Predatory fungus turns prey into fluffy feasts
Beauveria bassiana is the kind of thing that’s fun to learn about only after you’ve confirmed it doesn’t attack humans. The fungus only targets small arthropods like arachnids or insects, but is so thorough in their destruction that you can’t help but cringe on their behalf. Especially considering the whole “exploding the corpse” part.
Eating bugs from the outside in…
The process starts with B. bassiana boring its way through the bug’s with a mix of enzymes, basically digesting its way into the softer innards. From there, the fungus eats the bug’s blood (or rather, hymolymph) until the bug dies. To make sure it doesn’t have to share the dying feast, B. bassiana leaves a wake of antimicrobial agents, killing off any other microbes that might also enjoy eating the body.
…then back out again
Once the nutrition has been exhausted, the fungus eats its way back out of the body so that it can move on to another host. It emerges through seams in the corpse’s exoskeleton, covering it in a layer of white fuzz. The fuzz is made of a mix of thin fibers and new fungal spores, which then facilitate transfer to any neighboring arachnids or insects, like pollen sticks to a bee’s legs. Once contact has been made, the process can repeat itself.
Controlling the spored scourge
B. Bassiana was brought to human attention in 1835 when it was found killing silkworms in Italy. To the chagrin of humans, it doesn’t show much preference for one arthropod over another and our attempts focus its hunger on unwanted species like bedbugs or mosquitoes haven’t proven fruitful so far. The one species that does stand out is a grain-eating beetle, which seems to have the only antifungal compound in its body that can actually overpower the predatory fungus. Perhaps this arms race will swing back in the other direction and other insects arthropods will develop stronger antifungal properties, but for now the fungus seems to have the upper hand on over 700 species of animal worldwide.
Source: A downy killer wages chemical warfare by Beth Mole, Science News
