Biology and predatory potential of aphidophagous syrphids on guava aphid, Aphis gossypii Glover (Hemiptera: Aphididae).

Abstract

The biology of four species of aphidophagous syrphids, namely, Paragus serratus (F.), Episyrphus balteatus (De Geer), Ischiodon scutellaris (F.) and Dideopsis aegrota (F.) was studied on guava aphid, Aphis gossypii Glover, during 2007-08 and all the four species successfully completed their life cycle on A. gossypii. P. serratus had the shortest life cycle on A. gossypii with a total developmental period of 20.7 ± 1.36 days, followed by E. balteatus (21.5 ± 1.17 days), I. scutellaris (21.8 ± 0.91 days) and D. aegrota (26.3 ± 1.08 days). The total larval period of P. serratus, I. scutellaris, E. balteatus and D. aegrota averaged 9.8 ± 0.82, 10.6 ± 0.43, 10.0 ± 0.56 and 11.2 ± 0.64 days, respectively. The pupal period, fecundity and longevity of the syrphids on A. gossypi i were recorded. In order to complete the larval period, each larva of P. serratus, I. scutellaris, E. balteatus and D. aegrota required a total of 333.7 ± 59.12, 380.7 ± 75.85, 410.8 ± 87.60 and 472.5 ± 56.89 numbers of A. gossypii , respectively.