Relationships with Fungi

Val (our crew chief) recently tweeted about the huge variety of fungi in Cape Breton Highland, and Kejimikujik was not different! Everywhere we went we saw a variety of different types of fungi. It was only then that I realized that fungi are undervalued by most passerbys. Fungi, whether they look like the familiar mushroom cap, the shelf-like tree outgrowths, or the many types of mould, are fundamental parts of a healthy ecosystem. Without fungi organic matter would accumulate on the forest floor and nutrients would not be available to promote growth.

Fungus beetle feasting on a mushroom in Keji
Fungus beetle feasting on a mushroom in Keji

One surprising feature is that the typical mushroom cap is usually only a small outcropping of the entire organism. Mushrooms are actually only the reproductive outgrowths from an intricate interwoven network of hypha that travel through the soil. The gills or lamellae on the underside of mushroom caps can produce up to 1 800 million spores per mushroom cap, each of those spores are capable of creating more hyphae, which can then create innumerable mushroom caps. In short- there’s a lot more than meets the eye.

Fungi can have a number of different relationships with surrounding plants such as trees. Parasitic fungi can overwhelm a tree, causing the tree to die and will then continue to decompose the fallen tree. Many of the parasitic species are introduced to trees by the actions of our lovely insects. Fungi can also have a beneficial relationship with trees where the hyphae stimulate tree growth by increasing the absorption area of the roots, and in return the hyphae obtain sugar directly from the host (rather than through decomposition).

Hemlock shelf fungi are slowly decomposing this stump
Hemlock shelf fungi are slowly decomposing this stump

Even more interesting are the intricate relationships of insects and fungi. Like trees, fungi can be a huge nuisance for the insect, or even completely alter the insects’ normal behavior. In the latter case, is a well-documented case of proclaimed “zombie-ism”. The Ophiocordycep fungi attach the brain of afflicted ants, causing them to abandon their colony and latch onto main vascular vein on the underside of a leaf. The fungi then lives in the plant and cycles through to parasitize more ants. Entopathogenic fungi will live inside of the cuticle of insects before killing its host by penetrating the body cavity.

Of course you can also find instances of beneficial relationships between the crawling world and fungi. We commonly found rove and fungus beetles feasting on the mushroom caps of fungi, and many insects have been known to have even more involved relationships. Female scale insects often live inside of fungi where they benefit from having shelter from the environment, protection from predators and have close proximity to their food source (such as trees). In return, the fungi have a specialized feedings hyphae that enters the insect and uses it as a sugar-pumping conduit from the tree.

In exceptional cases, such as with termites and leaf cutter ants, the insects actually farm the fungi! They will provide food for the fungi, even weed out species of fungi that they don’t want, before eating their cultivated crops. There are numerous more examples of mutualism between both fungi and insects that are very interesting! (for instance look up scolytid beetles) Much like the underground network of hyphae, fungi have connections all through ecosystems ranging from plants, to insects, and even to larger animals. Without these little appreciated organisms we can very well expect that much (if not all) life that we see would collapse.

~Jill

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