An electropenetrography waveform library for the probing and ingestion behavior of Culex tarsalis on human hands

Authors: COOPER, ANASTASIA - Kansas State University; JAMESON, SAMUEL - Tulane School Of Public Health; PICKENS, VICTORIA - Kansas State University; OSBORNE, CAMERON - Kansas State University; Backus, Elaine; SILVER, KRISTOPHER - Kansas State University; Mitzel, Dana

Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2023
Publication Date: 12/9/2023
Citation: Cooper, A.M., Jameson, S.B., Pickens, V., Osborne, C., Backus, E.A., Silver, K., Mitzel, D.N. 2023. An electropenetrography waveform library for the probing and ingestion behavior of Culex tarsalis on human hands. Insect Science. 31(4):1165-1186. https://doi.org/10.1111/1744-7917.13292.
DOI: https://doi.org/10.1111/1744-7917.13292

Interpretive Summary: The recent rapid and geographically extensive emergence and re-emergence of several mosquito-borne diseases (Chikungunya virus, Zika virus, bluetongue virus) has demonstrated the importance of these infections to animal and human health. The pathogens that cause these diseases are unique in that their survival depends on complex interactions between the virus, the mosquito vector, and the mammalian host. The natural transmission cycle of these viruses relies on the bite of the mosquito for the acquisition or inoculation of the virus. The effects of infection on the feeding behavior of the mosquito are not well understood because the feeding behaviors occur primarily in opaque tissue making visualization difficult. Electropenetrography (EPG) has the potential to elucidate these behaviors by recording the electrical signals generated during probing. This manuscript is the first to describe the electrical waveforms associated with the feeding behavior of Culex tarsalis mosquitoes, the primary vector for many viruses (such as West Nile virus) causing disease in the United States. The optimum settings for EPG and different waveforms are described. These data and technology will facilitate future studies regarding pathogen acquisition and transmission as wells as pest and disease control strategies.

Technical Abstract: Culex tarsalis mosquitoes are capable of vectoring numerous pathogens affecting public and animal health. Unfortunately, the probing behaviors of mosquitoes are poorly understood because they occur in opaque tissues. Electropenetrography (EPG) has the potential to elucidate these behaviors by recording the electrical signals generated during probing. We used an AC-DC EPG with variable input resistors (Ri levels) to construct a waveform library for Cx. tarsalis feeding on human hands. Biological events associated with mosquito probing were used to characterize waveforms at four Ri levels and with two electrical current types. The optimal settings for EPG recordings of Cx. tarsalis probing on human hands was a Ri level of 107 Ohms using an applied signal of 150 millivolts alternating current. Waveforms for Cx. tarsalis included those previously observed and associated with probing behaviors in Aedes aegypti: waveform families J (surface salivation), K (stylet penetration through the skin), L (types 1 and 2, search for a blood vessel/ingestion site), M (types 1 and 2, ingestion) and N (an unknown behavior which may be a resting and digestion phase before stylet withdrawal). However, we also observed variations in the waveforms not exhibited by Ae. aegypti, which we named types L3, M3, M4, N1, and N2. This investigation enhances our understanding of mosquito probing behaviors. It also provides a new tool for the automated calculation of peak frequency. This work will facilitate future pathogen acquisition and transmission studies and help identify new pest and disease management targets.