Shotgun metagenomic case study of a Tenebrio molitor colony collapse

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Presenter(s)

Dewey Leierer

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Student Bio

Dewey Leierer is from Wichita, Kansas and is a senior at Kansas State University majoring in Biochemistry and minoring in Entomology. Dewey has always adored insects, and she has been involved in undergraduate entomology research since her freshman year. She currently works as a laboratory assistant to Dr. Brenda Oppert at the USDA. Dewey began her research on mealworm colony collapses in May of 2021 and has presented it at the Regional Heartland McNair Research Conference and the National Entomological Society of America conference. She is also passionate about science communication and currently serves on the board of the Kansas Science Festival Foundation. Dewey has been accepted into Kansas State University’s Graduate Program and will begin pursuing a PhD in Biochemistry this fall.

Abstract or Description

Recent years have highlighted the importance of establishing sustainable farming practices. Thus, there is a need to identify nutritious and sustainable ingredients to supplement livestock diets. The yellow mealworm, Tenebrio molitor, is one of the most promising candidates for this. In both commercial and research rearing, mealworms are often kept in densely populated colonies, allowing pathogens to spread quickly. Pathogens can cause expensive colony collapses that result in massive losses of food. Here, we report an instance of a colony collapse in a USDA-ARS research facility. The colony was noted as sick several years ago and exhibited a loss of fitness. However, a mite infestation in May of 2021 led to the colony’s collapse, and the pathogen-induced loss of fitness likely allowed mites to overtake the colony. We used shotgun metagenomic sequencing to identify pathogens present in the colony. In addition to identifying bacteria pathogenic to T. molitor, we identified bacteria associated with illness in humans and animals. Prioritizing colony hygiene can prevent the accumulation of dangerous and prevent costly colony collapses. Furthermore, insect-specific industry standards for antimicrobial processing methods should be established and enforced to ensure the safety of the livestock who consume them. Supplementing Kansas’ livestock diets with mealworm protein will move us towards more sustainable agricultural practices while also feeding our livestock more nutritious foods. This study can be used to assist both commercial and research in preventing future colony collapses and as reference of pathogens that may affect mass rearing.

Mentor

Dr. Brenda Oppert

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Comments

TJ Montes3 years ago

Can these bacteria pathogens that affect farm animals, be passed down to humans, and would it affect our health?

• • 1 comment

Dewey Leierer3 years ago

Yes most of the pathogens that affect mammalian farm animals would be able to infect humans. However, we would only be at risk to contract them from T. Molitor if we were the ones eating them and they were uncooked. It is mostly an issue for animals like poultry who would be fed live mealworms. The pathogens we found that can infect humans, mainly mammalicoccus scuiri and lentus, are also largely opportunistic and unlikely to infect people. They have been associated with cases of endocarditis and a few other types of infections in humans though.

Brenee King3 years ago

Very thorough and informative project. You mentioned that currently there are no insect specific food guidelines. Do you know of any efforts to try and change that?

• • 2 comments

Dewey Leierer3 years ago

Thank you! To my knowledge, not in the US right now. Insects are currently categorized by the FDA as "mince meat" in products intended for human consumption, and the microbial limits set for products in that category are really not specific enough to be fit for fully protecting animal and human consumers from possible pathogens. I am not aware of the details of insect specific food guidelines for animal feed though, if there are any. However, most insect farms do things like freeze dry or bake their bugs to disinfect them before packaging. One issue is that many animals will be fed live T. molitor, and live T. mol is unable to be disinfected by most traditional methods because most methods we have would require the bug to be dead.

Brenee King3 years ago

I appreciate the additional information!

Brenda Oppert3 years ago

Hi Dewey, great job!

• • 1 comment

Dewey Leierer3 years ago

Thank you!

David Leierer3 years ago

Very interesting. You and your team did a great job!

• • 1 comment

Dewey Leierer3 years ago

Thank you!

Michelle Le3 years ago

Hello Dewey! Amazing presentation and very informative. Would these bacteria pathogens still affect animals if they were treated through a process that didn't involve heat such as freeze-drying?

• • 1 comment

Dewey Leierer3 years ago

Thank you so much! Processing methods that don't require heat like freeze-drying and irradiation should also be sufficient for getting rid of pathogens. A few companies in the US who produce insects for humans to eat freeze-dry their insects to clean them.

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Jeannie Brown Leonard3 years ago

Thanks for sharing your work! If a supply of healthy mealworms could be assured (by following your recommendations), would there be any resistance to supplementing livestock diets with mealworms (e.g., cost, supply, knowledge)?

• • 1 comment

Dewey Leierer3 years ago

Thank you! The main resistance to supplementing diets may be the stigma of feeding things bugs. Besides that, they are incredibly cheap, able to be mass produced extremely fast, and there is a vast amount of knowledge among mealworm farmers on how to make this possible. However, most guidance on farming these insects is not published on and just shared between farmers on forums and websites. It would be great if we could help get some of their guidance and wisdom published to help out others who are interested in rearing mealworms.

Dawn Tallchief3 years ago

Thanks for sharing your research!

• • 1 comment

Dewey Leierer3 years ago

Thank you!

Ngoc Vuong3 years ago

This is a very interesting study. Based on your findings, what recommendations would you have for policymakers (specifically those who deal with agriculture policy) and special interest groups that represent the agriculture industry? I'm also curious if in your review of the literature, whether you came across economic studies that have compared the costs and benefits of a mealworm protein-supplemented diet with the status quo?

• • 1 comment

Dewey Leierer3 years ago

Thank you! I would recommend policymakers consider passing more insects-as-food legislation similar to what Europe has been doing. Europe recently approved yellow mealworms as aquafeed, and it would be great if we could have that here as well. As we start incorporating insects into our food supply chain, we need to give support to insect farmers as many of them are really struggling right now. I did not come across any studies comparing the cost dollar for dollar of supplementing diets with mealworms. However, they are generally very cheap, and the main benefit will be the increased nutrition we can provide to our animals (per pound of protein, mealworms have more iron than beef!). Ideally, they can replace a portion of grain-filler in many animals' foods.