| The housefly (Musca domestica) is an important public health pest. Its resistance to commonly used insectides is becoming an obstacle for effective control of this pest. Therefore, the research and management of insecticide resistance is an important part of the housefly prevention work. In this study, we conducted bioassay against three insecticides using field populations collected across Tianjin. We also amplified fragments of mdae7, vsscl and cyp6dl genes respectively and obtained their sequence information by direct sequencing. The allele distribution frequencies of these genes in the studied populations were also recorded.By comparing with the the historical data including the resistance levels in the Musca domestica, and the amounts and types of insecticides used in house fly control, we revealed the trend of resistance development, and make suggestions for resistance management. The main findings are as follows1. Resistance against the three commonly used insecticides (deltamethrin, propoxur and D DVP) was dected in house flies in Tianjin city. Deltamethrin resistance remains at a re latively high level with a resistance factor of around30fold. Similar situation was lo found for DDVP resistance. However, much lower resistance to propoxur was observed2. As compared with the resistance data in history, houseflies displayed a varia ble levels of insecticide resistance in the last decade. Great change in resistance was detected for propoxur, the resisance factor in S1region decreased from86-f old in2003to1.4-fold in2013.,likely because propoxur faded out from the insec ticide list for housefly control, providing a successful case for insecticide resistanc e management by a insecticide-rotation strategy.3. Diverse genetic variations in mdae7, vsscl and cyp6dl genes associated with insecticide resistance were detected in house flies used in this study. We found seven genotypes for mdae7gene and5for vsscl gene. The frequencies of resist ant alleles stay at a relatively high level,. |
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