The Bug Geek

Insects. Doing Science. Other awesome, geeky stuff.

Category Archives: Fungi and Lichens

A fungus ate this moth’s head

It’s been far too long since we’ve had a good gross-out parasite post, so let’s rectify the situation, shall we?

I captured this gruesome scene at the end of June, in the park where I was camping.

This poor unidentifiable moth met a horrifying end in the grips of an entomophathogenic fungus, which, though technically not a parasite, is nevertheless growing gangbusters out of the moth’s head.

While non-pathogenic fungi use less gory approaches to dispersal and propogation, relying on things like wind and water, entomopathogenic (EP) (entomo=insect; pathogenic=disease-causing) fungi use insects and other arthropods as their food source and means of spore transmission.

EP fungi produce spores that attach to, sprout on, and penetrate the outer shell (or cuticle) of their host.  Once they’ve breached the outer barrier, they feed on the nutrients available inside the host, ultimately killing them. What you see in the photo above is the final stage – the host has been killed, and the fungus has produced mature fruiting bodies from which more spores will be produced.

One of the most fascinating aspects of these fungi is their ability to alter their hosts’ behaviours – sometimes in ways that maximize the likelihood of spore dispersal, and sometimes in ways that actually harm the fungus and help the host fight off the infection – there seems to be a finely tuned evolutionary tradeoff at play in these systems that permits both the fungus and the host to persist and thrive despite the unpleasantness of the interaction between them.

For example, a fungal infection may lead a host to seek out sunlight or other sources of heat; by raising their body temperature (a so-called “behavioural fever”), the host can sometimes make its body inhospitably warm for the invader. Other EP fungal infections, such as those seen in pea aphids, can cause an infected aphid to move to unusual, more exposed parts of the plant to feed. This could be the fungus’ way of ensuring better spore dispersal, or might be the aphid’s way of preventing the fungus from spreading to the rest of its colony. Some fungi seem to make female hosts more attractive to males (presumably to aid in spore transmission), while others cause hosts to seek out elevated sites before their deaths (as was most likely what happened to this moth).

This is all terribly reminiscent of the mind-controlling hairworm I posted about last year, and behavioural changes have also been shown to be induced by insect parasitoids; it’s clear that behaviour modification is a useful strategy for many organisms that rely on a host to complete their life cycle!
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ResearchBlogging.org

Roy HE, Steinkraus DC, Eilenberg J, Hajek AE, & Pell JK (2006). Bizarre interactions and endgames: entomopathogenic fungi and their arthropod hosts. Annual review of entomology, 51, 331-57 PMID: 16332215

Grosman AH, Janssen A, de Brito EF, Cordeiro EG, Colares F, Fonseca JO, Lima ER, Pallini A, & Sabelis MW (2008). Parasitoid increases survival of its pupae by inducing hosts to fight predators. PloS one, 3 (6) PMID: 18523578

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Crushing on mushrooms

I’m assisting in an ecosystems-based ecology course this term, and it is a FREAKING RIOT.  The labs are  entirely field-based, and we take students out to explore different types of ecosystems in the region around The University, often with the help of various experts.  For today’s lab, we had a fungus expert leading the way.  After a brief lecture, we set the students loose in the woods, armed with paper bags and pocket knives for collecting specimens.  We were only supposed to bring back ONE species each.

I think I got a little carried away. (And this little pile was what remained after grudgingly handing over other Really Cool Stuff to students who hadn’t had as much luck as I did).  

What amazed me most was when we all regrouped – we laid out our treasures in a circle, and there was hardly any overlap in species; almost everyone had picked something unique.  Holy diversity, Batman!

I think the brownish jelly cup fungus (bottom left corner) and the yellow-capped Pholiota sp. (top right corner) were my favourites, but I also developed a huge crush on coral fungi.  One student found a clump as big as a soccer ball!  We found several shades of them too, including a soft purple.

Here’s a look at some of our goodies.  I think I’ll be paying more attention to these beauties in the future!

Small Green Things

I returned home with three EXTRAORDINARILY DIRTY dogs.  

We are most definitely in the thick of spring thaw.   The ground is hard and crunchy in the shady nooks and sopping wet and muddy in the sunnier ones.  We’ve swung from +16 to -16C in the past week.  The “frozen” patches over bodies of water are deceptively thin…as the small mugsly dog found out (Me: “Um, small dog?  You may wish to reconsider your choice of places to stan…”  SPLASH!  FRANTIC PADDLING IN VERY COLD WATER!  Uproarious laughter of cruel human!)

It was  far too cold for active bugs yesterday; we barely broke the freezing mark.  There is, however, a distinct and lovely new shade of GREEN in my woods.   Moss is growing like gangbusters now that the snow is gone, as are a few teeny-weeny plants. 

In the absence of bugs, today I present Small Things That Are Growing

in the forest:

Raspberry

Looks rather like Bisphorella citrina

New shoots on moss

and in an open field, on bare, exposed rock:

Fern-like moss...is this a moss?

Brilliant green moss

Reddish star-shaped moss

And now I shall scan the link of over 200 moss photos that Susannah provided not long ago, and try to figure some of these out.

Friday Fungi

I’m increasingly amazed by the diversity of fungi I find on my walks, and sometimes even more so by their choice of habitats.  These tiny delicate gems, for example, were cozily nestled with dozens of others beneath the bark of a dead tree, in a gap that couldn’t have been wider than 5 milimeters or so.   The longest of these is only about 3mm long; their “heads” must have been butting right up against the bark.

Itsy-bitsy fungi

Not 20 meters away, on the other end of the growth charts and in a different environment altogether, I found these gorgeous Polypores:

Large Polypore fungi

Bathing in the soft glow of mid-morning light, the colourful caps on these mushrooms were rugged and dense and longer than my hand.

Underside of Polypores

Fire-coloured beetle

This chunky fella was hanging out with a group of his buddies…four others…beneath the bark of a rotting hardwood tree.  The ambient temperature was just warm enough to allow the critter to slowly crawl away from the exposure to fresh air and the geek with the camera. 

Superficially, this larva looks a lot like that of the Red Flat Bark Beetle I spoke of the other day; it has a similar flattened, reddish-yellow, elongage body, prominent head and “pincers” at the rear.   Indeed, on first glance, it’s what I assumed the larva to be.  Closer inspection revealed some differences, however.   For starters, the head does not share the characteristic “triangle” shape of C. clavipes.  Note also the long hairs protruding laterally on each segment.

The urogomphi (“spines” on the last segment) on this animal are also heavier, darker, and more prominent.  There are rounded lobes on either side.

I’ve pinpointed it to a member of the Fire-Coloured Beetle family, Pyrochroidae: Dendroides canadensis.  It’s the most common Pyrochroid in this area.

Once assumed to be predaceous, it is now understood that Pyrochroid larvae are wood- and fungus-eaters.  I found these beautiful tiny mushrooms growing just above the larva’s resting place…I wonder if they will become a spring snack?

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