PROBING BEHAVIOR OF POTATO LEAFHOPPER (HOMOPTERA, CICADELLIDAE) ON ALFALFA INFLUENCED BY PLANT WATER-DEFICIT

Probing behavior of adult potato leafhopper, Empoasca fabae (Harris), on alfalfa, Medicago sativa L., plants maintained at 3 water levels, w as monitored using an AC electronic feeding monitor. Two waveform feed ing types were predominant in occurrence and duration: I-a, multiple-c ell laceration; and I-c, continuous ingestion without stylet movement. Number of probes per insect did not differ significantly among water treatments. Mean number of waveform events per insect, I-c waveform ev ents per insect, waveform events per probe, I-c waveform events per pr obe, and I-a waveform events per probe, occurred significantly more of ten on high and moderate water than on low water. Probing duration per insect, I-a waveform duration per insect, and I, waveform duration pe r event were not significantly different among water treatments. Durat ion of I-c waveforms per insect were significantly longer on low water than on high or moderate water, whereas duration of I-a tended to be longer on high and moderate water. Probing duration per probe was not significantly different among water treatments. Duration of I-a wavefo rm per probe was significantly longer on high and moderate water than on low water, whereas duration of I-c was significantly longer on low water than on high and moderate. Probing duration per event and I-c wa veform duration per event were significantly longer on low water than on high and moderate. Water deficit in alfalfa results in a shift of p robing behavior in potato leafhopper from predominantly I-a to I-c wav eforms, the latter being a behavior that is less injurious to the plan t.