Parasitism and phenology of Dasineura mali (Diptera: Cecidomyiidae) in Canadian apple (Rosaceae) orchards

Citation

Cossentine, J.E., Brauner, A.M., Franklin, J.L., Robertson, M.C., Buhl, P.N., Blatt, S., Gariepy, T.D., Fraser, H., Appleby, M., Grigg-McGuffin, K., Mason, P.G. (2020). Parasitism and phenology of Dasineura mali (Diptera: Cecidomyiidae) in Canadian apple (Rosaceae) orchards. The Canadian Entomologist, [online] 152(3), 355-373. http://dx.doi.org/10.4039/tce.2020.15

Plain language summary

The apple leaf curling midge is an invasive insect pest in Canada where it causes damage to apples. Here we look at the life cycle of the insect in British Columbia, Ontario, and Nova Scotia to find out when and where damage take place. In addition, we look at the natural enemies that kill the apple leaf curling midge and document their occurrence in all three provinces. The natural enemies include parasitoids -- tiny insects that lay their eggs inside of the apple leaf curling midge, and kill the midge as they grow and develop.

Abstract

The apple leaf midge, Dasineura mali (Kieffer) (Diptera: Cecidomyiidae), an invasive alien pest established for many years in Nova Scotia, Canada, has invaded Ontario and British Columbia, Canada apple (Malus domestica Borkhausen; Rosaceae) orchards, damaging growing tips of trees. Molecular analysis indicated that Nova Scotia populations are genetically different from Ontario and British Columbia populations. Pheromone trap captures, oviposition on growing apple terminals, and the incidence of third instars indicate three D. mali generations in each province. Platygaster demades Walker (Hymenoptera: Platygastridae), released in Nova Scotia in 1993, parasitised 34% of the third midge generation in that province and was reared from D. mali for the first time in 2016 in the Fraser Valley of British Columbia. Lyrcus nigroaeneus Ashmead (Hymenoptera: Pteromalidae) parasitised up to 21% of D. mali in southwestern Ontario. Synopeas myles (Walker) (Hymenoptera: Platygastridae) was recorded from D. mali for the first time, one specimen in each of Nova Scotia and Ontario, and was the most important parasitoid in British Columbia. Synopeas myles parasitism in Okanagan and Similkameen, British Columbia orchards increased from 0% to a mean of 30% of D. mali larvae from 2014 to 2016. Other minor parasitoids included Platygaster tuberosula Kieffer (Hymenoptera: Platygasteridae) in all three provinces and Aphanogmus vicinus Förster (Hymenoptera: Ceraphronidae) in British Columbia.