Control strategies against Tuta absoluta in tomato greenhouses

Abstract: Tuta absoluta (Lepidoptera: Gelechiidae) is an exotic pest very challenging to control. For a sustainable pest control, alternative approaches, including biological control, must be pursued. Therefore, laboratory, semi-field, and field trials were conducted in 2011-2012 to evaluate different control measures against T. absoluta and their side effects on predatory mirids (e.g., Dicyphus errans). In particular, Bacillus thuringiensis, emamectin benzoate, rynaxypyr and spinosad were tested and compared with the untreated control, and in the field also with the release of Macrolophus pygmaeus. In laboratory, rynaxypyr and B. thuringiensis were the most and the least effective against all instars larvae, respectively. In semi-field conditions, numbers of eggs laid by T. absoluta females on tomato plants, treated and untreated, were not significantly different, while the highest and the lowest numbers of larvae emerged on tomato plants treated with B. thuringiensis and rynaxypyr, respectively. In the field, the lowest population levels of T. absoluta were found in the rynaxypyr treatment in both years. However, all the tested insecticides could reduce the infestations of tomato borer without any evident side effects on the two predatory mirids D. errans and M. pygmaeus sampled on tomato plants during field surveys.