A comparative study of the antennal sensory organs in four medical and forensical flies: Lucilia sericata (Meigen), Triceratopyga calliphoroides Rohdendorf, Fannia scalaris (Fabricius) and F. canicularis (Linnaeus)
Li Xin-yu Liu Xian-hui Zhang Dong
Department of Zoology, College of Nature Conservation, Beijing Forestry University, Beijing 100083, China
The blow flies [Lucilia sericata (Meigen), Triceratopyga calliphoroides Rohdendorf (Diptera: Calliphoridae)] and the latrine flies [(Fannia scalaris (Fabricius) and F. canicularis (Linnaeus) (Diptera: Fanniidae)] are common and synanthropic species of medical and forensic significance in eastern Asia, which can work as a mechanic vector of pathogens. As the most important sensory organs involved in finding food sources, mates, and suitable oviposition sites, antennal sensilla of flies are always assumed as recommendable model in olfactory studies and have received sufficient attention so far. However, several distinctive and confused phenomena of antennal sensilla still remain to interpret. For example, though setiferous plaques on antennal pedicel are discovered in most families of Calyptratae, there is also lack of these structures in some species in the same family; despite of the wide distribution of pedicellar in Diptera, no reliable electrophysiological evidence on their function has been addressed; given sensory pits and sacculi on antennal funiculus might be the most unique character of unsegmented flagella, like those in flies, their formation during evolution have never been revealed. Thus stereoscopic microscope, light microscope, scanning electron microscope and laser scanning confocal microscope are employed to examine both external and internal sensilla on antennae of these fanniids and calliphorids with an emphasize on their adaptive significance. Three interesting sensillar characters of these species are detected, with possible evolutionary implications. Unlike the three-chambered sacculi in the two fanniids, extensively complex sacculi in the calliphorid species were firstly discovered. Expect for the common intact pedicellar buttons in other species, every pedicellar button in L. sericata is perforated by three pores perforated. Setiferous plaques on antennal pedicel are also another particular structure in L. sericata, which are absent in other species. After a series of comparative investigations, the functions or development of these specific structures are discussed according to the life history of these flies.
Keywords: comparative morphology, sensory organs, Calliphoridae, Fanniidae
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