Genomics of ash-emerald ash borer interactions

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The emerald ash borer (EAB) is an invasive wood-boring beetle whose larvae tunnel under the bark of ash trees and can kill an infested tree within a few years. EAB was introduced accidentally from China, and since its discovery in the Detroit-Windsor area in 2002, the insect has spread across Ontario and into Quebec (as well as large parts of the USA), killing millions of ash trees in forests, parks and city streets. Ash is a key species in urban forestry, making up a significant proportion (up to 40%) of street and park trees in municipalities across Canada. During ash infestation EAB is feeding in the phloem resulting in the progressive destruction of the vascular system of the tree. Infected trees cannot be identified until the beetles emerge from the bark. Thus, there is an urgent need to develop innovative tools to detect and monitor new infestations for effective management of this alien insect, based on a molecular characterization of the ash response to EAB. Mechanisms of resistance to EAB are currently unknown. Asian species of ash show greater resistance than North American species, and some laboratories have begun looking for biochemical processes that underlie the resistance mechanisms. To date, the focus has been on leaf biochemistry in relation with adult feeding and vascular cambium for larval feeding. The overall approach is composed of screening mature ashes in various environments with variable degrees of infestation by EAB and also to develop a protocol for experimental infestation of potted green ash trees with EAB under controlled conditions. Infested and control tissues will be harvested and used for analysis of ash vascular cambium at the gene and protein expression levels. Identification and characterization of EAB-induced genes of ash will open unexplored avenues for elucidating resistance and susceptibility mechanisms to EAB and for developing diagnostic markers.