Translated Abstract
Background:
Blattodea commonly known as cockroaches, is an ancient species, also a kind of alien species. Since 1980s, we can see cockroach all over the country. Blattodea belongs to incomplete metamorphosis insect， whose life history consists of three stages: egg, nymph and adult. There are mainly 5 kinds of cockroaches， including Blattella Germanica, Periplaneta America,Periplaneta Australasiae, Periplaneta Japonica and Periplaneta fuliginosa. Among them, Blattella germanica and Periplaneta Americana are the most common. The Periplaneta America is usually distributed in the warm regions of the South and the eastern coast of China. Blattella germanica is more widely distributed duing to its strong fecundity and well adaptability. It is also distributed in the west of China and the cold regions in the north. With the rapid development in recent years， the transport revolution and population flowing provides convenience for the spread of cockroach. At the same time, cockroach control has never ceased. From the early inorganic insecticides to organochlorine pesticides， it has gone through hundreds of years＇ development from early high efficiency and high toxicity to modern high efficiency and low toxicity or even non-toxic. Since pyrethrin was developed in China in the 1970s , it has been widely applied in agriculture, forestry and health industry because of its high efficiency, low toxicity and low residual. But the resistance caused by irrational usage of pesticides has become a prominent problem. In 1996-2009,literature reports that German cockroach generally were resistant to common insecticides There are 1/3 tested areas of Blattella germanica were resistant to permethrin.
Objective:
To master the infestation status and the fluctuation of the Resistance Coefficients of cockroach to common insecticides, we conduct this investigation and the experiment , providing a scientific basis for cockroach management in Xi＇an.
Methods:
The investigation was in accordance with the National Medical Vector Monitoring Scheme, using stickingstrap method. In the whole city， six monitoring sites were selected, and each monitoring site selected five monitoring industries, including market,hotel,catering,hospital and residential. The monitoring frequency is once a month from January to December. Film Method recommended by WHO was used to test cockroach pesticide resistance. The diluent pesticide film with acetone configured different concentrations. The measured concentration of diluted solution of 2.5 ml in 500ml transparent jar,scrolling the jar,the dilution liquid was evenly dispersed to form membrane on the bottle wall and at the bottom of the bottle. Carrying out the experiment within 24h after the acetone volatilize completely. Applying the mixture of paraffin and Vaseline on the bottle neck of the bottle to prevent the worms from escaping. The blank control group was 2.5ml acetone. Each group was 10 healthy male adults and placed in a jar. Counting the knockout number of the insect at different time points. 3 times repeated and the experiments were carried out as before. KT50 95%CI and the resistance coefficient were calculated.
Results:
In 2013-2017, a total of 18960 sticking papers were retrieved, and the positive number was 1315, the average infestation rate was 6.65%, the average cockroach density was 0.24 pieces. The highest was in 2013. The lowest was in 2016. After chi square test， the differences of infestation rate between years were statistically significant( χ2=131.71,P=0.01). The highest average density was in 2013, and the lowest average density was in 2017. ANOVA tests shows the results were statistically different( F=2.830,P=0.03). The cockroach density trend of 2013-2017 showed a single peak distribution, whose peak was from July to August and the trough in December. A total of 4318 cockroacheswere caughtdruing 5 years，after identification,of which the average composition of Blattella germanica accounted for 95.11%, P.fuliginosa5.03%,P. japonica 0.69%. Through chi square test,cockroach species between years were different(χ2=394.046, P=0.01). Blattella germanica was the dominant species in Xi’an. Among the five monitoring industriess, the Catering was 19.24%,whose infestation rate was the highest; and the lowest was 3.32%. Meanwhile, the cateringindustriesgot the highest density of five monitoring industriess, that is 0.73; monitoring of industries average density is the lowest in hospital industries, 0.03. By the chi square test, different industries monitoring cockroach infestation rate had significant difference (χ2=564.38, P=0.01); Among the five monitoring industriess，the hospital industries of cockroach density for a minimum of 0.03, the highest density of dining industries was 0.73. Through analysis of variance, different industriess of cockroach density had significant difference (F=13.218,P=0.01). Among the six monitoring sites, the rate and density of different monitoring sites were not exactly the same.The KT50 of sensitive insects were dichlorvos 7.232min, chlorpyrifos 3.892min, dichlorvos 4.863min, propoxur 5.110 min, deltamethrin 7.099min, cypermethrin 5.540min. The KT50 of the field insects were dichlorvos 31.985min, chlorpyrifos 6.592min, dichlorvos 16.902min, propoxur 5.780min, deltamethrin 8.125min, cypermethrin 15.691min. After calculation, Blattella germanica resistance coefficient of acephate, DDVP and beta-cypermethrin were 4.42, 3.48 and 2.83 respectively.According to the classification criteria,there has low resistance to those three insecticides; and resistance coefficient to deltamethrin propoxur decamethrimwere 1.69, 1.13 and 1.14.
Conclusion:
1. The average density of cockroaches in Xi＇an was 0.23,and the average infestation rate was .generally includeing German cockroach, Periplaneta fuliginosa and Periplaneta japonica. Blattella germanica was the dominant species.
2. The infestation rate differed between industries. Catering was the highest, and the residential was the lowest.
3. Blattella germanica in Xi’an has developped low resistance to acephate, dichlorvos and cypermethrin.
Translated Keyword
[Cockroaches, Infestation, Insecticide, Resistance]
Corresponding authors email
