The Institute of Bee Health at the University of Bern, Switzerland has carried out a study to explore the effects of two popular neonicotinoids, thiamethoxam and clothianidin, on the sperm of drones, or male honey bees. 
 
 Lead researcher Lars Straub said the presence of the chemicals could be "one reason behind the struggling bee numbers we've seen over the past 15 years in the northern hemisphere." 
 
 The pesticides are widely used in the USA. The European Commission is currently reviewing a temporary ban it imposed in 2013. 
 
 There has been an alarming decline in the bee populations in North America and Europe over the past 15 years. Bees account for an estimated 80 percent of plant pollination by insects. 
 
 'Inadvertent contraceptive effects' 
 
 The researchers, led by Straub in Bern assigned batches of drones from 20 bee colonies to either insecticide exposure or control groups. They then took semen samples from males once they had reached sexual maturity. 
 
 The study published in the British journal Proceedings of the Royal Society B showed that widespread neonicotinoid use may have "inadvertent contraceptive effects" on the insects which provide fertilisation worth billions of dollars every year. 
 
 Male honey bees exposed to the neonicotinoids at levels found in fields showed, on average, around 39 per cent less living sperm. In addition, the mortality rate of the drones exposed to the pesticides during the study was almost doubled. 
 
 Bee studies in Braunschweig 
 
 Honey bee queens make a single mating flight from the nest to collect sperm from as many as 20 different males, which they store within a dedicated organ over their entire lifespan. This is essential for the hive's survival as it provides genetic diversity which is essential for resistance to disease, parasites and environmental challenges. 
 
 "The process of the queen's mating flight is a one-time thing so it's really important that she collects plenty of quality sperm," Straub said. If she does not, then worker bees will sense the queen is ineffective and kill her. "As the primary egg layer and an important source of colony cohesion, the queen is intimately connected to colony performance," the paper said. 
 
 The new study adds reduced sperm quality to the list of possible causes for "colony collapse disorder" in Europe, North America and elsewhere, which has alternatively been blamed on mites, a virus or fungus, pesticides or a combination of all of them. 
 
 Previous studies have found neonicotinoids can cause bees to become disorientated to the extent that they cannot find their way back to the hive, and can lower their resistance to disease. 
 
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 jm/kl (AFP, Royal Institute) 

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– Just when you thought things couldn’t get worse for bees, a new study suggests we've been inadvertently feeding them birth control. Previous research has shown the world's most widely used pesticides, neonicotinoids, have hurt the lifespan and reproduction of honeybee queens and reduced the number of bumblebee queens, reports the Guardian. But new research out of the University of Bern in Switzerland finds two neonicotinoids, thiamethoxam and clothianidin, also cut live sperm in males by 39%. Sperm viability was also 8% to 11% lower than in bees not exposed to the pesticides, reports National Geographic. Here's why that's a big problem: A queen bee collects sperm from up to 20 males to ensure genetic diversity when she reproduces. If that sperm is of poor quality, worker bees will kill the queen to protect the colony, reports Deutsche Welle. "As the primary egg layer and an important source of colony cohesion, the queen is intimately connected to colony performance," researchers say. There's more bad news: In addition to reducing live sperm, scientists found exposure to thiamethoxam and clothianidin also cut bee lifespans by a third, from 22 days on average for unexposed bees to 15 days. In fact, only 68% of male bees exposed to neonicotinoids lived to reach sexual maturity at 14 days, compared to 83% of unexposed bees. These "important lethal and sub-lethal effects" could have "severe consequences for colony fitness, as well as reduce overall genetic variation within honeybee populations," scientists say, though they acknowledge that disease, habitat loss, and parasites are also responsible for recent colony losses. (See how one pesticide-maker is trying to help.)