BSF Good- Pesticide Bad: Pest Management Strategies for BSF Colonies

​A recent post was made on the BSFL Facebook page with regards to how to prevent fire ants (for those not from a region with fire ants, Solenopsis invicta, I pray you never know the experience of their sting or bite- truly a curse upon the land) from getting into their colony. See the following link to learn more about these hounds from Hades.
 
https://fireant.tamu.edu/learn/history-of-the-red-imported-fire-ant/
 
Many individuals responded, and based on my last reading, the advice given was spot on- the main point, do not use insecticides that could come in contact with your BSF. Now, this post is not about the fire ant (the less I think about them the better), but more about integrated pest management (IPM) and how to use it with your colony.  A brief review of IPM can be found at:
 
https://landscapeipm.tamu.edu/what-is-ipm/history-of-ipm/
 
The basic tenants of the black soldier fly are, 1) biological control, 2) cultural control, and 3) pesticides. With regards to the BSF, nothing has been developed with biological control (using nature to combat nature- e.g., parasitoids, predators, etc). However, with regards to the other two items, there is a bit of information available.
 
Cultural Control:  The manipulation of the environment to prevent pests. Under these circumstances, there are a number of pests to consider. Obviously the house fly and other insects that colonize decomposing waste is an issues. Here are some potential solutions to these issues:
 

1. Keep your place clean! This rule applies to your buckets used to transport food waste or other materials to your larval containers. And, it also applies to the actual bin in which you are rearing your larvae. You want to keep your larval density high to prevent other pest flies from colonizing. You also might consider cleaning out your bins periodically.  The waste you collect from your bins can still be composted for later use.
2. Use the smell test.  That’s right; keep a mental log of the smells emanating from your bins. If you detect rot, something is probably going wrong and you will want to check for the presence of pest flies, which leads to my next point.
3. Be a good shepherd. Periodically, look through your bin. Make sure your larvae are healthy (actively moving and feeding), no other insects are present, and the waste is being digested efficiently. There is no reason for waste to remain in the bin longer than four or five days- the larvae should recycle it in that amount of time. Furthermore, daily checks can reduce the likelihood of over-feeding.
4. Check your feed. If you are using a grain diet to raise larvae for your colony- make sure it is dry. If it is wet, other insects will come in and attempt to colonize it. This is bad for two reasons, 1) spoils your resource, which is an expense, and 2) creates a population of pests. If you find there is a problem, remove the wet grain with larvae and get rid of it. You could always introduce it to your BSF larvae and let them digest it.
5. Air out the joint!  You want good ventilation to prevent ammonia build-up as well as reduce the likelihood of strong odors accumulating that will attract pest species.
6. Use sticky traps.  These are glue boards (often used for collecting mice and other rodents) or sticky strips specifically for flies. You might hand these in your facility to collect and flying pests (not talking about birds) that are attracted to your site.

 
Insecticides. These are compounds made for controlling arthropod pests. To date, there is only one study on the impact of insecticides applied directly to adult or larval BSF. There is a more recent study on insecticides and larvae as well (posted recently in blog with regards to mycotoxin). Here are the links:
 
http://www.bioone.org/doi/pdf/10.1603/0022-0493-95.3.598
 
http://www.tandfonline.com/doi/pdf/10.1080/19440049.2017.1299946
 
The takeaway from this study is very simple. BSF adults are highly…highly….HIGHLY sensitive to insecticides. Do not apply them in your facility as you run the risk of killing your adults. Their sensitivity makes sense. Most insecticides are applied to areas in facilities (e.g., chicken layer houses) where adult pest insects aggregate. These sites are very different from those used by adult BSF. In fact, adult male BSF never return to the facility where they developed, and females only return to lay eggs… typically in the bottom of the facility. Consequently, BSF are rarely exposed to these insecticides. I recall when I did this study that I determined adult BSF were 30X more sensitive to these insecticides than the control house fly population used. What this means is the population of house flies that we used, which was considered extremely sensitive to insecticides could not hold a candle next to the level of sensitivity of the adult BSF population I was studying. 
 
As far as larvae, they also are sensitive to these compounds. But, another issue is the concerns with potential insecticide contamination. You do not want to risk your BSF larvae bioaccumulating these compounds; especially, if you are feeding them to livestock, poultry, fish, or reptiles. So- the simple response is- do not use insecticides. Rely on cultural methods for keeping your facility clean.
 
As far as the fire ant- the best strategy is to do as suggested in the responses- place the legs of your tables on which you place your BSF bins in containers of soapy water. Fire ants will not be able to get to your bins – just make sure to check the containers every few days to make sure water is still present. If it looks low- add more soapy water. 

Author

Jeff Tomberlin, PhD, Caretaker of BSF
Twitter: @FliesFacility
Director, EVO Conversion Systems
evoconsys.com