Comparative functional morphology of the mouth brushes of mosquito larvae (Diptera, Culicidae)

Structural and morphological features of the feeding brushes of fourth instars of four species of mosquitoes were studied using light and scanning electron microscopes. The fine structure of the elements of the lateral palatal brushes, anteromedian palatal brushes, mandibular brushes and combs, and maxillary brushes of each species was investigated and related to feeding behavior. The movement of the mouth brushes in living larvae was observed by stereomicroscopy under laboratory conditions. Mouth brush function and morphology varied among the species studied. The brushes of Culex quinquefasciatus Say, Cx. tarsalis Coquillett, and Aedes aegypti L. were more complex than those of Anopheles albimanus Wiedemann. The main role of the filaments of the lateral palatal brushes (LPB) was to generate and maintain water and particle flow around the larval head. In Ae. aegypti, most of the LPB filaments were provided with stout pointed teeth at the tips which were useful in the brushing of food material. In An. albimanus, the LPB filaments were simple and very closely packed and were used to stir the water surface film to direct the floating materials into the area of the mouth opening. The filaments of the anteromedian palatal brush (APBr) in the Culex species were branched. In Ae. aegypti, the APBr contained long bladelike filaments and short teethlike elements, whereas in An. albimanus, the APBr filaments were all long and bladelike. The morphological structure of the spicules and setae of the mandibular brushes and combs and the maxillary brushes are described. The main function of these brushes is to direct and concentrate particle flow.