Evaluation of host testing by comparing ingestion and settling behaviours

Abstract

The electrical penetration graph (EPG) technique is being developed for rapid assessment of host range of potential xylem feeding invaders in New Zealand. Stylet penetration behaviours of adult spittle bug Carystoterpa fingens were monitored for 12 h on grape, lemon, apple and kiwifruit plants using EPG. A multiple-choice test of all four plant species was conducted concurrently with the EPG tests for comparison. In EPG tests the longest probing and ingestion periods were recorded on grape and lemon, while the shortest probing and ingestion periods were recorded on apple. Results for kiwifruit were intermediate and not significantly different from the other plant types. In the multiple-choice tests, more insects were found on grape and lemon than on apple and kiwifruit. The similar ranking of the host plants in both multiple-choice and EPG tests suggests that EPG is a valid tool for rapidly assessing host feeding acceptance and preference.