Prey stage preference and functional response of the Coccinellid, Nephus arcuatus Kapur in response to Nipaecoccus viridis (News(.

The spherical mealybug, Nipaecoccus viridis (News.), is a serious pest of citrus and other crop and non-crop plants. In this study the feeding behavior of Nephus arcuatus Kapur, the most important predator of N. viridis in Khuzestan province. This study was assessed out by determining prey stage preference of larvae and adult of lady beetles to different stage of mealybug and functional response of adult female lady beetles on its preferred prey. All experiments were conducted in laboratory at 30±1ºC, 65±5% RH, and a photoperiod of 14:10h (L: D). The results indicated that the eggs and females of mealybug were preferred more than any other stages by most stages of N. arcuatus. While, 1st instar was less preferred. Functional response was determined using logistic regression and the parameters, were estimated by non-linear regression using SAS program. The result revealed type III functional response of N. arcuatus. Constant (b) and handling time were 0.00811 and 0.2819 h, respectively. The maximum attack rate (T/Th) was calculated as 85.1 eggs. The eggs laid by female were increased with increasing prey density while, the food exploitation efficiency and efficiency of conversion of ingested food decreased. According to our results, N. arcuatus can be applied as an effective biological control agent against N. viridis.