Morphological characterization and distribution of antennal sensilla of irradiated female mosquito, Culex pipiens (Diptera: Culicidae) with gamma radiation

Abstract

Culex pipiens mosquito is considered as one of the most dangerous insect pests that affect humans and animals worldwide as they transmit epidemic and fatal diseases. Antennal structure of the normal and irradiated female mosquito, Culex pipiens was examined using scanning electron microscopy to study the changes in the antennal segments and associated sensilla when 1–2 days old pupae were irradiated at low dose (20Gy), moderate (40Gy) and high (80Gy). The antenna of the female C. pipiens is filamentous in shape and consisted of scape (S), pedicel (P) and flagellum (F) which has 13 flagellomeres. Various types of sensilla with distinct morphological characters and morphometric features were recorded. Sensilla trichodea are the most abundant sensilla observed, with other types like sensilla chaetica, sensilla basiconica (grooved peg), sensilla coeloconica and sensilla ampullaceal. Morphological changes were recorded to the antennal segments and their associated sensilla due to the doses of gamma radiation (20, 40 and 80Gy) such as shrinkage, curved of sensilla into different directions, irregularity in shape, swollen in some parts and some sensilla gathered into dense collections. These changes were obviously demonstrated at 80Gy and 40Gy doses whereas little malformations were observed when the pupae irradiated with 20Gy dose. The antenna has lost most of different types of sensilla and some of its segments became transparent with high and moderate doses. These changes also recorded in the distal 13th flagellomeres segments with the three used doses of gamma radiation compared to control ones.