N7 waveforms are similar to those noted by Tjallingii described for aphids where it is believed to correlate with cell penetration. N4-a and N4-b patterns are clearly distinguishable from other waveforms and have been confidently attributed to the sieve element feeding phase . In addition, strong correlation between honeydew excretion and N4-b phase provides further evidence of SCH727965 phloem LY2157299 ingestion activity. Generally pathway activity decreased over the first 6 h of feeding with a concomitant increase in phloem sap ingestion . The increase in N4-b activity was paralleled by an increase in honeydew production. In some varieties there was an initial peak in N4-a activity which declined during later stages of feeding. The other EPG waveforms did not show any clear pattern except for NP. Rice varieties Rathu, Babawee and F1 showed increase in NP percentage duration in the last three h of the 12 h feeding period. The presence of the salivation waveform indicates the first time that the stylets encounter the sieve element. There was no significant difference in the time to the first N4-a waveform for BPH across all rice varieties . BPH on Azucaena took the shortest time to reach the sieve element of 3.4 h and reached the phloem in a similar time when feeding on Nipponbare, IR694 and TN1. N4-b waveform represents phloem acceptance and successful phloem ingestion. There were significant differences in the time to the first N4-b waveform on the different rice varieties. Based on frequency of the N4-b waveform, BPH was unable to successfully ingest sieve element sap on Rathu Heenathi and Babawee. The qualitative differences between N4-a and N4-b timings indicate that BPH has a similar ability to locate the sieve element across all varieties but there is variation in the ability to successfully sustain phloem sap ingestion. The average percentage duration of seven EPG waveforms from BPH on the twelve rice varieties during the final 5 h of the 12 h feeding period was calculated . A Kruskal-Wallis nonparametric analysis indicated that all EPG activities varied significantly between rice varieties except for salivation . BPH feeding patterns on Rathu Heenathi and Babawee were markedly different when compared to other varieties.