Black Soldier Fly Larvae as a Tool for Managing Animal Waste and Providing a Food Source for the Aquaculture Industry

Black Soldier Fly Larvae as a Tool for Managing Animal Waste and Providing a Food Source for the Aquaculture Industry

Summary

We have successfully grown sufficient omega-3 enhanced and non-enhanced larvae to conduct a 9-week feed trial. Our trout feed trial will be completed at the end of February 2008. We have modified an existing grow-out container for black soldier fly produced by a commercial company in Texas (ESRI International LLC) and are currently evaluating it indoors for use on a dairy next summer (2008). Although we have been delayed in achieving our objectives, the study is progressing and we anticipate completing all the proposed tasks by May 31, 2009 (see request for no-cost time extension).

Objectives/Performance Targets

The following is an update for each objective of the proposal:
Objective 1) 20-week rainbow trout feed trial using prepupae

Task 1) Grow prepupae for feed.

Idaho State University researchers have grown the omega-3-fatty acid enhanced prepupae required for the fish feed trial. Researchers at Texas A&M University have also grown (non-enhanced) prepupae required for the feed trial.

Task 2) Conduct feed trial

The University of Idaho has analyzed the fatty acid and amino acid content of the omega 3 fatty acid enhanced and non-enhanced prepupae (Table 1-3). The researchers have also developed the test diets to meet all nutritional requirements of trout, and initiated a 9-week trial in December 2007. The change in weight of fish 4 weeks into the trial suggest fish fed black soldier fly prepupae enhanced with omega-3 fatty acids (BSE) gained slightly more weight than the fish fed non-enhanced prepupae (BSN), but both groups gained less weight than our commercial fishmeal-based diet (control) (Table 4). The differences, however, were not significant when compared using an ANOVA.

Task 3) Conduct taste test. Pending completion of task 2.

Objective 2) Adapt proven methods of growing black soldier flies to dairies in Idaho

Task 1) Hire a student to work on the project.

University of Idaho was not been successful at finding a qualified MSc student to work on this project in September 2006. They decided to hire a technician for a shorter period of time to work on the project (see 2007 annual report).

Task 2) Design a larval grow-out system. We have concluded that we should initially focus on a system that will function in the summer, when temperatures are naturally conducive to larval growth, before evaluating the system for winter use (the energy input in the winter may be cost prohibitive). Researchers at ISU and U of I spent the spring and summer of 2007 determining a suitable container design with low energy input and easy maintenance for larval growth on dairy farms. Eventually we decided to modify a container model produced for smaller scale black soldier fly culture by ESR International LLC (Figure 1). Their container designs are patented and experimentally used in Asia to reduce restaurant waste. We are currently testing (winter 2007-08) the containers (Figure 2) at ISU to determine if any further modifications will be required before the summer on-farm trial period.

University of Idaho has identified a dairy farmer interested in testing four containers. Due to the frequent spring frost we will start the on-farm trial in late June 2008 (pending approval of our no cost time extension on the project – see attached request). The manure at our test facility has been processed using a separator. Although this removes some of the nutrients from the solid waste, we have been successful at raising the black soldier flies on the substrate. The time from egg to prepupae is approximately four months using this processed manure. This is (~2 times) longer than what is observed/reported with poultry manure; however, we have not observed a difference in the rate of larval growth using raw and separated manure, and the latter is much easier to work with. We have found that if fish offal is not added to the manure during the last couple of weeks of growth the prepupae are significantly smaller (~50%) and our yield is much lower. In fact, on a large scale we are unable to harvest the prepupae if they are fed manure only. If fish offal is added to the manure for two weeks or more, 60 kilograms of processed (wet ~40% water) manure yields approximately 3 kg of prepupae. Approximately 40% of the waste remains. We are currently investigating the quality of this fertilizer. Preliminary results indicate tomato plants grow faster and are more productive when this substrate is combined with sterile soil at 50% compared to the negative control and a commercial potting soil fertilizer.

Objective 3) cost benefit analysis. Pending completion of objectives 1 and 2.

Objective 4) plan and design a commercial pilot scale project. Pending completion of objectives 1, 2, and 3.

Outreach and education: We have had several local, national and international newspapers cover this project (see Appendix A for the article in Associated Press and U of I’s press release covering this project). Also, three Western US agricultural radio stations have featured our project. We did not present at the State Fair this fall (2007) because we did not have sufficient data. We intend to have a demonstration in the fall of 2008 (pending approval of our no cost time extension).

One undergraduate student at ISU and two undergraduate students at Texas A&M University have been trained in how to raise black soldier fly larvae and conduct feed conversion studies.

Accomplishments/Milestones

• Trained 3 students to grow black soldier fly larvae

  Cultured 25 Kg of Omega-3 fatty acid enhanced and non enhanced black soldier fly prepupae

  Analyzed the fatty acid content and amino acid profile of the black soldier fly

  Formulated feed for the rainbow trout feed trial

  Initiated a 9-week rainbow trout feed trial

  Constructed a container for growing black soldier fly larvae on diary farms in Idaho

Impacts and Contributions/Outcomes

Outreach: grant announcement was covered by Associated Press and distributed to over 200 newspapers in the US and several international journals. Three Western US agricultural radio stations reported on our project.

Collaborators: