Antennal Sensory Structures of Lissorhoptrus oryzophilus (Coleoptera: Curculionidae) with Notes on Aquatic Adaptations

Abstract

A scanning electron micrograph study was conducted of adult Lissorhoptrus oryzophilus Kuschel to determine the types and locations of sensory structures on the antennae. The antenna consists of a scape, six-segmented funicle, and club. Females had significantly longer antennal segments than males, but no other sexually dimorphic characteristics were found. Trichoid sensilla, two types of squamaform sensilla, tuft hairs, and hydrofuge scales were found on the antennae. The distal third of the club was densely covered by trichoid sensilla that likely function in gustation and olfaction. Hydrofuge scales were on the antennal club, and plumose hydrofuge scales were on the rostrum. Squamiform sensilla were among the plumose hydrofuge scales on the rostrum. The information gained from this study may be used to design electrophysiological studies to provide information about the attractiveness of volatile compounds from rice plants and potential weevil pheromones. Aspects of the plastron of the weevil are also discussed. The antennae of rice water weevils have sensilla and hydrofuge adaptions for an aquatic environment and were found to be unique when compared to five species of terrestrial weevils.