Abstract
Insecticidal thiamethoxam and related heterocyclic compounds were examined using American cockroaches to see if they decayed to the acyclic neonicotinoid clothianidin and what was responsible for activity. The minimum insecticidal dose was 1.4 nmol for thiamethoxam, and 2.0 mmol for clothianidin, while the doses for triazine and thiadiazine analogues were evidently larger than that for clothianidin. In a physiological salt solution of thiamethoxam for 7 days, the appearance of clothianidin could not be confirmed, while the related compound triazine partly decayed to clothianidin. From these results, the prodrug concept does not necessarily apply to thiamethoxam but does to the triazine in the present experiment. Insecticidal and neuroblocking tests were also conducted for three chloronicotinyl derivatives of thiamethoxam, triazine and thiadiazine analogues, six N-desmethyl derivatives and three acyclic clothianidin analogues. © Pesticide Science Society of Japan
