Potential of the entomopathogenic fungus, Metarhizium anisopliae s.l. for control of red spider mite, Oligonychus coffeae Nietner on tea crop

Abstract

ABSTRACT The present study evaluates the pathogenic efficacy of an entomopathogenic fungus, Metarhizium anisopliae s.l. (=M.anisopliae) against the red spider mite, Oligonychus coffeae damaging teaplants. Laboratory studies revealed that M. anisopliae s.l. was pathogenic onO. coffeae and exhibited 78% mortality. Evaluation of formulated 5% aqueoussuspension (AS) of M. anisopliae (1000 ml containing 2 × 107 conidia/ml in 400L of water/ha) against O. coffeae through micro-plot study revealed a maximumof 68.2% reduction in mite’s population in sprayed plots, as compared toFenpyroximate (5% EC), where a 67.5% reduction in mite’s population wasrecorded. Furthermore, large-scale field trials with aqueous suspension ofentomopathogen revealed that 1000 and 1200 ml doses of M. anisopliae s.l. 5%ASeach in 400 L of water/ha significantly reduced O. coffeae’s population in thetea gardens of Dooars and Darjeeling regions, India. Metarhizium anisopliaes.l. was more effective than standard acaricides and was non-pathogenic to thebeneficial insects present in the tea gardens. Metarhizium anisopliae s.l. 5%AShad no phytotoxic effect on the tea leaves, with acceptable organolepticattributes. Thus, M. anisopliae s.l. isolate can be commercialized as analternative natural acaricide to reduce the load of synthetic acaricides in thetea crop.