Effects of the pesticide dimethoate on a non-target generalist carabid, Pterostichus melas italicus (Dejean, 1828) (Coleoptera, Carabidae)

This study draws attention to the toxicity of dimethoate at sub-lethal concentration to beneficial carabid beetles living inolive groves agroecosystem of Calabria, Italy. Short- and long-term effects of dimethoate on a non-target generalist predatorin agroecosystems, Pterostichus melas italicus (Dejean, 1828) (Coleoptera, Carabidae) adults, were quantified by toxicitytest, total haemocyte counts and morphometric analyses. In laboratory toxicity tests, beetles of both sexes exposed to fieldconcentration of this toxicant showed a reduction of activity and a mortality of 10% after 72 h. Moreover, the impact ofdimethoate on the total haemocyte counts (THCs) was recorded as a significantly lower number of circulating haemocytes intreated animals compared to controls at 48 h. Morphometric analyses showed that dimethoate caused long-term sub-lethaleffects as a reduction of some morphometric parameters in P. melas italicus populations from two olive groves (treatedand natural). In addition, a significant reduction in body size of females from long-term treated olive grove and a sexualdimorphism alteration were observed. As a result, data suggested that dimethoate may cause sub-lethal effects on thisnon-target carabid species.