J Gulsar Banu
Central Institute for Cotton Research, India
GulsarBanu is a Principal Scientist at Central Institute for Cotton Research (ICAR), Regional Station, Coimbatore, Tamil Nadu, India. She has more than 21 years of research experience in Biological control of insect and nematode pests in plantaion crops and cotton.
Mealybugs (Hemiptera:Pseudococcidae) are phloem feeding insects that constitute a family with about 2000 species, some of which are major pests of agricultural crops. The cotton mealybug,Phenacoccussolenopsis Tinsleyattacks more than >194 plant speciesin India. The control of mealybug is very difficult because they are characterized by waxy covering of the body which hinders the penetration of pesticides. This feature of mealybug makes the application of only a few systemic insecticides for the control of mealybug. Moreover repeated application of chemical insecticides has disrupted biological control by natural enemies leading to pest outbreak and sometimes in the development of resistance. These problems high lightened the need for the development of novel insect control alternatives. A new native entomopathogenic funguswas isolated from Phenacoccussolenopsis Tinsley from India and identified as Cladosporiumcladosporioides (Fresen.) de Vries. The entomopathogenicity of C.cladosporioides against nymphs and adults of P.solenopsis was studied at different doses viz., 106,107 and 108 conidia per ml. Nymphs were found to be more susceptible to infection than adults. A maximum of 100 per cent mortality of nymphs was recorded at 107 and 108 conidia per ml on nine days after inoculation (DAI) whereas at the same concentration 100 per cent mortality of adult was recorded on 10 DAI. When conidial suspension was sprayed on mealybug complete removal of waxy coating was observed within 24 hours after inoculation. When tested, C.cladosporium showed higher amount of lipase activity.Since pesticides cannot penetrate the heavy layers of wax that shield the body of waxy ovisac, reduction of the wax content of mealybug through application of C.cladosporioides could be one of the potential tool to control them. However more studies are needed to determine if C.cladosporioides can be used in IPM program of Cotton.
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