Fumigation activities of ethyl formate on different strains of Liposcelis bostrychophila

The psocid, Liposcelis bostrychophila is a prevalent insect pest in large grain depots in P.R. China. Our previous research proved that ethyl formate killed psocid adults of susceptible strain within 24 h, and the fumigation efficacy at relatively low temperature was better than that at relatively high temperature. In this paper, fumigation activities of ethyl formate on DDVP and PH₃ resistant strains of L. bostrychophila were studied by the sealed jar fumigation method under different ethyl formate concentrations, fumigation times, and temperatures. Results showed that treatment time and concentration significantly affected fumigation effectiveness of ethyl formate against L . bostrychophila adults at 30⁰C. The 50% lethal concentrations (LC₅₀) of ethyl formate against two resistant strains increased as the temperature increased from 20⁰ to 30⁰C. At 27±0.5⁰C and 24 h fumigation, the LC₅₀ were significantly lower for DDVP and PH₃ resistant strains than that of the susceptible strains and the LC₅₀ of DDVP resistant strains were significantly lower than that of PH₃ resistant strains.