Do bugs bother humans or the other way around? Study reveals some surprises

Insects and spiders often receive little attention from people except when we hunt them. However, as arthropods – creatures distinguished by a hard exoskeleton and jointed legs – they play a vital role in maintaining the ecosystems that humans depend on. It is remarkable that arthropods represent approximately 84% of all known animal species.

A study recently published in Scientific reports reveals how human activity affects arthropod biodiversity and how non-biological factors, such as daily temperature variations and proximity to the ocean, affect arthropod biodiversity in urban areas.

The research revealed some surprises and indicates how homeowners, landscapers and city planners can ensure a healthy mix of these small but vital neighbors.

Community Science Helps Study

Biodiversity refers to the variety of life forms in a given area. Generally speaking, greater biodiversity leads to a healthier and more resilient ecosystem. In urban settings, high biodiversity has been linked to benefits such as better air quality, reduced flood risks and even better human mental health.

To assess arthropod biodiversity and associated factors in the Los Angeles Basin, scientists from the USC Dornsife College of Letters, Arts and Sciences collaborated with researchers from the Los Angeles County Museum of Natural History’s BioSCAN project .

BioSCAN is a community science project led by the Natural History Museum and supported by about 80 volunteers who helped place small tent-like mesh structures, called Malaise traps, in yards, gardens and other locations of greater Los Angeles. From these traps, scientists collected flying arthropods such as bees, flies and moths. They also collected spiders by hand from the same locations.

Unforeseen discoveries about arthropod biodiversity

During this year-long project, museum staff surveyed arthropods to determine the diversity of groups living in each area. The results were surprising.

“In general, we thought most arthropods would be similarly affected by environmental factors such as land covered in asphalt or concrete and temperature fluctuations over a 24-hour cycle,” said the lead researcher. Melissa Guzman, Gabilan assistant professor of biological and quantitative and computational sciences. Biology at USC Dornsife. “Instead, we found a surprisingly wide range of responses to factors such as these, both within closely related groups and between different groups.”

For example, the prevalence of hard surfaces such as concrete and asphalt has had contrasting impacts on different insect populations. While it increased the diversity of fruit flies in the family Drosophilidae, it appeared to decrease the diversity of crane flies in the superfamily Tipuloidea.

Interestingly, spider diversity was high around hardcover lands. The researchers also found that temperature appeared to influence the diversity of fungus gnats in the family Mycetophilidae as well as Syrphidae, a family that includes bee-like hoverflies. The diversity of these insects decreased as the mercury increased.

Researchers speculate that higher temperatures in summer dry out plants eaten by aphids, a food source for many hoverflies. Additionally, non-native bees feed more at higher temperatures and therefore compete for the same foods that some hoverflies need.

Knowing how diversity among different species relates to factors such as land value, land cover and temperature can help planners and developers adjust their projects in ways that boost biodiversity and deliver its benefits to people. all Angelenos.

Many new species discovered

Brian Brown, curator of entomology at the Museum of Natural History, pointed out another surprising result that delighted researchers: The project revealed that many arthropod species that scientists didn’t know lived in the Los Angeles area , including nearly 50 species previously unknown to science.

“Based on this, we have a new understanding of what the biodiversity of Los Angeles is in terms of insects,” he said. “So instead of the 3,500 or 4,000 species we previously thought, we now think there are almost 20,000 species living here in ‘insect city’.”

Researchers credit Los Angeles community members who participated in the BioSCAN project as instrumental in understanding the region’s biodiversity and, therefore, playing a key role in conservation efforts. As a tribute, they named each new species after a participating family.

The results have lessons for humans

Despite some of the study’s challenges (it doesn’t account for seasonal variations in precipitation and temperature, for example), the researchers say the results indicate how Angelenos can ensure they increase arthropod biodiversity.

“Prioritizing green spaces and reducing pesticide use would be a big step forward,” says Guzman. “And planners and builders could include microhabitats designed to allow a wider variety of species to thrive.”

Although the study focused on the Los Angeles area, researchers believe similar findings would apply to other similar communities, guiding real estate developers and landlords in many cities across Western America North.