Responses of <i>Sitobion avenae</i> (Hemiptera: Aphididae) to water-deficit stress on drought-resistant wheat cultivars

The English grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), is a significant pest on wheat worldwide. Drought-resistant wheat cultivars have been developed to increase yield under water-deficit conditions. However, the effects of drought-resistant wheat on responses of S. avenae under water deficit are still unknown. Here, we examined the responses of S. avenae to seedlings of different wheat cultivars (drought-resistant: Chang-6794, Fan-6, and Yunhan-618 and drought-susceptible: Xinong-585) under three different water treatments. The aim was to assess how wheat drought-resistance and water-deficit stress affect selected life-history traits, honeydew production, and dehydration responses of S. avenae. Our results revealed that second-instar S. avenae presented shorter developmental times on drought-resistant cultivars and with increasing water-deficit stress, showing high plasticity of this trait in response to different environmental conditions. Test aphid individuals from the drought-susceptible Xinong-585 tended to have longer lifespan, higher adult fresh mass, and higher fecundity, compared to those from drought-resistant cultivars. This aphid species tended to produce higher amounts of honeydew on drought-susceptible Xinong-585 than on drought-resistant cultivars. Compared with Xinong-585, this aphid species tended to have higher absolute-water contents on the drought-resistant cultivar Chang-6794 only, showing cultivar-specific effects. Overall, drought-resistant cultivars also tended to be more resistant against S. avenae infestations under all water levels, suggesting a link between drought and aphid resistance in wheat. Our results provide insights into complex interactions between water stress levels and wheat drought resistance and have significant implications for wheat production and the development of integrated management programs for aphids in the context of climate change.