Research: Spotted Wing Drosophila (SWD) in Ontario

Spotted Wing Drosophila (SWD) is a relatively new pest and there are a lot of questions about how this insect will behave in Ontario fruit crops. Fortunately there is a great deal of research underway across North America which will help us learn how to monitor SWD and how to manage it economically. OMAFRA specialists are working with colleagues in Canada and the USA to collaborate on projects and share information.

Here in Ontario, there are several projects in progress. It is important that stakeholders be connected to these projects to help keep these projects relevant to the needs of Ontario fruit growers.

Enhanced monitoring and management of spotted wing drosophila, an invasive pest of soft skinned fruit in Ontario

Project Team: Rebecca Hallett, Rose Buitenhuis, Tara Gariepy, Hannah Fraser, Justin Renkema

Source of Funding: OMAFRA / U of G Research Program 2011/2012 (Production Systems Plants: Plant Protection)

Objective: (1) To develop better traps, an improved attractant and molecular identification tools to monitor spotted wing drosophila (SWD). (2) To learn more about the population dynamics in Ontario, including which crops and wild hosts support SWD. (3) To develop a novel push-pull management strategy using plant volatiles to repel and attract SWD. (4) To assess endemic parasitoids and predators that may attack SWD.

Findings so far: Traps with large entry areas and large surface areas for attractant volatilization improved captures of SWD. Yeast-sugar-water lures improved captures compared to apple cider vinegar, but synthetic blends of fruit volatiles did not improve captures. Field edges appear to be important overwintering habitat and certain wild host species support SWD populations, but specific movement patterns from field edges to crop interiors were not always evident. In the laboratory, several plant essential oils were highly repellent to SWD flies and reduced egg-laying in ripe fruit. On a small scale in the field, oils also reduced egg-laying in fruit. We are currently exploring technologies to more effectively disperse repellents throughout the crop and test their efficacy in combination with attract and kill systems. The genetic structure of SWD in Ontario is being determined using molecular barcoding; these results are being used to assess a predatory beetle species and will be used to study endemic parasitoids for biological control.

Life history and seasonal movements of the spotted wing drosophila, Drosophila suzukii, in a multi-crop setting

Project team: Dr. Rose Buitenhuis, Vineland Research and Innovation Centre; Hannah Fraser, OMAFRA

Source of funding: Niagara Peninsula Fruit and Vegetable Growers Association

Objective: (1) Study spotted wing drosophila (SWD) life history and seasonal movement between overwintering sites, alternative hosts and crops in Niagara. (2) Provide industry with knowledge on local SWD occurrence, biology and behaviour which is essential to predict outbreaks and to develop more effective control methods.

Findings so far: SWD persists in the landscape well into the cold season. No SWD were recovered late winter to spring. Although it is suspected that SWD overwinters in Niagara, this could not be confirmed. In 2013, the first SWD in Niagara was found July 4. Early detection of SWD at the beginning of the season can be accomplished by trapping or by fruit collections. For traps, ACV bait is recommended because of its ease of use and similar performance compared to the yeast + sugar bait. No clear patterns of movement between wild hosts and crops were observed.

Temperature-dependent development and overwintering in the spotted wing drosophila

Project team: Jonathan Newman, Gerry Ryan, Lisa Emiljanowicz, Aaron Langille

Source of funding: OMAFRA / U of G Research Program

Objective: (1) To investigate how life history parameters (e.g. stage-specific development time, reproductive output, mortality and lifespan) are likely to fluctuate with temperature. (2) To investigate the ecology of overwintering in SWD. (3) to create a population model of SWD to allow spatial and temporal forecasting.

Findings so far: Temperature curves have been generated for SWD. Current work is focussed on identifying upper and lower developmental critical points. A newly initiated overwintering experiment will investigate how SWD overwinters in Ontario climates and how this depends on diapause induction, developmental stage and ecotype. The forecasting model is now almost complete and should be submitted for publication in late February 2014.

A population demography study of SWD by our group is currently in press in the Journal of Economic Entomology (details to follow).

Monitoring and management of spotted wing drosophila in Ontario 2013

Project Team: Pam Fisher, Anne Horst, Denise Beaton, Hannah Fraser, Leslie Huffman, Margaret Appleby, Melanie Filotas

Source of funding: Ontario Berry Growers Association, Ontario Highbush Blueberry Growers Association. This project was funded in part through Growing Forward 2, a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of Growing Forward 2 in Ontario.

Objective: To monitor for spotted wing drosophila using traps and fruit monitoring and to provide growers with accurate, current information on SWD control.

Findings to date: Spotted wing drosophila was trapped across Ontario in both 2012 and 2013, as far north as New Liskeard and in all major fruit growing regions in Ontario. First trap captures of SWD were coincident with late strawberry -early raspberry harvest in most regions. When trap captures were pooled by region, populations showed similar patterns in each region, but were highest in southwestern and south-central Ontario. Infested fruit was detected slightly earlier than the first trap captures. From mid-July to mid-September, infested fruit was common. Growers can monitor for SWD using traps for adult flies, however on farm trap captures are not a good indicator of early SWD populations. Weekly salt water fruit immersion is more effective than on-farm trapping to detect early infestations and to evaluate the success of SWD control programs. Actual infestation rates can be underestimated with salt water immersion tests, however it seems to be a good predictor of presence or absence.

Research on SWD in recent years has supported the development of much information to inform growers on how to recognize and manage this pest.

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