Abstract: 【Aim】 Aphelinus maculatus is one of the important parasitic wasps parasitizing on the cotton aphid, Aphis gossypii, discovered in recent years. There is little study on the biological characteristics including behavior and habits of Ap. maculatus so far. In order to explore and utilize this wasp effectively, it is important to ascertain its biological characteristics. 【Methods】 The emergence rhythm, mating behaviors, duration of various stages of mating, mating frequency, mating competition, sex ratio of offsprings reproduced by different reproductive modes, and longevity of adult Ap. maculatus were observed and recorded under microscope in the laboratory, and the parasitization process of this parasitoid on A. gossypii nymphs, the ovipositor insertion time of Ap. maculatus adults when parasitizing and feeding on A. gossypii, and the parasitization and feeding selection of Ap. maculatus adults to different day-old nympyhs of A. gossypii were also observed. 【Results】 Ap. maculatus adults emerge mainly at 6∶00-10∶00 am. Female and male adults mate on the day of emergence. The mating process can be divided into four phases: courtship, precopulation, copulation and postcopulation. The copulation duration is short, only lasting for 5.5±0.2 s. One male can copulate with 2-4 unmated females within 3 h, while the female only copulate once. Mating competition occurs among females and also among males. Ap. maculatus can reproduce offspring by parthenogenesis and amphigenesis. Only male offsprings are reproduced by parthenogenesis, but both female and male offsprings by amphigenesis. The parasitization process can be divided into such steps as searching host, examining host, probing insertion site, parasitic oviposition or feeding host, and cleaning and carding. The decision of parasitic oviposition or host feeding is related to the ovipositor insertion time into aphid body. When the ovipositor insertion time is longer than 4.8 min, adult wasps are more likely to feed host. Ap. maculatus wasps prefer to feed the early instar nymphs of A. gossypii, rarely feed 4 d or 5 dold nymphs, but can parasitize different dayold nymphs of A. gossypii. One female wasp can parasitize 14.8 A. gossypii nymphs and feed 3.7 A. gossypii nymphs on the average within 24 h. The adult longevity of Ap. maculatus is related to nutrient supplement after adult emergence. Adult wasps fed 10% sucrose and 10% honey could live 24±2.5 d and 28±1.6 d, respectively. 【Conclusion】 Ap. maculatus can reproduce by parthenogenesis and amphigenesis. Mating competition occurs among both females and males. The adult longevity of Ap. maculatus can be prolonged by supplying sucrose or honey.

Key words: Aphelinus maculatus, Aphis gossypii, biology, parasitism, behavior, reproduction, mating, longevity