Abstract:

Objective: The observation and analysis of the ultrastructure of the antennal sensilla of the male and female of Chouioia cunea (Hymenoptera: Eulophidae) can provide a basis for the research on the olfactory receptive mechanism of the C. cunea and lay a foundation for further exploring the internal structure, mechanism of action and related functions of each sensilla. Method: Scanning electron microscopy was used to observe the morphological structure, type, number and distribution of antennal sensilla of the male and female. A total of 10 males and 10 females were observed, and their antennal sensilla were described, compared and analyzed in detail. Result: The antennae of male and female were significantly different, with female of 11 sections, male of 12 sections, and male had swollen antennae scape. From the base of the antennae to the end of the antennae, the number and types of the sensilla increased gradually, among which the number and types of the sensilla on the flagellum were the most abundant. In terms of the types of the male and female sensilla, the female had two more sensilla than the male, which were sensilla mammilliformia Ⅱ and sensilla coeloconica. As for the morphological structure of the male and female sensilla, the sensilla trichodeaⅠof the female were longer than that of the male. The sensilla mammilliformia Ⅰ of the male was significantly longer than that of the female. The sensilla mammilliformia Ⅲ was newly discovered in our study, and there were significant differences in the morphological structure between male and female. The number of antennal sensilla of the female was about twice that of the male. There were significant differences in the number of Sensilla trichodea Ⅰ, Ⅱ, sensilla placodea, sensilla chaetica, sensilla mammilliformia Ⅰ and Ⅱ between male and female. The most abundant sensilla on the female antennae were the sensilla trichodea Ⅰ, while the sensilla trichodea Ⅱ had the largest number on the male antennae. From the perspective of the distribution of sensilla, sensilla trichodea Ⅰ was distributed in all the flagellar segment of the female antennae, but it was mostly distributed in the funicle of the male. The sensilla trichodea Ⅱ is distributed in each flagellar segment of the antennae of the male, but it is mostly found in the clava of the female antennae, but not in the funicle. Conclusion: The phenomenon of sexual dimorphism of antennal sensilla is obvious between the male and female, and the morphological structure, types, number and distribution of the sensilla are different, which could be related to the different functions of the antennal sensilla of male and female.

Key words: Chouioia cunea, antennal sensilla, parasitoid, scanning electron microscope, sexual dimorphism