Reaction of different sorghum genotypes to infestation by the sugarcane aphid, Melanaphis sacchari Zehntner

Sugarcane aphid, Melanaphis sacchari, is emerging as a serious pest of sorghum during periods of prolonged drought or low humidity. Host plant resistance can be deployed to minimize the losses due to this pest. Evaluation of a diverse array of sorghum genotypes for resistance to this pest in Andhra Pradesh, India, indicated that CSH 9, DJ 6514, ICSV 197, ICSV 745, IS 14334, IS 10712, and TAM 2566 suffered lower aphid damage and had low density of alates. Aphid infestation was lower on 1st and 2nd leaves as compared to that on the 5th and 6th leaves. Aphid infestation resulted in an 18.5-55.8% decrease in total phenol content over the healthy leaves. The differences in tannin content of immature and mature seeds of the test genotypes were non-significant. The tannin content of grains showed a positive correlation with phenol content of healthy (r=0.42) and aphid infested leaves (r=0.29). Coccinellid density was significantly associated with aphid damage score (r=70*). The results suggested that ICSV 745, ICSV 197, and ICSV 112 had moderate to high levels of resistance to sugarcane aphid, and therefore, these genotypes can be deployed in areas prone to aphid outbreak