Quite unexpectedly for a Fungi Friday entry, this post starts with an insect ...
... the Scathophaga stercoraria ... a very common and widespread species of fly. On this enlargeable opening shot the fly is posing on the top of some green plant ... and if you enlarge the picture, and explore the details, you will certainly notice some kind ow white powder on the fly's hair, especially on the abdomen ... well, that's the part that connects this scene to the Fungi Lovers community. The fly on the photograph is dead and the white powder ...
... is a product of a pretty fascinating pathogenic fungus, the Entomophthora muscae.
This parasitic fungus has a unique and creepy life-cycle. When an Entomophthora spore lands on the fly, it enters the host's body and begins to grow, feeding off the insect's organs and body fat. Once the host is getting near its death, usually at sunset, the doomed flies start to climb along stems and leaves of the vegetation, until they reach the top, and raise their wings in a characteristic pose, before expiring. Then, after some days, from the dead host's abdomen, minuscule fungal structures called conidiophores sprout out. Upon maturation, the conidiophores eject tiny white spores, which spray down on the surrounding area and can infect new victims.
The climbing behavior of the Entomophthora muscae's victims seems regulated by fungal growth inside their bodies, but the exact mechanism is still being researched. I found a relatively extensive article that talks about some laboratory researches, and states that "Invasion of the nervous system grants the fungus direct access to host neurons and may be mechanistically important for achieving behavioral manipulation of the host fly."
The fly on this photograph seem to have died more recently, I found it in a characteristic pose on the top of the Plantago lanceolata plant, the abdomen is swollen, but the fungus hasn't released the spores yet.
A few days ago, when these photographs were taken, I witnessed this phenomenon for the first time. I saw many dead flies that morning, the atmosphere was slightly eerie and mysterious. I thought that maybe the insects were killed by some pesticide used on the nearby cultivated fields, but then at home, after a relatively short Internet search I found the scientific story about this fungus, and all together was a very exciting learning experience.
The Entomophthora muscae doesn't attack only this fly species, the Scathophaga stercoraria ... but also the common Houseflies (Musca domestica) and a variety of species from the Calliphoridae, Culicidae, Drosophilidae, Muscidae, Sarcophagidae, Scathophagidae, Syrphidae and Tachinidae Family.
Epizootic outbreaks or this disease are quite normal in most temperate regions, in spring and autumn.
Epizootic it's another new term I learned today ... it means a disease event in a nonhuman animal population analogous to an epidemic in humans.
This fungal disease was first described by the German biologist Ferdinand Julius Cohn in the year 1855.
It has been seen as a potential biological agent for controling the populations of some disease caring, potentialy dangerous species ... but to these days, the Entomophthora muscae hasn't become anything like that. There are many technical difficulties in controlling flies with Entomophthora muscae. The fungus is sensitive to temperature and when the air temperature is high, the prevalence of the disease decreases to very low levels. Houseflies infected with this fungus were able to rid themselves of the infection by resting at temperatures that inhibited the growth of the fungus. Entomophthora muscae is a fastidious organism and cannot be easily cultured artificially. Colonies are usually maintained through direct fly to fly transmissions.
And that's it ... here are the sources I used to learn new stuff about this fascinating organism and tell this fly killer story :
As always in these posts on HIVE, the photographs are my work - THE END.