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A bee lands on a flower

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Mike Groll

How Are Insects Affected By Climate Change?

We often talk about the big effects of climate change, but what about the small? Dari from northwest suburban Grayslake wrote in asking about climate change’s impact on some of our tiniest living things: insects.

The temperature and moisture in the environment play a major role in the lives of insects, said Professor Alex Harmon-Threatt, a pollination ecologist at the University of Illinois. That’s because most insects are ectotherms; they depend on external sources of heat. Changes in their environments can alter their metabolisms, or shift when they emerge so that they don’t line up with the plants they need.

And as Harmon-Threatt explained, the disruption of these little creatures could have a major impact. Her focus is on pollinators, like bees. She said if pollinator populations decrease, so will the plants that depend on them to reproduce. That includes fruits and vegetables that provide much of our nutrients.

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MELBA LARA, HOST: Something as big as climate change can impact even the little parts of life. Today in our weekly climate conversation, we’re talking really small: insects. We got this question from a listener.

DARI FROM GRAYSLAKE, IL: Hi, my name is Dari and I live in Grayslake, Illinois. And I’d really like to know how insects are affected by climate change.

LARA: Here to help us find out is Dr. Alex Harmon-Threatt. She’s a pollination ecologist at the University of Illinois. And let’s jump right in: what’s the impact of climate change on insects?

DR. ALEX HARMON-THREATT: This is a great question., and I’m super excited that someone asked it. So most insects are ectotherms, meaning that the environment actually plays a really important part in regulating their movement and population growth and development rates. So as the climate changes, those fluctuations actually can have a pretty big effect.

Particularly, we see things like a lot of changes in metabolism. They run through fat storage much faster, which means that they have less time to actually be alive in the environment. The other concern is not just changes in temperature, but changes in moisture. So a lot of insects are very sensitive to changes in moisture. And one of the big impacts of climate that we don’t talk about quite as much is that we’re expected to see wild swings in the amount of precipitation that we’ll get.

LARA: You study pollinators with a focus on bees, are we seeing changes in climate affect them already?

HARMON-THREATT: Yeah, so we are actually already seeing changes in climate affecting bees. In most cases it is actually really difficult to disentangle climatic changes from changes in habitat loss, reductions in nutrition, exposure to increase insecticide pressures, and things like that. But there are some cases where we know that the habitat hasn’t been changed that drastically, but we’re also still seeing a lot of declines.

And this particularly happens in species like bumblebees that tend to live at higher altitudes or higher latitudes, and we see a lot of decline of pollinators in those colder areas. It can also potentially cause what we refer to as “phenological shifts,” meaning that the pollinators may be emerging earlier or later, which might actually put them out of step with some of these plants that they really need, which can be obviously pretty bad.

LARA: We’ve been hearing warnings about the decline in bee populations for a while now. But if bee populations were to get really low, what is the latest science telling us about the ripple effect of that in our environment?

HARMON-THREATT: Most flowering plants require pollinators of some sort. As those pollinators decline, that means that plants that are reliant on pollinators, they are going to decrease the number of seeds that they make. As those plants aren’t able to reproduce effectively, that’s going to actually have all of these negative ripple effects throughout the ecosystem; decreasing populations, both of flowering plants, but then anything that depends on them.

Now, the most direct connection to humans is that this is also where we get most of our micronutrients. We wouldn’t have all the fruits and vegetables that we really need in our diet. The things that your doctors are always harping on you to make sure that you’re eating, without pollinators we’ll have far fewer of them. They’ll be much more expensive, and will contribute to a lot of malnutrition globally.

LARA: My spouse has planted some bee friendly plants out in the backyard and it’s been very thrilling to see a lot of bees in the backyard this summer. What else can individual people do if they want to help?

HARMON-THREATT: One of the big things I tell people is that; remember that most bees live in the soil. Most native bees are living below ground. And so when you have things like really heavy mulch, or really, you know, kind of dense grass, it’s not super great for pollinators. They also need plants that they like, so native plants are often very good.

Or if you live in an area where you can’t put in native plants, or where it’s maybe a challenge - because I will tell you that I’ve been fined by the city for having plants that were too tall because they were native. They got a little - you know, seven feet is a little tall for a front yard. So putting in what are referred to as “nativars,” so native cultivars, can also often be kind of a nice compromise. So a species that’s native to this area, but has been cultivated by horticulturalists to actually reduce their height or keep them from spreading really aggressively and things like that. But overall, native plants are really encouraged and there are lots of plant species lists out there that people can get their hands on.

LARA: That’s Dr. Alex Harmon-Threatt with the University of Illinois. Thanks so much for talking with us.

HARMON-THREATT: Thank you so much for having me.

See ongoing stories from WBEZ and the Local Media Association, and listen to interviews with experts about climate change topics in our region.

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