Ion-regulatory Physiology of Aquatic Dipteran Larvae
Mosquito and midge larvae adapt well to changes in habitat salinity. Our research studies the ion transport mechanisms, and their regulation, in organs of these insects. We utilize both freshwater and brackish water dwelling species to understand the mechanisms that have evolved in response to these two distinct habitats. In addition, results of our research can be used to predict changes in the mosquito and midge species composition by increased environmental salinity from the continued use of road salt. This is important because these insects are vectors of disease but also play important roles in the food chain and ecosystem.
Hydromineral balance is essential to the survival of all animals and is achieved through the actions of ion transporting epithelia that are regulated by neuroendocrine factors. Mosquitoes and midges have specialized organs that permit them to survive a wide range of environmental salinity. Under freshwater conditions, where larvae face dilution of body fluids, the anal papillae of mosquitoes and midges take up salts (e.g. NaCl) from the habitat. Under saline conditions, where larvae face concentration of body fluids a unique specialized salt secreting epithelium in the posterior rectum of some mosquito larvae remove excess salts from the hemolymph. The midgut and Malpighian tubules also play a role in maintaining hydromineral balance. Despite identification of relevant organs responsible for hydromineral balance in mosquito and midge larvae, the molecular and physiological mechanisms at work in these organs are poorly understood, as is their neural and endocrine regulation.
Our research is aimed at filling this void by elucidating the molecular basis of salt (ion) transport and how these mechanisms are regulated by neural and hormonal factors. This fundamental knowledge can permit the development of novel and specific agents to affect control on mosquito and midge populations. These agents can be targeted at the level of the molecular ion transport machinery or at the neural and hormonal level. For example, recent advances have been made in the development of synthetic peptide hormone analogues which disrupt normal hormonal signaling in target insects. Results of our research will also contribute to an understanding of mosquito and midge population distribution related to environmental salinity levels. Continued use of road-salt can ultimately lead to invasion of inland waters by salt-tolerant mosquito and midge species which inhabit coastal areas.
The laboratory uses a combination of molecular and physiological techniques including PCR, qPCR, Western blotting to identify tissue-level expression of genes, intracellular microelectrodes and ion-selective microelectrodes to measure membrane potentials and ion composition in biological fluids and Scanning Ion-selective Electrode Technique (SIET) to measure real-time movement of ions across transporting epithelia.