Determining Temperature-Dependent Development and Mortality Parameters of the Swede Midge (Diptera: Cecidomyiidae)

The swede midge (Contarinia nasturtii Kieffer) is an invasive insect in North America whose feeding has caused a decline of over 60% of total canola acreage in Ontario, Canada since 2011. Temperature-dependent development and mortality information are important to develop an effective pest management strategy for this insect; as the most comprehensive study on C. nasturtii development was completed on populations from the United Kingdom in the 1960s, new geographically relevant information is needed. Contarinia nasturtii eggs, larvae, pupae, and adults were reared from wild populations collected from Elora, Ontario, and allowed to develop at different temperatures. Resulting development rates were fit to a series of growth models and the model with the best relative goodness-of-fit was selected to represent the given life stage. Eggs from Ontario populations developed more quickly than their UK counterparts at temperatures below approximately 17°C, but more slowly at temperatures above 17°C. The same phenomenon was observed in larvae at 20°C. Pupae from both populations had similar development rates, and adult longevity was similar as well. This information will inform the management of C. nasturtii, and may help prevent its spread to other canola-producing regions of North America.