Electrical penetration graph comparisons of squash bug, Anasa tristis (Hemiptera: Coreidae), feeding on watermelon and its relatives

Electrical penetration graph (EPG) technique is a useful tool for studying the feeding behavior of piercing and sucking insects. The squash bug is a serious pest of watermelon in United States and is the vector of cucurbit yellow vine disease (CYVD). Stylet penetration behavior of the squash bug on watermelon (Citrullus lanatus), var. “Royal Sweet” and four of its relatives was recorded for twenty hours using EPG. All EPG waveforms were analyzed and duration and time to initiation of different probes were measured. Squash bugs made the longest probes in Royal Sweet and the shortest probes in Citrullus colocynthis. EPG parameters of squash bugs given access to C. colocynthis lines and P. fistulosus, such as short duration probes, taking longer to reach to the vascular tissues, and reducing the duration of vascular feeding, may be an indication of the presence of squash bug resistance factors.