Tomato leafminer, Tuta absoluta, and insecticide resistance:a new challenge for control strategies

Abstract: The tomato leaf miner, Tuta absoluta (Lepidoptera), is a significant pest of tomatoesthat has undergone a rapid expansion across Europe, North Africa and parts of Asia during thepast six years. One of the main means of controlling this pest is through the use of chemicalinsecticides. In the current study leaf-dip bioassays were used to determine the susceptibility ofT. absoluta strains established from field collections to several insecticides. Additionally, thepara-type sodium channel and acetylcholinestaerase gene from T. absoluta were cloned andsequenced. This revealed the presence of three kdr/super-kdr-type mutations (M918T, T929I andL1014F) in the sodium channel gene and mutation (A201S) in the acetylcholinesterase gene. Toassess the prevalence of these mutations in 27 field strains from 12 countries high-throughputTaqMan diagnostic assays were developed. The results showed the presence of these mutations athigh frequency in T. absoluta populations world-wide and suggests pyrethroids and organophosphatesare likely to be ineffective for control. These results also support the idea that therapid expansion of this species over the last six years may be in part mediated by the resistance ofthis insect to chemical insecticides hence adding new challenges to control strategies for this pest.