Some approaches in management of sucking pests on chilli with special reference to tarsonemid mite, polyphagotarsonemus latus bank

Leaf curl in chilli is known due to gross effect of injury caused mainly by thrips, Scirtothrips dorsalis Hood and mite, Polyphagotarsonemus latus Bank. Investigations on population dynamics, influence of sowing time, histology of damage symptoms, varietal reaction pertaining to these pests and efficacy of botanicals, biopesticide and newer molecules against chilli mite were carried at Indian Institute of Vegetable Research, Varanasi during Kharif season of 2006-08. Incidence of mite P. latus commenced from third week of Sept and continued almost throughout the crop period exhibiting highest peak in the first week of Nov (20.8/plant). Thrips persist from 2nd week of Sept to first week of Nov being maximum (2 thrips/ three terminal leaves) in the first week of Oct. The higher mite-thrips infestation in early growth phase reduced the yield to a greater extent than late growth stage. The July planted crops suffered less infestation of sucking pests during early growth phase and consequent yield increase. Of the 15 genotypes screened against thrips-mites infestation and severity of leaf curl symptoms, the promising lines with higher tolerance index were NEC, G-4, PDG-50, R-Line, VNS-4, VNS-4-1, PDC-24 and Punjab Lal. At cellular level, thickening of epidermal layer (upper epidermis in case of thrips; lower epidermis in case of mites), elongation of palisade cell layer, shrinkage and deformation of parenchyrnatous tissues were the common changes in both the cases. In thrips infestation, the mesophyll cells formed number of small round shaped aggregation of cells which was clearly distinct to that of mite infested leaves. The occurrence of Actinomycetes, a bacterium (gram negative) and fungus pathogens invading mites were recorded under natural condition. In laboratory evaluation, actinoniycetes and bacteria caused mortality to the extent of 20-30%. A phytoseiid predator, Arnblyseius ovalis and antocorid hug, Orius insidiosus were found frequently associated with P. latus. Solvent extracts of Kochea, Calotropis Tridax and Duranta proved highly effective against chilli mite in laboratory evaluation. Vertimec @0.75 ml/lit, mycozal (Beauveria bassiana) and proporgite among newer molecules and solvent extract of Calotropis, Kochea as well as Castor and Neem oil among botanicals showed promising results in the control of chilli mite under polyhouse condition.