Abstract
A soybean variety ‘Adams’ is known to be resistant to soybean dwarf disease. The number of nymphs and survival rate of Aulacorthum solani decreases remarkably on ‘Adams’. To understand the resistant mechanism of ‘Adams’, we compared the feeding behavior of A. solani adults on resistant ‘Adams’ and susceptible ‘Suzukari’ soybean varieties using an electronic monitoring system (EMS). On ‘Adams’, two ingestion waveforms, the Irss and the Is waveform were observed. The Irss waveform was recorded just after the S waveform, suggesting ingestion from non-phloem. This waveform was not observed on ‘Suzukari’. A. solani on ‘Adams’ probed frequently and repeated short-term phloem ingestion, while A. solani on ‘Suzukari’ ingested from phloem continuously for a long period. Consequently, the total phloem ingestion time was shorter on ‘Adams’ than on ‘Suzukari’. These results suggest that a decrease of ingestion from phloem on ‘Adams’ causes a reduction of nutrient uptake in quality and quantity, and eventually a decrease in survival rate, reproduction and development of A. solani.
