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Roaches and DL-Methionine


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North Carolina State Agricultural & Life Sciences Department determined of the twenty naturally occurring amino acids, at least ten must be present in an insect’s diet. These ten, called essential amino acids, include lysine, tryptophan, histidine, phenylalanine, leucine, isoleucine, threonine, methionine, valine, and arginine. The other ten amino acids are considered “non-essential” because they can be synthesized from other amino acids or similar chemical building blocks. Insect diets and human diets require the same ten essential amino acids!

Certain roach species still need all ten amino acids, but can subsist on a poor protein diet due to bacterial symbionts that synthesize certain essential amino acids to the benefit of the host roach.

Let's examine the facts:

Roaches need methionine.

DL-methionine is a 50/50 mix of the D and L isomers of methionine. And although only the L isomer is used by the roach, there is no indication that the D isomer is inherently toxic or otherwise harmful to the roach.

Why then is methionine, or the chemically synthesized version DL-methionine, vilified?

Bruce Stevens, professor of physiology and functional genomics in the University of Florida college of medicine, first discovered the pesticide properties of methionine while cloning genes that regulate amino acid metabolism in 1998. Working with co-author James Cuda of UF's department of entomology and nematology, Stevens later found this amino acid to be effective against many insects, including yellow fever mosquito larvae, tomato hornworm, and Colorado potato beetle. Noting the very curious phenomenon to have this nutrient amino acid that humans can't live without, yet at the concentrations they put on the leaves, was toxic to the crop-destructive caterpillars of certain butterflies. It was determined that mega doses of methionine disrupt an ion channel that controls nutrient absorption in larvae with an alkaline intestine.

That does NOT mean that any feed or feed ingredient that contains DL-methionine is toxic to roaches! There are many feed ingredients in normal amounts are needed and beneficial. In larger doses, those same ingredients can be toxic and some are used as ingredients in insecticides. Two notable such ingredients, sodium chloride and copper sulfate. Let's not forget without those two substances, most organic life forms on the planet would cease to exist.

Proper context is important to understanding. Are you using feeds with DL-methionine and getting good results? If yes, continue to do so. When veterans of the hobby have done so for decades, it is a safe bet that it is ok.

Disclaimer: This phrase is trademarked and not to be used without the permission of Ricky Bobby Inc.

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THANK YOU for this! I've used multiple feeds containing DL Methionine in it, and was confused as to why people said it was toxic, considering I noticed no ill effects whatsoever! Makes sense now. 

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