Liu_2008_Pestic.Biochem.Physiol_91_45

Effects of high temperature on insecticide susceptibility and fitness were studied in the field population of Plutella xylostella (L.) (Lepidoptera: Plutellidae) (R DBM) and a susceptible field-insectarium population of P. xylostella (S DBM). R DBM displayed 18.3-fold resistance to methamidophos and 74.0-fold resistance to avermectin. The population growth tendency index (I) values were 41.8 (S DBM) and 27.7 (R DBM) at 25 C, and 1.19 (S DBM) and 0.23 (R DBM) at 33.5 C. The level of methamidophos resistance in the progenies of R DBM declined sharply when reared at high temperature for one generation. The increase of susceptibility to methamidophos appeared to pass from generation to generation. S DBM displayed higher up-regulation of Hsp70 expression at high temperature than R DBM. It was suggested that low fitness in R DBM caused by high temperature might be involved in the sharp decline of methamidophos resistance under high temperature conditions.