The biodiversity of terrestrial insects in Brazil, which includes animals such as butterflies, bees and beetles, shows a downward trend. This is one of the effects of a survey conducted by researchers from the State University of Campinas (Unicamp) and the Federal Universities of São Carlos and Rio Grande do Sul. Data collected from forty-five clinical investigations on the subject, in addition to questionnaires sent to researchers who have been reading insects for years.
“If you are insects, you break all food chains from nature to the base. If they do not have caterpillars to feed the birds, the birds will decrease. If they do not have insects to feed the wasps, their numbers will decrease and once they do, they will begin to cause an imbalance that can lead, for example, to the accumulation of pests, either in cities or in agriculture”, André Freitas, professor at the Institute of Biology of Unicamp and one of the researchers of the project, Warns
The study presents 75 trends, most of them reducing them, over 22 years for terrestrial insects. For aquatic insects, the study shows 75 trends over 11 years on average. Most of them involve a relief in the number of animals. the Research Foundation of the State of São Paulo (FAPESP) and the National Council for Scientific and Technological Development (CNPq). The text published this week in the foreign journal Biology Letters.
Among terrestrial insects, for example, studies have indicated a trend toward population decline or loss of species diversity. The scenario is different in aquatic groups, in which the number of species or Americans has remained solid or, in some cases, increased. The researchers note, however, that this difference will be reevaluated in the future.
Global trend
Freitas points out that other studies, especially in the United States and Europe, had already shown a reduction in the number of insects in those regions, but there is little information about the situation in tropical countries.
“There they have decades of knowledge appearing that there is a decline of all kinds, not only of pollinators,” he says. He explained that here the diversity of insects is much greater, with a variety of species from 10 to 20 to one. , to temperate countries.
The researcher explains that to perceive the scenario of insects, long-term studies are basic because those animals have short life cycles. “[The investigation of an] insect is almost like an electrocardiogram, full of peaks and valleys. It will be a zigzag line with giant amplitudes, however, you can see if it is going up or down. To have this [kind of information], you need very long time series, and we had very few [in Brazil],” he says.
In that sense, studies with at least five years of research were foreseen. “What we have learned is that maximum studies imply that there is indeed a decrease in insects in Brazil. There are several studies that imply stability, and even some show an increase. . But what’s worrying is that if you just look at the number of studies that show an increase, a stability or a reduction, the ones that show a reduction are more frequent,” Freitas said.
The reasons for the decline are not part of the survey, however the researcher presents some hypotheses for this picture, contemplating knowledge discovered in other parts of the world, for example, “indiscriminate use of pesticides; expansion of the extension of villages and agricultural and livestock activities”. domains, which decrease the dominance of herbarium habitat, and urban lighting in giant villages, because insects tend to be attracted by light bulbs, spin and die.
Insects and the environment.
The researcher admits that insects are related to negative things, such as the transmission of diseases, but it is essential not to forget the importance of these animals for the balance of the environment.
“The decline of insects, in general, will favor a few species of pests. These will have a much more wonderful effect on our lives,” he warns. It reminds us that wonderful imbalances can result that only human-related pests such as cockroaches, mosquitoes and some ants remain as they will have food and an environment available.
Bee pollination is the best-known example of the role of insects in maintaining biodiversity. But insects have other environmental benefits, such as the fact that they are the first step in the decomposition of biological matter.
“Whether it’s leaves falling to the ground or dead animals, beetles, ants and termites cause the number one degradation of this material. Without insects, for example, forests would be more and more trunks and leaves piled on top of each other, because the bacteria that cause the final decomposition first have fragmentation,” says Freitas.
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