Plant water stress intensity mediates aphid host choice and feeding behaviour

Abstract

1. The effects of drought-induced changes in plant quality on aphid performance and population growth is well-studied. The response of aphid behaviour to plant water limitation has received less attention. Water limitation may affect host-plant colonization by altering the attractiveness of plants. Additionally, plant water limitation may inhibit feeding site establishment and phloem ingestion. 2. Our goal was to examine bird cherry-oat aphid (Rhopalosiphum padi L.) host selection and feeding behaviour under water limitation. We assessed aphid response to well-watered, mildly-stressed, and highly-stressed wheat (Triticum aestivum L.) by evaluating (i) host-plant selection through two-choice assays, (ii) feeding behaviour using the electrical penetration graph technique, and (iii) phloem ingestion by quantifying honeydew production. 3. Aphids were less likely to select highly stressed plants than a mildly stressed or well-watered alternative. Aphids did not distinguish between mildly stressed and well-watered plants. Aphid feeding behaviours, including duration of phloem ingestion, were not affected by water availability. However, honeydew production was reduced under both levels of water limitation. These results suggest that the volume of phloem ingested by aphids per unit time declined on stressed plants. The combination of lower colonization and diminished access to food on stressed plants may lead to a reduction in aphid abundance, independent of the direct effects of nutrition on individual aphid performance. 4. This study highlights the potential contribution of herbivore behaviour to documented changes in aphid abundance on stressed plants and underscores the important role of plant water stress intensity in mediating plant-herbivore interactions.

Drought has negative consequences on aphid fitness and plant vigor: Insights from a meta‐analysis

“…Although many studies have reported reduced aphid fitness when exposed to drought‐stressed hosts (Banfield‐Zanin & Leather, 2015 ; Dai et al., 2015 ; Foote et al., 2017 ; Kansman et al., 2020 ), studies have reported null (Mewis et al., 2012 ) and positive (Oswald & Brewer, 1997 ) effects. Multiple factors could explain these contrasting observations, including differences in aphid or plant biology.…”

Root aphid (Aploneura lentisci) population size on perennial ryegrass is determined by drought and endophyte strain

“…However, a recent meta-analysis encompassing 55 published studies on the effect of drought on sap-feeding insects, showed that, for Poaceae (n = 24 studies), aphid tness is generally reduced under low soil moisture conditions (Leybourne et al 2021). For example, the tness of the foliage aphid Rhopalosiphum padi L. was reduced when feeding on drought-stressed wheat (Triticum aestivum L.) (Kansman et al 2020). Multiple factors could explain the variation between these studies including aphid and/or host biology.…”

Invasive ant establishment, spread, and management with changing climate

“…Interactions with bugs native to the ants' introduced range may also be important for facilitating invasion [37]. Honeydew producers may benefit from intermittent drought due to increased nitrogen availability in phloem [48], which may reduce honeydew excreted per individual [49]. Elevated carbon dioxide and/or temperature affect population growth, behaviour, honeydew production, and chemical communication of sap-sucking insects sometimes to the benefit of the ants or their trophobionts, but often dependent on host plants, seasonal timing, ant attendance, or natural enemies [7, [50][51][52][53][54].…”