A sublethal dose of thiamethoxam impaired the foraging and discrimination ability of the ant Camponotus japonicas

[Objectives] The sublethal effects of thiamethoxam, a neonicotinoid insecticide, were evaluated on the foraging and discrimination behaviors of the ant Camponotus japonicus, with special attention on the indirect effects through individual communication among ants. [VI el hods J By simulating the foraging situation, the change of foraging ability of ant in different treated groups was observed. Through the Y-tube test and EAG (electroantennography) test, the ability of different treated groups of ants to the nestmates and non-nestmates was observed. Based on the changes in the discrimination ability, the ability of different treatment groups of ants to discriminate the heterologous ants was observed in the aggressive behavior test. [Results] There was no significant difference in the ability of different treated ants to find food, but there was a difference in foraging efficiency. The control ants performed recruiting behavior, while the indirectly treated ants and the directly treated ants did not. The control ants showed difference to indirectly treated ants and directly treated ants in discriminating the nestmates and non-nestmate, the control ants could discriminate the non-mates well, but the others couldn't discriminate the non-nestmates well. When discriminating the nestmates, there was no significant difference among different treated ants. In the attack tests,the direct treatment with sublethal thiamethoxam remarkably reduced the aggressive behavior when compared to the control ants. However, the aggressive behavior of indirectly treated ants showed no significant differences from control and directly treated ants. [Conclusions] The sublethal thiamethoxam can directly affect the foraging and discrimination ability of the ants. Through the communications between the ants, the directly treated ants can deliver these negative effects to others which have not been directly exposed to insecticides. The treated ants affect the development of colony of the ants.