7 minute read
The Ecology Process: The Unusual Techniques Scientists Use To Study Ecosystems
By: Denise Knapp, Ph.D., Director of Conservation and Research
You’ve likely seen it in cartoons or on TV, if not in person: the geeky scientist collecting insects with a butterfly net, frantically swiping through the air for their prize then marveling at the tiny creature they have then trapped inside a jar. You may have chuckled at those strange people — you wouldn’t be alone — who are so fascinated by bugs that they want to collect one of everything. Trust me, it gets so much stranger.
Insects, together with other arthropods like spiders and centipedes, are the most species-rich animal group on the planet. They also do a wide variety of jobs, from the more picturesque act of pollinating flowers to the less fun feat of breaking down waste. So, it makes sense that they are found in all kinds of places, with all kinds of behaviors — and that it takes all kinds of strange techniques to collect them when you want to understand our biological diversity and how to rebuild food webs from the bottom (native plants) up, like we scientists at Santa Barbara Botanic Garden do.
It starts with meeting them where they are at. Are they mostly flying around or hunkered down on (or in) a plant? Are they buried deep in the soil or in the plant litter? Are they active during the day or are they more of a nighttime kind of creature? Come with me as I lead you on a tour of just a few of the odd ways that entomologists (or ecologists, like those of us at the Garden) collect these critters.
Shake Them Loose
For those insects that feed on plants, you have to go to them. About half of all insects are herbivores, and about 70% of those are specialists that can only feed on a narrow range of related plants. Our favorite technique for getting those that like the green stuff is what’s called a beat-sheeting method, together with an aspirator (also called a pooter). We are literally beating the bugs off the plants and then sucking them up into a vial! First you place a white sheet stretched onto a frame beneath the plant of interest, and then you gently but vigorously shake the plant until the bugs fall off onto the sheet. Quickly you spring into action with the aspirator, with one tube that goes from the bug to the vial and another tube that goes from the vial into your mouth. When you suck on the tube, it draws the bug into the vial. Luckily, a layer of muslin or mesh keeps us from ingesting the hapless insect.
Flying Insects Love Color and Light
For flying insects, we typically trick the bugs into coming to us and then trap them there. Many dayflying insects are attracted to the color yellow, so we put out a yellow bowl with soapy water and after a while, voilà — bowl ’o’ bugs. The soap in the water breaks the surface tension so these tiny nimble creatures can’t crawl out. It’s sad, I know, but not harmful. An insect’s fine features help us identify them — the small patches of hairs or bristles, vein patterns on the wings, or the number of antennal segments — and we can’t see those details if they are moving.
After dark, black lights are great for night-flying insects like moths since most flying bugs are drawn to light. Black lights emit a type of UV light, which insects see but humans don’t. The UV lights also give off some heat, which helps to lure the insects. Then we diabolical scientists can pick off the bugs we most want with an aspirator.
Creepy Crawlers Watch Out
We use a similar method to capture insects that crawl around on the ground. This version is called a pitfall trap, because — as the name implies — the insects fall into a pit. We have to be careful to bury the trap so that it doesn’t stick up above the soil; for tiny bugs this would act like a fence.
Collecting bugs from soil and plant litter is tricky. Sure, movement is a dead giveaway, but bugs are often quite tiny, which makes them difficult and time-consuming to separate from the small bits of soil and duff. Luckily, there is a smarter way! If you put soil and plant litter into a Winkler extractor device, with its internal mesh layers, and create heat using lights (see opposite photo), the bugs will separate themselves for you. They do this because they like to move downward and away from heat. Finally, jars of soapy water or ethanol at the bottom collect them for our research.
Preserving for Research
Once you’ve collected the insects, you need to preserve them for long-term scientific examination. For the bugs that we have collected dry and dispatched in the field, they must be pinned pronto, before they get brittle. But the bugs collected by way of soapy water still need to be preserved in ethanol so that they don’t decay. Once we bring these bonanzas of bugs back to the lab, common household items help us finish the job. Bit by bit, we pour our bug stew into a plastic coffee filter and then use paintbrushes and forceps to transfer the bugs into vials of ethanol for later sorting, identification, and imaging.
For hairier insects like bees, the preservation is even more detailed than this. If you pin bees straight out of ethanol, they will end up looking permanently like wet dogs! Among other things, this makes the important identifying patterns on their bodies difficult to see. So, the bees need the diva treatment, via tea strainer and blow-dryer. First, you put a small clump of bees in the tea strainer — which acts like a little washing machine — and put them through a few wash-rinse cycles. Then it’s time for a blowout, which fluffs them up in a flash!
I may be in the minority in finding bugs always fascinating, often beautiful, and, many times, quite cute, but I hope that we can all appreciate that if we didn’t have them to pollinate our food, break down our waste, feed the food web, and maintain order in the ecosystem, we’d be in a world of trouble. You can help support them, and the many animals that depend on them, by building habitats with native plants. The diversity of life that you support will make our world more functional — and, if you’re asking me, even more fascinating.
