Study: Monarch Caterpillars Get Angry When They’re Hungry
Humans aren't the only animals that get "hangry" when deprived of a meal.
"The less food that is present, the higher their level of aggression," study coauthor Elizabeth Brown of Florida Atlantic University told New Scientist.
The idea for the study was born when the wife of fellow Florida Atlantic University researcher Alex Keene saw two monarch caterpillars fighting over a milkweed plant in the couple's garden, The New York Times reported.
"I decided to investigate monarch caterpillars because I was intrigued by their combative behavior, which I observed first-hand in my own garden," Keene explained in a Florida Atlantic University press release. "They are large and easily recognizable compared to many other insects. These are charismatic animals that everyone loves, and there's a growing appreciation for their potential to tell us about how the brain controls behavior."
The researchers gave the caterpillars three different amounts of food, New Scientist reported. The less milkweed the caterpillars received, the more aggressive they became. The caterpillars who were larger and closer to metamorphosis were the most aggressive, probably because they required more energy, Brown said.
Caterpillar aggression looked like a "combination of boxing and 'bumper' cars," the press release detailed, with caterpillars head butting or knocking other caterpillars away from the food.
"I went to grad school with a guy who played rugby in college," Keene told The New York Times. "A flying head butt is a fair assessment."
The attacked caterpillar would then shuffle away from the food, defeated. This is a big problem for the losing caterpillar, since monarch caterpillars essentially eat non-stop from hatching to forming a cocoon.
The researchers hope to build on this study to learn more about the genetic drivers of aggressive behavior.
"There's a lot we could learn about more complex animals from this ecologically relevant insect model," Keene told New Scientist.
The research could also have conservation implications. Monarch caterpillars mainly dine on milkweed: They can strip an entire plant in two weeks and, when they are at their largest, consume a leaf in less than five minutes, the press release noted. But this dependence on milkweed has made the species vulnerable. The number of monarch butterflies has decreased in the U.S. over the last 20 years, according to the U.S. Fish and Wildlife Service, and one factor is the use of pesticides that harm milkweed.
"It's interesting to think about how this would potentially impact the survival of these caterpillars, when they're crowded onto plants," University of Michigan monarch biologist D. André Green, who was not part of the study, told The New York Times. "The amount of milkweed is decreasing. This may become a bigger issue."
- Why Millions of Monarch Butterflies Are Dying in Mexico - EcoWatch ›
- How a Plastic-Eating Caterpillar Could Help Solve the World's ... ›
- Most Meat Will Be Plant-Based or Lab-Grown in 20 Years, Analysts ... ›
- Lab-Grown Meat Debate Overlooks Cows' Range of Use Worldwide ... ›
- Will Plant-Based Meat Become the New Fast Food? - EcoWatch ›
EcoWatch Daily Newsletter
One city in New Zealand knows what its priorities are.
Dunedin, the second largest city on New Zealand's South Island, has closed a popular road to protect a mother sea lion and her pup, The Guardian reported.
piyaset / iStock / Getty Images Plus
- No Country Is Protecting Children's Health, Major Study Finds ... ›
- 'Every Child Born Today Will Be Profoundly Affected by Climate ... ›
By Jeff Masters, Ph.D.
Earth had its second-warmest year on record in 2020, just 0.02 degrees Celsius (0.04°F) behind the record set in 2016, and 0.98 degrees Celsius (1.76°F) above the 20th-century average, NOAA reported January 14.
Figure 1. Departure of temperature from average for 2020, the second-warmest year the globe has seen since record-keeping began in 1880, according to NOAA. Record-high annual temperatures over land and ocean surfaces were measured across parts of Europe, Asia, southern North America, South America, and across parts of the Atlantic, Indian, and Pacific oceans. No land or ocean areas were record cold for the year. NOAA National Centers for Environmental Information
Figure 2. Total ocean heat content (OHC) in the top 2000 meters from 1958-2020. Cheng et al., Upper Ocean Temperatures Hit Record High in 2020, Advances in Atmospheric Sciences
Figure 3. Departure of sea surface temperature from average in the benchmark Niño 3.4 region of the eastern tropical Pacific (5°N-5°S, 170°W-120°W). Sea surface temperature were approximately one degree Celsius below average over the past month, characteristic of moderate La Niña conditions. Tropical Tidbits
- NASA and NOAA: Last Decade Was the Hottest on Record - EcoWatch ›
- Earth Just Had Its Hottest September Ever Recorded, NOAA Says ... ›
In December of 1924, the heads of all the major lightbulb manufacturers across the world met in Geneva to concoct a sinister plan. Their talks outlined limits on how long all of their lightbulbs would last. The idea is that if their bulbs failed quickly customers would have to buy more of their product. In this video, we're going to unpack this idea of purposefully creating inferior products to drive sales, a symptom of late-stage capitalism that has since been coined planned obsolescence. And as we'll see, this obsolescence can have drastic consequences on our wallets, waste streams, and even our climate.
- Consumer Society No Longer Serves Our Needs - EcoWatch ›
- Electronic Waste: New EU Rules Target Throwaway Culture ... ›