Conventional wisdom about neonics is that they affect the neurology of arthropods, but are relatively safe for mammals. New research is turning this convention on it’s head, showing that exposure to the pesticides can affect brain development in rodents. Symptoms included “brain shrinkage, weight loss and reduced movement.” Perhaps the potential risks to humans (and remember, many seeds are coated with neonicotinoids and they become a systemic pesticide expressed throughout the plant, even the parts we consume) might help us sympathize with the bees.
For the full story, check out the BBC science and environment site.
One of my former interns, Rebecca Wynd, made this awesome map of hives and native plant gardens in the East Bay as her final project in a GIS class here at UC Berkeley. She notes that this map only depicts a fraction of the hives in the area, as many bee keepers prefer not to divulge hive location due to issues including concerned neighbors and theft. Nevertheless, it does a great job showing the resources urban areas can provide! Click the link to check it out: Urban Bee Map
Congrats to Alex and Cause!
Filtering across Spatial Scales: Phylogeny, Biogeography and Community Structure in Bumble Bees. Alexandra N. Harmon-Threatt & David D. Ackerly. PlosOne
Invasive species management restores a plant–pollinator mutualism in Hawaii. Cause Hanna, David Foote, Claire Kremen. J of Applied Ecology
Scientific American just published a really cool info-graphic documenting the loss of bee species in Illinois. Half as many species interactions as exited 200 years ago persist today, though new plants have arrived on the scene and some bees are visiting them. Tragically, numerous species have been lost locally.
I’m learning Adobe Illustrator. Had some fun making an landscape like those I work in in Yolo Co., CA. Can you spot the hedgerow?
Were the pollinator communities of yesterday similar to the ones we see today? Or have there been dramatic shifts in community structure that mirror the changes to the landscape made by humans? Are there any traits that make species more or less vulnerable to these changes? These are the questions a team of researchers set out to answer by examining entomological collections of bees from across the Northeastern US. This historic data can help determine whether native bee populations reflect the effects of over a century of development.
The researchers found that rare bee species declined over time, though many had to be excluded from analyses because they were not collected during the past decade. The trend was strongest for bumble bees, which experienced declines of 30% in the past 140 years. Only a few species exhibited recent steep declines, with more species showing long-term shifts in abundance. The researchers suggest these populations be monitored closely as slow declines could indicate impending collapse. Over the same period, non-native bee species increased 9-fold.
The most vulnerable species are those with limited diets (specialists), limited flight periods, and larger body sizes. Species found to increase were those in lower latitudes; the authors of the study posit they may be expanding their ranges in response to climate change. Interestingly, other characteristics that have been found to affect bee population structure in previous studies such as nest location (ground- versus twig-nesting) and sociality (solitary versus social) did not impact rates of decline.
It seems smaller bees that are active over longer seasons and visit a wide variety of flowers may be the winners, whereas big specialist bees may be the losers. Bumble bees are particularly vulnerable, which is worrisome because they are often keystone pollinators in natural systems, visiting a wide variety of plant species. In fact, one study that simulated the removal of pollinators from a system found that losing bumble bees had the most rapid and pronounced effects on the deterioration of plant diversity and abundance. Bumble bees are also able to buzz pollinate, and some plant species require this kind of pollination to reproduce. The message from this study is clear- some key bee species are declining and we need to figure out ways to conserve their populations to maintain healthy ecosystems.
Bartomeus et al. 2013. Historical changes in Northeastern US bee populations related to shared ecological traits. PNAS 110(12): 4656-4660.
Claire Kremen, my PI, just wrote an insightful piece that appears on the UC Berkeley Blog arguing why neonicotinoid pesticides should be better regulated by the EPA and the Farm Bill ought to be changed to better reflect agricultural practices that don’t disrupt bee biology (and are better for the soil, wildlife, and people too).
In other news, Oregon just permanently banned the neonicotinoid pesticides responsible for the thousands of bumble bee deaths this past summer. Will other states follow suite?