Exploitation of Metarhizium anisopliae (Metch.) sorokin for management of gall weevil, Alcidodes colaris in pigeon pea

Mortality of Alcidodes colaris grubs to varied doses of Metarhizium anisopliae was evident. The lowest dose of 1 x 10⁸ conidia/litre water caused 33.3% and was followed by next high dose (2 x 10⁸ conidia/l), which caused 48.6% on 15^th day of treatment. Further increase in conidial load not brought significant increase in grub mortality. Similar was the response at 30^th day of treatment with highest % mortality. Therefore, further field scale studies were conducted to verify the performance of M. anisopliae isolate (Ma2) @ 2 x 10¹², 1 x 10¹² and 5 x 10¹¹ conidia/ha vis-a-vis recommended insecticides (chlorpyriphos 400g a.i./ha & endosulfan @ 700 g a.i./ha) and untreated check against pigeon pea gall weevil. Drenching of M. anisopliae @ 2 x 10¹² conidia/ha at 15 days after germination did not lag much behind the cliemical toxicants in pest suppression. Efficacy came at par with chemical toxicants at 30 days after treatment. The yield difference between fungus and chemical drenching was only 4%.