Forest fires will start earlier and earlier in the future

The Dilemma of Insect Counting: More and more land is used for agriculture, which means more pesticides are used and fewer diverse crops grow. In addition, cities are growing, which is why forests and other wilderness areas are declining. All of this leaves insects with fewer places to shelter and pollinate. Added to this is climate change, which is causing them problems. This is proven by numerous studies from all over the world.

However, scientists who want to study insect mortality face a methodological dilemma. A study published in March in the journal Ecology and Evolution illustrates this. Researchers studied bumblebee populations in California. To determine the species of bumblebee, they must capture the animals. It is also possible to catch insects and then release them again. But that is more complex. In addition, researchers cannot collect all the animals in a population and most species are endangered anyway. The researchers therefore caught 100 individuals at 17 different locations. So it may be that they did not find a certain species, but in reality it has not disappeared, but is rare. It is also possible for insects to change their location due to climate change. However, the researchers only examined areas where historically many bumblebees appeared. That’s because it would be too time-consuming to collect bumblebees all over California. There are also more than 260 bumblebee species. The researchers collected bumblebees during the average main flight time. However, this may differ for some species.

Complete species censuses would therefore be very time-consuming and costly. Nevertheless, the study shows clear tendencies. They conducted studies in six different habitats, ranging from coastal to mountainous regions. The western bumblebee, formerly one of the most common species in California, has not been found at any of these sites. In addition, there is a large number of worldwide studies, all of which show that insect populations are declining. So scientists cannot say for sure how many animals of a species still exist. However, you can prove that the total stock is declining.