Can Beetles Stop the Hemlock Woody Adelgid?

Headlines from news sources responding to a pair of scientific articles from 2013 that highlighted the importance of scale in assessing the effect of invasive species. Photo by Diana Lutz.

Headlines from news sources responding to a pair of scientific articles from 2013 that highlighted the importance of scale in assessing the effect of invasive species. Photo by Diana Lutz.

Five years ago this month, I wrote in a post titled Preventing Invasive Fire that, “Absolute regulation of invasive species is not possible. We cannot search every inch of soil that enters a country for microorganisms, dormant insect eggs, or plant seeds. But controls must be imposed, and more severe ones than currently in place. The intensely focused damage (biodiversity loss) that a male and female zebra mussel, emerald ash borer beetle, Asian carp, or fire ant can have on a vulnerable ecosystem is much greater than the thinned-out costs of higher taxes or more stringent customs inspections.”

The following year, I discussed the merits of Integrated Pest Management in helping eradicate or at least control pests, which are sometimes introduced from other countries. Reading today about a plan in North Carolina to use beetles as a predator of the hemlock woody adelgid, an aphid-like invasive species from east Asia, I am reminded of those two posts from the past, inspired by Cornell courses in environmental governance and entomology.

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Throwback Thursday: IPM

A ladybug relative nymph in the foreground and a mature individual in the background. The tiny thing next to the nymph might be a larvae.

Yesterday, as James and I were on one of our birding walks around Xandari, we ran into José Luis, who had a couple new things to show us about the gardens and orchard that he runs. At first, it looked like a ragged young tree, its leaves half-devoured and its trunk stained black. But we quickly learned Continue reading

Integrated Pest Management (IPM)

Photo by Milo Inman, India

During my last post I mentioned this agricultural strategy in passing, and I’m actually fairly surprised that the topic hasn’t come up anywhere on the blog before. After all, IPM is an increasingly effective and interdisciplinary way to curb economic losses in crops around the world, and one that often attempts to reduce reliance on environmentally unfriendly chemicals like pesticides.

Completely eliminating an agricultural pest is not the ultimate goal of IPM. In fact, due to ecological intricacies and the risks of removing certain species from an ecosystem, merely lowering the number of pests to numbers that do not cause significant economic damage is more advisable. Achieving this reduction in pest populations “requires an understanding of the ecology of the cropping system, including that of the pests, their natural enemies, and the surrounding environment,” according to Professor Anthony Shelton of the Entomology Department at Cornell University. For example, knowing that a certain pest caterpillar species has certain predator species, a farmer might introduce some of the natural predators into his crop to prey on the harmful caterpillars. If the farmer also physically removes the caterpillars by hand and the pest population dwindles to zero, the natural predators might turn to a beneficial insect, like a pollinator, or even attack the crop itself. This is a very vague and hypothetical example but one that reflects the need to understand causes and effects in an ecosystem if one is planning to employ IPM effectively.

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