Being exposed to low doses of pirimiphos-methyl and chlorfenapyr has detrimental effects on the mobility of Trogoderma granarium.

Abstract

Sublethal effects of insecticides may negatively affect several biological and behavioral traits of insects. The lethal effects of pirimiphos-methyl and chlorfenapyr have been previously tested successfully against Trogoderma granarium, but little knowledge is available about their diverse effects at low concentrations on male and female beetles. Herein, the sublethal effects of pirimiphos-methyl and chlorfenapyr on the mobility of T. granarium males and females were investigated. Lethal concentrations (LC) of pirimiphos-methyl and chlorfenapyr were lower for T. granarium females than males. LC values on males were LC10 = 0.000788 and 0.00139 mg a.i. cm-2 , LC30 = 0.00350 and 0.00535 mg a.i. cm-2 , and LC50 = 0.00986 and 0.0110 mg a.i. cm-2 for pirimiphos-methy and chlorfenapyr respectively. LC on females were LC10 = 0.000704 and 0.00136 mg a.i. cm-2 , LC30 = 0.00323 and 0.00428 mg a.i. cm-2 , and LC50 = 0.00925 and 0.0110 mg a.i. cm-2 for pirimiphos-methyl and chlorfenapyr respectively. The walking duration of beetles exposed to LC30 of pirimiphos-methyl was significantly lower than the individuals exposed to LC10 and LC30 of both insecticides and control ones. LC30 -exposed males remained more time on their back (101.7 s) than females (46.9 s), while the latter stayed immobile longer time than males (381.7 s vs. 371.9 s). The highest speed was recorded for control beetles (14.7 mm/s females vs. 12.44 mm/s males), while the lowest speed was observed in LC30 -treated males (8.36 mm/s) and females (9.66 mm/s). Overall, males and females exposed to low concentrations of pirimiphos-methyl and chlorfenapyr showed reduced motility. This knowledge can be exploited further to exploit behavioral effects of insecticides for effective pest management programs in warehouses. This article is protected by copyright. All rights reserved.