Looking for Artificial Lights for Adult Black Soldier Fly

This should be an interesting post for most people. Looking out for artificial lighting for the BSF breeding has long been an effort in this industry, as an efficient light source can eliminate the variability caused by sunlight quality due to weather or seasonal changes, and thus secure a stable black soldier fly egg production. There are couple key studies in this field that I have to acknowledge for developing our final product of a high efficiency LED breeding lamp.

Tomberlin, J. K. and D. C. Sheppard (2002). "Factors influencing mating and oviposition of black soldier flies (Diptera: Stratiomyidae) in a colony." Journal of Entomological Science 37(4): 345-352.

--In this study the researchers mentioned they have tested 40-watt Sylvania Gro Lux light and 430-watt Pro Ultralight Light System, but neither of these lights had triggered mating nor unfertilized eggs were deposited, and by accessing direct sunlight successful mating was observed and fertilized eggs were collected. This suggested that sunlight are different than those two artificial lights and black soldier fly adults need direct sunlight for successful mating as well as for formation of fertilized eggs.

Zhang, J., et al. (2010). "An artificial light source influences mating and oviposition of black soldier flies, Hermetia illucens." Journal of Insect Science 10(202).

--The researchers in this studies tested a few dozen light sources and found quartz iodine lamp is working for the black soldier fly, at 60% efficiency compared to sunlight. The study suggested a wavelength range from 450-700nm is responsible for successful mating of black soldier fly adults. However hatching rate was not investigated in this study.

Oonincx, D., et al. (2016). "Photoreceptor spectral sensitivity of the compound eyes of black soldier fly (Hermetia illucens) informing the design of LED-based illumination to enhance indoor reproduction." Journal of insect physiology 95: 133-139.

--Unlike the previous studies, this one took another approach to find the effective light. The researchers identified three types of photoreceptor cells in the compound eye of BSF, which can be excited by UV, blue color, and green color lights, respectively. A LED made with this color mixture were proven to be able to trigger black soldier fly mating and producing fertilized eggs, though the study did not give out a fertilization rate, but it did indicate the fertilization rate is higher than using fluorescent lamps, which is barely emitting any light at the UV range.

Nakamura, S., et al. (2016). "Small-scale rearing of the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), in the laboratory: low-cost and year-round rearing." Applied Entomology and Zoology 51(1): 161-166.

--In this study a system composite with two 40-watt fluorescent lamps supplemented with a 20-watt LED with spectrum from 400-800nm triggered mating in small cages (20x23x35cm) and fertilized eggs were obtained. When compared with flies bred under sunlight, the eggs produced under the LED system has lower fertilization rate.
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The study from Zhang et al. (2010) had profound influence in the Chinese BSF breeding industry, as most breeding centers I visited had installed some quartz iodine lamps as light supplement. Though I did not see any breeding center had this lamp used as sole lighting source, as the main lighting source is still sunlight. The lights are only turned on when it's cloudy outside, or during the winter as this light emits huge amount of heat and can also be used as heating source. However this lamp has a big disadvantage and that is the energy consumption--as at least 500-watt is needed and usually people will use the 2000-watt version.

Qaurtz iodine lamps are installed in most breeding facilities and will be turned on when it's cloudy outside. Though I have heard people complain it's not working other than providing heat, so during winter it's turned on for most of the day.

Farmers are using the quartz iodine lamp in many ways--some illuminate from the side, and some from the to; off course the results will be different. Generally if casting from overhead can provide better results.

The EVO Consortium has long been looking for more efficient lighting sources, and there are indeed many lamps we found that works and we have observed couple key phenomenons:

1. Many lights work. For example, we have found many fluorescent type lamps from the market work for black soldier fly, with different color temperature, from 5500k to 7000k. Fluorescent lamps with different color temperature doesn't seem matter much for the mating.
2. Some CFL/LED can trigger mating pair formation, though the mated females oviposited unfertilized eggs.
3. Light power is important. For the same model of lights, if the 100-watt doesn't trigger any mating, sometime if you triple the power--the 300-watt version of this light source can stimulate mating.
4. When using sunlight as light source, a consecutive cloudy days not only decreased the amount of eggs produced, but the hatching rate of these eggs decreased too.

Generally, any light appears to be white, orange, or red has fair amount of useless wavelengths for black soldier fly breeding

With the current known information, about 70% of the light in natural sunlight is useless for black soldier fly breeding. Though because sunlight is free for us to use, we wouldn't mind or care. However it will be a different story when this applies to artificial light source which is powered by electricity with a cost--no one wants to pay for energy used to produce useless lights. The less "useless light" the lamp produces, the more efficient it is, as long as this lamp covers all the lights needed by the black soldier fly.

​So how to improve the lighting? Based on our researches there are basically two approaches to find better light sources.

First approach is testing hundreds of lights from the market and find the best one for our BSF. The advantage of this approach is that you can usually find a lamp that's very cheap and working, the quartz iodine lamps for example, usually cost under $10 USD per piece. On the other hand, the disadvantage of this approach is also very obvious, using the iodine lamps as example again, around 80% of the energy were used to generated useless lights which resulted in extremely high operating cost.

​The second approach is to find out what lights does black soldier fly need for both mating stimulation and egg fertilization, then assemble the lights accordingly. The challenge of this approach is that we still know very little about how the light impact the black soldier fly physiology process that's responsible for mating success. Right now we only know what the black soldier fly compound eye can see, but potentially there are many more organisms that might be sensitive to the lights too, for example, the ocelli; the pigment cells on the body that make this insect black might be sensitive to the lights too, as we already know about human that even though we cannot see UV with our eyes, the UV helps us to produce substances such as vitamin D that's critical for our health.

Based on all the information obtained, we hypothesize that:

1. Theoretically, all the lights can stimulate black soldier fly breeding if power is not a factor to consider. This means, given enough power, 2000-watt for example, many lights can become effective to the adult black soldier fly and for stimulating mating, but not necessarily egg fertilization; though higher the power it requires, the higher percentage of the energy was used for useless wavelengths, and thus less efficient.
2. The mating pair formation does not mean a successful mating, as the light quality during the pair formation is also important for the fertilization to happen.
3. Lights for black soldier fly adult is not just for them to be able to see each other--it's also a required and ongoing condition to trigger more complex physiology processes that helps egg fertilization.

Above are the experience we wanted to share with you of what we know about the artificial light for breeding black soldier fly. With an overall consideration, we decided to use LED technology to assemble the best light possible as of today. 

Purchase or learn more about this LED HERE

Author:
Spring Yang
EVO Conversion Systems
JM Green