author(s)
Naglaa M Youssef and Nabil M Ghanim

abstract
Searching rate, mutual interference, and killing power were studied for two predator species, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) and Hyperaspis vinciguerrae Capra (Coleoptera: Coccinellidae) fed on the cotton mealybug, Phenacoccus solenopsis Tinsley under laboratory conditions of 27±2°C and 70±5% RH. The predator C. carnea showed relatively higher searching rate on the prey nymphs in comparison with its adults. By increasing predator density, the searching rate on prey adults was slightly decreased in comparison with prey nymphs. Mutual interference value on adults was lower than on nymphs. On another hand, Killing power (as K-value) of C. carnea and H. vinciguerra was generally higher on P. solenopsis nymphs in comparison with adults. Generally, C. carnea larvae were more effective on the nymphs and adults of cotton mealybug, P. solenopsis than H. vinciguerra adults. So, the predator C. carnea can play an effective role in controlling P. solenopsis population when the predator: prey ratio is about 1: 10. Accordingly, in augmentative biological programs of P. solenopsis by predators, predator: prey ratio has to be accurately estimated to minimize the negative effects of interference on foraging efficiency.