戈林泉 130Pesticide Biochemisty and Physiology.docx

1、戈林泉 130Pesticide Biochemisty and PhysiologySubmitted to Send correspondence to:Pesticide Biochemisty and Physiology Jin-Cai Wu School of Plant Protection Yangzhou University Yangzhou 225009, P.R. China-0514-*-0514-* E-mail: jc.wu Mating pair combinations of insecticide-treated male and female Nilapa

2、rvata lugens Stl (Hemiptera: Delphacidae) planthoppers influence protein content in the male accessory glands (MAGs) and vitellin content in both fat bodies and ovaries of adult females.Lin-Quan Ge1, Li-Ping Wang1, Ke-Fei Zhao1, Jin-Cai Wu*1, Liu-Juan Huang1, Zhen Min1, James D. Barry2 1School of Pl

3、ant Protection, Yangzhou University, Yangzhou 225009, China2DuPont Crop Protection, Stine-Haskell Research Center, Newark, DE* Corresponding author: jc.wuABSTRACTThe brown planthopper, Nilaparvata lugens (Stl) (Hemiptera: Delphacidae), is an insect pest in which offspring are produced by the mating

4、of adult males with adult females. This species is a classic case in which pest resurgence is induced by insecticides. In the past, studies of resurgence mechanisms have focused on insecticide-induced stimulation of reproduction in adult females. To date, however, the role that males play in the res

5、urgence mechanisms of N. lugens has not been investigated. The aim of the present study is to examine changes in protein levels in male accessory glands (MAGs) induced by the insecticides triazophos and deltamethrin and to determine their relationship with vitellin content in the fat bodies and ovar

6、ies of adult females in the context of mating pairs. Our results show that protein content in MAGs is significantly affected by male mating status, insecticide, and insecticide concentration. Insecticide application induced increased protein levels in MAGs. A greater quantity of MAG products was tra

7、nsferred to females via mating. Thus, protein levels in MAGs significantly decreased after mating. Experimental matings indicate that vitellin content in both fat bodies and ovaries of adult females in mating pairs consisting of a treated male and an untreated female (t ck) is significantly greater

8、than that of females in pairs consisting of an untreated male and an untreated female (ck ck ). Under various concentrations of the two insecticides, vitellin levels are highest in mating pairs consisting of a treated male and a treated female (t t ), followed by mating pairs consisting of an untrea

9、ted male with a treated female (ck t ). These findings demonstrate that 1) insecticide-treated males have an effect on female reproduction via mating; 2) the reproductive effects of insecticides on males can be transferred to female reproduction via mating; and 3) the reproductive effect of insectic

10、ides is strongest in mating pairs in which both the males and females are treated compared to pairs in which only one individual is treated. These findings provide valuable information about the role of males in pesticide-induced resurgence of N. lugens.Key words: Nilaparvata lugens, insecticides, m

11、ating factor, transference, vitellin1. IntroductionThe brown planthopper Nilaparvata lugens (Stl) (Hemiptera: Delphacidae) is a classical insecticide-induced resurgent pest 1-2. Among insecticides, pyrethroids (deltamethrin) and organophosphates (triazophos, methamidophos, parathion and diazinon) ar

12、e known to induce population resurgence of this species 3-6. Physiological mechanisms for the pesticide-induced resurgence of N. lugens involve stimulation of fecundity 4,6-8. Thus, insecticide-induced stimulation of fecundity is one of the main causes of N. lugens resurgence. However, studies of in

13、secticide-induced stimulation of pest fecundity have concentrated on the reproduction of adult females while ignoring insecticide-induced reproductive effects in adult males. N. lugens reproduces sexually; both males and females are involved in mating pairs. Therefore, we hypothesize that insecticid

14、e-induced reproductive effects in males can be transferred to females via mating and that this process influences female reproduction. However, this effect is not well understood. For insects with sexual mating, many studies have examined the effect of male mating factors (accessory gland products,

15、AGPs) on female reproductive performance. Males transfer not only sperm but also AGPs, which may be expensive to produce, and the amount or quality of these substances may decrease with increasing male mating frequency 9,10. AGPs transferred during mating are known to affect several behaviors in ins

16、ects, among which reduced female receptivity and increased oviposition are the most common11,12. In the variable field cricket Gryllus lineaticeps Stl, female lifespan is augmented by AGPs 13. Male diet and larval host influence the duration of copulation, but male diet does not influence female fec

