The grain aphid Sitobion avenae (in the photo from the website Agroterra) and the bird cherry-oat aphid Rhopalosiphum padi are considered two of the most significant aphid pests of cereal crops worldwide and their damages to agricultural and horticultural crops are compounded by their potential to act as vectors for disease, their high reproductive potential, and their ability to impose massive nutrient loss through the rapid extraction and utilisation of phloem. Due to their presence on different possible host plants, how they make their host selection?
Previous researches indicated that S. avenae prefers winter the wheat Triticum aestivum and may distinguish among different cultivars of the same species of wheat. The preference-performance hypothesis predicts a female oviposition preference to correspond with hosts that are best suited for offspring development that means good food and few enemies for offspring… but is it true also for aphids?
According to the data published by Michael R. Wilson & Simon R. Leather, Sitobion avenae and Rhopalosiphum padi generally have a preference for nutritionally superior hosts. However, the preference of both species changes towards a nutritionally inferior host after infestations of the harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae), that killed aphids showing a trade-off between high-quality nutrition and avoidance of predation. Such a capability is often seen in vertebrate ecology, but has been far less investigated in invertebrates and it has been frequently considered unrealistic in arthropods. On the contrary, as assessed by Wilson & Leather, ”this investigation demonstrated the ability in aphids to make preferences based on the nutritional quality of potential hosts. Furthemore, it appeared evident the ability to perceive past activity of natural enemies and to make decisions based on these perceptions to forfeit the intake of nutritionally superior food and minimise the risk of predation.”
Michael R. Wilson & Simon R. Leather (2012). The effect of past natural enemy activity on host-plant preference of two aphid species. Entomologia Experimentalis et Applicata , 1-7 DOI: 10.1111/j.1570-7458.2012.01282.x