Host suitability for the sugarcane aphid Melanaphis sacchari (Hemiptera: Aphididae) on sorghum, sorghum-sudangrass, millets and other forage grass species

Authors: Armstrong, John; HOBACK, WYATT - Oklahoma State University; Springer, Timothy

Submitted to: Trends in Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2021
Publication Date: 12/1/2021
Citation: Armstrong, J.S., Hoback, W.W., Springer, T.L. 2021. Host suitability for the sugarcane aphid Melanaphis sacchari (Hemiptera: Aphididae) on sorghum, sorghum-sudangrass, millets and other forage grass species. Trends in Entomology. 17:1-11.

Interpretive Summary: Often grain sorghums and forage grass species used for grazing or hay are grown in close proximity to one another and can act as source/sync when infested with sugarcane aphids (SCA). We evaluated several forage grass species to determine if they were capable of generating high numbers of sugarcane aphids that would provide a source to grain sorghum. The forage sorghums and sorghum x sudans TX 7000, SPX 46214, SPX 49313, Trudan and Sordan were very good hosts for sugarcane aphids. Hybrid Pearl millets such as Leafy 22 and Millet 32 were categorized as intermediate host but lost the ability to generate high numbers of SCA with the age of the plant. Other grass forage species such as Aberdeen 812 barley, Parakeet millet, and LA 481 soft red winter wheat were poor hosts for the SCA and could be utilized to substitute for other forage grasses that generate high numbers of SCA in grain sorghum production areas.

Technical Abstract: The sugarcane aphid (SCA), Melanaphis sacchari (Zehntner) became a perennial pest of grain sorghum in the United States beginning in the summer of 2013. Susceptible grain sorghum has been considered one of the most optimum hosts utilized by SCA although it is widely known that other grass species used for grazing, haying and silage also serve as hosts. We evaluated the reproductive capacity, preference/non-preference, and feeding damage caused by SCA on eleven forage and grass species, including pearl millet, proso millet, forage sorghums, sorghum x Sudan grass hybrids and a related grass, Saccharum ravennae. The study was conducted on younger plants, infested one week after emergence, and an identical evaluation was conducted by infesting at two weeks post emergence, with both experiments carried out for five consecutive weeks post-infestation. Sorghums, sorghum-sudangrass forages such as TX 7000, SPX 46214, SPX 49313, Trudan and Sordan supported a high reproductive potential and were highly preferred over millets sp., wheat and barley. The sorghums, sorghum-sudangrass forages sustained the highest damage ratings when the plants were infested at one week and two weeks of age. Sugarcane aphids had a mid-level reproductive potential on millets Leafy 22 and Millet 32 when plants were infested at one week of age but were lower in aphid numbers at two weeks of age. Millets were not as suitable in terms of hosting sugarcane aphids when compared to the sorghums. Barley Aberdeen 812, soft red winter LA 841, and millet Parakeet did not support any sugarcane aphids when infested at two weeks, and thus are not considered sustainable hosts. These findings identify the forage grass species that could be used in the sorghum production regions that would help reduce threatening populations of the sugarcane aphids, and demonstrates the need for developing resistant SCA sources for Sudan and sorghum-sudangrass forages.