Rove beetles (Coleoptera Staphylinidae) – Their abundance and competition with other predatory groups in Bt maize expressing Cry34Ab1, Cry35Ab1, Cry1F and CP4 EPSPS proteins

• The effect of four different GM maize hybrids on rove beetles abundance were tested.
• Competition between Staphylinids and other predatory groups were assessed.
• No effects of GM maize on rove beetles were detected.
• Competition had stronger effects on rove beetles.

This study investigated the effects of different GM maize crops on the abundances of rove beetles. It also investigated competition between rove beetles and other epigeic arthropod predatory groups (ground beetles and spiders). Altogether a total of 5926 rove beetle individuals belonging to 25 species were collected. Whilst the average number of rove beetle individuals per replicate per sampling date varied and, moreover, decreased each year, there were no observed differences in rove beetle abundance when compared between isogenic and GM maize plots within the study period. Furthermore, no clear trends on positive correlations between weed coverage and rove beetle abundances were detected. Altogether a total number of 76,070 ground beetle individuals and 11,126 spiders (including all Araneae) were collected with pitfall traps. Analyses revealed a strong negative relationship between rove beetles and the other two groups in each treatment and year. According to the results the effect of interspecific competition on rove beetle abundance in GM maize is much higher than the effects of treatments including both Bt toxins and extra glyphosate applications.