Recording central neurophysiological output from mosquito larvae for neuropharmacological and insecticide resistance studies. (November 2021)

• Record Type: Journal Article
• Authors: Norris, Edmund J.; Bloomquist, Jeffrey R.
• Is Part Of: Journal of insect physiology. Volume 135(2021)
• Publication Date: 2021-11
• Subjects: Aedes aegypti -- Central nervous system -- DDT -- DFDT -- Mosquito neurophysiology; Insects -- Physiology -- Periodicals; Insectes -- Physiologie -- Périodiques; Insects -- Physiology; Periodicals; 571.157
• DOI: 10.1016/j.jinsphys.2021.104319
• Languages: English
• ISSNs: 0022-1910

Abstract

Graphical abstract: Highlights: Novel method to record nerve firing of mosquito larvae central nervous system. Larvae pinned and organs were removed to provide access to ventral nerve cord. Electrode connected to axons of nerve cord allowed for high signal-to-noise ratio. Allows for characterization of drugs/neurotransmitters on mosquito CNS. Method can characterize insecticide resistance produced at the level of the nerve. Abstract: Resistance to currently utilized chemical insecticidal agents represents a significant threat to public health and food security worldwide. Better understanding the neurophysiological effects of available and candidate insecticidal molecules is valuable for characterizing the mechanisms of insecticide resistance, as well as the design and study of novel control chemistries. In this paper, we describe a method of recording nerve firing from the central nervous system of Aedes aegypti fourth instar larvae. In short, mosquito larvae were immobilized by placing small pins through the head and siphon of the larvae in a wax dish, ventral side down. A single, longitudinal, dorsal incision from the distal abdomen to the pronotum of the larva was made, the alimentary canal removed, and the ventral nerve cord severed between the second and third abdominal ganglia. A recording suction electrode was connected directly to axons within the severed end of the connective in a novel way to record nerve firing in the ventral nerve cord at a high signal-to-noise ratio with conventional electrophysiological equipment. Using this novel method, we report the effects of four neuroactive compounds using this method: octopamine, pilocarpine, nicotine, and γ-aminobutyric acid (GABA). The utility of this recording technique for elucidating target site mechanisms involved in insecticide resistance is demonstrated with p, p '-dichlorodiphenyltrichlorethane (DDT) and its difluoro analog (DFDT).