Evaluation of strains of Beauveria bassiana and Isaria fumosorosea to control sugarcane aphids on grain sorghum

The sugarcane aphid [ Melanaphis sacchari (Zehntner)] has become a persistent problem to sorghum [ Sorghum bicolor (L.) Moench] producers in the United States since its first identification on grain sorghum near Beaumont, TX, in 2013. Since then, this aphid “super‐clone” has spread to almost all sorghum‐growing areas of the country. Growers have managed the sugarcane aphid using Insecticide Resistance Action Committee (IRAC) Group 4 insecticides and the use of resistant hybrids. In order to provide additional methods of control especially for organic sorghum production, two strains of the fungal entomopathogens Beauveria bassiana and one strain of Isaria fumosorosea as well as water and Sivanto (flupyradifurone) were applied to the sugarcane aphid susceptible sorghum hybrid DKS53‐53 in a randomized complete block design (RCBD) with four replications at Tifton and Fort Valley, GA. Aphid number, plant damage, grain yield, plant dry biomass, and plant height were measured for each treatment. As compared to the treatment with water, only the plots treated with Sivanto had significantly less aphid number and plant damage and significantly more grain yield and increased plant height. Thus, the applied entomopathogens did not reduce sugarcane aphid number, did not reduce plant damage, and did not increase grain yield in either location as compared to the treatment with water (the negative control). Thus, these three strains of entomopathogens were ineffective for controlling the sugarcane aphid under these field conditions.