Dear colleagues:
I am interested in this topic because I want an organism that consumes food waste at a high rate and the data for insects and worms seem more homogeneous. I have to admit that terrestrial isopods have me completely surprised. Some species reproduce at much higher rates than other invertebrates. However, the data in the literature speak of very low daily intakes of less than one mg per g of live weight. On the other hand, as they live at overcrowding levels of tens of thousands per square meter they could compensate this low feeding rate. Even so, it is not clear to me. The species that I keep in the laboratory as a companion to the terrariums is Porcellio laevis. I don't know if I have minimized the effect of terrestrial isopods as detritivores. I know that isopods crush the food considerably and help the bacterial processes of decomposition. I do not care whether they degrade directly or indirectly. I want to know their exact contribution and I repeat, the results are very disparate and confusing. For example in these papers:
Effects of Terrestrial Isopods on the Decomposition of Woodland Leaf Litter Author(s): M. Hassall, J. G. Turner and M. R. W. Rands Source: Oecologia , 1987, Vol. 72, No. 4 (1987), pp. 597-604.
Abd El-Wakeil, Khaleid. (2015). Effects of terrestrial isopods (Crustacea: Oniscidea) on leaf litter decomposition processes. The Journal of Basic & Applied Zoology. 69. 10.1016/j.jobaz.2015.05.002.
These studies report composting rates of more than 70% of the biomass ingested (~millipedes), which is logical if we look at their diet. But the most surprising thing is that they also talk about feeding conversion ratios (FCR) between 1.5 to 2, which would place them at the same level as the tenebrionidae. I would like to set up a discussion on isopods can be used on an industrial scale to firstly degrade waste and secondly to compost. The thousands of isopods I have in my lab inside terrariums don't seem to be effective enough to attract attention. Judging by their numbers the breeding conditions are appropriate. In short: I don't know what to think of isopods. I guess I'll have to do a lot of tests before I decide.
Any suggestion?
Thanks
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Daniel Patón. Numerical Ecology. Ecology Unit
Department of Plant Biology, Ecology and Earth Sciences
Faculty of Sciences. University of Extremadura
Avda. Elvas s/n 06071 Badajoz (Spain)
https://orcid.org/0000-0003-2500-3964
https://www.researchgate.net/profile/Daniel_Paton/
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At the densities that these animals can be at their combined effect is enormous. I believe that some studies may not have been conducted under ideal environmental conditions.
Hello DanielI have a large, unkempt compost heap into which I put all types of garden waste. The waste includes whole plants at the end of the growing season...broccoli, cabbage, peppers, pumpkins, peanut shells, carrot tops and all the rest of it. Perhaps 300 pounds of very coarse material go in per year, all very well aerated. Below about 6 inches into the heap, right on top of a thoroughly chewed mass, there is a solid mass of isopods chewing away. A fresh mass of material is mostly reduced in less than a month. There are few earthworms in the heap. Years ago, I kept rabbits and their droppings also went into the heap. Then there were zillions of worms along with the sowbugs. No rabbits, no worms. The rate of processing with isopods far exceeds that of worms. Best regards, Jim Des Lauriers
Dear James. Absolutely revealing. Thank you very much. That's exactly what I suspected. Isopods have a higher reproductive rate than worms. It has to show in consumption. The problem is that I think some research work with isopods has not been done under conditions that are ideal for these animals. Thanks
Daniel; The only conditons that I pay any attention to are;
1. Well aerated.
2. High humidity but not saturated.
3. Unprocessed material is thick enough for it to be dark at the isopod layer.
Cheers, Jim Des Lauriers
Dear @Jim:
These are precisely the conditions in which I have isopods as companion species for different insects. The reproduction is so incredible that I think I will replace insects (Pycnoscelus surinamensis, Eublaberus spp. and Tenebrio molitor) as food waste degraders by isopods in the plastic boxes that I show in the photography. We shall see. Your instructions are crystal clear. I came to the same conclusion by trial and error.
Regards
D
Daniel; I'm happy that my observations have confirmed your work. When I was working, I maintained Tenebrio colonies as a food source for animals in a lab. Fish, lizards, some amphibians and many birds eat them. The main trick for keeping the beetle colonies healthy was a dry environment while, at the same time, providing enough water. I fed them red bran meal and supplied water with Opuntia (cactus) pads or sliced potatoes. Maintained that way, they thrived! I also used them to clean skeletons of medium sized vertebrates (if the body parts were mummified). Have a good day, Jim
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