Comparison of the Antennal Sensilla and Compound Eye Sensilla in Four Drosophila (Diptera: Drosophilidae) Species

Abstract

Antennal sensilla and compound eyes of fruit flies, Drosophila melanogaster (Meigen), Drosophila suzukii (Matsumura), Drosophila immigrans (Sturtevant), and Drosophila hydei (Sturtevant) (all Diptera: Drosophilidae), were observed with stereoscopic microscopy and scanning electron microscopy. The results showed that the antenna consists of 3 segments: a proximal scape, a pedicel, and a flagellum composed of a funiculus and a dendritic arista. Six morphologically distinct types of sensilla were observed on the antenna: chaetica, microtrichia, trichoid (Tr I, Tr II), basiconic, clavate, and coeloconic (Co I, Co II). Basiconic sensilla were significantly shorter than other sensilla in the funiculus of D. melanogaster. The number of clavate sensillae was less than other sensilla in the funiculus of D. melanogaster and D. immigrans, but was greater in D. suzukii and D. hydei. Moreover, coeloconic sensilla were absent in D. suzukii and D. hydei. The length and abundance of the chaetica sensilla on the compound eyes were different significantly among the 4 species. Drosophila hydei had chaotic sensilla with the greatest length and abundance; they were lowest for D. suzukii. Based on the previous literature, the possible functions of these sensilla are discussed. We inferred that fruit flies may regulate their behaviors according to the information detected by these sensilla.