Insects and cellulose…

[kinyonga]

“Although cellulose is abundant in plants, most plant-feeding insects, such as caterpillars and grasshoppers, do not use it. Cellulose is a nonramified chain of glucose units linked by P-1,4 bonds (Fig. 1C) arranged in a crystalline structure that is difficult to disrupt. Thus, cellulose digestion is unlikely to be advantageous to an insect that can meet its dietary requirements using more easily digested food constituents. The cellulase activity found in some plant feeders facilitates the access of digestive enzymes to the plant cells ingested by the insects. True cellulose digestion is restricted to insects that have, as a rule, nutritionally poor diets, as exemplified by termites, woodroaches, and cerambycid and scarabaeid beetles. There is growing evidence that insects secrete enzymes able to hydrolyze crystalline cellulose, challenging the longstanding belief that microbial symbionts are necessary for cellulose digestion. The end products of cellulase action are glucose and cellobiose (Fig. 1C); the latter is hydrolyzed by a P-glucosidase.”…
https://www.insectomania.org/insect-species/digestion-of-carbohydrates.html

 

[kinyonga]

“There are approximately one million insect species in the world, but only 78 are known to digest cellulose.”…
“Most cellulase enzymes found from insect guts are not produced by the insects themselves, but by microbial symbionts. Researchers have found certain active enzymes that break down crystalline cellulose. In this way, insects can have active cellulose digestion of their own.”…

https://encounterswithwildlife.wordpress.com/category/physiology/

 

[kinyonga]

Food for thought…if caterpillars don’t use cellulose (see quote in my first post here) …do they pass through the chameleon’s intestines with the help of their own cellulose stomach content or do the chameleons need more roughage from other sources for the caterpillars to pass through the intestines?