Lure-and-kill as Reduced-risk Strategy for Managing Helicoverpa spp. on Conventional Cotton Crops within Transgenic Cotton Fields

Abstract

Lure-and-kill strategy was evaluated for the management of eggs, larvae and adults of Helicoverpa spp. on conventional cotton crops located adjacent to transgenic (Bollgard II) cotton crops in a commercial cotton field in Australia. In this study, a newly developed Helicoverpa moth attractant called Magnet, (AgBiotech Pty Ltd, Australia) containing thiodicarb (Larvin 375) insecticide, was applied strategically as attracticide to BollgardII (transgenic (Bt)) cotton crops surrounded by conventional cotton crops. The study showed that the application of the attracticide onto BollgardII cotton crops indirectly reduced Helicoverpa spp. adult populations on adjacent conventional cotton crops by 91.5 per cent compared to 40 per cent on conventional cotton crops located near an "untreated" BollgardII cotton crops. Similarly, the number of Helicoverpa spp. eggs and larvae on the conventional cotton crops located near the "treated" BollgardII crops was significantly lower than the conventional crops near the "untreated" Bollgard II crops. In terms of gross margin, there was a saving of $11.40 per ha for Helicoverpa spp. control on conventional cotton located adjacent to the BollgardII cotton crops treated with the attracticide compared to conventional cotton crops adjacent to the "untreated" BollgardII crops. The predominant natural enemies identified from the study plots were predatory beetles, bugs, lacewings and spiders. The results showed that the number of predators per metre recorded on Bollgard II cotton crops treated with and without Magnet mixed with insecticides and the adjacent conventional cotton crops were not significantly different (P>0.05). In conclusion, the use of the attracticide formulation in a "lure-and-kill strategy on transgenic (Bt) cotton crops could conserve predatory insects and reduce Helicoverpa spp. infestation and the overall cost of pest control on adjacent conventional cotton crops.