| We investigated the primary parasitoids of the cotton leaf-roller, Sylepta derogata Fabricius, in the Yangtze River and Huihe Valley, and did some research on the biology and parasitic behavior of Apanteles derogatae in thia paper. Besides, we surveyed the population dynamics of Sylepta derogata Fabricius and its primary parasitoids in different cotton fields. At the same time, we did the pilot study of tropism reaction of Apanteles derogatae to different cotton variety. The results were as following:Some parasitoids of the cotton leaf-roller, Sylepta derogata Fabricius, which were collected in the cotton fields of the Yangtze River and Huihe Valley were identified and studied in this paper. These parasitoids are Apanteles derogatae (Watanabe), Goniozus japonicu(sAshmead), Sympiesis sp., Elasmus philippinensi(sAshmead), Xanthopimpla punctata ( Fabricius ) , Brachymeria lasus ( Walker ) and Lydella grisescens (Robineau-Desvoidy). Among them, Apanteles derogatae and Sympiesis sp. are the dominant species of the larval stage. Brachymeria lasus is the dominant species of the larvae-pupae period. The rate of parasitism of cotton leaf-roller reached 25.7% under the natural condition. It was concluded that the parasitoids played an important role on controlling the population of cotton leaf-roller.Apanteles derogatae Watanabe is a major larva endoparasitoid of Sylepta derogatae Fabricius. Its biological characteristics were investigated under laboratory conditions using S. derogatae as the host. The adults emerged on daylight, with the peak emergence at 6:00-10:00 and 15:00-17:00, and 92.6% of them mated on the day of emergence. Female adults only mated once in her life. It also can oviposit without mating, but all of the offspring after emergence was males. Male-biased adult sex ratio were found in laboratory populations (♀:♂=0.66:1). The longevity of adults decreased with the increase of temperatures from 17℃to 33℃when honey-water solution was... |
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