Residual efficacy of chlorfenapyr for control of stored-product psocids (Psocoptera).

The residual effect of chlorfenapyr (Phantom) was evaluated for residual control of three stored-product psocid species: Liposcelis bostrychophila Badonnel, Liposcelis entomophila (Enderlein), and Liposcelis paeta Pearman (Psocoptera: Liposcelididae). Chlorfenapyr was applied to individual arenas with a concrete surface at rates of 0, 2.8, 13.8, 20.6, 27.5, 55, and 110 mg active ingredient (AI)/m2. Adults were exposed on the treated arenas and mortality assessed after 1, 2, and 3 d. The procedures were repeated weekly on the same treated arenas for 3 wk to assess residual efficacy. At each week, mortality of all species was low after 1 d of exposure but notably increased after 2 or 3 d. L. entomophila was the most susceptible species, with 99-100% mortality at rates of 13.8 mg/m2 or higher. Similarly, mortality of L. paeta after 3 d of exposure at the same concentration ranged from 92 to 100%. L. bostrychophila was the least susceptible species, with mortality of < 60% during the third week after application at rates < or = 27.5 mg/m2. However, even for this species, mortality after 3 wk was 90% or higher at rates > 27.5 mg/m2. Complete mortality of all species occurred after 3 d exposure at the highest rate tested of 110 mg/m2. Thus, our results show that chlorfenapyr is effective against major psocid species at the application rates evaluated in this study.