Symbionts of Symbionts of Termites

Eastern Subterranean Termite

Reticulitermes flavipes, Eastern Subterranean Termite

Wood is a difficult material for organisms to digest. The rotting and decomposition of fallen trees can take years to complete. Wood is mostly cellulose reinforced with lignin. The lignin is refractory to digestion by many organisms and is a barrier to the utilization of cellulose as a food source. The lignin must be processed in order to access the cellulose. Utilizing wood as a food source in termites is not an individual species project but a collaboration of many species.

Termites have special structures in the gut to house symbiotic microorganisms including flagellate species that only exist in the guts of termites. The termites chew wood, grind it into small pieces, coat it with digestive fluid and create a suitable environment for the flagellates to survive. The flagellates contribute digestive enzymes and nutrients such as vitamins to the termites. Flagellates in the genus, Trichonympha, do not act alone. The flagellates themselves have bacterial symbionts that live both externally and internally. Advances in DNA technology have facilitated identification of bacterial symbionts and opened a path to their study.

Termites can host a diversity of flagellate species. The flagellate, Trichonympha agilis has deep invaginations in its plasma membrane that are colonized by bacterial symbionts in the Genus, Desulfovibrio. Desulfovibrio are clearly external, but their close association can facilitate exchange of substances between the bacteria and the flagellate. Bacterial endosymbionts, Candidatus Ancillula trichonymphae, are widely distributed among species in the genus Trichonympha. The endosymbionts are present in the cytoplasm in the anterior portion of the flagellate. The endosymbiont complexes found in termites are complicated and will require years of study to comprehend their functions and relationships.

Strasser & Colleagues. ‘Candidatus Ancillula trichonymphae’, a novel lineage of endosymbiotic Actinobacteria in termite gut flagellates of the genus Trichonympha. Environmental Microbiology (2012) 14(12), 3259–3270.

Posted in Biomaterials, by jjneal, Environment, Taxonomy | 1 Comment

More Termites

Termite Glyptotermes chiraharitae

Glyptotermes chiraharitae

A new species of termite, Glyptotermes chiraharitae, was recently described by Amina Poovoli and K. Rajmohana. The termite was found flying in the Malabar Wildlife Sanctuary at Kakkayam, India. The termite is not a pest, but other species in the Genus are pests in Sri Lanka.  Glyptotermes chiraharitae is a damp wood termite limited in range to evergreen forests of the Western Ghats.

Posted in by jjneal, Taxonomy | 1 Comment

Bed Bug Bacterial Genes

Bed Bug

Underside of Immature Bed Bug

Lateral gene transfer, the movement of genes from one organism to another is a relatively frequent occurrence in host/symbiont relationships. Lateral gene transfers can be detected by comparing the sequence of bacterial genes to DNA sequence in the host. A comparison of bed bug DNA with the genes associated bacteria* found 805 sequences that could have arisen from lateral gene transfer. This is a large number for an insect species. Most lateral gene transfers from bacteria to insects are lost over time, but some occasionally evolve into insect genes that provide a novel function.

*Benoit & Colleagues. Unique features of a global human ectoparasite identified through sequencing of the bed bug genome. NATURE COMMUNICATIONS 7:10165 2 Feb 2016
DOI: 10.1038/ncomms10165

Posted in Biomaterials, by jjneal, Environment | 1 Comment

Living With Flea Markets

Flea Market

Artist: Stephen Pastis*

Why are they called “flea markets”?

Etymologists do not agree on an undisputed source. Some attribute “Flea Market” to the outdoor bazaar of 1880s Paris, France which was described as “le marché aux puces” which literally translates into “Market of Fleas”. This is a supposedly derisive term indicating that articles sold there might be infested with fleas.

Can you bring fleas into your home by buying used articles? A review of the biology of the cat flea says, “Yes”.  The cat flea is the most common flea found on dogs and cats in North America. The adults colonize a cat or dog, mate, feed and excrete copious amounts of blood in their feces which are food for the larvae. The flea eggs are laid by the female, but do not attach to the animal. The eggs roll off the animal and onto pet bedding carpet, or any article of clothing underneath places the animal rests.

