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

Abstract

Aphids are abundant in natural and managed vegetation, supporting a diverse community of organisms and causing damage to agricultural crops. Due to a changing climate, periods of drought are anticipated to increase, and the potential consequences of this for aphid–plant interactions are unclear. Using a meta‐analysis and synthesis approach, we aimed to advance understanding of how increased drought incidence will affect this ecologically and economically important insect group and to characterize any potential underlying mechanisms. We used qualitative and quantitative synthesis techniques to determine whether drought stress has a negative, positive, or null effect on aphid fitness and examined these effects in relation to (a) aphid biology, (b) geographical region, and (c) host plant biology. Across all studies, aphid fitness is typically reduced under drought. Subgroup analysis detected no difference in relation to aphid biology, geographical region, or the aphid–plant combination, indicating the negative effect of drought on aphids is potentially universal. Furthermore, drought stress had a negative impact on plant vigor and increased plant concentrations of defensive chemicals, suggesting the observed response of aphids is associated with reduced plant vigor and increased chemical defense in drought‐stressed plants. We propose a conceptual model to predict drought effects on aphid fitness in relation to plant vigor and defense to stimulate further research.

Drought stress increases the expression of barley defence genes with negative consequences for infesting cereal aphids

“…The observation that drought stress had a negative effect on plant physiological processes is in line with previous findings (Ivandic et al, 2000;González et al, 2008;Aslam et al, 2013;Zeppel et al, 2014) and the wider conclusion of meta-analyses (Cornelissen et al, 2008;Leybourne et al, 2021). We identified similar negative effects of drought stress on both plant types: the above-and below-ground dry mass decreased to similar levels when exposed to both drought stress conditions, although, the mass of Hsp5 was lower than Concerto under controlled conditions, indicating that…”

“…Elevated HvTHIO1 levels in Concerto under the drought stress conditions could contribute towards the observed trend of greater reduction in aphid fitness (compared with Hsp5) under the water stress treatments, or could contribute to the increased expression of aphid detoxification genes when feeding on this plant type. Furthermore, a recent meta-analysis indicated that the defensive processes of plants are generally heightened under drought stress conditions and growth and vigour are reduced, with negative consequences for aphids (Leybourne et al, 2021); the findings of this research are in line with the conclusions drawn from this meta-analysis.…”

“…There is evidence that plant resistance against aphids can mediate the extent to which aphids are negatively affected by drought, with aphids feeding on resistant plants showing a smaller decrease in fitness under drought conditions compared with aphids feeding on susceptible plants (Oswald and Brewer, 1997;Dardeau et al, 2015). Our recent meta-analysis highlighted a knowledge gap regarding the interaction between plant resistance traits and drought (Leybourne et al, 2021). Examining these interactive effects is becoming more important as alternative pest management methods (including breeding for plant resistance against insect pests) are increasingly needed and droughts are more likely in the future.…”

“…Drought-mediated changes in plant physiology are widely reported (Cornelissen et al, 2008) and have been associated with negative consequences for herbivorous insects across multiple herbivorous insect groups (Huberty & Denno 2004). A recent meta-analysis of aphid responses to drought stress in plants indicated that drought-induced reduction in aphid fitness is also associated with a reduction in plant growth and vigour and an increase in the tissue concentrations of plant defensive compounds (Leybourne et al, 2021). There is evidence that plant resistance against aphids can mediate the extent to which aphids are negatively affected by drought, with aphids feeding on resistant plants showing a smaller decrease in fitness under drought conditions compared with aphids feeding on susceptible plants (Oswald and Brewer, 1997;Dardeau et al, 2015).…”

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

“…The effect of drought on phloem-feeding insects has been variable. Drought has been reported to reduce the tness metrics such as survivorship, fecundity and density of phloem-feeding insects (Huberty et al 2004;Leybourne et al 2021), while other studies linked drought with an increase in pest abundance (Mattson et al 1987;Pretorius et al 2016). For example, moderate drought events have promoted populations of the rice root aphid (Rhopalosiphum ru abdominalis Sasaki), a pest of wheat (Triticum aestivum L.) (Kindler et al 2004).…”