Comparative morphology of sensilla of antennae, maxillary and labial palpi of adult Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), with specific reference to the typology and possible functions

Abstract

Abstract Background The lesser grain borer Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) is a cosmopolitan insect pest of stored cereal grains. In this study, the fine morphology of antennae, maxillary and labial palpi as well as the typology, morphology and distribution of associated sensilla were comprehensively examined by scanning electron microscopy. Results On antennae, six types of sensilla were identified, s. trichodea, s. chaetica, two subtypes of s. basiconica, s. ampullacea and s. styloconica, in addition of Böhm's sensilla (Bs). Sensilla trichodea and basiconica were the most abundant sensilla types in the club flagellomeres. Mouth parts of R. dominica were adapted for chewing; maxillary and labial palpi consisted of four and five segments, respectively. Galea of maxilla was two segments, the distal one ended with a brush like organ composed of a dense field of long s. basiconica. The sensilla of maxillary and labial palpi were long and short s. trichodea, s. basiconica, s. styloconica and s. ampullacea. Only one big sensillum digitiformium was found on the lateral side of the distal segment of the maxillary palp. Conclusions We summarized the validated structures of different types of sensilla on antennae and palpi of R. dominica and proposed the potential functions of them in detection of ecologically relevant stimuli.