Biology project in search of first author: imaging the brain of popular farmed insect Black Soldier Fly

by Holly_Elmore4 min read9th Apr 2021No comments

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Rethink PrioritiesWelfare biologyLife sciences researchInvertebrate welfareRequests (Open)
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I developed this project as an employee of Rethink Priorities. Without access to a lab or instrument core facilities, I cannot complete it myself. I will gladly collaborate with anyone who wants to do the imaging work to obtain funding or connections. I also commit to assisting whoever completes this project in publishing the results in an academic journal if they so desire. The project is very straightforward, but potentially high impact because Black Soldier Fly larvae are and will be farmed in such numbers and because the study of its nervous system has been so neglected. Because of the short timeline and defined labor requirements, I think this is an excellent opportunity for a high school, undergraduate, or graduate student to gain low-committment lab experience while working on an effective animal altruism/animal welfare project. 

If you are interested in working on this project, have a lead on someone who is, or want to share useful resources, please message me at holly@rethinkpriorities.org


Abstract 

Black Soldier Fly (Hermetia illucens) is poised to become one of the largest insect crops in the coming decades, with trillions of larvae projected to be raised for slaughter each year. Yet little is known about the capacities of these animals for sentience or suffering. H. illucens is a dipteran, in the same Order as powerhouse model insect Drosophila melanogaster. Comparatively much is known about the cognitive sophistication of D. melanogaster as well as their capacity to suffer, and this information could be leveraged to assess the capacities of H. illucens. Here, I proposed confocal or lightsheet microscopy of larval H. illucens brains so that the images may be compared to those of D. melanogaster. 

Research Plan 

Specific aims 

  1. Obtain detailed images of the H. illucens larval brain.
  2. Use detailed images of the H. illucens larval brain to compare to D. melanogaster’s larval brain, which has been extensively studied in connection to its behavior, which has been used to infer D. melanogaster experience.
  3. Improve our understanding of the experiences of H. illucens larvae.
  4. Predict the experience of H. illucens larvae under farmed conditions.

Research design and methods

The plan is to obtain detailed images of the brain using confocal or lightsheet microscopy. 

No culturing should be necessary, so any larvae will do. (It would be ideal to use the same strain as farms, though they may not be available in small enough quantities, and little is known about the worldwide genetic structure of H. illucens.)

New protocols may have to be developed for preparing H. illucens tissue for imaging, though the well-developed D. melanogaster protocols may suffice and at the very least serve as an informed starting point. 

Images of the H. illucens  larval brain will be compared to similarly-obtained images of the D. melanogaster larval brain, which has been linked to experiences of pain and indicators of possible suffering and sentience by extensive study. The H. illucens image should be taken with a specific D. melanogaster reference in mind so they can be prepared as similarly as possible to minimize uncontrolled variation between them. The selection of a D. melanogaster reference will depend on many factors, most notably the availability of similar technology and skill for the H. illucens imaging and how well that reference captures brain features relevant to sentience and suffering.

Budget and Justification 

Obtaining larvae: ~$20 from pet food stores or free from colleagues.

  • Extra expense may be justified to obtain strains being used in agriculture, although it is not clear how distinct these are from those available for sale in smaller amounts due to the young age of this crop

Expert hours (if paid): ~$100/hr for:

  • ~ 3-10 hours of dissection (depending on whether H. illucens has major differences from D. melanogaster in this respect, like toughness of cuticle)
  • ~ 3-5 hours of clearing, staining, and mounting
  • ~ 5-10 hours of imaging
  • (Hours and cost estimates from Seth Donoghue)

Reagents: price may vary based on access to economies of scale.

  • Seth Donoghue (pers. comm.) says: “Marginal supplies costs are probably ~$50 for fixing and staining a bunch of brains, but could easily be $1000-$2000 if you have to buy all the supplies in quantities that they are actually sold in.”

Confocal/lightsheet microscopy: ~$40-$60/hr, depending on the instrument core and number of hours spent (representative fees chart), for 5-10 hours of imaging. 

Total cost ranges:

Cost range to first author: 

  • $0, just labor if materials and extra labor are provided by lab or university;
  • $5,400 if undertaken entirely alone, buying all reagents, and with permission only to use university facilities and access instrument core.

Cost range to lab that uses confocal/lightsheet on insects: 

  • $400 plus opportunity cost of lab members involved in helping;
  • Up to $3,910 if all expert labor is paid for separately

Resources and Environment 

Ideally, this work would be undertaken by a student or researcher who understands its purpose and has access to: 

  • lab facilities, including:
    • insect incubation areas,
    • a dissecting scope, and
    • sample prep reagents
  • experts in using confocal microscopy, and
  • either a lab confocal microscope or access to an instrument core.

I believe it would be possible to complete this work by:

  • rearing H. illucens at home and
  • paying for an expert to complete to prep and imaging OR
  • paying an expert to do some of these steps and obtaining training on, say, operating the confocal microscope

Timeline 

1-3 months.


Obtaining flies, rearing larvae, preparing them for imaging, and imaging requires about a month. 

Allowing for inevitable delays, this project seems ideally suited for a two- to three-month summer research project undertaken by a high schooler or undergraduate student under the supervision of a lab. This would also be suitable as a few months side project for a graduate student.

Open Questions

  • What can we say about the differences between D. melanogaster and H. illucens based on brain imaging alone? What can’t we tell?
  • What differences in brain anatomy between D. melanogaster and H. illucens could lead us to believe that H. illucens is not sentient or less sentient?
  • What differences might we expect between the brains of H. illucens larvae and D. melanogaster larvae?
    • Particularly on the basis that D. melanogaster larvae are less mobile while H. illucens larvae are highly mobile as the only life stage that feeds?

Resources

Contact

Holly@rethinkpriorities.org 

Papers 

Lemon, William C., Stefan R. Pulver, Burkhard Höckendorf, Katie McDole, Kristin Branson, Jeremy Freeman, and Philipp J. Keller. “Whole-Central Nervous System Functional Imaging in Larval Drosophila.” Nature Communications 6, no. 1 (November 24, 2015): 7924. https://doi.org/10.1038/ncomms8924.

Pereanu, W. “Neural Lineages of the Drosophila Brain: A Three-Dimensional Digital Atlas of the Pattern of Lineage Location and Projection at the Late Larval Stage.” Journal of Neuroscience 26, no. 20 (May 17, 2006): 5534–53. https://doi.org/10.1523/JNEUROSCI.4708-05.2006.

Rein, Karlheinz, Michael T Mader, and Martin Heisenberg. “The Drosophila Standard Brain.” Current Biology, n.d., 5.

Sprecher, Simon G., Albert Cardona, and Volker Hartenstein. “The Drosophila Larval Visual System: High-Resolution Analysis of a Simple Visual Neuropil.” Developmental Biology 358, no. 1 (October 2011): 33–43. https://doi.org/10.1016/j.ydbio.2011.07.006.

Tully, T, V Cambiazo, and L Kruse. “Memory through Metamorphosis in Normal and Mutant Drosophila.” The Journal of Neuroscience 14, no. 1 (January 1, 1994): 68–74. https://doi.org/10.1523/JNEUROSCI.14-01-00068.1994.

Acknowledgments

Thanks to Jason Schukraft for his research in Black Soldier Fly larvae and for suggesting the research topic. Seth Donoghue provided estimates of costs and labor. 

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