will feed in wood,” she said. “We have to collect the adults, get
them to lay eggs, rear the larvae on an artificial diet, and put the
larvae in logs. It’s not going to be easy.”
Gould is excited about the prospects of using biocontrol on
a new invader from China, the spotted lanternfly. It has been
found only in six counties in Pennsylvania so far, but Gould
expects it to spread widely. She is already studying an egg para-
sitoid in quarantine, but the lanternfly lays its eggs in the fall
and the parasitoid is only active in spring, so it isn’t promising.
Collaborators in China have identified another possibility,
which she hopes to begin testing soon.
“We think the spotted lanternfly has to feed on tree-of-
heaven in its last nymphal stages and first adult stages,” Gould
explained. “Tree-of-heaven is an invasive and exotic plant, so if
the lanternfly only ate tree-of-heaven, that would be awesome,
because we’d love to kill [that tree]. But it doesn’t. It’s also a pest
on grapes and fruit trees.”
According to the researchers, one of the biggest challenges
to fighting invasive insects is that by the time land managers
or entomologists discover a new invader, it’s usually too late
Left to right: Spathius galinae in release cup. Researchers at the University of Rhode Island’s Biological Control
Laboratory work in a secure facility to analyze the potential of a number of different insects to control invasive pests.
Ready for release: In a lab, EAB eggs were applied to the bark of these ash bolts and hatched out larvae that were
allowed to grow inside the bolt. “Then lab-reared Tetrastichus planipennisi were put into chambers with the bolts so that
they could parasitize the EAB larvae,” explained Ryan Crandall, who finally placed the bolts containing Tetrastichus, as well
as cups containing adult Spathius galinae (at right), in six different sites in Massachusetts, Connecticut, and New York. Inset:
Tetrastichus larvae in an emerald ash borer gallery, where it feeds on and kills the EAB larva.
to eradicate it using conventional means. This often leaves
biocontrol as the best option.
To Joe Elkinton, who said his most successful biocontrol
effort was the use of a parasitic fly to control invasive winter
moth populations in Maine, Massachusetts, and Rhode Island,
the bottom line is balancing costs and benefits even when the
control agent isn’t entirely host specific.
“We have to ask ourselves, ‘do we care more about the close
relatives of the pest and that their populations will be reduced,
or do we care more about losing our ash and hemlock trees?’” he
said. “Because when we lose those trees, all the insects that feed
exclusively on those trees are also going to die, and that has eco-
system-level implications. So we need a rational discussion as we
anticipate the future of biocontrol. We need to weigh the cost of
doing nothing with the cost of introducing a biocontrol agent.”
As he told Slate magazine for an article on this subject, “In
the absence of biocontrol, there is no solution.”
Todd McLeish is a freelance science writer and the author of three natural history
books. His next book, Return of the Sea Otter, comes out in March 2018.