Study On The Hormesis Induced By Insect Growth Regulator On The Diamondback Moth,Plutella Xylostella (L.)

Diamondback moth, Plutella xylostella L.(Lepidopra:Plutellidae), is major damage cruciferous vegetables, almost distributed in cruciferous planting areas, is a worldwide pest. DBM have more generations in one year, and generations overlap serious. Also propagation speed, resistance to pesticides rapidly, so the diamondback moth is very difficult to prevention and control. In this paper, we research on hormesis associated with four insect growth regulators (flufenoxuron, lufenuron, chlorbenzuron, tebufenozide) on the diamondback moth of growth and development, and chemical ecology.Observational studies on the DBM of growth and development, designed four IGRs (flufenoxuron, lufenuron, chlorbenzuron, tebufenozide) to deal with the1instar larvae of the DBM, and observed their growth and development. The results show that:there were the hormesis phenomenon appeared of larvae, pupae and adults of the DBM, which were dealed with flufenoxuron. Lufenuron was significantly inhibited the growth and development of larvae of the diamondback moth, but the pupae and adults appeared hormesis phenomenon. Chlorbenzuron showed significant inhibition of growth and development of larvae and adults of the DBM, even though hormesis happened with the pupae. Tebufenozide stimulate with the growth and development of larvae and pupae of the DBM, but it inhibited the growth of the adult.Designed flufenoxuron, lufenuron, chlorbenzuron, tebufenozide deal with the larvae of diamondback moth, respectively; and observed their mating behavior and reproduction. The results are as follows:the diamondback moth appeared hormesis which were fed on leaves treated with flufenoxuron; the diamondback moth treated with LC30and LC40had the highest pupation rate, emergence rate and mating success rate. The DBM treated with lufenuron showed hormesis, stimulate increased pupation rate and emergence rate by low concentrations (LC10and LC20), were decreased by inhibited at high concentrations. The diamondback moth treated with the LC70of chlorbenzuron had the highest mating success rate of all. The mating rate of the DBM treated with tebufenozide appeared peak also at low concentrations LC20, and higher concentration of LC60, LC70.Study on Insect growth regulators impact on the chemical communication between diamondback moth and host plants. The results show that, the directional selection behaviors of the DBM to host plants were affected significantly by IGRs; females affected more inhibition than males. However, the hormesis phenomenon were appeared with the DBM to the correct orientation of plant volatiles, which treated with flufenoxuron, lufenuron and tebufenozide, except chlorbenzuron.This experiment also found that the males treated with chlorbenzuron always had higher success rate of directional selection on plant volatiles than females.Studies on IGRs impact on the chemical communication of sex pheromone of the DBM, the directional selection behavior of sex pheromone of adults were showed significant inhibition by the IGRs. However, hormesis appeared in the correct orientation of sex pheromone of the DBM treated with flufenoxuron and tebufenozide. We found a phenomenon that female-directed correct rate higher than males’, treated with a particular concentration of all IGRs.Also found in the experiment, the high concentrations of chlorbenzuron actually rised the correct choice rate of sex pheromone of the DBM.