Aphid fecundity and defenses in wheat exposed to a combination of heat and drought stress

Abstract

Plants are routinely subjected simultaneously to different abiotic and biotic stresses, such as heat, drought, and insect infestation. Plant–insect interactions in such complex stress situations are poorly understood. We evaluated the performance of the grain aphid (Sitobion avenae) in wheat (Triticum aestivum L.) exposed to a combination of heat and drought stresses. We also performed assays of the relative water content, nutritional quality, and responses of phytohormone signaling pathways. Lower relative water content and accumulation of soluble sugars and amino acids were observed in plants exposed to combined heat and drought stress. These conditions increased abscisic acid levels in the absence of aphids, as well as leading to higher levels of jasmonate-dependent transcripts. The grain aphid infestation further increased abscisic acid levels and the abundance of jasmonic acid- and salicylic acid-dependent defenses under the combined stress conditions. Aphids reared on plants grown under drought stress alone showed lower net reproductive rates, intrinsic rates of increase, and finite rates of increase compared with aphids reared on plants in the absence of stress. The heat-treated plants also showed a decreased aphid net reproductive rate. These findings demonstrate that exposure to a combination of stresses enhances plant defense responses against aphids as well as altering nutritional quality.

Stressful times in a climate crisis: how will aphids respond to more frequent drought?

“…7). This finding is consistent with our prediction and is supported by a large body of literature reporting elevated plant defence and decreased plant growth and vigour under drought stress (Templer et al, 2017;Beetge & Krüger 2019;Xie et al, 2020), indicating that these plant responses mediate the impact of drought stress on sap-feeding insect herbivores. These changes could be caused by increased contact between aphids and plant defensive compounds, a reduction in the availability of nutrients in the phloem sap, or/and a reduction in the growth and development of new plant tissue which is often the preferred feeding site for many aphid species, although this can differ between aphid-plant combinations (Leather & Dixon, 1981).…”

Effects of drought and mycorrhiza on wheat and aphid infestation

“…Such results were found for Brevicoryne brassicae L. and Myzus persicae Sulzer, which reproduced better on plants of Brassica oleracea (Brassicaceae) under constant medium drought than on control plants or plants experiencing severe or pulsed drought (Tariq, Wright, Rossiter, & Staley, 2012). Aphids of S. avenae on T. aestivum plants under drought stress (10% SWC) had a reduced performance compared to those on non‐stressed plants (20% SWC), which may have been related to an upregulation of phytohormone‐regulated defense responses in the plants (Xie et al., 2020).…”

Study of Productivity and Economic Evaluation of Intercropping Cowpea With Maize Under Three Irrigation Water Levels and Their Response to Insect Infestation and Viral Infection

“…These results are in the same context as those obtained by Varsani et al (2019) who indicated that leaf aphids population was significantly higher on benzoxazinoids-deficient maize plants. Also, Xie et al (2020) reported that there were lower net reproductive rates of aphids, intrinsic rates of increase and finite rates of increase under drought stress compared with aphids reared on plants in the absence of stress.…”