Research on the Inert Dust against Phosphine Resistance of Cryptolestes Ferrugineus

Laboratory tests were carried out in order to evaluate the efficacy of five inert dust (Puliangtai, G-1, G-2, G-3 and G-4) against the high level phosphine resistance Cryptolestes ferrugineus (Stephens). The relative phosphine resistance of two strains of Cryptolestes ferrugineus (Stephens) was measured by the method of knockdown at 2 mg/L of phosphine. The insects were exposed to the five inert dust on filter paper inside petri dishes for 1 day at 30 ± 1 and 65 ℃ ± 1% relative humidity. Then, the adults were held for 4 days with food at the same conditions without inert dust in surface bioassay. Also, they were placed in 25 ± 1 and 65 ℃ ± 1% relative humidity in grain bioassay. In surface bioassay, two strains (JXCF and YYCF) of Cryptolestes ferrugineus (Stephens) were susceptible to the five inert dust at 0.08 g/m 2 and 0.1 g/m 2 . G-3 appeared the most effective treatment against both strains, since its efficacy was 3-6 times higher than the other four inert dust tested. YYCF strain was more susceptible than JXCF, with 1-4 times higher mortality level. This research indicated that inert dusts were effective on phosphine-resistance Cryptolestes ferrugineus (Stephens) populations.