Monitoramento e caracterização da resistência da traça-do-tomateiro Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) a diamidas

Abstract

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is currently one of the most important pests for tomato growing in Brazil, but it has gained prominence in the world scenario mainly after its introduction in some European countries, North Africa, East and in neighboring countries China, the world's largest tomato producer. Diamides are the newest insecticides used to control this species. In the initial registration phase, these insecticides showed a very effective control, with a homogeneous response at low doses. However, after two years of use, the first reports of control failures emerged. Therefore, the objective of our study was to identify populations resistant to these insecticides, and later to characterize this resistance genetically. The populations of T. absoluta submitted to the first experiments presented significant variations in response to diamides, with heterogeneous resistance levels to chlorantraniliprole, cyantraniliprole and flubendiamide with resistance ratios based on LC50 values reaching 288,995 times for chlorantraniliprole, 18,423 for cyantraniliprole and 80,413 to flubendiamide. After being subjected to successive selections with increasing doses of chlorantraniliprole the population of America Dourada (AMD) showed the highest level of resistance already mentioned for chlorantraniliprole with a resistance ratio of 1,076,957 times, and the selection of this population in laboratory has also increased plus the level of resistance to cyantraniliprole and flubendiamide, noting the cross-resistance between these insecticides. However, no cross-resistance was observed with other classes of insecticides. The characterization of the resistance of T. absoluta to diamidas was autosomal, incompletely recessive and monophatorial. There was no direct association of resistance levels observed with enzyme activity, indicating that metabolism is not involved with T. absoluta resistance to diamides.