Analysis of cockroach density and insecticide resistance of Blattella germanica in Xiamen from 2021 to 2023

WANG Xiaoyan; CAI Chunxiang; WU Sihan; LEI Lei; CHEN Bin; HUANG Jingwen; KE Xuemei

doi:10.19821/j.1671-2781.2025.05.004

Abstract：Objective To understand the population composition,density,infestation rate,seasonal fluctuation and distribution of cockroaches in Xiamen,and the resistance of Blattella germanica to three commonly used insecticides,so as to provide a scientific basis for the prevention and control of cockroaches.Methods From 2021 to 2023,the sticky trap method was used to monitor the density of cockroaches in six types of habitats in Xiamen.In 2023,the residual film method was used to determine the resistance of Blattella germanica to three commonly used insecticides,and the resistance level was determined based on the median knockout time(KT50).Excel 2007 and SPSS 27.0 softwares were used for statistical analysis.The rank sum test and Chi-square test were performed for cockroach density and infestation rate,respectively.Results The dominant species of cockroaches captured in Xiamen was B.germanica from 2021 to 2023,with a composition ratio of 99.38%.A total of 4 889 rooms were monitored,of which 373 rooms were positive,with an infestation rate of 7.63%.4 415 effective sticky cockroach sheets were recovered,and 4 011 cockroaches were captured,with a density of 0.91 cockroaches/sheet.The cockroach density in 2022 was higher than that in 2021 and 2023.The peak of cockroach density occurred in May,with a density of 1.19 cockroaches/sheet.The peak of infestation rate occurred in July,with an infestation rate of 8.98%.The highest density of cockroaches was found in farmers'markets(3.37 cockroaches/sheet),followed by catering industry,residential areas,hospitals and hotels,and the lowest density was in supermarkets(0.02 cockroaches/sheet).The highest infestation rate of cockroaches was in the farmer's market(20.12%),followed were captured by residential areas,catering industry,hotels and supermarkets,and the lowest infestation rate was in hospitals(0.69%).The resistance ratios to chlorpyrifos,cypermethrin and propoxur were 13.71,11.18 and 2.95,respectively.Conclusions B.germanica is the dominant cockroach species in Xiamen,and farmers'market has the highest infestation rate.B.germanica has high resistance to chlorpyrifos and cypermethrin and low resistance to propoxur.Insecticides should be used scientifically and reasonably based on the results of insecticide resistance surveillance to delay the development of resistance.