17、undity. However, mating order and male larval diet influence female fertilization success 14. Many studies of other insects have also demonstrated that male accessory gland peptides regulate reproductive performance. For example, the adult male accessory glands of Drosophila melanogaster Meigen synt

18、hesize and secrete a peptide that represses female sexual receptivity and stimulates oviposition15. Multiple mating in the female moth Utetheisa ornatrix (L.) increases fecundity but does not increase longevity or egg mass 16. Lay et al. (2004)17 have found a greater role of male Locusta migratoria

19、(L.) in reproduction, with peptides from white secretions of the male accessory glands (MAGs) found in developing eggs. In addition, the fecundity of adult female Spodoptera litura F. increases when females mate with male moths with high quality sperm 18. More interestingly, Pszczolkowski et al. (20

20、06) 19 have found that in Heliothis virescens (F.), juvenile hormone (JH) stored in the MAGs is transferred to females via mating and that this process promotes JH synthesis and egg development in mated females. However, the effect of insecticides on adult male reproduction and the transference of t

21、his effect to the reproductive performance of adult females via mating have not been studied to date. The present study is designed to examine the effects of sublethal doses of two common insecticides, deltamethrin and triazophos, that stimulate the fecundity of N. lugens on protein content in MAGs

22、and on vitellogenin in fat bodies and vitellin in ovaries of adult female N. lugens. We utilize controlled matings between insecticide-treated males and females and control males and control females. Our aim is to understand the effect of insecticide-treated males on the reproductive performance of

23、females via the mating process. 2. Materials and methods 2.1 Rice varietyRice (Oryza sativa L.) variety Huai Dao 13 (japonica rice) was used in trials. This variety of rice was selected because it is commonly planted in Jiangsu province, China. Seeds were sown outdoors in a standard rice-growing soi

24、l in cement tanks (height 60 cm, width 100 cm, and length 200 cm). When seedlings reached the six-leaf stage, they were transplanted into 16-cm diameter plastic pots with four hills per pot and three plants per hill. Rice plants used in experiments had reached the tillering stage.2.2 InsectsA labora

25、tory strain of N. lugens that was originally obtained from the China National Rice Research Institute (CNRRI; Hangzhou, China) was reared in a greenhouse at an ecological laboratory at Yangzhou University. 2.3 InsecticidesTwo insecticides were used in trials: the pyrethroid 2.5% deltamethrin EC (Yan

26、gnon Chemical Co. Ltd., Yangzhou, Jiangsu, China) and the organophosphate 20% triazophos EC (Changqin Pesticide Co. Ltd., Jiangdu, Jiangsu, China).2.3 Experiments design Four concentrations of each insecticide (1, 3, 6 and 12 ppm of deltamethrin and 10, 20, 40 and 80 ppm of triazophos) were selected

27、 based on previous results from a sublethal test 6,20. Eighty third-instar nymphs were released per hill. Rice plants at the tillering stage were sprayed 24 h after insects were released using a Jacto sprayer (Maquinas Agricolas Jacto S.A., Brazil) equipped with a cone nozzle (1-mm diameter orifice,

28、 pressure 45 psi, flow rate 300 ml/min). Control plants at the same stage were sprayed with a mixture of emulsifiers and tap water similar to the composition of the insecticides but lacking their active components. Each treatment was replicated three times. The treated and control plants were covere

29、d with cages (screen size: 80-mesh). When the nymphs reached the fifth (final)_instar), nymphs on treated and control plants were collected and a single nymph from each plant was placed inside a glass jar (diameter 10 cm, height 12 cm) with untreated rice plants (26 2C and 16L:8D).Males and females

30、were separated one, two, and three days after adult emergence, with 20 males and 20 females per replicate used separately to measure protein content in the male accessory glands (MAGs) and vitellin content in the fat bodies and ovaries of adult females. To examine the effect of mating pairs consisti

31、ng of treated or untreated males and females on vitellin content in the fat bodies and ovaries of females, four mating combinations were designed: 1) treated males (t) treated females (t), 2) t untreated females (ck), 3) untreated males (ck) t, and 4) ck ck. For each of these combinations, we made t

32、hree replicates of 20 males and 20 females each. Vitellin content in the fat bodies and ovaries of females was determined prior to and after mating.2.4 Extraction of protein from MAGs Protein from MAGs was extracted using the methods of Chen et al. (1988) 15 and Smid et al. (1997) 21. Individual adult males of N. lugens were dissected under a zoom-stereomicroscope (model XTL20, Beijing Tech Instrument Co., Ltd., Beijing, China) in a cooled petri dish. MAGs were removed and placed in separate, pre-weighed