Assessment of predatory activity of insects against Lymnaea auricularia and Gyraulus convexiusculus.

摘要

Predatory activity of eight species of insects/insect larvaymph viz., Laccotrephese ruber., L. griseus, Diplonychus rusticum, Ranatra elongata, Cybister tripunctatus, Sternolophus sp., Hydaticus sp. larva and nymph of Anax parthenope was studied against two vector snails of Punjab viz. Lymnaea auricularia rufescens and Gyraulus convexiusculus. Two numbers of insects/larvaeymphs were exposed to 10 snails of average size in biologically balanced aquaria for seven days. L. auricularia on an average, was predated upon 80% by L. ruber, 6.2% by L. griseus, 40% by D. rusticum, 71.2% by C. punctatus, 20% by Sternolophus sp., 67.5% by larva of Hydaticus sp. and 50% by nymph of A. parthenope. Average consumption of G. convexiusculus has been 3.7% by L. ruber, 5.0% by L. griseus, 61.2% by D. rusticum, 72.5% by C. tripunctatus, 22.5% by Sternolophus sp., 5% by Hydaticus sp. larvae and 90% by A. parthenope nymph. Ranatra elongata did not consume any of the two snail spp. So, it was observed that L. ruber was the best predator of L. auricularia, while G. convexiusculus was maximum consumed by A. parthenope nymph. An assessment of predatory activity was made in the present study in order to control snail biologically and to keep an aim on the non-chemotherapeutic control of snails.