Related Experiment Video
Updated: Sep 16, 2025
AC-DC Electropenetrography for the Study of Probing and Ingestion Behaviors of Culex tarsalis Mosquitoes on Human Hands
Published on: November 29, 2024
A waveform library for the study of probing and ingestion behaviors of Culicoides sonorensis using AC-DC
Anastasia M W Cooper1,2, Cameron J Osborne1, Victoria Pickens1
1Kansas State University, Manhattan, KS, USA.
Background:
Culicoides sonorensis biting midges transmit arboviruses that negatively affect animal welfare and production in ruminant livestock operations. However, little is known about the probing and ingestion (i.e., biting) behaviors that occur inside host tissues, even though these behaviors may directly affect pathogen acquisition and transmission. Electropenetrography (EPG) allows for indirect visualization and quantification of these behaviors by measuring the changes in electrical signals that arise during probing.
Methods:
Using an alternating current-direct current (AC-DC) electropenetrograph, a waveform library for C. sonorensis biting behaviors was constructed from recordings of 70 adult females fed to repletion on human hands. The waveforms were characterized using each combination of four Ri levels (107, 108, 109, and 1010 ohms) and two electrical current types (AC, DC). Five response variables related to the count and duration of the waveforms were analyzed for each waveform family, applying likelihood ratio tests and Tukey's procedure to detect significant differences among the means of the eight treatment groups. The probability of transitioning between the waveform families was assessed on the basis of a frequency table of transition events, and multiple exact binomial tests were used to identify nonrandom transition events. Videography and interruption experiments were used to correlate behaviors with waveforms.
Results:
Waveforms generated by C. sonorensis included waveform families J/K (stylet penetration through the skin); L (types 1, 2, 3, 4, and 5; preparation of an ingestion site); M (types 1, 2, 3, 4, and 5; ingestion); N (types 1 and 2; an unknown behavior that may be a resting phase); and W (withdrawal). The waveforms generally occurred in that order, sometimes with multiple transitions between L, M, and N. Significant differences in the number of waveform events by insect for J, K, and L were observed between some DC treatment groups. The optimal setting for EPG recordings of C. sonorensis probing on human hands was an Ri level of 108 ohms using an applied DC signal of 75 millivolts (mV).
Conclusions:
EPG uniquely enhances our understanding of C. sonorensis probing and ingestion behaviors, which will facilitate further exploration and guide the development of EPG procedures for other biting midges and telmophagous insects.
