Study On Reproductive Biological Characteristics And Individual Development Of Encarsia Japonica Viggiani

Encarsia japonica Viggiani is an endoparasitoid of Bemisia tabaci and is the dominant species of B. tabaci parasitoids in Fujian province. This paper studied the reproductive biological characteristics of E. japonica, including the reproductive mode, female- and male-producing behavior, female fertility, offspring sexual ratio and male insemination capacity. Morevoer, the individual development of female and male of E. japonica were observed in this paper. The main conclusions are as follows:1. The reproductive modes of E. japonica were that the females with gamogenesis produced female offsprings, and the females with parthenogenesis and autoparasitism produced male offsprings. The male eggs were layed on the female larvae or pupae of primary parasitoids in whiteflies. But the females with gamogenesis could not autoparasitize and not produce male offsprings.2. The parasitic behavior of E. japonica divided into four stages: ① testing hosts with antenna; ② inserting the ovipositor into hosts to detect internal environment; ③ ovipositing and pulling ovipositor; ④ combing out after ovipositing. The time of detecting host with antenna of females with female-producing was longer than that with male-producing. When laying female eggs the ovipositor pierced the head and apex of B. tabaci, but when laying male eggs the ovipositor pierced the edge of head and apex of B. tabaci, not laying on the body of primary parasitoids. When laying female eggs the time of detecting host was longer than laying male eggs, and also ovipositor wobbled obviously. After laying female eggs E. japonica had behavior of combing out, but not after laying male eggs.3. The average fecundity of E. japonica was 48.6 eggs on B. tabaci on cauliflower, and 31.4 eggs on tomato. The ratio of female and male was 4.75 on cauliflower, and 3.61 on tomato. The emergence rate, survive rate and adult longevity is better on cauliflower than on tomato. So cauliflower is the more suitable host plant.4. One male E. japonica could make 74.6 eggs fertilized in average, and the insemination capability was positively related with longevity of adult male. The insemination capability of adult male decreased as with mating times increased. Each male could mate for 6 times at most in life, and then the females mated later hardly layed eggs.5. During embryo development of female eggs of E. japonica, the dark matter in eggs would change. After eggs developed 12h, the extraembryonic membrane appeared. After 24h the extraembryonic membrane disappeared completely. When 24-30h the egg membrane began to separate from egg shell. When 34-36h the head began to depress, and two dark lines appeared. When 40-44h the larva contour formed which began to squirm in egg shell. The developmental duration of egg was 43.15h in average.6. The female offspring larvae of E. japonica developed 3 instar stages. The first instar larvae firstly put head out of egg shell, and the egg shell would be existed in the tail of larvae for a moment. The duration of first instar larvae was 8.75h in average, the second instar larvae 49h. The third instar larvae had cylindrical tail and old one appeared large C-shaped. The third instar larvae developed 133.75h. The female pupas were yellow early and black late with yellow plaque. The development duration of pupae was 133.75h, and from egg to adult was 473.62h.The male eggs of E. japonica were layed nearby its female larvae or pupae in B. tabaci, and the male larvae developed on female parasitoids. The male eggs hatched in 1～2d. The male larvae developed 3 instars, and the third instar larvae also appeared large C-shaped. The male pupae and adults were black.