Learn about how to control pests of spices!
1. Turmeric Skipper:
The turmeric plant is damaged by the caterpillars of the skipper butterfly which fold the leaves and feed from within. It is widely distributed in India and several other countries. The adult skipper butterfly is purplish black with white spots on the wings. Antennae are apically prolonged beyond the club into a hook or small recurved point. It is also a pest of ginger.
The female butterfly lays eggs on the leaves of the turmeric plant. Caterpillars are green in colour with a stout body and a black head. Pupation takes place within the leaf folds in a fluffy cocoon and after completion of development adult emerges.
The pest seldom causes economic damage. Hence, no specific control measure is generally required for this pest.
2. Leaf Beetle:
This beetle is commonly found in Orissa and neighbouring areas. The adults and grubs both feed on the leaf tissue of turmeric, brinjal and cucurbits. The adults are small 5.6 mm long. Elytra are dark brown in colour with apical one third portion blue in colour.
The female beetle lays eggs singly. The eggs are thrust in leaf tissue. Incubation period lasts for about 8-10 days. The grubs are small 6-8 mm long, yellowish-white in colour with a black head. The anal end projects inwards and the excreta falling on the dorsal surface serves as a protective covering for the grub. The grub period lasts for about 10-12 days. Pupation takes place in the soil or between the leaves under the covering of faecal matter. Emergence of adult takes place in about 15-25 days depending on climatic conditions.
The simplest method of control is hand picking of the grubs.
Regarding chemical control, spraying with dichlorvos 300 ml/ha or endosulfan 1000 ml/ha is very effective.
3. Banana Lace Wing Bug Stephanitis Typicus Dist. (Hemiptera- Tingidae):
This lacewing bug is a small insect with black body, measuring about 4 mm in length. The wings of the bug are transparent, shiny and reticulate in nature. The thorax bears lateral expansions extending to the side of the head. Nymphs and adults both occur in colonies on the lower surface of the leaves of turmeric, banana, cardamom etc. Infestation results into dwarfing and distortion with yellow patches and necrotic spots. Sometimes the pest causes severe damage.
Eggs are laid in the parenchymatous tissue of the leaves. Nymphs upon hatching suck plant sap and inject toxic saliva in the tissue. In warmer climatic conditions there may be several generations in a year. One life cycle is completed in several weeks.
Spraying of fenitrothion @ 600 ml/ha or phosphamidon @ 300 ml/ha is extremely effective to control this pest. Spray should be particularly directed to the lower surface of leaves, since the nymphs as well as adults occur there.
4. Green Peach Aphid:
This aphid is cosmopolitan in distribution and is polyphagous. It attacks the plants belonging to the families Cruciferae, Solanaceae and fruit trees like citrus and peach. The plants of great medicinal value i.e Khurasani Ajvayan as well as capsicum are infested by the Heliothis armigera, Aphis gossypii, and Myzus persicae.
Damage is caused by both the nymphs as well as adults which are oval and soft bodied, and are found on the underside of the tender leaves and shoots of Ajvayan and chillies. They suck the cell sap from the tissues. With the result leaves curl and dry up. Due to secretion of honey dew, sooty mould develops on the leaves which also inhibit growth.
The adult aphid is small in size measuring about 1.5-2.5 mm. The body colour is green with dark green thorax. The honey dew tubes, (cornicles) are fairly long. Both nymphs and adults suck the sap of Ajvayan leaves. It also transmits virus disease of plants.
Life History:
In the tropical climatic condition no males occur i.e. sexual forms are never produced. The females breed by parthenogenesis and viviparously and nymphs mature in 1-2 weeks. A female aphid may give birth to young ones for about 2-weeks, in her life, and produces about 12-14 nymphs per day and these nymphs mature and start reproducing in a week’s time. In the cloudy weather, rapid multiplication takes place.
Spraying the crop with dimethoate @ 600 ml/ha or phosphamidon @ 300 ml/ha or methyl demeton @ 800-1000 ml/ha is effective to control this pest.
5. Common Cutworm:
This is a polyphagous, cosmopolitan cutworm of sporadic importance on a wide range of crops, occasionally the damage by this pest may be devastating. Seedlings are cut through above the ground level, one caterpillar my cut through a number of seedlings in one night. Root crops may be deeply gnawed, often at level well below the soil surface. Besides other plants, it has also been reported as a pest of mint plants.
Life History:
The eggs are laid on the stems of crop plants or on the soil and they hatch in 10-14 days. Each female may lay up to 1000 eggs.
The early instars tend to remain on the foliage of the host plant for 1-2 weeks, then as the caterpillars develop they gradually move down into the soil and assume the cutworm habits. They usually remain in the soil during the day and come to the surface to feed at night. Sometimes the older caterpillars may tend to remain in the soil all the time feeding on the root crops. The grey-coloured mature larva is 30-40 mm long and with faint dark lines along the side of the body.
The pupa, is smooth, shiny-brown with two spines at the rear, 20- 22 mm long. Pupation takes place in the soil. The adult moth is 30-40 mm across the wings, the forewings are grey-brown or black with dark brown kidney shaped markings; the hindwings are almost white in the male but darker in the female. There are several generations in a year depending on the climatic conditions.
Chemical control by using fenitrothion, trichlorphon and carbaryl is quite effective provided they are put on at high volume when the caterpillars are young. The older caterpillars are notoriously less susceptible to pesticides, and when they are in the soil it is difficult to achieve contact with insecticide. Fenitrothion has generally given the best control of many cutworm species.
Baits are sometimes used against cutworms either as a proprietary formulation or using fenitrothion with bran bait but in general the use of baits has not met with much success.
