Abstract: 【Aim】 The interaction between figs and their pollinating fig wasps represents a classic system of co-evolution and mutualism. In addition, there are various species of non-pollinating fig wasps living on each fig species. Under the selective pressure of living within fig syconia, the fig wasps have evolved many adaptive morphological characteristics. Antennal sensillum, as the unit of communication system of fig wasps, is one of the best morphological characteristics to reflect the evolutionary adaptation. This study aims to investigate the morphological diversity and evolutionary adaptation of the antennal sensilla of fig wasps. 【Methods】 Fifty-four types of 24 species of fig wasps on 15 fig species from Hainan and Yunnan provinces, China were selected as the materials. The morphology of antennal sensilla of these species was observed by the scanning electronic microscope. Based on the molecular phylogeny tree, thecharacter evolution of the antennal sensilla was analysed, and the evolutionary adaptation of morphological characteristics was discussed. 【Results】 Our results show that the extremely sexual dimorphism of the antennal sensilla exists in most species of fig wasps. There are differences in the morphological characteristics of the antennal sensilla between the pollinators and the non-pollinators ovipositing outside the fig syconia and also between the pollinators and the non-pollinators ovipositing inside the fig syconia. The morphological characteristics of the antennal sensilla of the pollinating males and the non-pollinating males without male polymorphism are much degenerated. The morphological characteristics of the antennal sensilla among the non-pollinating males with male polymorphism do not show significant difference. Character evolution analysis of the types of the antennal sensilla reveals the multiple independent evolution of these morphological characteristics and the relationship with evolutionary adaptation. 【Conclusion】 The diversity of the antennal sensilla of fig wasps are very rich, revealing the diagnostic characters for evolutionary adaptation. Due to the different ecological pressures and functions for males and females, they evolved different adaptive characteristics, which correlate with different oviposition behaviors of females and with different mating strategies of males. Our study provides new insight on the morphological adaptation, evolutionary trend, behavioral strategies, and ecological relationship of fig wasps.

Key words: Fig wasps, antennal sensilla, sexual dimorphism, male polymorphism, character evolution, adaptation, evolution