control the pest.

3. Cut worm

Agrotis ypsilon R.
Family: -Noctudiae
Order: - Lepidoptera

• Economic Importance

The cutworms are cosmopolitan insects and have been reported to occur throughout the country and particularly serious in low lying areas which remain water logged for considerable injury is done by Agrotis ypsilon to potato crop in India. The damage to the crop varies from 12 to 35%.

• Marks of Identification

Moth is medium sized (22-26mm longer), stout with grayish brown wavy lines and sports on fore wings and creamy white wings. The moths are active at dusk and are attracted by light. Full-grown caterpillars are 40-48mm long dirty black in colour and have habit of coiling at slightest touch.

• Nature of damage

The caterpillars hide during the day in cracks and crevices in the soil or in debris around the plants and feed on tender leaves of shoots during night by cutting them near the ground level. The destruction is much more than actual feeding.

• Life history

A female lays 300-350 eggs (maximum 1800) in 10-15 clusters of 20-35 eggs on ventral leaf surface or moist soil. The incubation period is 4-7 days. Larval period lasts for about 3-5 weeks pupation takes place in the soil and moths emerge from pupae in 11-18 days. A generation is completed in 5-9 weeks.

• Host plants

It is a polyphagous insect and feeds on potato, pulses, barley, oats, tobacco, peas, gram, cotton, tomato, lucerne, chilies, brinjal and other vegetables.

• Control measures

1) Heaps of green grasses may be kept at suitable interval in infested field during evening and next day early in the morning alongwith caterpillars to destroy, 2) clean cultivation and mechanical destruction of caterpillars also help in reducing pest infestation. 3) Irrigation also brings them on the surface and birds shall predate them. 4) 5% Carbaryl poison bait at the rate of 25-60kg/ha controls the pest effectively and 5) Soil application of chlordane or Heptachlor dust at the rate of 50kg/ha found effective against the pest.

4 Aphids

Macrosiphum oisi K.
Family: -Aphididae
Order: - Hemiptera

• Marks of Identification

Aphids are tiny yellowish soft-bodied insects, the adult is along 1mm long and has two projections called cornicles on the dorsal side of abdomen.

• Nature of damage

Aphids are found in large colonies on underside o leaves and tender shoots. The nymphs and adults suck the sap. Therefore, the affected leaves turn yellow, get wrinkled and destroyed. The insect also exude honeydew on which fungus develops, rapidly covers the plant with sooty mould that interferes with the photosynthetic activity of the plant. As a result, the growth of plant is stunted and yield is affected adversely. Besides, they act as a vector for transmitting by aphids. The loss caused on this account is far more severe than by their feeding and devitalizing the plant.

• Life history

Adults and apterous forms reproduce parthenogenitically. Single female produces 8-22 nymphs/day. The nymphs are completed in 7 to 9 days and several generations are completed in a season.

• Host plants

It is a polyphagous species have been recorded on cabbage, brinjal, radish, chilly, tomato, tobacco, sanhemp, sweet potato etc.

• Control measures

Spraying with 0.05% endosulfan, 0.02% phosphamidon, 0.03% dimethoate, methyl demeton or thiometon control the pest effectively.