This NY Times article by Katherine J Wu discusses the monarch butterfly caterpillars’ behavior when food sources are diminished. Researchers have recently observed and studied caterpillars who, when food- stressed, use “bumping, boxing, and body-checking” to protect their food source. The caterpillar’s must consume large amounts of food before their metamorphosis transition into butterflies. This caterpillar aggression has been underappreciated and under- researched but could aid entomologists in the preservation of monarchs and milkweed plants. As milkweed plants continue to decline, this battle could be a key factor in monarch survival. Larva are born hungry and consume a significant amount of food as they grow in size. As caterpillars grew, their aggression increased, likely because food/energy consumption in these final stages before metamorphosis are especially important. Dr. Keene’s spouse observed this behavior in their backyard and Dr Keene, interested, looked for research on this but found none. He decided to fill the gaps.
This study discusses the aggression induced by limited resources in monarch caterpillars. The authors highlight the fact that food sources, like milkweed, can limit development in these species. The competition for food has shown to trigger aggressive or territorial behavior in a number of species. They found that monarch caterpillars can model resource availability and aggression interactions. The measured aggression by quantifying the number of aggressive attacks/physical contact and tracked the location and quantity of attacks throughout developmental stages. The display of these aggressive attacks or lunges become more common throughout development and peak just before metamorphosis, when demand for food is highest. These attacks also increased when food availability decreased/ was particularly low. The authors acknowledge a high level of variability between individual caterpillars.
Overall, I thought the NYTimes article did a good job of representing the scientific research. I think the purpose of the article is to share this novel behavior that has been observed in monarch caterpillars. The author acknowledges that there has been limited data surrounding this area and emphasizes the potential importance of researching this phenomenon/behavior as milkweeds (essential for monarch populations) are declining. The author also recognizes that this research has been conducted in a lab-setting which may provide different variables and circumstances and resulting behaviors in natural settings. I think these kinds of studies are important as they provide insight into how species will respond to changing environments, like reduced milkweed populations. As climate change continues to stress ecosystems around the world, I believe that an understanding and appreciation for this kind of research becomes increasingly important. (Not to mention, reading about hangry, boxing caterpillars is a nice escape from current COVID progressions/articles/stress).