Imidacloprid-induced hormesis on the fecundity and juvenile hormone levels of the green peach aphid Myzus persicae (Sulzer)

Pesticide-induced hormesis may be an alternative mechanism for pest resurgence which is a serious problem in agriculture. Confirmation of the general phenomenon of hormesis may have significant implications for the design of pest control strategies and pest resistance management practices, although this has proved difficult due to the lack of appropriate methodology and the absence of well-defined mechanisms to support the experimental observations. In this study, a model-based approach to describe a dose-response relationship incorporating the hormetic effect was applied to the detection and estimation of imidacloprid-induced hormesis in the green peach aphid, Myzus persicae (Sulzer). The results indicated that imidacloprid at low concentrations induced stimulation of fecundity, however, high concentrations inhibition. This was reflected in an inverted U-shaped curve and related to the change of juvenile hormone III (JH III) levels in M. persicae. Fitting the data with quadratic and Weibull functions, which included a parameter for hormesis, showed that the magnitude of the hormetic effect was 31.31% for fecundity and 32.21% for JH III levels. The presence of hormesis in fecundity induced by imidacloprid may be related to the change in JH III levels in M. persicae. (C) 2010 Elsevier Inc. All rights reserved.