Coeloides qinlingensis Dang et Yang, 1989 (Hymenoptera: Braconidae) is a biocontrol agent of several scolytid pine pests in Southwest China. We examined the fine morphology of the antennae of adult C. qinlingensis, as well as the type, shape, and distribution of antennal sensilla, via scanning electron microscopy. The antennae of female and male C. qinlingensis are filiform and comprise a scape, pedicel, and 31–36 flagellomeres. We detected sexual dimorphism in antennal flagellar length but not in the length of other subsegments. A total of nine morphological types of antennal sensilla varying in cuticular pore structure are present in both sexes, including nonporous types (sensilla trichodea, sensilla chaetica (2 subtypes), and sensilla coeloconica); apical pore types (sensilla basiconica and sensilla auricillica); and multiporous types (dome-shaped sensilla and sensilla placodea (2 subtypes)). Dome-shaped sensilla and sensilla auricillica are reported for the first time for C. qinlingensis, and their shape differs from that of sensilla in other parasitic wasps. The functional morphology of the sensilla of C. qinlingensis was compared with that of the sensilla of other parasitic wasps, including those that parasitize concealed insects. This information provides a foundation for further research on the chemical communication and behavior of C. qinlingensis.

Tomicus yunnanensis, a notorious forest pest in southwest China, primarily employs infochemicals to coordinate mass attacks that overcome host tree defenses. However, secondary visual cues, particularly detection of host color changes, also aid host location. This study characterized the compound eye structure and vision of T. yunnanensis using electron microscopy and phototaxis tests. The apposition eye contains 224–266 ommatidia, with asymmetry between left and right. Quadrilateral facets occupy the dorsal third, while hexagonal facets dominate elsewhere. Each ommatidium comprises a large corneal lens, an acone-type crystalline cone from four cone cells, and an open-type rhabdom formed by eight retinular cells (R7–R8 centrally, R1–R6 peripherally), surrounded by two primary and at least seventeen secondary pigment cells. Dark/light adaptation alters cone size/shape and rhabdom cross-sectional area/outline (without pigment granule movement) to regulate light reaching the photoreceptors. Behavioral observations showed peak flight activity occurs between 7:00–11:00 AM, with no nighttime activity. Phototaxis tests revealed females are highly sensitive to 360 nm, 380 nm, and 700 nm wavelengths, while males exhibit high sensitivity to 360 nm and 400 nm. This work enhances knowledge on the integration of visual and olfactory sensory information in beetles for host location and non-host avoidance.

Pollinating fig wasps (Agaonidae) engage in an obligate mutualism with Ficus species, which is mediated by host-specific chemical cues. However, the role of visual perception in host recognition remains poorly understood, particularly because of a lack of structural studies of their compound eyes. We investigated the ocular morphology of female Ceratosolen gravelyi (exclusive pollinator of F. semicordata) using scanning/transmission electron microscopy. The oval apposition eyes contain 228–263 ommatidia, which are asymmetrically distributed between the left and right eyes. Each ommatidium comprises a biconvex corneal lens overlying a tetrapartite eucone crystalline cone; proximal cone cells reveal an interlaced labyrinth. Pigment cells encapsulate each ommatidium, and numerous pigment granules and mitochondria are present in both pigment and retinular cells. Nine retinular cells comprise a unit, with eight photoreceptors (R1–R8) forming the rhabdom from the cone base to the basal matrix; a ninth cell replaces R8 in the apical third of the rhabdom. Optical metrics, including F-number (1.1°), acceptance angle (10.0°), and ommatidial sensitivity (0.26 µm²/sr), indicate diurnal activity in bright environments. These adaptations suggest that their eyes are critical for processing visual cues during host interactions, which advances our understanding of multimodal sensory integration in fig–wasp mutualism.

Interspecific mating can increase when sympatric species mature simultaneously, posing challenges for mate recognition and resource utilization. Cuticular hydrocarbons (CHCs) contribute to desiccation resistance and act as chemical signals in communication. However, it is not sufficiently understood how the CHC traits of sympatric species respond to overlapping ecological, reproductive, and seasonal pressures. This study examines variation in cuticular hydrocarbons among five Ficus semicordata ‐associated fig wasp species and explores potential links between CHC profiles, mate recognition, and seasonal environmental variation, complemented by male mate‐choice assays in two species. Species‐specific CHC profiles with sexual dimorphism, combined with male mate choice, are consistent with a potential chemical basis for mate recognition. Species that share resource acquisition strategies (functional groups) tend to exhibit similar CHC patterns. The CHC composition adjusted seasonally among the four dominant species, and these patterns varied among functional groups and between sexes. This indicates that even under shared host and comparable macroclimatic conditions, species and sexes maintain distinct chemical profiles through adjustments in the composition and proportions of CHC. These findings provide a foundational framework for predicting how chemical traits mediate ecological adaptation and speciation in coexisting insect communities under spatiotemporal pressures.

Interspecific mating conflicts emerge when sympatric species mature simultaneously, requiring mechanisms for mate recognition and competition reduction. This study examines how cuticular hydrocarbons (CHCs), lipid-based mate attraction cues, resolve these challenges in five Ficus semicordata-associated fig wasp species. Species-specific CHC profiles with sexual dimorphism, combined with male mate choice, prevent crossbreeding while ensuring reproductive isolation. Functional groups sharing resource strategies exhibit convergent CHC patterns, yet seasonal changes and interspecific interactions drive phenotypic plasticity. Trophic-level CHC convergence reflects climate adaptation, revealing functional redundancy. Sex-specific adaptations arise: males optimize mate-search efficiency, whereas females prioritize offspring survival, mirroring their reproductive roles. This dual chemical system balances niche partitioning (via signature compounds) and environmental adaptability (via shared functional traits), illustrating how chemical traits mediate ecological adaptation and speciation in coexisting insect communities under spatiotemporal pressures.