One of the biocontrol successes of recent years involves the fungus Entomophaga maimaiga, which was introduced into the U.S. to control the gypsy moth caterpillar. It has worked pretty well, turning a forest-destroying scourge into an occasionally irritating pest. But it’s not that simple, as a US Forest Service article (read it here) points out:
When E. maimaiga was introduced for the biological control of GM near Boston, MA in 1910-1911, workers concluded that the introduction was a failure because they were unable to find infected caterpillars.
It was not until 1989 that E. maimaiga was discovered as the primary cause of an extensive GM epizootic in New England and several adjacent states. Since then numerous epizootics have been observed as the fungus spread across eastern North America, and scientists are working to determine how E. maimaiga will affect the long-term dynamics of the gypsy moth. …
Why did it take multiple decades for the fungus to take hold? What can we do to make sure it remains effective? Good questions:
The fungal pathogen Entomophaga maimaiga has become prevalent in gypsy moth populations throughout North America. How the fungus spreads and what affects its ability to infect GM populations is still not entirely understood.
Researchers, as you might expect, are looking into it. Let’s hope they succeed; we’ve got enough invasive-species problems without gypsy moths coming back.
By the way, I didn’t know until I read this piece how the fungus works, but it’s kind of creepy: “The fungus spreads through aerial dispersion of actively ejected asexual spores from cadavers of gypsy moth larvae it has killed.” Sort of like that scene in Alien where the monster bursts out of the guy’s chest.