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Climate Change Could Decrease The Number Of Bugs In Missouri

Robert Marquis, a professor emeritus of biology at University of Missouri-St. Louis, looks for caterpillars on oak trees.
Jose Fabrara
UMSL biologist Robert Marquis and researchers from other universities found that many insects that eat leaves of Missouri oak trees are vulnerable to mid-spring frosts and droughts.

Many insects that feed on Missouri oak trees could be threatened by climate change, according to a study from the University of Missouri-St. Louis. 

Researchers from UMSL and several other universities looked at more than 250 insect species in Missouri, including leaf-tying caterpillars. Biologists reported in the journal Frontiers that the insects’ populations took major hits after mid-spring frosts and summer droughts, decreasing as much as 95% for some species.

While the study shows that populations were eventually able to recover, they may not if climate change makes droughts and spring frost events more frequent, said Robert Marquis, a professor emeritus of biology at UMSL. 

“These kinds of events actually will eventually show a long-term decline of insect populations in Missouri,” Marquis said. 

The study focused on insects that eat the leaves of white oak and black oak trees in Missouri. A cold spell in the spring could hurt caterpillars by disrupting their metabolism and killing off young oak leaves they feed on, according to the report. An analysis of mid-spring frost events between 1991 and 2011 showed that the insects’ populations climbed back up within a couple of years. 

Researchers also found that after the summer drought in 2012, it took up to five years for many insect populations at Cuivre River State Park in northeast Missouri to climb back up to normal levels. Scientists could not find some species, such as the slug caterpillar, again at the state park after the drought.

“These were all relatively abundant before the 2012 drought, so it’s surprising that we don’t see them anymore,” Marquis said. “They’re probably still there, but in such low abundance we just don’t see them in our sampling, or it’s possible they have gone extinct locally.” 

More research is needed to determine how climate change will affect insects in Missouri in the coming decades, Marquis said. He plans to study how insect species in southern Missouri have dealt with mid-spring frosts in recent years.

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Eli is the science and environment reporter at St. Louis Public Radio.