Biology subjects

MacQuarrie, C. J. K.

Publications and source records attributed to MacQuarrie, C. J. K..

3 recordsLinked to original sources

bioRxiv2026

Temperature impacts on mating and oviposition of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)

Local temperatures can shape the ability of introduced species to flourish and disrupt novel environments. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive beetle that threatens ash trees in North America and Europe. To assess the role of temperature on EAB reproduction, we reared groups of adult beetles at one of four temperatures (12, 15, 18, and 21 {degrees}C) and measured reproductive success (laying fertilized eggs and egg hatching). There was no effect of rearing temperature on EAB female lifespans but no eggs laid at 15 or 18 {degrees}C hatched, suggesting these temperatures disrupt the reproductive process of EAB. Females reared at 21 {degrees}C, however, consistently laid eggs that hatched. We then used these results to assess the likelihood of reproductive success over the previous ten years in eight cities in Canada that host EAB. All locations experienced temperatures of [≥] 21 {degrees}C, but the number of hours and the number of days above this critical temperature were highly variable. There were ample opportunities in all locations for EAB to reproduce, but EAB in cooler cities would experience thermal limitations thus slowing the spread of EAB populations.

ecology↗

bioRxiv2025

Climate change has already reshaped North American forest pest dynamics: Insights from multidecadal process-based modelling

Ongoing anthropogenic climate change has the potential to modify the population dynamics of forest pest insects by shifting the distribution of suitable climate conditions for their development. We used processed-based temperature-driven physiological models to assess the impact of changing climate conditions between 1951 and 2022 across North America on eight important forest pest insects, namely western spruce budworm, eastern spruce budworm, spongy moth, hemlock woolly adelgid, mountain pine beetle, southern pine beetle, spruce beetle and emerald ash borer. Our analyses revealed substantial changes in climate suitability resulting in pronounced northward and elevational shifts for most pest species although the magnitude and spatial patterns of these shifts varied both geographically and among species. We also showed that shifts in highly suitable conditions were more important at the colder edge (either northern or upper elevation) than at the warmer boundaries for several species, either driven by the Arctic amplification or elevation-dependant warming. Our results indicated that both the total area and the host tree biomass exposed to highly suitable climate conditions have increased for many pest species over the last decades, further exposing ecosystems to elevated risk. Our analyses also identified areas (e.g., western Canada) that are increasingly exposed to overlapping, potentially cumulative and interacting, biological disturbances. We also showed that climate change has already contributed to increasing the climatic suitability and geographic spread of exotic forest pest species in North America. Changes in climate suitability over the past seven decades across North America likely represent early signals of continued and potentially accelerating shifts under ongoing anthropogenic climate forcing. In this context, efforts to limit the expansion of pest populations under future climate change scenarios will be key to mitigating their cultural, ecological and economic impacts.

physiology↗

bioRxiv2024

The distribution of the hemlock woolly adelgid in Canada.

The hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae) has distinct native and invasive populations in Canada. On Canadas west coast the adelgid is a native insect feeding on western hemlock, Tsuga heterophylla (Raf.) Sarg. and mountain hemlock, Tsuga mertensiana (Bong.) Carriere (Pinaceae). In eastern Canada, the adelgid is an invasive species that attacks and kills eastern hemlock, Tsuga canadensis (L.) Carriere (Pinaceae). We obtained all records of A. tsugae in institutional and public databases and develop updated range maps, phenologies and dispersal estimates for the species in British Columbia and eastern Canada In British Columbia A. tsugaes distribution is centred around the lower mainland and on Vancouver Island but with populations in the interior and along the Pacific coast that have been poorly explored and which could be sources of biological control agents to manage invasive populations in the east. In eastern Canada, the adelgid has invaded all of southern Nova Scotia, portions of the Niagara region in Ontario as far west as Hamilton, and at least one site on the north shore of Lake Ontario. No populations have been found in New Brunswick, Quebec or Prince Edward Island. Finaly, we estimated the rate of spread in Nova Scotia at 12.6 {+/-} 8.2 to 20.5 {+/-} 27.21 km/year.

ecology↗