Extensive regional variation in the phenology of insects and their response to temperature across North America

Abstract

Climate change models often assume similar responses to temperatures across the range of a species, but local adaptation or phenotypic plasticity can lead plants and animals to respond differently to temperature in different parts of their range. To date, there have been few tests of this assumption at the scale of continents, so it is unclear if this is a large‐scale problem. Here, we examined the assumption that insect taxa show similar responses to temperature at 96 sites in grassy habitats across North America. We sampled insects with Malaise traps during 2019–2021 (N = 1041 samples) and examined the biomass of insects in relation to temperature and time of season. Our samples mostly contained Diptera (33%), Lepidoptera (19%), Hymenoptera (18%), and Coleoptera (10%). We found strong regional differences in the phenology of insects and their response to temperature, even within the same taxonomic group, habitat type, and time of season. For example, the biomass of nematoceran flies increased across the season in the central part of the continent, but it only showed a small increase in the Northeast and a seasonal decline in the Southeast and West. At a smaller scale, insect biomass at different traps operating on the same days was correlated up to ~75 km apart. Large‐scale geographic and phenological variation in insect biomass and abundance has not been studied well, and it is a major source of controversy in previous analyses of insect declines that have aggregated studies from different locations and time periods. Our study illustrates that large‐scale predictions about changes in insect populations, and their causes, will need to incorporate regional and taxonomic differences in the response to temperature.

The buzz around biodiversity decline: Detecting pollinator shifts using a systematic review

“…These ranged from continental studies to individual states, but do not paint a representative picture of global pollinator trends. Previously, literature focusing on phenological mismatch prioritized bee taxa, 13 , 31 and this study affirms that changes may be more widespread across pollinator groups. Incorporating phenology/climate datasets into future pollinator studies will strengthen the understanding of species responses.…”

“…1 Some species have been able to adapt and shift their range or establish in new areas as spring and summer seasons lengthened, whereas many species have risked population declines due to impending pressures such as habitat loss, decreased thermal tolerances, and resource competition. 8 , 9 , 10 , 11 , 12 , 13 Pollinator species are sensitive to temperature and precipitation fluctuations. For bumble bees, climate thermal limits can exceed the physiological thermal limits of the species, leading to range shifts or declines in species richness.…”

Chasing and surfing seasonal waves: Avian migration through the US tracks land surface phenology in fall, but not spring

“…Temperature, precipitation and vegetation biomass can affect the availability of insects (Shipley et al, 2020;Williams, 1961;Winkler et al, 2013). Birds may follow the emergence of aquatic insects as emergence progresses northward with warming temperatures (Nash et al, 2023;Shipley et al, 2022), though there is substantial regional variation in insect phenology (Dunn et al, 2023).…”

Seasonal Patterns in the Frequency of Candidatus Liberibacter Asiaticus in Populations of Diaphorina citri (Hemiptera: Psyllidae) in Florida

“…The link between temperature and plant development is well documented [ 18 ]. The relationship applies to insects like D. citri [ 19 , 20 , 21 ], but there is regional variability in the response [ 22 ]. Diaphorina citri requires new growth (often called flush) to complete its lifecycle [ 23 ].…”