Urbanization Is Driving Moths Away; ‘Strong Pattern’ of Insect Decline Observed [Study]

There is a noticeable decline in the population of moths in urban areas. However, the researchers need to find out if they are disappearing simultaneously or if some are vanishing faster than others.

Moth Population Declines in Urban Areas

A new study noticed a "strong pattern" of decline among moth populations across all stages in urban areas. The same pattern is also observed in rural areas.

The results come from a year-long survey that tracked and evaluated adult and larval moths in lower latitudes. Severe temperatures in these latitudes are killing off insects, which are vital to the area's environment.

"Subtropical and tropical environments have the greatest insect abundance and diversity and are areas seeing the greatest expansion of cities worldwide," lead author Michael Belitz, who researched while working at the Florida Museum of Natural History, said in a statement. "The urban heat island effect in these areas may be especially detrimental to insects."

In connection with the investigation, the scientists gathered moths from various locations in Alachua County, Florida, at different phases of development. This kind of area has a heat issue.

The light from the sun is reflected into space in rural areas with fewer artificial structures. On the other hand, light remains in the atmosphere and warms up in areas with higher concentrations of concrete and asphalt. Consequently, cities may become roughly 7 degrees Fahrenheit warmer than rural areas. Because the temperatures in lower latitude locations are already high, this can create an unavoidable dome of heat.

The survey involved 35,000 moths categorized as "macro" or "micro" moths. In the former's case, well-known species could fly great distances due to their wide wingspans. On the other hand, the latter are smaller and have a shorter range.

Since giant moths are considerably more likely to escape the so-called heat dome in the lower latitudes, it was essential to determine the number of macro and micro moths in the sample. Micromoths cannot flee their surroundings and the severe temperatures they encounter, so they are likely to suffer.

"There's no doubt that insect declines are a real phenomenon. The harder question to answer is where these declines are happening fastest. Is it different in tropical compared to temperate regions?" co-author Robert Guralnick, curator of biodiversity informatics at the Florida Museum, said in a statement.

ALSO READ: Xerces Blue Butterfly Wiped-Out Due to Urban Development; First Distinct Insect Species Extinct by Human Activity

Spanish Butterflies At Risk of Extinction

Meanwhile, another study suggests that some butterflies in Spain could become extinct due to rising global temperatures. The butterflies in Catalonia showed superior community-level body temperature regulation than their counterparts in the United Kingdom. They orient their wings towards the sun to warm themselves when it's cold.

However, both populations seek cover from the heat when the temperature rises. Rising temperatures may initially benefit British butterflies, but if they cannot adapt quickly enough, Spanish butterflies may not survive.

Like all insects, butterflies are "cold-blooded," meaning they regulate their body temperature according to their environment. Understanding how butterflies thermoregulate is necessary to identify which species are most susceptible to the effects of climate change.

RELATED ARTICLE: Rare Butterfly Species Named After 'Lord of the Rings' Villain Sauron; Needs Attention for Further Research

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