By: Kevin T. Chang
Almost everyone has heard of the plight of the honeybees and bumblebees, and for good reason- they are the prime pollinators in the world and of course, make the sweet and viscous liquid that many of us love: honey. However, you might not have heard of a cousin of the two species that are just as important- the stingless bee. While they may not occupy the spotlight, it occupies a just as important role- primary pollination duty in environments where its relatives falter. Conserving populations of these important insects not only carry benefits for biodiversity, but also world economy. In Brazil alone, these bees provide a pollination service worth billions of US dollars to crops commercialized worldwide! 1So what’s the problem? You might’ve guessed already- pesticides. As you may know, bees produce honey from collected nectar and pollen from various plants. When these plants are treated with pesticides, in this case organophosphate pesticide chlorpyrifos (CPY), the resources that bees collect and subsequently use as food can be contaminated. While many studies in the past have shown that pesticide usage affect bee colonies negatively, no one has really looked into the exact reasons for colony decline in stingless bees until recently.2 That is, we know that pesticides do something bad to the bees, but we really have no idea what exactly it is- and if we can find out what exactly causes these important colonies to die off, then maybe we can fix it! Thanks to some researchers out of Brazil, we might now have some clues to solve the mystery.
Queen bees- it’s a term that’s made its way into our everyday speech designating a particularly dominant woman in a social group. This term, of course, came from the actual queen caste in bees- a larger, fertile female who is the mother of all the larvae, or baby bees, in the colony. The other castes of bees, from worker bees to drones, all serve the colony to insure the survival of their queen and subsequently, the next generation. However, how are queen bees different, and why do some bees become queens while others only become workers? You might’ve heard of the term “royal jelly”- it’s a special food that the worker bees will feed the larvae that will eventually become queen bees.3 However, this isn’t the case in stingless bees- instead of a special food, they simply oversaturate the queen-to-be with lots of regular food: up to seven times the normal amount!4 As you might’ve guessed, this makes stingless bees particularly susceptible to pesticides. When the collected pollen gets contaminated, so does the honey that gets fed to the queen larvae. A Brazilian research team lead by Charles F. dos Santos of Pontifical Catholic University of Rio Grande do Sul wanted to find out exactly what would happen when these larvae are exposed to CPY.
The experiment began with 441 queen larvae, all with equal conditions (same plate, temperature, humidity and food amount), but with different pesticide doses. Of these 441 larvae, only 149 survived, but interestingly enough, some who did survive did not turn out as queens. In fact, the higher the pesticide exposure, the higher the rate of failure among the survivors. This came as quite a shock- as the research team noted in their publication, the “adverse effect of CPY, i.e. the significant skew in caste differentiation … from queens to workers, was a surprise because we expected to see increased larval mortality.”1 What does all this mean? Well, when exposed to pesticide, queen larvae have a much lower survival rate- and even if the larvae survive, some don’t develop properly into a queen! This effectively adds an additional layer of risk for stingless bees in particular. Without a queen, a colony is essentially doomed to die as the next generation will not be born. After all, no amount of workers or abundance of food is worth anything without a queen to use those resources on!
But is this really that big of a deal- they’re just bees, right? After all, it’s very easy to ignore insects such as bees in favor of larger, fluffier, and cuter animals to conserve. “It’s a crisis on top of a crisis,” Dr. May Berenbaum, of the University of Illinois at Urbana- Champaign, told Smithsonian Magazine. “[It had previously been projected that] commercial beekeeping [might] cease to exist in the United States by 2035—and that was before colony collapse disorder. And we can’t count on wild pollinators because we’ve so altered the landscape that many are no longer viable.”5 One thing is certain: bees are worth saving, whether it be for the good for your wallet, the planet, or even for the sweet, sweet liquid we all know and love.
- dos Santos, C.F., Acosta, A.L., Dorneles, A.L., dos Santos, P.D.S. & Blochtein, B. Queens become workers: pesticides alter caste differentiation in bees. Scientific Reports 6, 31605 (2016).
- Wu, J.Y., Anelli, C.M. & Sheppard, W.S. Sub-Lethal Effects of Pesticide Residues in Brood Comb on Worker Honey Bee (Apis mellifera) Development and Longevity. PLoS ONE 6, e14720 (2011).
- Kamakura, M. Royalactin induces queen differentiation in honeybees. Nature 473, 478-483 (2011).
- Fernando dos Santos, C., de Souza dos Santos, P.D. & Blochtein, B. In vitro rearing of stingless bee queens and their acceptance rate into colonies. Apidologie 47, 539-547 (2016).
- Berenbaum, M. (ed. Zax, D.) 29 (Smithsonian Institution, Smithsonian Magazine, 2007).