Temperature and host plant influence alate formation in the hedgehog grain aphid, Sipha maydis (Hemiptera: Aphididae)

The hedgehog grain aphid (HGA), Sipha maydis Passerini (Hemiptera: Aphididae), is a significant pest of cereal crops and is present in the United States. Like other aphids, it exhibits wing polymorphism, producing both winged and apterous morphs influenced by environmental factors such as temperature and host plant quality. This study evaluated the effects of temperature and host plant species on life history traits and wing induction under controlled laboratory conditions. Two weeks after nymphs being placed on host plants, a significant interaction between host plant and temperature was observed for number of aphids and winged morph proportion. The highest aphid populations occurred on wheat and barley at 30 °C (356 ± 70 and 344 ± 42, respectively), while sorghum supported consistently lower populations, peaking at 15 °C (37 ± 4). Wing induction was greatest on sorghum and barley at 25 °C (26.9 ± 7.5% and 10.1 ± 1.6%, respectively), while no differences were observed among temperatures on wheat (x̄ = 9.2 ± 2.0%), suggesting that the host may have induced a stress-related morphological response to promote dispersal, particularly on sorghum, the least suitable host. Supercooling points (SCPs) of winged and apterous adults reared at 25 °C were also measured. While SCPs did not differ significantly between morphs, they varied by host plant: aphids reared on wheat froze at −16.7 °C, compared to −18.7 °C on sorghum and −18.6 °C on barley, indicating host-mediated cold tolerance. These findings underscore the ecological plasticity of HGA and provide valuable insights for improving outbreak prediction and integrated pest management strategies across diverse environmental conditions.