Influence of intrinsic and extrinsic factors on Hemipteran feeding behavior measured using electropenetrography

Arthropod vectors drive the spread of plant pathogens by actively acquiring and transmitting the pathogens to plants. Understanding vector feeding behavior reveals the impact of its variation on disease transmission and inoculum dynamics. Electropenetrography (EPG) is a technique through which feeding patterns and processes of piercing-sucking insects can be observed, and the development of quantitative analytical methods useful for prediction based on EPG is an area of opportunity. In this work, applications of wavelet transform, a signal analysis method, is utilized to differentiate instances of feeding events, for the purpose of studying the effects of factors intrinsic or extrinsic to the vector on its feeding behavior. Not all feeding of a given nominal type is the same with respect to the dynamics of vectored inoculum, and the primary focus in this study is on factors that differentiate feeding with respect to these dynamics. Investigated intrinsic factors include demographic classifications such as sex, developmental stage, and morph, beginning with the observation of morphological differences, specifically alate versus apterous forms. Extrinsic factors to be investigated in this work will generally concern bioclimatic variables, here beginning with heat. Controlled thermal regimens were used to observe effects on feeding. Through signal analysis, specific feeding events (e.g. xylem ingestion, phloem ingestion) were classified, and then signal or wavelet parameters were estimated for statistical analysis and hypothesis testing. The first systems investigated are the Aphis gossypi on cotton plants and Planococcus spp on pepper plants, in which repeatable effects of both demography and heat were observed.