Characterizing and assessing the wheat-aphid complex under varying temperature and humidity

Abstract

Aphids (Hemiptera: Aphididae) are known for their remarkable adaptability and diversity, with most species richness found in temperate regions and worldwide distribution. Climate change is expected to affect aphid populations, especially their overwintering success. In this study, we aimed to investigate the diversity of wheat aphid populations and dynamics of overwintering success of aphids across early to late sown wheat. We employed both morphological and molecular techniques to distinguish and characterize six aphid species: Rhopalosiphum maidis, Rhopalosiphum rufiabdominalis, Rhopalosiphum padi, Sitobion avenae, Schizaphis graminum, and Metopolophium dirhodum. Among these, Rhopalosiphum maidis and Rhopalosiphum rufiabdominalis found to affect at the vegetative stage of the crop, while the other species were found to affect at the reproductive stage. Notably, we observed that aphid populations were more abundant on early-sown genotypes and decreased with normal and late sowing dates. The differences in peak aphid populations among different sowing dates revealed that delayed in sowing dates minimize aphid attack by producing asynchrony between host plant and the aphid population. Conversely, the environmental factors such as temperature, relative humidity, rainfall and bright sunshine hours varied across the sowing dates where early sown wheat genotypes are exposed to lower temperatures at vegetative stage and late sown genotypes are susceptible to higher temperatures at the terminal stage. These changes in environmental factors across different sowing dates affected the timing and duration of aphid life stages, including overwintering success. Nevertheless, understanding the diversity and distribution of aphid species in wheat crop and its response to different sowing dates could be crucial for developing effective pest management strategies, particularly in the context of climate change. Overall, this study highlights the need for ongoing aphid monitoring and adaptive management approaches that account for the dynamic interactions between pests, crops and the environment.