Individual Development And Effects Of Tetracycline Hydrochloride On The Reproductive System Of Encarsia Formosa

Bemisia tabaci(Gennadius)(Hemiptera:Aleyrodidae)is an important economic pest in worldwide,single control method won’t obtain very good result,and chemical control will bring a lot of problems such as environmental pollution,food safety and other issues,and now,biological control is an effective mens of controllong B.tabaci.Encarsia formosa(Gahan)(Hymenoptra:Aphelinidae)is an important parasitoid of the B.tabaci nymph.E.forrmosa is thelytokus,which is induced by an intracellular parasitic and vertical transmission bacteria-Wolbachia.Wolbachia has a wide distribution in parasitic wasp.It can regulate the host’s reproduction,for parasitic wasp,Wolbachia mainly induce parthenogenesis.The previous tests proved that antibiotics can effectively remove the Wolbachia from the host.The ovariole number in E.formosa varies between different research and did not have detailed results and didn’t pay attention on the developmental stages before eclosion.In this article,we designed a kind of facility for rearing,and discussed effect of parasitization by E.formosa on development of B.tabaci nymph;dissected the different stage of E.formosa to get the corresponding morphology of ovarioles;analysed the development time and the distribution of ovarioles number of E.formosa;located the Wolbachia in E.formosa adults;established the relationship between the concentration of antibiotics and the effect about removal amount of Wolbachia;fed E.formosa by tetracycline hydrochloride continually and then analyse the influence:the sex ratio of offsprings,the amount and the morphological changes of ovarioles.1)The results indicated that the nymphs continued to develop despite the instars when the parasitization happened.The molting from 2nd to 3rd instar and 3rd to 4th instar of parasitized nymphs was synchronous with that unparasitized ones.The developmental time of 4th instar nymphs was prolonged.E.formosa preferred parasitizing bigger B.tabaci nymphs when one instars were provided.The parasitized 2nd and 3rd instars were,respectively,bigger than that unparasitized ones during observation period.Whereas,seven days after parasitization the parasitized 4th instars was smaller than that unparasitized nymphs,although the former was bigger than the latter when the parasitization happened.These indicated that the host instar at parasitization affected the effects of parasitization on development of B.tabaci.The mortality(61.11%)of nymphs exposed at 2nd instar was significantly higher than that exposed at 3rd or 4th instar.The percentage(48.39%)of black pupae was higher when B.tabaci 4th instars were exposed to wasps than that when 2ncd or 3rd instars were used.2)The development time of E.formosa is 15.2±0.1 d;E.formosa with a life cycle consists of five parts:egg,larva,prepupa,pupa and adult.The dissection results indicates that E.formosa’s ovarioles number has the following 4 sides symmetry situations:six(3+3);eight(4+4);ten(5+5);twelve(6+6)and 2 kinds of asymmetry situations:seven(4+3)and nine(5+4),the situations of eight comprises 89.97%.In the prepupal stage,the ovarioles can be observed,but the number is unclear,within the pupal stage,the number of ovarioles is clear.3)Located Wolbachia in E.formosa adults by FISH(Fluorescence in Situ Hybridization),the result indicated the Wolbachia mainly exsist in the abdomen.We used the relative quantitative PCR to establish quantitative relationship between the concentration and effect of Wolbachia removal.The result indicated that therer is not significant difference of the removal effect between different concentrations of tetracycline hydrochloride,but the Wolbachia was much less in F1 generation after fed by 10 mg/ml tetracycline hydrochloride.4)We fed the wasps by 10 mg tetracycline hydrochloride/ml sucrose water for 24 h and for 4 generetions continually,then found that the F4 female adults were still infected with Wolbachia,among offsprings,the proportion of male was higher than female and reached the highest in F2 and partly of males were infected with Wolbachia too.The number of ovarioles in F4 generation is 8,but the width was less than the normal significantly.