Functional morphology of mouthparts and antennal sensillae of two co-generic aphidophagous ladybirds

Abstract

Functional morphology of sensillae on the antennae and mouthparts of two co-generic aphidophagous ladybird species, viz. Coccinella septempunctata and Coccinella transversalis (Coleoptera: Coccinellidae) were studied using scanning electron microscopy to determine their structure, functions and sex-specifc variations. Their mouthparts comprise of mandible, maxilla, maxillary palps, labrum, labium and labial palps. Sensillae were present on diferent mouthparts, viz. maxillary palp, labial palps, and the clypeus. Maxillary palps were the main prey-holding apparatus with three distinct regions, viz. proximal, middle, and distal segments. Labial palps provide initial gripping of the prey with three similar regions as that of maxillary palps. Six diferent types of sensillae were identifed on the mouthparts of C. septempunctata, viz. chaetica, trichoidea, coeloconica, placoidea, basiconica, and styloconica, while those on C. transversalis had seven diferent sensillae with the inclusion of sensilla campaniformia. The female antennae were greater in length than the male ones in both species. The scape and pedicel segments of the male antennae were greater in length, while fagellomeres were shorter in length than those of the female antennae of the two species. Six types of sensillae, viz. chaetica, trichoidea, basiconica, coeloconica,ampullacea, and campaniformia were identifed on C. septempunctata antennae, while those of C. transversalis had eight with the addition of sensillae sporangia, and styloconica. These sensillae on mouthparts and antennae of both the ladybird species have crucial functional roles in foraging, prey-location, and prey capture.