Can intraspecific variation in an herbivorous mite alter responses to drought-stressed host plant? A common garden experiment in the context of climate change

Abstract

AbstractThe effects of drought stress on plants and phytophagous arthropods are topics currently extensively investigated in the context of climate change. Dryness not only impacts cultivated plants but also their parasites, which in some cases are favoured by drought. It represents a major challenge that agriculture is facing in a perspective of intensification of drought. Direct effects of drought on herbivorous arthropods typically produce bigger offspring and faster development but attractiveness can also occur. However, how much responses to abiotic factors differ among populations of a species remains poorly documented. The impact of drought-stressed plants on key life-history parameters is here investigated for a major agricultural pest, the two spotted spider mite, Tetranychus urticae, depending on the climatic conditions of the localities at origin. Sampled localities represent a rather wide range of core climate conditions across the mite’s native distribution area with contrasting climatic profiles, ranging from wet temperate to cool Atlantic localities to medium to dry hot Mediterranean localities. Plant drought stress effects on mites was estimated by measuring four life history traits: development time, fecundity, sex-ratio and emigration rate in a common garden experiment made of two modalities: well-watered and drought- stressed bean plants. Mites feeding on drought-stressed plants displayed shorter developmental time and attempted to leave leaf patches less often, and young females were more fecund. The mites originating from wet temperate to cool Atlantic localities respond more strongly to drought than mites originating from medium to dry hot Mediterranean localities, suggesting local adaptation of T. urticae populations to various aridity values and indicates that mite feeding behaviour is shaped by the climatic conditions they faced in the area of origin.