Cotton Insect Pest JASSIDS

Jassids in Cotton

Common Name : Jassids

Local Name : Tudtude

Scientific Name : Amrasca devastans (Dist.)

Family : Cicadellidae

Order : Hemiptera

Pest Category :Sap feeder

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Description of insect Stages:

Eggs:

Jassids Insect Stage

Eggs are curved, elongated and yellowish-white in color, and deeply embedded in the midribs of large veins on the undersurface of the leaves.

Nymph:

Nymph's are flattened, pale yellowish-green with a characteristic way of

moving diagonally in relation to their body, and remain confined to the lower surface of leaves during the daytime.

Adult:

Adults are about 3.5mm in length. They are elongated and wedge-shaped

with pale green body. Forewings and vertex have black spots. Adults are very active with sideway movements but quick to hop(hence referred to as leafhoppers) and fly when disturbed.

Nymphs of Jassids in cotton

Natur of Damage:

Both nymphs and adults suck the plant sap and introduce salivary toxins that impair photosynthesis in proportion to the amount of feeding. 1 and 2 instar nymphs feed near bases of the leaf veins, later installs get distributed all over the leaves but feed chiefly on the under the surface of leaves.

Symptoms:

The affected leaves curl downwards, turn yellowish, then brownish before drying and shedding. Severe incidence leads to stunting of young plants and results in"hopper burn" injury. The fruiting capacity of the infested plants is

significantly affected and in many cases heavy infestation on young plants Downward curling &cause death of plants. Severeincidence during the late season leads to reduced yields.

Jassid Adult Stage

Life History:

The female inserts about 15 eggs inside leaf veins. The incubation period ranges from 4-11 days. The nymphal period occupies 7-21 days depending upon weather conditions. Eleven generations have been estimated to occur in a year. Nymphs molt five times. An average number of eggs laid by a female is about 15 with a maximum of 29.

Seasonal Dynamics:

Nymphs and adults have different seasonal fluctuation patterns. Jassids survive on a variety of wild hosts during the dry season. Populations of the jassids occur throughout the year. The fluctuations of nymphal and adult populations vary within the season.

The nymphal population build-up occurs from the second week of

seedling emergence. There has been an overall reduction in the status of jassids on cotton after 2001 mainly due to the wider use of neonicotinoid seed treatment chemicals. Jassids attain pest status between July-August months, at times threatening the crop stand. Depending upon the atmospheric weather variables the number of generations on cotton can be as large as eleven.

Pest Management Options:

Selecting jassid tolerant cultivars can reduce yield loss from jassids. Management of jassids during very early the crop growth stage should be attempted with a view to maintaining optimum plant stand. Insecticides of neonicotinoid group such as imidacloprid and thiamethoxam applied as seed treatment are efficient in suppressing the population of jassids on the crop for a maximum period of 45-50 days. However, the 'prevention is better than cure' approach of pre-sowing seed treatment with systemic insecticides aids in attaining proper plant stand however they also cause luxuriant plant growth leading to a higher attack by thrips during pre-flowering stage, especially when there are dry periods. Therefore, keeping a close watch of crop growth and weather conditions, post-emergence sucking pest management should be done on a need basis. Crops should not be sprayed with insecticides considering the populations of jassid nymphs or adults on plants. This is because the cultivars with jassid tolerance do not get affected even by the moderate to high levels of jassid population on them but grow with no symptoms of pest attack. Insecticidal sprays have taken up based on the population counts of jassids

Jassids Adult Stage

are often unnecessary. When the population of the generalist predator Chrysoperla carnea is more (at predatory to prey ratio of greater than or equal to 0.2) the decision to take up insecticidal spray should be abandoned. Spraying the crop should rd be done only at the time of appearance of 3-grade injury symptoms of yellowing and curling along the margin of the leaves in the middle to the upper portion of the crop canopy of at least 25 % plants in the field. A spray of 5 % neem seed kernel extract prepared on-farm or crude neem oil spray @ 1% suppresses the jassid population during pre squaring crop stage. In both cases, detergent/soap powder @ 1 gm/liter of spray fluid is to be added for getting uniform spray suspension. Chemical insecticides such as imidacloprid 200 SL @ 0.5 ml/lit and Thiamethoxam 25 WG @ 1-1.5 gm/lit of water can be used only when there are symptoms, indicative of susceptibility to high jassid injury. The conventional systemic insecticides should be alternated if more than one spray of systemic insecticides is to be sprayed. Sprays should be undertaken when the population of nymphs is more along with the second-grade injury to the crop. Jassid attack during reproductive crop growth can be managed using the conventional insecticides like Endosulfan @ two ml/ lit of water. As a thumb rule, the amount of spray fluid and the type of sprayer to be used at various crop growth stages are given in the table below.