Abstract:

Objective: The present study aims to clarify the species of the parasitoids in the galls of Cerroneuroterus yukawamasudai and deconstruct the biological characteristics of the predominant parasitoid species, so as to provide a scientific basis for biocontrol of the gall wasp. Method: Species of parasitoids and biology of a dominant parasitoid Torymus sp. in the asexual gall of C . yukawamasudai were surveyed by field investigation, indoor anatomy and laboratory experiment. Result: There were three parasitoid species in the asexual gall of C. yukawamasudai : Torymus sp., Pteromalus sp. and Chouioia sp. Among them, Torymus sp. was predominant parasitic natural enemy. The parasitoid occurred one generation in a year, and the larvae overwintered in the host asexual galls. The overwintering adults of Torymus sp. started emergence in late October, and laid eggs in the asexual galls. The parasitism rates of Torymus sp. to C . yukawamasudai were 18.00% and 21.86% in 2019 and 2020, respectively. Eclosion period of the parasitoid lasted for 81–85 days. Peak eclosion periods of male and female parasitoid were in mid-November and late November, respectively. The eclosion time was concentrated between 8:00–12:00 in every day, and its sex ratio (female/male) was 1︰2. The parasitic wasp was good at jumping and had the habit of feign death. Adults could mate on the same day after they emerged from the gall, and mated multiple times. Honey water supplementation significantly extended the longevity of male parasitoid, but not female parasitoid. Conclusion: Torymus sp., Pteromalus sp. and Chouioia sp. are found in the galls of the asexual galls of C. yukawamasudai . Parasitism rate of Torymus sp. to C. yukawamasudai is the highest, stating that Torymus sp. is the dominant species of parasitic natural enemies. Torymus sp. can be used as an important means to control C. yukawamasudai.

Key words: Cerroneuroterus yukawamasudai, Torymus sp., galls, biological characteristics, parasitoids