Functional and numerical responses of Nephus arcuatus Kapur feeding on Nipaecoccus viridis (Newstead)

Document Type : Original paper

Authors

1 Department of Plant protection, faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

2 Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran

Abstract

In this study, the functional and numerical responses of Nephus arcuatus Kapur, one of the most important predators of Nipaecoccus viridis (Newstead), were investigated. N. viridis egg densities (2, 4, 8, 15, 40, 65, 90 and 115) were individually presented to a single mated female (3 days old). The prey densities were replaced every day for 33 days. The functional response was determined using logistic regression and the parameters were estimated by non-linear regression. The results revealed type III functional response of N. arcuatus. Constant coefficient (b) and handling time (Th) were estimated to be 0.00505 and 0.4163 h, respectively. The maximum theoretical predation rate (T/Th) was calculated as 57.7 eggs. The reproductive numerical response, in terms of egg laid increased curvilinearly with prey density and females laid 1 and 229.5 eggs at densities of 4 and 115, respectively. In contrast, the food exploitation efficiency was decreased with increasing of prey density. The similar shapes of both functional and numerical responses indicated that both were linked and that they function simultaneously. According to the obtained results, a ratio 1:115 (predator: prey) could be probably provided with an effective control, when releasing this predator for biological control of N. viridis.

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