EPG analysis of Acyrthosiphon pisum feeding behavior onsix alfalfa varieties with different resistances

The feeding behavior of Acyrthosiphon pisum on six alfalfa varieties with different resistances, and the resistance mechanisms of these different cultivars, were examined using the electrical penetration graph (EPG) technique. The results showed that there were eight EPG waveforms of aphids feeding on alfalfa leaves, but the durations of the eight waveforms were different between the six cultivars. The resistance of alfalfa was consistent with the duration of the E1 wave, which was produced by A. pisum feeding on the phloem of the alfalfa varieties. The duration of the E1 wave was significantly different between the six different resistances of the alfalfa cultivars; the duration of the E1 wave was longer when the resistance of the alfalfa was stronger. The duration of the E1 wave on the most resistant cultivar was 36.83 min for ‘MF4020’, and the duration of E1 wave on the least resistant cultivar was 1.50 min on ‘Giant pastoral 37CR’.The resistance mechanisms of the different alfalfa cultivars to aphids are further illustrated by electrophysiology in research; it could provide the scientific basis for the breeding of alfalfa varieties with increased resistance to aphids