Drought alters interactions between root and foliar herbivores

Area of Science:

• Ecology
• Plant-insect interactions
• Climate change biology

Background:

• Drought and root herbivory significantly alter plant quality and trophic interactions.
• Climate change is predicted to increase drought frequency and severity globally.
• Understanding these impacts is crucial for predicting ecosystem dynamics.

Purpose of the Study:

• To investigate how drought stress and root herbivory affect the performance of generalist and specialist aphids on Brassica plants.
• To determine the role of plant chemistry in mediating these interactions.
• To assess potential generalized effects of abiotic factors on above- and below-ground interactions.

Main Methods:

• Experimental manipulation of drought stress and root herbivory levels.
• Quantification of aphid performance metrics (fecundity, intrinsic rate of increase, development time).
• Analysis of plant chemical defenses (nitrogen, glucosinolates) and physiological traits (water content, biomass).

Main Results:

• High drought stress exacerbated negative impacts of root herbivory on aphid fecundity and growth rate.
• Moderate drought stress, combined with root herbivory, influenced aphid performance, with species-specific optima.
• Increased glucosinolate concentrations under combined stress correlated with longer aphid development times.
• Plant nitrogen content positively correlated with aphid fecundity.

Conclusions:

• Drought alters interactions between foliar and root herbivores, with plant chemistry as a key mediator.
• Aphid species exhibited similar responses to drought and root herbivory, suggesting potential for generalized predictions.
• Abiotic factors like drought can significantly modify plant-mediated interactions between different trophic levels.