Neupane SB, Kerns DL, Szczepaniec A
Recent invasion of a new haplotype of sugarcane aphid (Melanaphis sacchari Zehntner) resulted in severe outbreaks of the aphids in sorghum (Sorghum bicolor L. Moench [Poales: Poaceae]) across the United States. Previous research and field observations suggested that both sorghum resistance and growth stage were important to their population dynamics in the field and hence effective and timely management to minimize economic losses associated with this pest. To explore this, we designed greenhouse experiments to quantify fecundity, prereproductive period, and longevity of sugarcane aphids across several vegetative and reproductive growth stages of a resistant (DKS 37-07) and susceptible (M77GB52 and DKS 38-88) sorghum hybrids commonly used in sorghum production. We found significant effects of sorghum resistance and growth stage on several life history traits and demographics parameters of sugarcane aphids. We did not, however, note any significant interactive effects of resistance and phenology on any of the response variables. Sugarcane aphids exposed to the susceptible sorghum produced significantly more offspring, had significantly greater intrinsic and finite rates of increase, and significantly shorter population doubling time than the aphids feeding on resistant sorghum. On the other hand, the impact of sorghum growth stage had more variable effects on life history of sugarcane aphids that were most frequently evident at the late reproductive stages. These outcomes support our hypothesis that sorghum in late stages of growth tends to be a better host for sugarcane aphids and highlight the importance of sorghum growth stage to sugarcane aphid life history and population growth potential.