| Scleroderma guani Xiao et Wu(Hymenoptera: Chrysidoidea: Bethylidae),which is ectoparasitoid of many Coleoptera and Lepidoptera insects.Due to its biological characteristic of high fecundity,wide host range and boring ability,it is applied to be an important natural enemy of larvae and pupae of stem borers in agriculture and forestry.More importantly,S.guani is also a typical sub-social insect with a series of behaviors,such as aggregation,cooperative foraging and parental care.Its studies in chemical ecology contribute to illustrate the adaptive behavior mechanism from non-social insect to eusocial insect.In order to explore the interaction between parenting behavior and internal physiological changes of S.guani,we tested the types and dynamic changes of hormones from female adults before and after parental care,and conducted the impact of these changes on ovarian development and behavioral phenotypes.This study is intended to provide an important scientific basis for the study of the relationship between parasitoid's behavior and hormone.(1)Ovarian development of female adults of S.guaniAccording to the physiological state and behavioral performance before and after parental behavior of S.guani,11 important physiological states of female adult bees were conducted: virgin female(no-feeding)(VF),female with mating(feeding)(FM),female with mating and feeding(FMF),female in early oviposition(F-EO),female in peak oviposition(F-PO),female with caring-early instar larva(F-EIL),female with caring late-early instar larva(F-LIL),female with caring mature larva(F-ML),spinning female with caring spinning mature larva(F-SML),female with caring early pupa cocoon(F-EPC),female with caring late pupa cocoon(F-LPC).By anatomical observation,the ovary development degree of female adults with different physiological conditions was compared,and the potential relationship between the behavior and ovary development degree was analyzed.The result showed: before parental behavior,there was no significant change in the body size and ovary of VF and FM.The body length of VF and FM was about 1477.50 ?m,while the width of FM was significantly increased(190.40±4.94 ?m).No fertile eggs were found in both females.After feeding,the body size of FMF was obviously changed,the abdomen was gradually enlarged,the internode membrane was widened,the body weight was increased(0.94±0.01 ?g/head),the length and width of ovary were significantly increased,which was more than 1.70 times of that of FM(L=2702.29±80.22 ?m,W=420.52±19.17 ?m).Both of them were pregnant females,and the average number of pregnant eggs was 38.14±2.397/head.The number of mature eggs in a single female ovary accounted for about 28.45%.At the early stage of oviposition,the length and width of ovary of F-EO were 1.50 and 2.80 times of that of FM(L=2754.26±69.63 ?m,W=537.01±21.29 ?m),respectively.The average number of pregnant eggs was28.35±2.48 per female,but the number of mature eggs in ovary increased significantly(43.10%).During the peak period of oviposition,the length of F-PO ovary was similar to that of F-EO ovary,but the width of F-PO ovary decreased(372.29±14.04 ?m),the average number of pregnant eggs(16.81±1.712 eggs/female)and the number of mature eggs(30.70%)decreased.Both F-EO and F-PO were pregnant.With the process of oviposition behavior,the weight of female adult wasps decreased significantly,the length and width of ovary decreased,the number of mature and immature eggs in ovary decreased,until the mature eggs were fully produced,and the progeny entered the stage of young larvae.During caring offspring,the abdomen of female adults was significantly reduced,the body weight decreased(0.68±0.01 ?g/female in F-EIL),and the length and width of ovary returned to FM level(1840.52 ?m,217.73 ?m).However,in F-SML,the ovary length of females increased(1994.13±68.70 ?m).From F-EIL to F-EPC,the proportion of pregnant females decreased gradually,F-EIL was the highest(82.86%)and F-SML was the lowest(32.57%),the average number of eggs per head was 14.77,which was lower than that of F-EO and F-PO.The length and width of ovary of F-LPC were 1.24 and 1.26 times of that of FM(L=1577.32±35.68 ?m,W=161.18±9.65 ?m),respectively.There were only 15.00% of pregnant females in F-LPC.The average number of pregnant eggs dropped sharply to 2.33±1.52/female,and no mature eggs were found in the ovaries.These results indicated that the ovary development of female adults of S.guani would be changed by mating,feeding and caring of offspring at their different developmental stages.(2)Dynamic changes of hormones in female adults of S.guaniWith the standard substance of insect hormones as the control,the hormone types in female adults of S.guani were detected by LC-MS,and the changes of hormone levels in female adults under different physiological conditions were compared and analyzed.The results showed that JH III and 20 E were detected in different physiological states.With the change of physiological state of female adults,the titers of JH III and 20 E were also changed.Corresponding to changes in the ovaries,the content of JH ? in VF and FM was lower(about1.75 ng/mg),but the 20 E titer of VF was lower(6.09±0.18 ng/mg),while that of FM was 5 times higher(35.35±1.41 ng/mg).After feeding,the titer of JH ? in FMF increased sharply to 32.69±0.29 ng/mg,indicating that nutrient intake would stimulate the increase of JH normal level.In contrast,the titer of 20 E in FMF decreased to the lowest(0.20±0.02 ng/mg).After oviposition,the titer of JH ? in F-EO and F-PO decreased sharply to 9.08±0.69 ng/mg and 4.72±0.25ng/mg,respectively.The 20 E titer increased to 27.45±0.24 ng/mg at the early stage of oviposition,and then decreased to 3.10±0.31 ng/mg at the peak of oviposition with the continuous production of mature eggs.With tending progeny of different developmental states,the titer of JH ? in female adults was always at a low level(0.18?4.05 ng/mg),there was the lowest in F-EIL stage and the highest in F-EPC stage.In contrast,during the development of progeny,the titer of 20 E from female adults changed from low level(F-EIL,3.82±0.09 ng/mg)to high level(F-LIL,28.52±0.21 ng/mg),and then decreased again(F-ML,5.28±0.71 ng/mg),and then restored to a high level(F-SML and F-EPC),and stabilized at 26.44 ng/mg,and lasted until the late stage(F-LPC,when the progeny was about to emergence),which was27.56±0.17 ng/mg(P?0.05).However,in F-LPC stage,the titer of JH ? in females was significantly increased to the maximum value of 71.79±0.63 ng/mg,which was 390 times that of JH ? in F-EIL stage.These results indicated that the levels of JH ? and 20 E in female adult wasps changed dynamically alternately with the development progress of offspring and different degree of caring requirements,which might be an important physiological factor for improving parental care.(3)Effects of exogenous hormone on parental care behavior of S.guaniUnder the interference of exogenous hormone(JHA),the behavioral performance of female adults was tested by choice-tests.When acetone was used as the solvent of exogenous hormone in vitro,high concentration of juvenile hormone would reduce the choice and care of female adults to offspring.The results showed that only 31.63% of female adults preferred their offspring after 12 h treatment with JHA,which was 0.44 times that of the control.After stimulation by JHA,58.90% female adults preferred to their offspring.In addition,high concentration of JHA interferes with the parental behavior of female adults in a short time after stimulation,and this interference decreases slowly with time. |
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