Sugarcane aphid-forage sorghum interactions and effects of abiotic and biotic conditions

Abstract

The sugarcane aphid (Melanaphis sacchari (Zehnter); (Hemiptera: Aphididae)) is a pest of (Sorghum bicolor (L.) Moench) in the United States. While it was originally found infesting sorghum in Florida in 1977, it was not until 2013 that it started to cause widespread economic loss in sorghum crops. To combat this pest, host plant resistance is being explored. Finding new sterile germplasm is a priority for sorghum breeders to be able to create new resistant sorghum lines twice as fast as using the fertile counterparts. The A3 cytoplasmic male sterile technique was tested and found suitable to improve a known sugarcane aphid resistant sorghum line, TX2783. Often screening trials are conducted in controlled environments using artificial lighting. Light-emitting diodes (LED) are used to reduce cost, space, and time to grow plants. I found that LED lights lowered the photosynthetic rates, altered stomatal conductance, and changed plant characteristics in different cultivars of sorghum. LED lights also altered damage ratings for resistant and susceptible plants when exposed to sugarcane aphids suggesting that these trials should not use LED lighting when searching for plant resistance. Lastly, I compared life history traits of aphids in aggregated groups to solitary aphids. Aphids reproduction was not sig Overall the results of these studies highlight the importance of experimental conditions when evaluating plant resistance traits and document much-needed sugarcane resistant traits in sterile lines of grain sorghum.