Mapping Antennal Sensilla of Boxelder Bugs (Boisea trivittata) as the First Step in Understanding Overwintering Aggregation Behavior

Understanding the overwintering behavior of boxelder bugs (<i>Boisea trivittata</i>) is critical for preventing initial aggregation and secondary movement inside structures. Like many Hemiptera, boxelder bugs exhibit behaviors driven by allomones, including host cues, and field observations suggest that alarm pheromones and chemical cues mediate their end-of-season aggregation. We mapped the external morphology, ultrastructure, and distribution of the antennal sensilla of overwintering boxelder bugs via scanning electron microscopy to understand the placement of antennal sensory structures. Cuticle morphology SEM identified 20 subtypes distributed across seven categories of sensilla, namely, sensilla trichodea, sensilla basiconica, sensilla chaetica, sensilla campaniformia, sensilla coeloconica, sensilla ampullacea, and sensilla bell-mouthed, though the distribution varied considerably depending on the antennal segment. The majority of sensilla on the scape, pedicel, and basiflagellomere were mechanoreceptors, with the distiflagellomere supporting a considerable number of chemoreceptors for olfaction. However, two patches of sensilla coeloconica were located distally on the outer lateral pedicel and basiflagellomere. Mapping the number, location, and distribution of sensilla present on their antennae enables further investigations of allomone-mediated seasonal aggregation, resulting in the development of more effective pest prevention strategies against this insect.