26 de juny 2012

BORINOTS D'HIVERNACLE

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Des de la dècada dels 80, dues subespècies del borinot Bombus terrestris s'han convertit en un dels pol·linitzadors principals dels agricultors que treballen amb hivernacles a Europa, Àsia, Austràlia i Amèrica del Sud.  

El problema ha sorgit, quan poblacions d'aquests individus s'han escapat del seu hàbitat artificial i han esdevingut abelles invasores que podrien desplaçar a espècies natives i propagar malalties. 
 
Per veure si aquesta preocupació estava justificada, l'equip d'investigació d'Alemanya i Polònia va iniciar una acurada investigació sobre la genètica de les poblacions d'abelles al voltant dels hivernacles al sud de Polònia. Les conseqüències d'aquest desbordament genètic són difícils de predir, però les troballes genètiques suggereixen que els governs haurien de considerar la imposició de normes més estrictes sobre les importacions de borinots si volen salvaguardar els brunzidors nadius




Since the 1980s, two subspecies of the buff-tailed bumblebee (Bombus terrestris) have become a mainstay pollinator for greenhouse farmers in Europe, Asia, Australia and South America. In 2006, growers purchased nearly 1 million colonies for indoor pollination of tomatoes, peppers and other hothouse crops, a research team reports in Conservation Genetics. The global bee trade, however, has a potential downside: buff-tailed bumblebees have escaped greenhouses and established feral populations in New Zealand, Japan, Australia, Tasmania, Chile and Israel. The invading bees can displace native species and spread disease. Researchers have worried that even in Europe – the bee’s native land – imported hives could lead to interbreeding with local populations, creating “mongrels” with potentially lower genetic fitness.
To see if that worry was warranted, the German-Polish research team took a careful look at the genetics of bee populations surrounding three greenhouses in southern Poland. The scientists collected a total of 588 worker bees from nine populations, including three collected inside the greenhouses. Then, they extracted DNA from one leg of each bee, and used four genetic markers to map bee relationships.
The numbers strongly suggested that the greenhouse bees had been out and about. Near the greenhouses, between 33% and 47% of the wild bees carried genes linked to the greenhouse hives. Farther away, 8% to 12% appeared to be related to the commercial bees. Although the results could be skewed by “statistical pitfalls,” the authors conclude that the greenhouse bees are “capable of changing the genetic structure” of wild populations. “The consequences of this genetic spillover are hard to predict,” they add, but the findings suggest that governments should consider imposing tighter rules on bumblebee imports if they want to safeguard native buzzers. David Malakoff | January 14, 2011

Source: Kraus, F., Szentgyörgyi, H., Rożej, E., Rhode, M., Moroń, D., Woyciechowski, M., & Moritz, R. (2010). Greenhouse bumblebees (Bombus terrestris) spread their genes into the wild. Conservation Genetics, 12 (1), 187-192 DOI: 10.1007/s10592-010-0131-7
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