The number of bee species observed in nature around the world has decreased by about 25% between 1990 and the last decade, according to a survey by Argentinian researchers. The results are bad news for both the environment these insects live and agriculture, as the different species of wild bees play a key role in the pollination of plantations.
The work, recently published in the scientific journal One Earth, was signed by Eduardo Zattara and Marcelo Aizen from the National University of Comahue in Bariloche.
“Many bee species are less geographically distributed and / or are losing population size. Fewer numbers of other species generally associated with human activity expand their distribution and abundance. The bottom line is that the planet as a whole is losing biodiversity, ”summarized Zattara in an interview with Folha.
The researcher says the work came about as part of a larger project involving specialists from several countries, including Brazilians from USP. To get a global sample of bee diversity over time, the couple used the GBIF (English acronym for Global Biodiversity Information System) online database.
This system gathers so much information from zoology museums around the world from the 18th and 19th centuries, even photos and other records of living things made in recent years by “citizen scientists” using GPS-enabled smartphones – that is People willing to contribute to the database by sending information about the animals they encounter in their daily life.
The tool is important because, although there has been a lot of evidence of the population decline of various types of bees in other studies, work on this topic usually has a local or regional focus or only addresses certain subsets of bees (a line that includes around 20,000 different Species).
The GBIF data analyzed by Zattara and Aisen show two almost opposite trends. On the one hand, the number of bee records – sometimes when someone detects the presence of an insect – only increases over time, and that increase has accelerated since the 1990s. On the other hand, however, the number of species in these records is increasing, with the records peaking in the 1950s, remaining stationary for a few decades, and collapsing from the 1990s.
In theory, the phenomenon could be explained by the increase in records made by people who are not specialized in the database. In addition to being naturally unable to spot rarer species, individuals who contributed to GBIF in an amateur manner would tend to collect their data in environments of urban areas where diversity is naturally less.
However, the system data of other important groups of insects, wasps and ants show different trends: a slight decrease in the former (which starts before what is seen in bees) and even an increase in bees. Monday . This is an indication that GBIF information is indeed capturing a phenomenon that specifically affects honey producers. And the decline is seen across all of the continents analyzed, including South America, although the exact rate of fall from continent to continent is a decade or two apart.
What about the perpetrators? Zattara names the usual suspects: habitat loss, rampant use of pesticides, arrival of invasive species, and climate change. Incidentally, the researcher has an example right in his “backyard”.
It turns out that since the 1980s, Chilean farmers started importing the European species Bombus terrestris to pollinate their crops. The species was never allowed to be imported into Argentina, but the animals crossed the Andes and spread throughout Argentina.
Who pays for the duck is the so-called Mangangá or Muscardão (Bombus dahlbomii), the only member of the indigenous group of the Argentine Patagonia (it is a relative of the Brazilian bumblebees). The population has been drastically reduced as the European species competes with it for nesting sites and space in the flowers and brings with it diseases against which the Patagonian species has no defense.
And the situation also affects native plants, as the imported bee prefers to pollinate foreign flowers and leave the South American species in their hands. This kind of domino effect has to be repeated with small variations in the most diverse places in the world, with unpredictable consequences for biodiversity and agriculture.