Impact of foliar insecticide sprays on Melanaphis sacchari (Hemiptera: Aphididae) and natural enemy populations in grain sorghum

Host plant resistance, foliar insecticide application and natural enemies play a role in the management of Melanaphis sorghi (Hemiptera: Aphididae) in grain sorghum

“…Our findings suggest that predators may be more abundant in resistant sorghum (DKS37-07) compared to the susceptible cultivar (DKS53-53). Predators of M. sorghi reported in this current study ( C. septempunctata , H. convergens , H. sinuate , C. maculata , S. loewii , C. sanguinea , and H. axyridis ; Hemerobius sp., C. valida , C. quadripunctata , and C. plorabunda ; A. obliqua , P. clavatus , and E. americanus ) have been reported from the invasive range of M. sorghi in southeastern United States ( Szczepaniec, 2018 ; Lytle and Huseth, 2021 ). For both resistant and susceptible cultivars, parasitoids ( L. testaceipes and Aphelinus sp.)…”

“…We hypothesized that the changes in natural enemy populations between sprayed and unsprayed could be a simple reflection of fewer aphids resulting in fewer natural enemies. Differences in predators and parasitoids species abundance or composition are not uncommon because factors including but not limited to weather conditions and prey or host availability can cause their population to spatio-temporally vary ( Varenhorst and O’Neal, 2012 ; Whalen et al, 2016 ; Lytle and Huseth, 2021 ).…”

“…Exact aphid numbers were counted when the density was below 50, and when densities were above 50, the number of aphids were estimated. We recorded the presence and number of beneficial insects spanning 11 taxa that are known predators of M. sorghi ( Singh et al, 2004 ; Bowling et al, 2016 ; Lytle and Huseth, 2021 ). We identified parasitoid wasps [ Lysiphlebus testaceipes (Cresson; Hymenoptera: Braconidae) and Aphelinus sp.…”

“…Knowledge of the non-target impacts of insecticides used for M. sorghi can enable growers to make informed decisions about insecticide selection that decrease aphid infestation while preserving the abundance and activities of natural enemies. Several studies have recorded a multiplicity of predators and parasitoids in sorghum production systems in southern United States suggesting that natural enemies may play a role in suppressing M. sorghi population, especially at low densities ( Singh et al, 2004 ; Hewlett et al, 2019 ; Maxson et al, 2019 ; Lytle and Huseth, 2021 ). Despite the fact that previous studies documented more than 47 arthropod species feeding on M. sorghi ( Singh et al, 2004 ; Lytle and Huseth, 2021 ), not much is known about the role of natural enemies on M. sorghi in grain sorghum systems in the southeastern USA due to prolific aphid reproduction rate, and low natural enemies in the sorghum field at the initial aphid infestation (but see Lytle and Huseth, 2021 ).…”

“…Several studies have recorded a multiplicity of predators and parasitoids in sorghum production systems in southern United States suggesting that natural enemies may play a role in suppressing M. sorghi population, especially at low densities ( Singh et al, 2004 ; Hewlett et al, 2019 ; Maxson et al, 2019 ; Lytle and Huseth, 2021 ). Despite the fact that previous studies documented more than 47 arthropod species feeding on M. sorghi ( Singh et al, 2004 ; Lytle and Huseth, 2021 ), not much is known about the role of natural enemies on M. sorghi in grain sorghum systems in the southeastern USA due to prolific aphid reproduction rate, and low natural enemies in the sorghum field at the initial aphid infestation (but see Lytle and Huseth, 2021 ). Understanding the role of insect natural enemies in grain sorghum systems that incorporate foliar insecticide sprays and host plant resistance across multiple locations in the United States is crucial to refining our IPM strategies in managing this pest.…”