Climate change in the Pacific Northwest is driving the expansion of different insect species into the oak savannahs

According to a new study from Binghamton, State University of New York, climate change has caused rising temperatures in the Pacific Northwest, forcing some insect species to expand their habitat into the savannahs of oaks further north.

Climate Change on Invasive Species in the Western United States

(Photo: David Clode/Unsplash)

Dylan Jones exhibited two photos of oak leaves side by side. One, healthy and green, with the strange gall, a structure built by a herbivorous species of oak gall wasp.

The other leaf was yellowed and frayed, the victim of an insect population devoid of predators.

Warming temperatures in the Pacific Northwest have caused species such as Neurotereus saltatorius to expand their range into oak savannahs farther north.

In the native region, a few galls could be discovered on a single leaf; in the extended range, you could find hundreds of them on a single tree, said Kirsten Prior, assistant professor of biological sciences. “It’s quite common on Vancouver Island,” according to ScienceDaily.

Jones, a doctoral student in biological sciences at Binghamton University and a Clifford D. Clark Diversity Fellow, is the lead author of a study on the matter just published in the Journal of Animal Ecology.

Previously, field technician Julia Kobelt, then-undergraduate Jenna Ross, and assistant professor of biological sciences Thomas Powell were among the co-authors of “The Latitudinal Gradient in Species Variety Offers Elevated Niche Options for an expanding phytophagous insect”.

Oak savannas are grassy and shrubby environments with oaks as the main tree species. The oak in question, Quercus garryana, prefers a dry climate.

As a result, Prior said, oak savannahs are frequently found in the rain shadow of the West Coast Mountain Range.

Oaks, a diverse and ecologically important genus of trees found throughout North America, are home to a wide range of insect species, including oak gall wasps.

These species of wasps produce galls, which can be quite spectacular in their many forms, ranging from large apples to ones with multicolored spikes resembling sea urchins.

Interestingly, Alfred Kinsey – yes, that Kinsey – investigated oak gall wasps before moving on to human sexuality.

“This group of animals has long fascinated biologists and hobbyists because they are quite charismatic,” Prior said. “You can go into an oak tree and see all these structures.”

In addition to their herbivorous producers, these galls are home to a dazzling array of parasitoid wasps, one of the most diverse and ecologically significant groups in the animal kingdom, the latter for their role in controlling insect pests.

The parasitoid wasps lay their eggs in the gall and their larvae consume the oak gall wasp larvae after hatching.

Oak gall wasps are abundant throughout North America, but their evolutionary relationships and even the identity of some species are unclear.

A group of scientists from across the continent are working to change that, and Jones and Prior are among them.

Read more: 6 Invasive Insects You Should Kill Immediately According To Scientists

Insect disturbance and climate change

Since temperature and other environmental variables influence forest insect populations, future climate change is likely to affect forest insect outbreaks, according to the Climate Change Resource Center.

Larger and more frequent bug outbreaks may develop in some circumstances, while repeated outbreaks may be halted in others.

Since forest insect populations are controlled by climatic factors, future climate change will likely alter the outbreak dynamics of some forest insect species.

Larger and more frequent bug outbreaks may occur in some circumstances, but repeated outbreaks may be halted or reduced in others.

Fluctuations in temperature that directly affect insects, as well as decreased resilience of host trees induced by changes in precipitation, can all contribute to the development of forest insect populations.

Alternatively, disruption of local climate adaptation could result in the extinction of a limited population.

The role of biotic and abiotic causes on various forest insect population explosions is well understood.

According to the results of this study, the impact of climate change on epidemics would differ geographically as well as according to the various insect/host relationships.

Predicting the consequences of future climate change on insect-caused forest impacts will be difficult due to the complexity of the food webs and host tree dynamics of which most forest insects are part, as well as the uncertainty of climate projections.

Related article: Spotted lanternfly: Indiana state officials warn of invasive insect found in all three states

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