6. Chilli-Thrips:
This is the chief pest of chillies in all parts of India but is particularly severe where the crop is grown in dry weather. The thrips both, the youngs as well as adults attack the plant in all its stages, suck the sap from its tender portions and cause the leaves, buds and fruits to shrivel up. The distortions of the plant produced by the feeding of pests resemble to those caused by some leaf-curl virus disease or diseases.
Life History:
Reproduction is both, sexual and parthenogenetic. In case of sexual reproduction oviposition period lasts for about a month. About 100 eggs, which are very minute are laid just under the leaf epidermis @ 2-4 eggs/day. The young ones on hatching crawl on to the tender shoots for feeding.
After the second moult, these nymphs enter into a short semi-quiescent pre pupal stage and then pupate in sheltered places such as the leaf axils, leaf curies and the base of flowers and fruits. After 3-5 days the adults emerge, which have heavily fringed wings that are uniformly grey in colour. The whole life cycle is completed within 10-15 days. There are several overlapping generations in a year.
This thrips is also found on several other pints like bean, castor, groundnut, mango etc. The intensity of infestation on chillies at the same time of the year varies in different parts of the country and is mainly influenced by the prevailing weather conditions. Rainfall keeps the population down. The pest thrives best and multiplies rapidly in warm but not very dry weather.
The pest can be effectively controlled by dusting with 1% rotenone and 170 kg/ha is enough. Malathion 1% or lindane sprays 0.01% are also effective. In the earlier stages spraying with nicotine sulphate (1 : 1000) should be adopted. This thrips can also be controlled by spray with 0.03% dimethoate or monocrotophos.
7. Cotton Aphid:
This aphid is worldwide in distribution. It is polyphagous in nature feeding on a variety of plants belonging to families Malvaceae, Cucurbitaceae, Leguminosae etc. In addition to cotton, it is also an important pest of capsicum (chillies). The aphid is deep-brown to greenish-black in colour. The antennae are usually half as long as the body and the eyes are red.
The cornicles (siphonculi) are black. They live in colonies and suck the sap from the tender part of the shoots and underside of the leaves. Drainage of cell sap results in leaves curling up, like a cup. Tender portions become blighted. Honey dew secreted by the aphid encourages sooty mould on the upper surface of leaves.
Both the winged and wingless forms reproduce parthenogenetically and are viviparous. Each aphid may produce 8-22 offspring per day in its life of 2-3 weeks. A nymph moults four times before it becomes adult. One life cycle is completed in 7-9 days.
Control:
The pest can be controlled by use of dimethoate @ 600 ml/ha or malathion @ 1000 ml/ha or monocrotophos @ 800 ml/ha.
8. Cow Bug:
It is a membracid homopteran, commonly known as tree hopper. It is distributed throughout in India and is a minor pest of a variety of pints like chilli, sugar-cane, redgram, alfalfa etc. The bug has a black body. Pronotum is subtriangular, overlapping the prothorax. There are two hollow hornlike superhumeral arms giving the appearance of a dagger when viewed laterally.
The apex is projected posteriorly like a spine as is the case with other members of the family. Both the nymphs and adults suck the sap from the axils of branches. They excrete honey dew which invites ants. Damage to the stem is done by egg laying and not by sucking.
Life History:
The adult bugs mate during warmer season. Eggs are deposited on the tender branches, petiole, or midrib of a leaf which are not directly exposed to the sun. The female cuts a longitudinal slit on the bark and insert eggs. Eggs may be laid singly or in groups.
They hatch in about 8-12 days. The insect under goes five moults before it becomes adult. Newly hatched nymphs are soft bodied and shining. The colour of the nymphs in first reddish-brown which changes to brown with lateral dark bands. The nymphal period varies from 1-2 months.
Control:
It is a minor pest and no economic damage is done to the host plants. The pest can be controlled by spraying with dimethoate @ 600 ml/ha or phosphamidon @ 300 ml/ha or malathion @ one litre/ha, particularly on the stem.
9. Beetle Grubs:
Anomala bengalensis. Blanch. Holotrichia consanguinea Blanch, and Holotrichia reynaudi Blanch., (= H. insularis)
The larvae of the above beetles are known as white grubs which have been reported to damage chilli plants. Out of the above, Holotrichia reynaudi is common and very destructive pest of the chilli plants particularly in Rajasthan and other areas where the soil is sandy. The general features of all the white grubs are similar as Holotrichia consanguinea.
Life History:
Eggs are laid in soil and the grubs remain confined to the soil and feed on roots, while the adult beetles hide in debris or in the soil during the day but come out at night and feed on leaves. The incubation period of H. reynaudi ranges from 8-12 days.
The grubs remain active for 11-16 weeks and then overwinter in soil in the pupal stage. When the climatic conditions are favourable the beetles may emerge from the pupae in 2-3 weeks and later overwinter as adults. There is only one generation in a year.
Control:
The pests can be controlled by 5% carbaryl or 10% phorate granules or qunolphos dust @ 20-22 kg/ha.
10. Chilli Fruit Borer:
The chilli fruit borer is a serious pest of pepper, and has also been found damaging chillies.
Life History:
Eggs are laid on chilli fruits and the grubs bore inside and feed within the fruits. The adult beetles scrap leaves as well as chilli fruits. The egg stage lasts 5-8 days, grubs 20-30 and pupal stages last 6-7 days after which the adult emerges. The total life cycle takes about 40- 50 days. There are at least 4-overalpping generations in a year. The pest over winters in adult stage.
Control:
Spraying 0.1% lindane or 0.2% carbaryl will control L. nigripennis as well as other fruit boring pest.