1. Cotton leaf hopper
Common name: Cotton leaf hopper
Scientific name: Amrasca biguttula biguttula
Family: Cicadellidae
Order: Hemiptera
Distribution: Cosmopolitan
Host range: Cotton, okra, eggplant, castor, cucurbits, hollyhock, potato, sunflower, and many other Malvaceous plants
Damage:
- Both nymphs and adults suck cell sap from the leaves.
- Also inject toxic saliva in to plant tissues
- Affected leaves turn yellowish and curl.
- In case of heavy infestation the leaves turn dark brick red, become brittle and crumble.
Identification
- The eggs are pear shaped, elongated and yellowish white in colour.
- Nymphs are whitish pale green, wingless
- Adults are wedge shaped, 2-3 mm long, pale green in colour with a black dot on posterior portion of each forewing
- Adults of winter generation are slightly reddish in colour.
Life cycle
- Incubation period is 4-10 days
- Nymphal period is 7-21 days
- Adult longevity is 5-8 weeks
- 10-12 overlapping generations in a year
- Each female lays 15-30 eggs
- Mating takes place 2-16 days after emergence
- Oviposition begins 2-7 days after copulation.
Salient features
- Eggs are laid singly in the tissues of main veins on the under surface of leaves
- There is no true hibernation or diapause but the adults have the ability to tide over the adverse climatic conditions.
- The pest appears with the onset of cloudy weather and their population is adversely affected after heavy monsoon showers.
Other species
- Jassids like:
- Empoasca binotata
- Corizus rubicundatus
- Family: Cicadellidae
- Order: Hemiptera
Management
- Seed treated with imidacloprid (3g/Kg) gives protection up to 40-50 days after sowing.
- Soil application with carbofuran @ 1.0 kg/ha at the time of sowing.
- Spraying the crop with insecticides like phosphamidon @ 0.04% or dimethoate (0.03%) or oxy- demeton methyl (0.025%) or imidactoprid (0.0075%).
2. Shoot and fruit borers
- Important species:
- Earias vittella
- E. fabia
- E. insulana
Family: Noctuidae
Order: Lepidoptera
Distribution: North Africa, India, Pakistan and many other countries
Host range: Cotton, okra, sonchal, gulkhaica, holly hock and other malvaceous plants.
Damage:
- Larvae cause the damage
- Larvae bore into growing shoots, flower, flower buds and fruits
- Fruits become distorted and rendered unfit for consumption.
Identification
- Caterpillars are dull green, 20 mm, having tiny stout bristles and a series of longitudinal black spots on the body.
- The moths are yellow, about 25mm across the wings
Life cycle
- The moths live for 8-22 days
- Lay 200-400 eggs
- Eggs hatch in 3-4 days
- Caterpillars become full grown in 10-16 days
- Six larval stages.
- Pupal period is 4-9 days.
- During winter the life cycle is prolonged
- Several overlapping generations in a year.
Salient features
- The pest breeds throughout the year but during winter only pupae are found hiding in plant debris
- Lay eggs singly on flower buds, brackets and tender leaves
- Pupation takes place either on the plant or on the ground among fallen leaves
Management:
- Neglected okra fruits left in the field should be collected and destroyed.
- Clean cultivation and destruction of alternate host in the vicinity.
- Deep ploughing during summer to expose the pupae
- Grow tolerant varieties like Parkins Long Green, AE-57, PMS-8, Karnal Special etc.
- Avoid over use of nitrogenous fertilizers.
- Soil application with carbofuran (1.0 kg/ha)
- Need based application of triazophos @ 0.15% or cypermethrin 0.01% or deltamethrin 0.0028% or fenvalerate 0.01%.
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