Abstract
The big-eyed bug Geocoris varius (Uhler) is a polyphagous predatory species distributed throughout agricultural areas of Japan. Although G. varius has much potential as a biological control agent, relatively little is known about the effects of agrichemicals on this species. We therefore evaluated the toxicity of eleven agrichemicals on 2nd instar nymphs of G. varius by topical application and oral administration. Using topical application, Fluvalinate, Methomyl, Chlorfenapyr, Pyridalyl, Sulfur and Triflumizole were harmless or slightly harmful to nymph survival. Conversely, topical application of five agrichemicals, including two insect growth regulator (IGR) chemicals, Dichlorvos, Acetamiprid, Chlorfluazuron (IGR), Lufenuron (IGR) and Pyridaben were moderately harmful or harmful to nymph survival. An examination of the oral toxicity of Dichlorvos, Methomyl, Acetamiprid and Pyridalyl showed that these four agrichemicals had little effect (slightly harmful) on the survival of nymph bugs. We also evaluated the sub-lethal effects (No. of consumed eggs of Ephestia kuehniella and developmental days of nymph, and head capsule width of emerged adult bug) of Chlorfenapyr, Pyridalyl, Sulfur and Triflumizole. These results showed that the characteristics of treated nymphs was not significantly different from those of untreated nymph bugs.
