Erythrina stem borer moth in California – New taxonomic status and implications for control of this emerging pest

During the last 10 years, the Erythrina stem borer moth, Terastia meticulosalis, emerged as a pest of cultivated coral trees (Erythrina spp.) in California. Erythrina trees are valued for their moderate drought resistance and beautiful flame-like flowers. They are beloved enough to be considered Los Angeles's official “City Tree.” Thus, they are a valuable horticultural crop and are grown by many nurseries and occur throughout the landscape in coastal southern California. Coral trees have been heavily affected by T. meticulosalis recently. Using whole genome sequencing techniques, we analysed the origins of this and other infestations of Erythrina in coastal areas and found that they have likely originated from the repeated expansions of the native range of the species in Arizona, a process possibly driven by climatic factors and/or movement of plants by humans. We also found sufficient genetic differences between the western population of the moth and the rest of the New World populations to describe a new western subspecies, T. meticulosalis occidentalis Sourakov & Grishin ssp. n. (type locality USA: CA, San Diego Co., La Jolla). These findings are of economic importance for future attempts to control the moth's impact on activities surrounding the horticultural use of Erythrina spp. by the Californian landscape and nursery industries.