Biology and foraging behaviour of Oenopiakirbyi Mulsant (Coleoptera: Coccinellidae) on melon aphid, Aphis gossypii Glover

Abstract

Oenopia kirbyi Mulsant is an important naturally occurring predator of Aphis gossypii Glover in cucumber. Before recommending the natural enemy against any pest it is important to investigate the feeding efficiency and density responsiveness of the given natural enemy. We, therefore, studied the biology and predatory potential of O. kirbyi against this aphid in the laboratory at 25 ± 0.5 °C, 70 ± 5% RH and 12L: 12D photoperiod. Incubation, total larval, pre pupal and pupal period of O. kirbyi was 3.40, 15.26, 1.30 and 4.80 days, respectively. Females on an average laid 177.60 ± 6.38 eggs. Pre oviposition, oviposition and post oviposition period of O. kirbyi was 6.92, 23.22 and 5.48 days, respectively. Adult female and adult male consumed an average of 2634.78 and 2012.52 aphids in their life span of 38.50 and 31.38 days, respectively, whereas, total prey consumption during the larval stages was 535.90 aphids/ predator. All the predator stages exhibited a type II functional response to the aphid. Based on Rogers’s random predator equation, the attack rate was lowest (0.065) in the first-instar and highest (0.171) in the adult stage. Handling times of the adult and the fourth-instar stages (0.237 and 0.263 h, respectively) were much shorter than other stages. Study indicates that the adults and the fourth-instar grubs were the most voracious stages and could be considered for the biological control of the aphid after field evaluation.