Abstract

The suitability of three aphid species; Aphis craccivora, Aphis illinoisensis and Hyalopterus pruni for the coccinellid Exochomus nigromaculatus development and reproduction was evaluated. The three-aphid species were separately fed to larval instars and adults. The developmental period was significantly shorter (23.13 ± 0.29 days) when the coccinellid was fed on Aphis craccivora and longer (30.6 ± 0.32 days) when the predatorwas fed on H. pruni. The lowest immature stages mortality was recorde d when they were fed A. craccivora (6.67%) followed by those fed A. illinoisensis (8.33%) and H. pruni (12.5%). The ladybird larvae were significantly most voracious towards H. pruni (443.4 ± 32.35 nymphs/larva) but significantly least voracious towards A. craccivora (206.6 ± 20.11 nymphs/larva). Adult longevity was significantly longer and the feeding capacity was significantly higher when the predator was fed A. craccivora. E. nigromaculatus was most fecund when fed on A. craccivora (306.6 ± 37.81 eggs/female) and less fecund when fed on A. illinoisensis (186.6 ± 45.66 eggs/female). Laboratory measurements of the fitness parameters indicated that A. craccivora was the most suitable aphid prey for feeding laboratory colonies of E. nigromaculatus. In addition, this study might provide useful information for the utilization of this ladybird in IPM programs of broad bean and stone fruit trees.

Key words: Exochomus nigromaculatus, Aphis craccivora, Aphis illinoisensis, Hyalopterus pruni, development, feeding capacity, reproduction