Efficacy of indoxacarb and chlorfenapyr against Subterranean termite Heterotermes indicola (Wasmann) (Isoptera: Rhinotermitidae) in the laboratory

Efficacy, feeding deterrence and transfer of indoxacarb and chlorfenapyr by the subterranean termite, Heterotermes indicola (Wasmann), were evaluated in laboratory tests at Nuclear Institute for Food and Agriculture (NIFA), Peshawar, Pakistan during 2013-2014. Chemical concentrations tested ranged from 1 to 100 ppm (wt/wt) of indoxacarb and 1 to 7 ppm (wt/wt) of chlorfenapyr. Observations revealed that indoxacarb caused rapid mortality at doses > 50 ppm. At 10 ppm, mortality was relatively slower and ELT50 and ELT90 (effective lethal exposure times for 50 and 90% mortality) were recorded as 6.7 and 25.3 d, respectively. At concentrations below 10 ppm, it took longer for indoxacarb to cause 100% mortality. In comparison, chlorfenapyr caused rapid mortality at all tested concentrations except the lowest concentration of 1 ppm, and 100% mortality occurred at 9 d, ELT50 and ELT90 calculated as 2.7 and 8.6 d, respectively. Various concentrations of both termiticides ranging from 1 to 100 ppm (wt/wt) were evaluated in feeding deterrence and transfer studies. The results showed that indoxacarb did not deter feeding of H. indicola at any concentration, and only consumption of filter paper treated with 100 ppm indoxacarb resulted in 100% mortality. Chlorfenapyr did not deter feeding at concentrations below 100 ppm. Mortality remained low regardless of concentration and did not exceed 60% in the feeding deterrence tests. In transfer studies, indoxacarb was successfully transferred from donors to recipients at concentrations of 70 and 100 ppm. Chlorfenapyr transfer generally caused low recipient mortality and transfer from donors to recipients was only evident at 1 ppm where recipient mortality exceeded 80%.