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Extreme weather has increased seasonal insect activity

Earth’s climate is indisputably heating up due to greenhouse gas emissions. This rise in temperature is causing weather events that we can only classify as extreme and anomalous. But the challenge arises when we try to predict and analyze the impact of these anomalies.

According to researchers from the University of Florida, museum specimens could provide some answers. This unique approach was unveiled in a groundbreaking study, where the scientists used natural history specimens to highlight how unseasonably hot or cold days can extend the active time of moths and butterflies by nearly a month.

Robert Guralnick, the lead author and curator of biodiversity informatics at the Florida Museum of Natural History, expressed surprise at these findings, saying, “The results are not at all what we expected.”

Study produces unexpected results

Conventionally, climate change studies focus on how average temperature rises impact ecosystems. As the temperature climbs, flora and fauna in a specific area become active earlier in the spring and delay their dormant phase until later in the fall. 

Gradually, they adjust their habitats to survive in their most favorable climate conditions. However, erratic weather introduces an intricate layer to these patterns, generating unknown consequences that blur the scientists’ vision of the future of global ecosystems.

Guralnick acknowledges the existing hints in scientific literature that weather anomalies may cumulatively affect ecosystems. Yet, he noted, “there wasn’t anything that directly addressed this question at a broad scale.” 

This gap largely stems from the lack of sufficient data. While climate data collection has been consistent in many global regions for over a century, organism location and activity records remain elusive.

Digging through the archives of natural history museums

Natural history museums could offer a solution. Housing specimens for hundreds of years, these museums have now digitized their collections, making them accessible to the wider scientific community. However, digital museum records also bring their own set of challenges.

In 2022, Michael Belitz, co-author of this study, put together a dataset of moths and butterflies from museum collections. His goal was to provide a blueprint for other researchers who want to use similar data. This undertaking resulted in a comprehensive guide on collecting, organizing, and analyzing information from natural history specimens.

With this valuable tool, Belitz and his colleagues set out to detect anomalies in weather patterns. They focused on the eastern United States, analyzing records of 139 moth and butterfly species collected from the 1940s to the 2010s.

The findings were clear-cut: abnormal hot and cold weather has considerably modified insect activity, more so than the average global temperature increase over the past decades. The researchers noticed that the location and timing of extreme weather events affected insect response. In higher latitudes, warmer winter days prompted earlier spring activity in moths and butterflies. Unusually cold days, on the other hand, kept insects active longer across all latitudes, and the combination of extremely high and low temperatures had the strongest impact.

Elaborating on this, Guralnick explained, “If you have a succession of abnormally cold and warm days, it limits the ability of insects to function at peak performance. If cold doesn’t kill you, it slows you down, and it might force insects into a torpor. Insects can recover from the cold snaps pretty quickly and go on to have longer lifespans as a direct result of sudden temperature declines.”

Good and bad of extended insect activity

While extended insect activity might seem beneficial initially, co-author Lindsay Campbell, who studies mosquitos, highlights the potential downside. Longer or altered insect lifespans could lead to more opportunities for pathogen transmission.

She cites correlations between El Niño and rift valley fever outbreaks in East Africa. Anecdotal observations also link unusually warm or hot and dry springs, followed by a heavy precipitation event, to increased outbreaks. Campbell, an assistant professor at the University of Florida, warns about these potential repercussions.

Moreover, the stability of long-term ecosystems relies heavily on the synchronized activity of its components. Interestingly, plants may not respond to these extreme weather patterns the same way insects do. For instance, if moths and butterflies begin their activity too early, they might find plants that haven’t yet produced leaves or flowers, wasting their energy in a fruitless quest for food.

Adding to this, the constant redefinition of ‘extreme’ brings another layer of uncertainty. Will insects be able to adapt to these changes quickly enough?

“As average temperature and climate variability increases, an organism’s resilience is going to drop precipitously,” Guralnick warned. 

He stressed that the extreme events we witness today could become significantly more extreme in the future. At some point, organisms’ capacity to buffer against these rapid changes will reach its limit, raising questions about the long-term impact on global ecosystems.

This intriguing study shines a light on a lesser-explored dimension of climate change impact, emphasizing the need for a comprehensive understanding of the intricate relationship between climate change and ecosystem dynamics. 

It serves as a wake-up call for us to delve deeper into understanding and mitigating the effects of climate change on the world’s ecosystems, making it abundantly clear that every organism, down to the smallest insect, plays a crucial role in the vast web of life on our planet.

More about insects and climate change

Climate change is a growing concern, and its impacts on insects are a crucial area of study due to the essential roles that insects play in the ecosystems, such as pollination, decomposition, and serving as a food source for other organisms.

Temperature is a major factor influencing the life cycles, behaviors, and geographic distributions of insects. A shift in climate could have multiple effects on insect activity and populations:

Changes in Distribution

Climate change can affect the geographic range of insects. As the world becomes warmer, insects that prefer cooler climates could move towards higher altitudes or latitudes, while those that thrive in warmer conditions might expand their range. Some species might even invade new areas where they weren’t found before, potentially leading to new ecosystem interactions.

Altered Life Cycles

Warmer temperatures could speed up the life cycle of many insect species, leading to more generations each year. This acceleration could increase their population size if resources remain abundant. However, if these changes don’t align with the availability of food sources, such as plants for herbivorous insects, the outcome could be detrimental for the insect populations.

Increased Pest Activity

Certain pests, such as mosquitoes, ticks, and crop-damaging insects, could become more active with increasing temperatures. This could lead to higher risks of vector-borne diseases, like malaria or dengue, and increased crop losses, respectively.

Impacts on Biodiversity

Insects with limited geographic ranges or specialized diets could face extinction if they can’t adapt to the changing climate or move to new habitats. The loss of these species could disrupt the delicate balance of ecosystems, with repercussions up the food chain.

Mismatched Phenology

Phenology refers to the timing of biological events, such as flowering or insect activity. If climate change causes these events to fall out of sync—for instance, if insects emerge before their food plants have grown—they could face food shortages.

Increased Stress

Extreme weather events, such as floods, droughts, or heatwaves, can pose direct threats to insect survival. They can also exacerbate other stresses, such as habitat loss and pollution.

Overall, while some insects might benefit from climate change, many could face significant challenges. Given their essential roles in ecosystems, changes in insect populations can have ripple effects across the food web and biodiversity, affecting the overall health of ecosystems and potentially human societies too. Further research is essential to better understand these impacts and to guide effective strategies for biodiversity conservation in the face of climate change.


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