Developing a method to measure wild insect health and frailty: Jelle Boonekamp
Field crickets (Gryllus campestris) receive tags, which help researchers study them at the WildCrickets Field System in Spain. Photo courtesy WildCrickets.org.
June 16, 2022
If someone produced a reality television show about wild crickets, it might look like the WildCrickets Field System, a multiyear study based in a meadow in Northern Spain. More than 140 cameras pointed at cricket burrows capture the daily dramas and relationships of adult wild field crickets (Gryllus campestris). Researchers tag the crickets with tiny numbers at the beginning of their adult life and monitor their activities as they sing, eat, mate, fight, or succumb to predators.
A new cricket generation emerges and dies each year, making the species ideal for studying evolution and aging, says Jelle Boonekamp, an ecophysiologist with the University of Glasgow. The WildCrickets Field System has yielded some fascinating discoveries about cricket behavior, personality, and genetics.
With a grant from Wild Animal Initiative, Boonekamp and University of Exeter researcher Tom Tregenza plan to use the WildCrickets Field System in a new way — to measure frailty, an important indicator of health that could help us better understand wild insect welfare.
WHY WE FUNDED THIS PROJECT
In order to improve welfare for invertebrates, we first need to understand how to measure their welfare. Although we still know little about insect minds, physical health is an important component of welfare. This project will develop a model to evaluate the health of individual wild insects.
A novel study system
“Welfare or well-being is very difficult to measure in insects and other animals, because you cannot simply ask them, ‘Are you well?’ You have to use something else to ask about their welfare in general.” —Jelle Boonekamp
Photo courtesy Jelle Boonekamp.
This study represents Boonekamp’s first academic foray into wild animal welfare, but his previous research has focused on related topics, such as aging and longevity.
“I study how aging is impacted by your environment,” Boonekamp says. “I’m very interested in what happens to you later in your life and how that’s linked to what happens earlier in your life.”
Boonekamp has worked with insects and birds as study subjects. In one study, he examined the effect of larger brood sizes on mortality rate in wild birds. Compared to birds, he says, insects prove more challenging to study in the wild.
“They’re small, they often don’t live very long, and they’re just harder to track on an individual basis,” Boonekamp points out. “Most work on insects takes place in the lab.”
That’s why the WildCrickets Field System represents a unique and valuable tool for studying insects in the wild. Field crickets can’t fly, and they tend to stay close to their burrows, making it easier to capture their activities with a camera positioned above each burrow.
“We can follow them from the moment they emerge, and often we also know why they have died,” Boonekamp says. “We get detailed information about almost everything these crickets are doing.”
The WildCrickets Field System eliminates one of the major challenges of studying wild insects by providing a way to track individual crickets. Since wild animal welfare science focuses on the positive and negative experiences of individual animals, this setup offers a promising approach to studying insect well-being.
Measuring insect frailty
Two field crickets retreat to their burrow as a snake slithers past. Video courtesy WildCrickets.org.
The team has spent many hours watching video footage of wild crickets, observing the rhythms of their lives. The research team has even set up a citizen-science webpage that allows visitors to watch videos of crickets in the study meadow and tag significant events, such as eating or singing.
Mostly, he says, the cricket footage is pretty mundane. The crickets amble around their habitat, occasionally munching on vegetation or diving into their burrow. But sometimes these long stretches of quiet are punctuated by thrilling moments of action.
“It always gets your attention when a predator like a small lizard or a shrew tries to eat the cricket,” Boonekamp says. “Crickets can defend themselves very well, so they make this kind of pose where they’re upside down and use their hind legs to kick.”
The WildCrickets Field System has provided 12 years of data on cricket life histories, revealing valuable insights into aging and genetic variation. By studying frailty, Boonekamp hopes to reap scientific benefits for the field of wild animal welfare, as well.
“Health and welfare are concepts that have similarities,” Boonekamp says. “If you’re unhealthy, you’re probably also unwell.”
In human medicine, healthcare professionals use frailty to measure the health of elderly patients. Doctors can quantify frailty based on a number of indicators, including slow walking speed and weakness. If a medical provider considers 10 health indicators for a patient, and 3 of the 10 indicators are present, the patient would have a frailty index of 0.3. A 2018 meta-analysis found the frailty index to be a significant predictor of life expectancy.
Boonekamp plans to adapt this health measurement tool for wild insects, proposing a novel way to quantify frailty as a proxy for welfare. Twice a week, Boonekamp will take a subset of the crickets and measure various cricket health indicators, including body mass, running speed, bite force, and the reflectance of the cuticle, or skin, of the crickets. With this data, Boonekamp can obtain noninvasive metrics that paint a picture of health for the field crickets.
“Welfare or well-being is very difficult to measure in insects and other animals, because you cannot simply ask them, ‘Are you well?’” Boonekamp says. “You have to use something else to ask about their welfare in general.”
Boonekamp will track the crickets across their lives (with a median lifespan of 28 days) and investigate if the insect frailty index is correlated with shorter life expectancy. From a welfare standpoint, a validated insect frailty index could be adapted for use in many wild insect species that share similar physical traits.
Insects as individuals
Two field crickets fight outside a burrow in the WildCrickets Field System. Video courtesy WildCrickets.org.
As more researchers study insect pain, Boonekamp says it’s time to reevaluate the outdated assumption that insects don’t have positive and negative experiences simply because they have a different neurological layout than vertebrates. In other areas of research, many grant proposal applications don’t consider insect welfare at all, even though welfare is considered for all vertebrate species. Boonekamp hopes his research might raise awareness and someday lead to changes in this policy and others.
For the crickets who inhabit the WildCrickets Field System, this research might help people think of them from a new perspective, one that considers them as individuals and not simply members of a threatened species.
“We observe these field crickets losing a limb when fighting off a predator, and it’s quite likely that they do experience discomfort or pain,” Boonekamp says. “If that’s the case, then it’s really important to develop a study system and measuring techniques that enable us to learn more about this.”
Boonekamp’s proposed study is funded by Wild Animal Initiative’s Grants Program. If you are a researcher or student interested in pursuing wild animal welfare science, please take a look at our latest call for proposals. Wild Animal Initiative is accepting expressions of interest through June 30, 2022.
Each camera in the WildCrickets Field System points to a burrow, where field crickets live and die. Photo courtesy WildCrickets.org.
RELATED RESEARCH
The WildCrickets Field System has led to more than 20 research papers. Jelle Boonekamp has contributed to several of these studies, including “Telomere length is highly heritable and independent of growth rate manipulated by temperature in field crickets,” and “Evidence for genetic isolation and local adaptation in the field cricket Gryllus campestris,” both published in 2021.
This is the third story in a series of features on our spring 2022 cohort of grantees. Please subscribe to our newsletter to get future stories delivered straight to your inbox.
