Indoor Efficacy Of Four Insecticides Against Termites And Their Degradation In Soil

Termite is a group of socialized insect that causes serious damage in south area of the Yangtze River in China. Nowadays, termite control relys largely on chemical insecticides. Chlorpyrifos, bifenthrin, imidacloprid and permethrin belong to the termite prevention varieties that were recommended by China Association of Property Management Agents. They have also been widely applied in recent years. In this study, biological activity of chlorpyrifos, bifenthrin, imidacloprid and bifenthrin to a sub-ground termite. Reticulitermes chinensis Snyder,were assessed by topical application and by soil penetration test. We used clayey soil, loam and sandy soil of Bengbu area as the tested soil, and systematic study of the pharmaceutical distribution in the soil, degradation behavior. The feasibility of using these pesticides to control termites was based on the results in the Bengbu area.Biological activity test, the death of the LC50termite is the lowest chlorpyrifos,0.33mg/L; The highest is imidacloprid, the death of the LC50for163mg/L; Permethrin biphenyl, chrysanthemum of termites in death of ester of LC50were0.43mg/L,2.23mg/L. Thus it can be seen the elixir of the biological activity of termites order:chlorpyrifos> permethrin> bifenthrin> imidacloprid. In4kinds of medicament treatment soil soil penetration test, the group health potions, termites are going into the chlorpyrifos, imidacloprid different concentration of poison the soil, Chlorpyrifos group termite mean time to death than imidacloprid short. In sexual health potion group, termites neither enter bifenthrin, permethrin toxic soil, look at the time of death from the termites, the permethrin than permethrin caused by the short time of death of the termites in nearly12hours.In the test of distribution in indoor soil, we can see in the sandy soil experiment infiltrate-on agents slightly faster than clayey loam soil, and in the test of indoor soil column, gradient of results was more regular. Chlorpyrifos, bifenthrin, permethrin and imidacloprid in the clayey soil, loam, sandy soil in the1-7days after application,90%or more of soil chemical barriers are concentrated in the0-10cm soil column.The degradation tests interior and exterior showed that the degradation of Pharmacy in the soil was influenced by soil microbes. In addition to soil microorganisms, pesticide degradation in soil is also affected by soil physical and chemical properties. The trend of degradation speed of four pesticides in three sterile soil is the same, pharmaceutical degradation in non-sterile soil was faster than in sterile soil. The half-lifes of degradation of chlorpyrifos in the indoor test were from131.5days to245.1days, and the half-life of degradation in the field was about398.0days; the half-life of bifenthrin degradation in the indoor were from131.8days to257.2days, while the half-life of degradation in the field, was about894.0days; the half-lifes of degradation of permethrin in the indoor were from121.6days to217.9days, and in the field test, its half-life was about561.0days; the half-lifes of degradation of imidacloprid in indoor were from111.2days to172.2days, and degradation in the field test, its half-life was about443.0days.A scientific evaluation system about soil chemical barrier in termite prevention projects is not yet established currently. The studies make for the establishment of techniques and specifications of engineering construction of soil chemical barrier to prevent termite in Bengbu area, and are more important significance for prompting the applicability and operability of the construction techniques.