Biology and predatory potential of syrphid predators on Aphis fabae infesting Solanum nigrum L

Abstract

The biology and behaviour of Episyrphus balteatus, Eupeodes frequens [Eupeodes nitens], Metasyrphus corollae [Eupeodes corollae] and Betasyrphus serarius reared on Aphis fabae were studied under laboratory conditions. The average incubation period was 3.20 days for Episyrphus balteatus, 4.05 days for Eupeodes frequens, 3.28 days for M. corollae, and 3.10 days for Betasyrphus serarius. The larvae started feeding on the aphids from hatching to pupation. The average larval period for Episyrphus balteatus, Eupeodes frequens, M. corollae and B. serarius reached 6.75, 13.8, 7.4 and 10.25 days, respectively; the corresponding values of the average number of aphids consumed per larva were 416.25, 299.2, 354.4 and 288.75. For all predators, the duration of the 3rd instar larva was the longest. The larval period was significantly correlated with the rate of predation. A significant correlation was also observed between the size of the larva and the duration of the larval instar. The pupal period lasted for 6-7 days in Episyrphus balteatus, 9-12 days in Eupeodes frequens, 9-15 days in M. corollae, and 13.0 days in B. serarius. The longevity of male and female adults was greatest in Episyrphus balteatus (15.0 and 20.0 days) and lowest in Eupeodes frequens (6.67 and 8.67 days). Episyrphus balteatus was the most effective among the predators, followed by M. corollae, Eupeodes frequens and B. serarius.