Comparative susceptibility of chironomid larvae (Dipt., Chironomidae) to Bacillus thuringiensis serovar israelensis with special reference to altered susceptibility due to food difference

Abstract

AbstractBacillus thuringiensis serovar israelensis exhibited larvicidal activities, with varying degrees, against detritusfeeding larvae of the six species belonging to the subfamily Chironominae (Dipt., Chironomidae): Chironomus kiiensis, Chironomus yoshimatsui, Dicrotendipes pelochloris, Glyptotendipes tokunagai, Paratanytarsus sp., and Stictochironomus akizukii. Of these, the most susceptible were C. kiiensis, C. yoshimatsui, and Paratanytarsus sp.; in these species a high/rapid mortality (70–100%) occurred within 2 days at a bacterial concentration of 17 μg/ml. The least susceptible was S. akizukii. The degree of difference in susceptibility ranged from 10 to 1000 times among the six species.There was a marked difference in susceptibility between two larval populations of a euryphagous species, Pentapedilum tigrinum, when reared on different foods prior to treatment; the larvae reared on aquatic plant tissue were 100 times more susceptible than the larvae fed on detritus.