Toxicity of certain insecticides toSturmiopsis inferens, a larval parasite of sugarcane moth borers

Abstract

Susceptibility of adults and puparia of Sturmiopsis inferens Tns. [Tachinidae, Diptera] to 9 commonly recommended insecticide sprays against sugarcane pests was determined. The chemicals tested as emulsifiable concentrates include lindane 0.1%, endosulfan 0.1%, monocrotophos 0.05 %, quinaiphos 0.05 %, malathion 0.1%, dimethoate 0.1%, cypermethrin 0.01%, fenvalerate 0.01% and decamethrin 0.0014 %. Lindane, malathion, dimethoate, monocrotophos and quinalphos were highly toxic, while decamethrin had little harmful effect to the adults when exposed for 6 h to filter paper impregnated or sugarcane shoot bits sprayed with the chemicals. However, the insecticides had no harmful effect on the puparia and adult emergence was normal from the puparia sprayed with insecticides.In another study, susceptibility of adults to soil application of lindane EC, carbofuran G, chlorpyriphos G, Sevidol G and whorl application of lindane G, chlorpyriphos G and Sevidol G was tested in pot culture. Except for soil application of lindane EC, all other chemicals had no harmful effect to the adults in pot culture experiment. In a field trial, commonly recommended insecticides against shoot borer, Chilo infuscatellus Snell. viz., soil application of granules of lindane, carbofuran, chlorpyriphos and Sevidoi and folia spray of endosulfan did not affect the parasite activity. KEY-WORDS : Sturmiopsis inferens, safety of insecticides.Sturmiopsis inferens Tns. [Tachinidae, Diptera] is an important larval parasite of several species of moth borers that damage sugarcane in India (David & Easwaramoorthy, 1986).The level of natural parasitism varied from 6.5 to 26.2 % in shoot borer, Chilo infuscatellus Snell. (David & Easwaramoorthy, 1981), 20 to 50 % in stalk borer C. auricilius Ddgn. (Singh, 1977) and 5.8 to 10.2 % in Gurdaspur borer, Acigona steniellus Hampson (Chauflhary et al., 1980). S. inferens also parasitise minor pests of sugarcane like pink borer, Sesamia inferens Wlk., and sorghum borer, C. partellus Swinhoe.In India, insecticide applications are not widely practised in sugarcane culture compared to other cash crops. However, certain insecticides are occasionally applied for the management of moth borers especially shoot borer and sucking pests like leafhopper, Pyrilla perpusilla Wlk., whitefly Aleurolobus barodensis Mask. and scale insect, Melanaspis (') Institute Publication No 1030.

A 100 years of biological control of sugarcane pests in India: review and perspective.

“…Conservation of natural enemies occurs as a natural process in the relatively stable sugarcane crop ecosystem where pesticide consumption is far lower than in other crops [364,365]. Nevertheless, relative safety of conventional and non-conventional insecticides to T. chilonis [145,366], St. inferens [367], A. mayurai [368], C. flavipes [221], predatory spiders [229], D. aphidivora [369] and EPF [341] was examined to promote their selective application. Early and sustained activity of A. barodensis parasitoids in unsprayed plots rather than in aerially sprayed plots, despite lack of difference in pest population status [370], emphasized the role of conservation of natural enemies in a stable crop system.…”