Vector Surveillance and Control
LIU Yan, ZHAO Zhigang, HAN Yingnan, CAO Xinyue, SUN Qintong, CAI Tong, LIU Wenjie, WANG Xuejun
Objective To analyze the species composition, density distribution, seasonal fluctuation, and insecticide resistance of flies, particularly Musca domestica, in Shandong Province, China, thereby providing a scientific basis for the prevention and control of flies. Methods The cage trapping method was used for fly ecological surveillance, and the topical application method was employed to determine the insecticide resistance of M. domestica. Excel 2010 and SPSS 20.0 software were used to analyze the surveillance data statistically. The chi-square test was used to compare the composition of fly species. Fly densities were compared by the one-way ANOVA or the Kruskal-Wallis H test. The Probit regression model was used to calculate the median lethal dose (LD50), 95% confidence interval (CI), and virulence regression equation. Results From 2019 to 2023, a total of 10 371 fly traps were deployed in Shandong Province, capturing 68 668 flies, with an overall average density of 6.62 flies/cage. The dominant species were M. domestica, Sarcophagidae, M. sorbens, and Lucilia sericata, accounting for 57.31%, 10.35%, 8.26%, and 7.57% of the total catch, respectively. Among the four types of habitats, the density of flies in farmers' markets was highest, reaching 9.59 flies/cage, followed by green belts, catering surroundings, and residential areas, showing significant differences in fly density among different habitats (H=11.777, P<0.01). Fly density showed a unimodal pattern, with peak periods occurring from June to August. All habitats also displayed a unimodal pattern, with peaks occurring from June to July. M. domestica showed resistance to beta-cypermethrin, lambda-cyhalothrin, deltamethrin, permethrin, propoxur, temephos, but remained sensitive to tetramethrin, dichlorvos, malathion, and imidacloprid. Conclusions Shandong Province exhibits a diverse fly population, with dominant species, such as Musca domestica and Sarcophagidae, requiring targeted control efforts. Fly density peaks from June to August, and farmers' markets are key places for targeted fly control. Therefore, it is recommended that integrated control measures be implemented in key locations prior to peak fly activity periods to reduce fly density. M. domestica has developed varying levels of resistance to certain insecticides. Future control efforts should involve the scientific and rational use of insecticides to delay the emergence of resistance.