The effects of temperature on the development of polyphagous shot hole borer (Euwallacea sp.)

Polyphagous Shot Hole Borer (Euwallacea sp.) (PSHB) is an invasive ambrosia beetle originally identified as Tea Shot Hole Borer (Euwallacea fornicatus), but shown to be a different species based on nuclear and mitochondrial evidence (Rugman-Jones and Stouthamer, unpublished data). PSHB carries a complex of symbiotic fungi which are grown inside the galleries its forms under the bark of its host tree. Infestations of the beetle pose a threat to tree health due to the damage inflicted on the tree’s vascular tissue by tunneling and fungal growth (Eskalen et. al., 2012). The threat of PSHB is amplified by its large host tree range and lack of information regarding its life history characteristics. In order to fill in some of these gaps in knowledge and determine the rate at which the beetle can develop in different conditions individual PSHB adults were reared under a range of temperatures. Fully grown adults were placed within modified centrifuge tubes filled with semi-artificial media and allowed to develop at a constant temperature. At set intervals tubes were dissected to allow counts of each life stage present. PSHB developed rapidly at higher temperatures, with a 5°C difference reducing development time by over ten days, while beetles raised at moderately low temperatures showed minimal development. These findings will be useful in predicting population growth of PSHB populations and for predicting areas at risk.