Photo: 17 Year Cicada, Magicicada septemdecim, with Massospora cicadina fungus, Judy Gallagher
Judy Gallagher is an ASNV board member and a regular surveyor of local wildlife who also captures photos of what she sees, in particular the less common species.
I recently read a book on Fungi which inspired this month's column. I usually think of them breaking down and recycling dead matter, but some affect live organisms.
Weevil, Laphrastus taeniatus, with fungus, Judy Gallagher
I typically notice fungus on insects when I'm taking pictures, getting closer and closer, and the insect doesn't fly away. That's when I realize that it can't. This weevil may have been infected when it was alive, or it might have happened after it was already dead. I have no idea which fungus this is.
Cephalochrysa species Robber Fly with Fungus, Judy Gallagher
Here's a Soldier Fly, also affected by fungus, but likely not the same fungus that infected the Weevil.
There are many fungal pathogens with unknown life histories, but there are a few which scientists have studied, and their stories are remarkable and rather gruesome.
Secondary Screwworm, Cochliomyia macellaria, infected by Entomophthora species fungus, Judy Gallagher
Entomophthora species fungi infect flies. There are a number of different species, possibly a different one for each fly family. These fungi have an interesting way of ensuring their survival. Several days after a female fly is infected, the fungus takes over the behavior of the fly and directs it to a high point on vegetation or a wall. Then the fly dies and the fungus emits chemical signals that attract a male fly. The male fly mates with the lifeless female carcass. As time passes, more fungus grows, more chemical signals are emitted and the female carcass becomes even more attractive to males. The male flies become infected and the fungus is passed on.
17 Year Cicada, Magicicada septemdecim, with Massospora cicadina fungus, Judy Gallagher
Periodical Cicadas like the ones that we saw here a couple of years ago also have a fungal parasite, Massospora cicadina. Cicada nymphs are infected by spores in the soil as they burrow up from tree roots before emerging as adults. The fungal mass growing in the cicada's abdomen produces an amphetamine that makes the cicadas even more anxious to mate than normal. Eventually the rear segments of the infected cicada's abdomen fall off, revealing a white chalky mass of the fungus. This is called a Stage 1 infection, and it kills the cicada. As the infected cicadas fly around, spores drop from them, further spreading the infection. Infected males don't only attract females; they also attract healthy males by flicking their wings, a behavior that is normally restricted to females. Healthy cicadas that become infected through mating get a Stage 2 infection, which does not kill the adult, but the resulting spores lie dormant in the soil and affect the next brood of cicadas. Massospora cicadina typically kills about 10 percent of the cicada brood.
Ant parasitized by Ophiocordyceps unilateralis complex fungus, Judy Gallagher
Possibly the most well-known of the fungi that parasitize insects is the Ophiocordyceps unilateralis complex. It affects tropical ants and isn't known in our area. Spores attach themselves to a foraging ant and slowly take over its behavior. The ant is compelled, zombie-like, to leave its nest, go to a vantage point about 10 inches off the ground, and attach itself to a leaf by its jaws. It then dies. The fungus feeds on the dead victim and eventually sends a fruiting body through the base of the ant's head. Spores are then launched, potentially infecting new ants. The fungus doesn't invade the ant's brain but uses bioactive compounds that affect the ant's nervous system and take control of its muscles.
Fungus Ant, Cyphomyrmex rimosus, farming fungus, Judy Gallagher
Not all insect/fungal interactions inspire nightmares. These ants, Cyphomyrmex rimosus, farm fungus. They bring plant material back to the nest to feed the fungus, and then the ants use the fungus as food. The ant at the bottom right in this picture is carrying fungus. The fungus could not survive without the ants' care.
The fungi described here have co-evolved with their insect counterparts. If the fungus kills off too many of the insects, the fungus will not thrive. If there is no control on insects, nature is also out of balance. Fungi play a crucial role in balancing biodiversity and maintaining healthy ecosystems
View more of Judy’s Observations from Meadowood articles here.