Sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididae), abundance on sorghum and johnsongrass in a laboratory and field setting

Abstract

In North America, the sugarcane aphid, Melanaphis sacchari (Zehntner, 1897) (Heteroptera: Aphididae), has recently become an eruptive and costly pest of sorghum, Sorghum bicolor (L.). This pest has spread throughout at least 17 U.S. states and in Mexico and Caribbean Islands. The sugarcane aphid's ability to overwinter on living annual and perennial hosts such as johnsongrass, Sorghum halepense (L.), in southern sorghum-producing areas and wind-aided movement of alate aphids appear to be the main factors in its persistence and geographic spread. The importance of johnsongrass to the sugarcane aphid-sorghum annual infestation cycle is in part related to the ability of the sugarcane aphid to switch between these hosts and its relative reproduction on sorghum and johnsongrass. Two host plant experiments were used to investigate this ability. Beginning at the same infestation levels, more aphids were found on johnsongrass from adults that originated on sorghum than aphids found on johnsongrass from adults originating from johnsongrass or sorghum. This supports field observations that after sorghum harvest, the sugarcane aphid can persist and reproduce on johnsongrass. Host switched colonies all performed at intermediate levels, suggesting effects of the prior host do carry forward to the switched host. Pest managers can utilize this information in areas where sorghum and johnsongrass are both parts of the agroecosystem in this region and for modeling endeavors considering dispersal of sugarcane aphid between hosts.