We began our exploration into the insect digestive system with Ann Carr’s lovely presentation on the foregut and the infrabuccal pouch. The infrabuccal pouch is a very neat structure that evolved independently in three orders: Hymenoptera, Isoptera and Coleoptera. It is basically a pocket in the mouth of an insect, like a termite, where it sequesters and “domesitcates” microbes that are used to aid in the digestion of its food.
What I found most interesting about her presentation is that there is an analogous structure found in Lepidopterans that is used for pollen digestion. The infrabuccal pouch of a Lepidopteran is similar in structure and found in the same area but has one big difference…SPINES!!!
These spines help to break down the pollen grains before they move into the foregut. I have been unable to find any publications or anyone that confirm whether there are microbiota in the Lepidopteran infrabuccal pouch. Which raises the question, is this a homonym? Meaning, is this a different structure deserving of a different name or is it a homologous structure? This also leads to our next…READER’S CHALLENGE!!
Can you find a paper that outlines the biotic makeup of the infrabuccal pouch in Lepidoptera OR can you find a paper that supports that this structure should be renamed as it does not serve the same function as the infrabuccal pouch in Hymenoptera, Isoptera and Coleoptera?
The winning paper of the week in our discussion group was, hands down, Keith Bayless with his paper about the evolution of flea-born transmission of bubonic plague in Yersinia pestis. I found this paper so interesting because, even as an entomologist, when I think of the PLAGUE I think of fleas passing it along with very little effort. It turns out that out of 2,000 species only 80 are even capable of harboring plague bacteria and the ones that can transmit the bacteria aren’t even that good at it! The flea only appeared to be excellent transmitters of the plague because they had such a close relationship with their host and could bite them (meaning us!) multiple times thereby increasing the chance of infection. There is a lot more interesting information in this paper and I encourage you to read it!
Other Papers This Week
1. The functional morphology of the honey stomach (aka crop) of the honey bee
2. Cephalotes ants and the special structures they have to harbor symbiotic organisms
3. Pretty cool paper on the proventriculus and the role it plays in the immunity of the tsetse fly
4. Ever wonder how starvation and parasitism effects foregut constriction in the midgut of Manduca sexta larvae? Here is your answer.
5. The contribution of the midgut bacteria of Aedes aegypti in blood digestion and egg production and how antibiotics affect it