Changes Of Mating Factors In Nialaparvata Lugens (St(?)l) Induced By Insecticides With Different Temperatures Via Mating

The brown planthopper, Nilaparvata lugens (St?l) (Homoptera: Delphacidae), is a classical resurgent pest induced by insecticides. Resent outbreak of N. lugens that occurred in China and other Asian countries has been mainly associated with pesticide overuse and resistance to imidacloprid. Use of synthetic pyrethroids and organophosphates (triazophos) is likely to induce the population resurgence. However, investigation on resurgent mechanisms mainly focuses on stimulation of reproduction of adult female induced by insecticides, effect of insecticide-induced male reproduction on resurgent mechanisms of N. lugens has not been understood so far. To date, the role that males play in the resurgent mechanisms of N. lugens has not been investigated.The present study examined changes of protein levels in both male accessory glands (MAGs) and female ovaries induced by the insecticides with different temperatures as well as the stimulating effect of treated-males on the fecundity of adult female via mating . The results are as follows:1. Changes of protein content in male accessory glands (MAGs) of N. lugens induced by two insecticides triazophos and deltamethrinThe results showed that male mating, insecticide types and their concentrations significantly affected protein content in MAGs of N. lugens adult male developed from third instar nymphs feeding on treated rice plants. Protein contents in MAGs both before and after mating for triazophos treatment, and before mating for deltamethrin one were higher than those for controls, however, those after mating for deltamethrin one were lower than those for control. Protein content in MAGs under high concentrations of two insecticides was significantly higher than that under low ones. Male mating and insecticide types also significantly affected protein content in MAG of N. lugens adult male developed from fifth instar nymphs feeding on treated rice plants. Protein content in MAGs before male mating under insecticide treatments was significantly higher than under control. In contrast, that after male mating was significantly lower than that under control. Additionally, mating combinations significantly affected protein level in MAG.s In general, there was a higher protein content in MAGs when males were exposed to insecticides as third instars compared to fifth instars (60 and 32μg/male, respectively), and there was a higher protein content before mating compared to after mating (59 and 33μg/male, respectively).2. Changes of protein levels in both MAGs and female ovaries induced by the triazophos with different temperatures .The protein content was also affected by different combinations of treated mating pairs and temperature. The current findings showed that when triazophos-treated males were mated with control female exposed to 26℃and 34℃, the ovary protein content in the female significantly increased compared to pairs of control males and control females. The adult males (♂t) developed from third instar nymphs treated with triazophos significantly stimulated the fecundity of the female via mating (♂t×♀ck) with untreated-female (♀ck) (control females), increasing the reproductive rate by 43.5 % as compared to the mating (♂ck×♀ck) of untreated-males and females. The high temperature significantly reduced the protein content in MAGs prior to mating and after mating. The maximum protein content in MAGs was found at 26℃, followed by that at 20℃,and a minimum content was found at 34℃. The protein content in MAGs after mating was significant lower than that prior to mating, with a decrease of 40.2%. The change in the protein content of female ovaries under different temperatures was similar to that for MAG.s, and the maximum content was at 26℃, followed by 20℃, and a minimum content at 34℃. In contrast, the effects of mating status and triazophos concentrations on the protein content of the female ovaries were different from that in MAGs. These findings indicated that the reproductive effects of insecticide on male can be transferred to females via mating. The present findings provide valuable information for understanding the potential role that males play in the pesticide-induced resurgence of N. lugens.