The Bees Are Buzzed

Wright et al, report in Science that "Caffeine in Floral Nectar Enhances a Pollinator's Memory of Reward".  Some flowers, including those of, of course, coffee plants, but also citrus and tea,  incorporate a bit of caffeine in their nectar.  Curiously, according to the authors, all the citrus varieties they studied did this but not all the coffee plants.  As any college bunny getting ready for exams knows, caffeine helps keep you alert and enhances the memory.  Fortunately the bees appear to dislike the taste of solutions with dangerous (to bees) levels of caffeine.  They will not be buzzing your energy drinks but they do have a fondness for sodas.

That's the good news.   The bad news is that bees are disappearing.  One of the causes is the use of neonicotinoid  pesticides and organophosphates.  The later has been used to wipe out Varroa mites, one of the major pests of bees.  It turns out that these pesticides make the bees stupid, wiping out brain cells that the bees use to learn things, like where the good caffine nectar is.  Industry, of course, doesn't want to know

"Christian Maus, a safety manager at Bayer Crop-Sciences which makes clothianidin, cautions that it's tough to determine what happens to bees in nature from this study, because it was conducted on isolated bee brains in direct contact with insecticides, without any of the normal protective barriers or metabolism."

Various organizations have filed a suit against EPA approval of two neonicotinoids because the effect on bees was not dealt with, other organizations are seeking ways to limit exposure.  For example, corn seeds are often coated with the neonicotinoids to protect the seeds from pests.  When the seeds rub against each other in hoppers during planting the neonicotinoids are released.  The newly formed Corn Dust Research Consortium recently accepted proposals to limit the pesticide dust, either by making the seeds stickier or limiting powders seed lubricants needed for flow of the seeds through mechanical planters.

The emphasis here is on commercial apiaries, but anyone walking about, even in the biggest cities knows that wild pollinators are also important.  Eli, for example,rents to a bunch of carpenter bees in his wooden fence.  Large, one could even say bumbling insects, they calmly go about their business, interacting with the birds and squirrels which make the miniature carrot patch a delight.  The wild pollinators are not having the best of times, which is bad news

Garibaldi, et al, again in Science, point out how key these guys are

The diversity and abundance of wild insect pollinators have declined in many agricultural landscapes. Whether such declines reduce crop yields, or are mitigated by managed pollinators such as honey bees, is unclear. We found universally positive associations of fruit set with flower visitation by wild insects in 41 crop systems worldwide. In contrast, fruit set increased significantly with flower visitation by honey bees in only 14% of the systems surveyed. Overall, wild insects pollinated crops more effectively; an increase in wild insect visitation enhanced fruit set by twice as much as an equivalent increase in honey bee visitation. . .

Human persistence depends on many natural processes, termed ecosystem services, which are usually not accounted for in market valuations. The global degradation of such services can undermine the ability of agriculture to meet the demands of the growing, increasingly affluent, human population (1, 2). Pollination of crop flowers by wild insects is one such vulnerable ecosystem service (3), as the abundance and diversity of these insects are declining in many agricultural landscapes (4, 5). 

 Garibaldi, et al, looked at the relative roles that domesticated and wild pollinators play in 41 crop systems distributed across the globe.  One might call this macroecology.  Burkle, Marlin and Knight,  replicated an  study in a small area, near Carlinville IL done by Charles Robinson in the late 1800s, who categorized the types of pollinators that visited different plants.  That study had already been replicated in the 1970s.

The news is not good.  The number of different interactions between plants and pollinators had declined by almost 50% (ok 46%)

Bee extirpations contributed substantially to the observed shifts in network structure. Of the 407 lost interactions, 45% (183) were lost because bee species were extirpated from the study region; all 26 forbs remained present. It is unlikely that the dramatic loss of bees observed in the contemporary data set resulted from differences in sampling effort between the historic and contemporary studies. Robertson observed the pollinators of each forb species for 1 to 2 years before moving on to other species. In our intensive resurvey over 2 years, we found less than half (54 of 109) of those bee species. Although Robertson’s sampling effort in each season is unknown, we were able to extrapolate our data based on sampling effort and found that our observations were close to the “true” richness (table S1). If Robertson’s sampling was less intense on a per plant species basis than ours, then the bee extirpations are a conservative estimate. Furthermore, the loss of bees was nonrandom, such that bees that were specialists, parasites, cavity-nesters, and/or those that participated in weak historic interactions were more likely to be extirpated (table S2), congruent with other findings. Specialists were lost more than generalists (even after correcting for potential observation bias), despite the fact that their host plants were still present 

With all types of pollinators declining the hard place is not as far away as one might hope.  Jason Tylianakis puts it bluntly

Are concerns of a pollinator crisis exaggerated, and can we make do with better management of honeybee colonies? Two articles in this issue provide compelling answers to these questions. On page 1611, Burkle et al. demonstrate that native wild pollinators are declining. On page 1608, Garibaldi et al. show that managed honeybees cannot compensate for this loss.