18.3 Wednesday, Jan. 4 Multi-modal pumping in drinking mosquitoes KIKUCHI, K.; CHATTERJEE, S.; LEE, W.-K.; STREMLER, M.A.; MOCHIZUKI, O.; SOCHA, J.J.*; Toyo U.; Virginia Tech; Argonne National Lab.; Virginia Tech; Toyo U.; Virginia Tech firstname.lastname@example.org
Mosquito-related diseases such as malaria and dengue fever affect millions of people globally every year. Such diseases are transmitted through feeding, yet little is known about the internal mechanics of feeding in mosquitoes. Mosquitoes use a pair of serially-arranged cibarial and pharyngeal pumps in the head to generate forces that transport food from the source to the esophagus via the proboscis. We directly observed the action of these internal pumps using synchrotron x-ray imaging at Argonne National Laboratory. In two species (Aedes vexans and A. cinereus), we recorded x-ray videos of sugar water enhanced with an iodine contrast agent moving through the mosquito’s head. Our footage revealed multiple modes of drinking in the mosquito. In the most commonly observed mode, the pharyngeal and cibarial pumps operated out of phase, cycling at a frequency of 2.9 ± 0.4 Hz, a mechanism of drinking that appeared to transport a continuous line of fluid into the gut. In a second mode of pumping, the cibarial and pharyngeal pumps expanded and contracted in phase, with both pumps distending to a greater volume than in the first mode, a form of pumping that transported a discrete bolus of fluid with each event. This second mode occurred only intermittently. To investigate the functional significance of these two modes of drinking, we created a new analytical model of pumping with system dimensions based on three-dimensional measurements of mosquito heads, obtained from synchrotron radiation microcomputed tomography. Dynamic similarity was maintained by matching dimensionless Reynolds, Womersley, Strouhal, and Stokes numbers. Our results demonstrate that mosquitoes can modulate aspects of feeding performance by changing the relative timing of pump expansion and contraction.