Scientists from the United States and Mexico have found a noticeable decline in the number of insects in the rainforest in the national reserve El Yunque (Puerto Rico), reports Science Alert. In addition, many insect-eating animals have disappeared. According to experts, this reflects the global trend that threatens food security around the world, since arthropods are needed for pollination of many crops.
In 2014, an international team of researchers estimated that over the past 35 years, the number of invertebrates such as bees and beetles worldwide has dropped by 45%. Europe has suffered the most, but now insects are also disappearing in the Americas. In 2017, another group of specialists examined the decline in the number of flying insects in Germany, suggesting that pesticides and habitat destruction are the cause.
Scientists conducted calculations of invertebrates in the 70s of the last century, as well as in 2013. It turned out that the biomass of arthropods over 40 years has decreased significantly, reaching 1/4 or 1/8 of the previous amount. From January 1977 to January 2013, the number of insects caught decreased 60 times. The number of insectivorous anoles lizards has decreased by 30%, and some species have disappeared from the forest. The number of frogs and birds has decreased. For example, the capture of the Puerto Rican Todi, which feeds on arthropods, was reduced by 90%.
Experts attribute this to global warming. Over 40 years, the average temperature in tropical forests has increased by 2.2 degrees Celsius. This disrupts the breeding cycle of insects that cannot lay eggs, and undermines the food chain, since arthropods provide food for many other animals.