Reproductive Biology And The Influence On The Fecundity Of Sogatella Furcifera(Horv(?)th) Under The Impact Of Insecticides

The white-backed planthopper(WBPH, Sogatella furcifera(Horv(?)th)) is an important migratory pest on rice production in Asia, belonged to the Hemiptera, Delphacidae. The nymphs and adults of WBPH phloem sap sucking rice damage and spread of southern rice black-streaked dwarf virus(SRBSDV), and it caused significant loss of rice yield in China. Chemical control is still the main technique in WBPH control and management. Chemical control has high-speed trait than other control measures, but the control measure could cause lower sensitivity and resurgence on pests and environmental pollution problems. There are a lot of Sogatellaf urcifera reproductive behavior research, but there is still some uncertainty. The mating and oviposition behavior of white backed planthopper(WBPH) and female parthenogenesis ability were studied in the paper on laboratory conditions, and defined effects of different growth stages of rice and breeding density on the ovary development and the mating rate of females of WBPH, and researched the effects of stress of thiamethoxam, cyantraniliprole, deltamethrin, avermectin on fecundity of lab population of WBPH, The results can lay the foundation for defined the the characteristics of reproductive biology of WBPH and evaluate the four pesticide's safety, and it could provide a theoretical reference for improve efficiency of Integrated Pest Management.1. Mating and oviposition behavior of S. furcifera(Horv(?)th).The mating and oviposition behavior of WBPH was studied in the paper on laboratory conditions. The results show that the peak of circadian emergence rhythm of females is between14:00~16:00, the peak of circadian emergence rhythm of males is between 12:00~14:00 and males emergence earlier than females. The peak of circadian mating rhythm is between 24:00~2:00 and12:00~14:00 respectively, the peak of circadian spawning rhythm is between 12:00~16:00. Both male and female can mate more than once. The fecundity of multiple mated females was significantly higher than single mated females. The longevity of virgin females longer than paired females. Virgin females can lay eggs, and the amount of eggs laid of virgin females were significantly less than paired females. The eggs laid by virgin females can't hatch, thus, WBPHhave no ability of parthenogenesis.2. Effects of growth stages of rice and breeding density on reproductive of S. furcifera(Horv(?)th).To studied the effects of growth stages of rice and breeding density on reproductive biology of WBPH, the WBPH were fed with rice at three-leaf stage, tillering stage and heading stage under different density(Each tube have 5, 10, 15, 20 S. furcifera respectively).No significant effect of growth stages of rice and breeding density on female ratio, female longevity and hatchability of WBPH. The nymphal duration was prolonged with the increase of density what fed with the same growth period of rice.The nymphal duration of each tube have 20 S.furcifera significantly longer than each tube have 20 S. furcifera by 2.8d when fed with rice at tillering stage. The nymphal duration which fed with rice at three-leaf stage longer than which fed with rice at tillering stage and heading stage.Under conditions of each tube have 15 S. furcifera,the nymphal duration of fed with rice at tillering stage shorter than treatments of three-leaf stage and heading stage by 0.23 d and 1.75 d, respectively.The nymphal survival rate decreased with the fed density increased when all S. furcifera were fed the rice at the same growth period. When all S. furcifera were fed the rice at thetillering stage,the nymphal survival rate of S. furcifera which fed on each tube have 15 insects significantly lower than the nymphal survival rate of S. furcifera with each tube have 10 insects by 12.86%.When each tube have 5 S. furcifera the nymphal survival rate of S. furcifera which fed with rice at three-leaf stage significantly shorter than which fed with rice at heading stage by 14.62%.The emergence rate of WBPH which fed with rice at tillering stage under the condition of each tube have 20 S. furcifera significantly lower than other density treatment which fed with rice at tillering stage by 14.87%?14.25% and 11.20%, respectively.There were no significant difference of fecundity per female of WBPH when fed with rice at the same growth period under different density. But under the same density, the fecundity per female of WBPH which fed with rice at tillering stage was more than which fed with rice at three-leaf stage, and the fecundity per female of WBPH which fed with rice at heading stage was least. The female fecundity of tillering stage group more than the female fecundity of heading stage group by 94 eggs.After a week of the emergence of WBPH, the rate of successful mating of WBPH which fedwith rice at three-leaf stage lower than which fed with rice at tillering stage, but higher than which fed with rice at heading stage. The rate of successful mating of WBPH reached more than 70%when all S. furcifera were fed the rice at thetillering stage, and the rate of successful mating of WBPH no more than about 30% when all S. furcifera were fed the rice at heading stage. There had similar rate of successful mating of WBPH which fed with the same growth stages of rice under the different density. A week after the emergence of WBPH, the speed of ovarian development of WBPH which fed with rice at three-leaf stage slower than which fed with rice at tillering stage,but faster than which fed with rice at heading stage.3. Effects of stress of four pesticides on fecundity of lab population of WBPH.To explore the effects of stress of thiamethoxam, cyantraniliprole, deltamethrin and avermectin on fecundity of lab population of S. furcifera(Horv(?)th), the relative fitness life-table of WBPH was formed.Thiamethoxam stress can inhibit the growth of F0 and F1 generation of WBPH. The nymphal duration of F0 and F1 generation of WBPH were prolonged significantly at the LC10 and LC25 concentration. when treated with LC10 and LC25, the fecundity of the F0 and F1 female adults were reduced by 22.24 eggs and 69.96 eggs, respectively. The population trend index were declined after treated with the LC10 and LC25 concentrations of thiamethoxam, the relative fitness were reduced by 0.12 and 0.36, respectively.The fecundity of the F0 female adults significantly less than control and the nymphal duration of F1 generation were prolonged significantly when treated with LC10 and LC25 of cyantraniliprole.when treated with LC10 and LC25, the fecundity of the F0 and F1 female adults were reduced by39.02 eggs and 44.17 eggs respectively, and the relative fitness were reduced by 0.23 and 0.34 respectively.The emergence rate of F0 generation were reduced, and the fecundity of the F0 female adults more than control but not significant when treated with LC10 and LC25 of deltamethrin. The nymphal duration of F1 generation were prolonged significantly and the fecundity of the F1 female adults were increased after treated with the LC10 and LC25 of deltamethrin. when treated with LC10 and LC25, the fecundity of the F0 and F1 female adults were reduced by 34.3 eggs and 55.7 eggs respectively, and the relative fitness were reduced by 0.16 and 0.20 respectively.No significant effect on F0 generation of WBPH under stress of avermectin, but nymphal duration of F1 generation were prolonged significantly at the LC10 concentration. The fecundity of the F1 female adults were significantly increased after treated with the LC10 and LC25 of avermectin. when treated with LC10 and LC25, the fecundity of the F0 and F1 female adults were increased by 53.66 eggs and 64.44 eggs respectively, and the relative fitness were increased by0.09 and 0.04 respectively.The research results showed that thiamethoxam and cyantraniliprole stress can inhibit the growth of WBPH population, but deltamethrin and avermectin stress can stimulate the proliferation of F1 generation of WBPH.