Morphology of antennae and mouthpart sensillae in Lasioderma serricorne (fabricius) (Coleoptera: Anobiidae)

Abstract

The cigarette beetle, Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae), is an important stored-product insect pest. In the present study, the external morphologies and distribution of the sensilla on the antenna and mouthparts of L. serricorne were described following scanning electron microscopy with the aim of understanding the behavioral mechanisms of this insect pest. On the antennae, various sensilla types were identified: Böhm bristles, three basiconic sensillum subtypes, two chaetica sensillum subtypes, three styloconic sensillum subtypes, as well as trichodea, capitulum, and campaniform sensilla. Interestingly, campaniform sensilla and two subtypes of styloconic sensilla (St1 and St2) were reported for the first time on L. serricorne antennae. The mouthparts of L. serricorne carried six different sensory structures including chaetica, basiconic, styloconic, auricillic, and trichodea sensilla, as well as long macrotubercles. Two subtypes of chaetica sensilla were recorded on the labrum, mandibles, and maxillary and labial palpi. A basiconic sensillum subtype (BS3) was distributed on the galea and lacinia, while subtype BS2 was also found on the lacinia along with long fan-like macrotubercles, which are hypothesized to help clean the area of the preoral cavity directly below the base of the labrum. Auricillic sensilla were also found on the galea. The labial palpi showed three subtypes of basiconic sensilla (BS3, BS4, BS5), whereas the maxillary palpi bears BS4, and BS5. Styloconic sensilla were also found at the top of the maxillary and labial palpi. Blunt basiconic (BS6) and trichodea sensilla were found on a tongue-shaped structure (pharynx) situated entirely at the midline of the preoral cavity. These findings improve understanding of the sensory perception of an important insect pest and could help to develop suitable control methods.