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Abstract: The wheat curl mite (WCM) is a major pest in cereal crops around the world and the vector of at least four known pathogens capable of reducing yields in crops such as wheat, corn, barley, oats, millet and rye. Current taxonomy recognizes WCM as a single species, Aceria tosichella; however, recent genetic, physiological and ecological studies have shown that WCM is likely to be a species complex. In this study we assessed genetic variation and phylogenetic relationships among WCM from four continents and a wide range of host plants using DNA sequence data from one mitochondrial gene, one nuclear gene and a single nuclear intergenic spacer region. Phylogenetic analyses revealed 11 unique mite lineages associated with specific plant hosts including wheat and barley. Host associations were consistent across continents, often with a single haplotype dominating a host plant regardless of geographic origin. The genetic and ecological differences identified in this study support the notion that WCM is a species complex in need of major taxonomic revision. These findings have implications for control of WCM globally, particularly within the context of identifying plants that form ‘green bridge’ refuges, assessing disease transmission risk, and identifying resistance in cereal genotypes to WCM and associated pathogens. [Copyright &y& Elsevier]

Dispersal involves many behavioural interactions that if inefficient or ineffectual would lead to serious fitness consequences. Such costs would be particularly dear for passively dispersing organisms for which direction of movement is determined by external forces. In this study, we investigated whether environment and morphology influence dispersal behaviours of a passive, aerially dispersing organism, the eriophyoid wheat curl mite, Aceria tosichella. We used a wind tunnel to generate stable wind speeds and analysed mite behaviour, morphology and dispersal rate for each wind speed treatment. We found that dispersal events were phenotype and context dependent with an important behavioural component. Aerial dispersal increased significantly via chains formed by individuals and mites dispersing in chains were significantly more elongated than controls. This difference in shape interacted significantly with wind speed but diminished at high wind speeds. Contrary to expectations, we found that an upright position was not related to the likelihood of being blown away. The results indicate that departure events for this mite are influenced by the interaction of behaviour, morphology and environment. Our study represents a substantial step toward explaining wheat curl mite dispersal and its colonization potential, with implications for passively dispersing organisms in general. • We tested how behaviour, morphology and environment influence passive dispersal. • Passive dispersal events are both phenotype and context dependent. • Most aerial dispersal is by mites engaged in chain-forming behaviour. • Regarding morphology, aerial dispersal relates to body shape rather than size. [ABSTRACT FROM AUTHOR]