Promoting Sustainable Biological Control of the Soybean Aphid by Examining the Effect of Biodiversity on Releases of the Parasitoid Wasp Aphelinus glycinis

Promoting Sustainable Biological Control of the Soybean Aphid by Examining the Effect of Biodiversity on Releases of the Parasitoid Wasp Aphelinus glycinis

Summary

Aphelinus glycinis was released at two sites of the U of MN Agricultural Experiment Station in the summer of 2013. These releases resulted in within-season establishment and in the Spring and Summer of 2014 we monitored these sites to determine whether A. glycinis had overwintered. We examined over 1,000 parasitoid mummies by rearing out adult wasps and found that none were A. glycinis. We therefore conclude that the releases conducted in 2013 likely did not lead to successful overwintering. We note that 2013-2014 was a particularly harsh winter and it may be that these parasitoids will be able to overwinter in this area during more typical conditions.

We also released Aphelinus glycinis at two organic soybean farms during the summer of 2014 – one in Northfield MN and the other in Cottonwood MN; both are in South-Central Minnesota. We released 75,000 individual parasitoids at both sites and recorded strong within-field establishment – in particular at the Northfield site. We will monitor overwintering success at these two sites during Spring/Summer 2015.

Lastly, we released A. glycinis into a buckthorn stand at the U of MN Agricultural Station in St. Paul in the Fall of 2014. Buckthorn is the overwintering host of soybean aphid and this experiment was designed to determine whether A. glycinis can use soybean aphid to overwinter in buckthorn. Releases were done into sleeve cages and these cages will be checked in April 2015 for evidence of successful overwintering.

Objectives/Performance Targets

We have made substantial progress on our objective to perform releases of A. glycinis into farmer’s fields and to evaluate the overwintering ability of this parasitoid in Minnesota. We switched the timing of objectives for logistical reasons and will be doing releases adjacent to native prairie vegetation during 2015.  

Accomplishments/Milestones

We have learned that A. glycinis can be released into soybean fields successfully using the methods developed during 2013. We have also developed a sleeve cage method for assessing overwintering success and implemented it for the first time over the 2014-2015 winter.

Impacts and Contributions/Outcomes

We have shown that A. glycinis can cause significant mortality of soybean aphids in the months post-release. However, this parasitoid will need to be able to overwinter to become established in Minnesota.

A presentation on this project was given at the 2015 NCR-SARE Farmers Forum, held in conjunction with the Northern Plains Sustainable Agriculture Society (NPSAS) Winter Conference. A video recording of this presentation is available online through NCR-SARE’s YouTube channel at: https://youtu.be/6bWYMNbcuI8?list=PLQLK9r1ZBhhFIETmMLo1dZBEVYZWXBIM1

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