Effects Of Insecticide On Copulation Preponderance And Reproduction Of Males Nilaparvata Lugens (St(?)l)(Homoptera:Delphacidae)

Brown planthopper (BPH) Nilaparvata lugens(St?l) is an important insect pest of rice in China and often outbreaks in the major rice producing areas in recent years.The use of pesticides was considered as the main factor for resurgence, especially sublethal dose of some insecticides stimulates the reproduction of N.lugens. Accordingly, the examination of BPH resurgence mechanism was important significance for sustainable control of the pest. In this paper, we researched the changes of reproduction of female via mating with males which treated with insecticides, and effects of insecticides on mating behavior of BPH. The results are as follows:1. Effects of insecticide-treated males on female reproductionThe present experiment studied the changes of fecundity of females mated with males developed from 3rd and 5th instars treated with LC10 and LC50 concentrations of triazophos and deltamethrin and effect of multiple males on fecundity of females via mating. The results showed that fecundity of females that the males (♂t)developed from 3rd instar nymphs treated with LC50 triazophos were mated with treated females (♀t) was significantly higher than that that the untreated males(♂ck) mated with untreated females (♀ck) and♂ck×♀ck, increasing by 56.4% and 20.1%, respectively. Fecundity of females that the males (♂t) developed from 5th instars treated with LC50 triazophos were mated with treated females (♀t) was significantly higher than that that the untreated males(♂ck) mated with untreated females (♀ck), increasing by 41.3%. No significant differences of fecundity of females among other mating pairs were found. Fecundity of females that the males (♂t) developed from 5th instar nymphs treated with LC50 deltamethrin were mated with treated females (♀t) was significantly higher than that of other mating pairs. For both LC10 triazophos and LC10 deltamethrin treatments, no significant differences on fecundity of females for all mating pairs were found. For pairs of multiple males with single female, fecundity of females for the pairs of four treated males with single treated female and pairs of four treated males with single untreated female was significantly higher than that was significantly higher than that for four untreated males with single untreated female.2. Effect of insecticide on copulation preponderance of malesThe present paper also studied effect of insecticide on both copulation times and mating time associated with copulation preponderance of males. The results showed that no significant differences of copulation times and mating time between males treated with LC10 and LC50 concentrations of both triazophos and deltamethrin and untreated males were found. However, copulation times of the males treated were higher than those of untreated males, increasing by 85 %.These findings provide valuable information for role of males in insecticide induced resurgence of the pest.