A team of international researchers wanted to study predation patterns in different areas of the world, so they decided to glue fake caterpillars on leaves and see what happened. These caterpillars made of clay would trick predators into biting them, and would leave teeth marks to help scientists identify various patterns.
- Researchers glued fake caterpillars onto leaves and analyzed the bite marks on them.
- They found the highest predation rate at the equator.
- Ants are the most responsible with keeping caterpillar populations under control.
The team was led by Tomas Roslin, professor at the Swedish University of Agricultural Sciences. They chose 30 different places all over the world where they placed the fake caterpillars. The great thing about this method is the fact that they can identify the predators by the bite mark it leaves.
If it is an insect, it would leave two small piercings in the clay. A bird has a bite which should produce marks the shape of a wedge. If they find teeth marks, then they know the predator was a mammal. Therefore, this technique offers accurate results and is easy to implement.
They chose different locations on six continents, ranging from the south of Australia to the Arctic, covering an area of 7,208 miles. The aim of the study was to analyze both the density of species, and the incidence of hunting. Results were published in the journal Science.
They discovered how predation was more intense at the equator and at lower altitudes. Therefore, at the poles, the fake caterpillars only had one-eighth the chance to get bitten, and the rates increased as they got closer to the equator. Also, increasing the altitude corresponded to a decrease in predation.
Also, results showed which types of predators had a greater influence on these patterns. For instance, their expectations were defied when they found that neither mammals nor birds, but tiny insects were the main predators around the equator.
These arthropods, such as ants, contribute to the balance of the environment, regulate the caterpillar population, and do not allow them to devour all the vegetation.
Image Source: Wikimedia Commons