Dan Aubrey’s coverage of Lars Chittka’s work on bees in last week’s issue explored scientists’ ongoing research into the fascinating lives, minds, and behaviors of bees, but as a recent Rutgers study shows, it’s not all sunshine and flowers for these hard-working honey makers.
Rutgers University recently announced that several of its scientists recently published a study that finds a “dramatic decline in the bee population at fruit farms in New Jersey and Pennsylvania.”
The study, published in the science journal Insect Conservation and Diversity, only demonstrates the decline and refrains interpreting the data as either a “natural phenomenon or a warning about a future threat to the world’s food supply.”
According to Rutgers media release, the scientists have been tracking the decline in bee pollination at fruit farms in New Jersey and Pennsylvania.
In the statement, Andrew Aldercotte — the study’s lead author and doctoral candidate in the Rutgers Department of Ecology, Evolution and Natural Resources — says, “This study is important because it is one of the first to assess trends in wild bee abundance in an agricultural system, where bees are providing an economically important ecosystem service.
“Despite widespread recognition of the need for long-term monitoring of pollinator abundances and pollination service provision, such studies are exceedingly rare.”
Although the study occurred over an eight-year period, scientists found it too short a time “to sound the alarm just yet” and “longer-term studies would need to be conducted to determine whether the decline represents a true drop in numbers of bees or a normal variation over a larger cycle.”
Aldercotte — along with professor Rachael Winfree and program doctoral candidate Dylan Simpson — analyzed data collected at 19 commercial farms in central New Jersey and eastern Pennsylvania during peak bloom periods from 2005 to 2012.
“The data represents pollination visits by 73 species of bees fitting into one of three broader categories — wild bees, bumble bees and honey bees —to the flowers of watermelon plants.”
The choice was for watermelons was that they “depend on bees for pollination because each plant has separate male and female flowers. Female watermelon flowers require thousands of grains of pollen — meaning it takes multiple bee visits — to bear fruit.”
According to the study, “There is widespread concern about declines in bees and the pollination services they provide. Bees are important pollinators in both agricultural and natural ecosystems, and bee population declines could adversely affect food production, as well as the reproductive success and future composition of natural plant communities
Yet, they write, “There have been surprisingly few long-term studies of bee populations that used standardized methods to measure changes in bee abundance over time and thus are able to detect decline in its most basic sense: a decrease in the number of individuals over time.”
By working in an agricultural system, the scientists could “directly measure bee declines as they are affecting crop pollination. We ask (i) whether there were trends in bee abundance at crop flowers over time and (ii) whether trends in abundance differed among bee taxa. In addition, we use data we collected on the per visit pollen deposition of bees to evaluate the strength of the relationship between total visitation by bees and the pollination services they provide.”
The scientists found that “pollination of watermelon flowers by wild bees decreased by more than half between 2005 and 2012. The decline was similar for bumble bees and other types of wild bees, while the population of honey bees, which aren’t native to the region and are managed in hives by farmers, remained stable.
Aldercotte says the New Jersey bee population “was still sufficient to pollinate crops despite the declines that were observed during the study, so that the crop supply wasn’t adversely affected.”
However, studies of other crops in other parts of the country show that insufficient pollination often reduces crop production.
The Rutgers study warns that “bee declines in agricultural systems could impact crop yields: Wild bees enhance the production of many crops globally, and yield for several important North American crops.”
And while the writers note that long-term monitoring programs collecting remains rare in bee studies, “momentum is building to fund and conduct long-term monitoring of bees and other pollinators, exemplified by the launching of the UK Pollinator Monitoring Scheme, and the National Native Bee Monitoring Research Coordination Network that is currently being developed in the United States.”
For more on the report, visit the July 27 Rutgers Today article at rutgers.edu/news/natural-phenomenon-or-warning.
To read the report, see the Royal Entomological Society article at their website, resjournals.onlinelibrary.wiley.com/doi/10.1111/icad.12589.
For Aubrey’s interview with Chittka and excerpts from his book, “The Mind of a Bee,” see the Sept. 21 edition of ‘Off the Presses.’