The larvae hatch and generally feed in the carpet or in cracks in the floor. So if a flea market vendor has a cat or dog that sleeps on carpets or other wares, then yes, those items could contain larvae or pupae of fleas. Bringing flea infested items into your home could result in a flea infestation.  Generally, flea infested items will have some mature fleas ready to jump on a host in response to heat. Thus, a potential buyer (or observant critic) could detect the presence of fleas and call them “Flea Markets”.


Posted in Art, behavior, by jjneal | 1 Comment

Bed Bug Vitamin B

Bed Bug

Underside of Immature Bed Bug

Insects that feed on a single source of food can have an imbalance in dietary nutrients. Bed Bugs feed only on blood which is deficient for the B vitamin complex. The evolutionary line leading to insects lost the genes needed to produce B vitamins long ago. However, insects retain genes necessary for uptake and conversion of B vitamins from their diet or from symbionts.

Like many insects, bed bugs harbor a bacterial symbiont, Wolbachia. Wolbachia receives protection, access to nutrients and distribution in the environment from Bed Bugs. Wolbachia uses some of the nutrients to synthesize excess vitamins including Vitamin B which allows the Bed Bugs to thrive. What is good for the Bed Bugs is good for Wolbachia.

Posted in Bed Bugs, Biomaterials, Environment | 1 Comment

Bed Bug Starvation Diet

Bed Bug

Underside of Immature Bed Bug

Bed bugs and many other blood feeders only stay on their hosts long enough to feed, then retreat to a protective harborage to digest their food. After the blood meal is digested, the bed bug must once again locate a host. This arrangement works well for rapid growth and development if the host can always be found nearby at night. However, humans are mobile. We take vacations, travel and may be away from home for extended periods. During such periods, bed bugs starve.

Bed bugs and other blood feeding bugs are adapted to surviving long periods without food. During starvation, bed bug metabolism is reduced to a low level that conserves energy and resources.

Bed bugs do not drink. They get all their water from blood feeding and metabolism. In starvation times, bed bugs must also conserve water.  In insects, water can enter and leave cells through pore forming proteins called aquaporins. One way to conserve water is to change the expression pattern of these proteins such that more water is retained and less water is eliminated. These genes have been sequenced* and their identification can facilitate studies of mechanisms underlying the tolerance of extreme dehydration and starvation.

*Benoit & Colleagues. Unique features of a global human ectoparasite identified through sequencing of the bed bug genome. NATURE COMMUNICATIONS 7:10165 2 Feb 2016
DOI: 10.1038/ncomms10165

Posted in Bed Bugs, behavior, Biomaterials, Environment | 1 Comment

Bed Bug Feeding Adaptations

Bed Bug

Underside of Immature Bed Bug

A major challenge for blood feeding insects is preventing blood platelets from aggregating (clotting) and blocking the blood intake tube. Sequencing of the Bed Bug genome* gives clues about adaptations for blood feeding. The Bed Bug has an expanded suite of apyrases, salivary proteins that interfere with ADP-dependent platelet aggregation.

Feeding without triggering pain is an important trait to avoid detection.  Bed Bugs have 12 members of the inositol polyphosphate phosphatase gene family that bind nitric oxide, and 6 members of the Ap4a_hydrolase family, genes encoding enzymes important in cell signaling pathways. Some of these genes likely are involved in deadening the detection of Bed Bug feeding by producing proteins that affect nerves and nerve signaling. Now that the genes are identified, it pave the way to study their effects.

*Benoit & Colleagues. Unique features of a global human ectoparasite identified through sequencing of the bed bug genome. NATURE COMMUNICATIONS 7:10165 2 Feb 2016
DOI: 10.1038/ncomms10165

Posted in Uncategorized | 1 Comment