‘Zombie Fungus’ Controls the Minds of Insects
It’s Halloween and there have been some spooky goings-on at the Attenborough Nature Reserve. Eerie ‘pig-like’ screams from water rails in the reedbeds, tawny owls hooting as they proclaim ownership of their woodland territory, but most scarily, zombies lurking in the undergrowth!
Whilst this sounds like the plot of a b-list horror movie, the actions of a fungus have made zombies very real at Attenborough.
Fungi are one of the most important groups of organisms to be found on the Nature Reserve. Over 450 species have been identified at Attenborough and most of the species can be seen in the autumn. Fungi do a wonderful job of breaking down dead and decaying matter, returning the nutrients back into the soil. However, there is a particular group of fungi which have a very sinister strategy for survival.
The so-called ‘Zombie Fungus’, Entomophthora, is one such fungus and the effects of which have been seen in the late summer and autumn.
The fungus uses a special mind control technique to take advantage of insects in order to help it spread. Just one microscopic germinated spore (akin to seeds in plants) ingested by an insect is enough to infect the host with this pathogenic organism.
Once inside the body of the host, the fungus grows rapidly. Digesting its guts and internal organs. The mycelium of the fungus, a mass of branching thread-like hairs or roots, then spreads to an area of the fly’s brain that controls behaviour. The fungus forces the host to land or climb up to the top of a tall plant or tree.
The reason for this is that like most other types of fungi, the zombie fly fungus needs to get its spore-bearing structures as high as possible in order to complete its lifecycle. The higher up the insect, the more likely the microscopic spores are to get caught in air currents when they are released and will, therefore, spread over greater distances.
The final act of the fungus is to get the insect to assume a position that aids in dispersal of the spores. In the case of flies, the wings are held spread open and the legs stiffen to raise the fly’s abdomen into the air. Just five to seven days after becoming infected, the fly dies.
By this stage, the growing fungus begins to burst out of every crack in the insect’s armour and it becomes visible for a couple of days before the spores are released and the fungal spores ‘seek out’ their next victim.
Surprisingly there are over 70 species of this group of fungi in the UK. Whilst Entomopthora muscae is the most commonly encountered species and infects flies like hoverflies, others use a similar technique to affect mosquitoes, ants and even earwigs.
Why not scan through the path-side vegetation on your next visit to Attenborough and see if you can spot a ‘zombie insect’ for yourself!