Maryann Tomasko Frazier
Senior Extension Associate, Dept. of Entomology, Penn State University
Maryann Frazier was the assistant state apiary inspector in Maryland before joining the Pennsylvania State University where she has been a senior extension associate in the Department of Entomology. Her current focus is on the effects of pesticides on honey production. She has also studied Africanized bees in Kenya.
There are many types of insect pollinators but the work horses of insect pollination are bees. There are about 3,500 species of bees in North America but the most adept pollinators of all are honeybees. Bees collect pollen because it is their source of protein. There are seven species of honeybees worldwide but only one species, Apis mellifera that occurs in nature here in the U.S. It was brought to the new world from Europe in about 1620.
Honeybees are critical to producing many crops because they are prolific pollinators who can be moved from location to location easily and they are good at focusing on a particular crop. Once they are locked onto a floral source such as apples or almonds, they stick with it.
As modern agriculture has moved to large monocultures of crops, bees have become even more critical to production. When it’s time for pollination, producers bring the bees in and when pollination time is over, they take the bees out. One reason for this system is that modern crop production uses pesticides throughout the year that can be harmful to bees. When bees are moved from one area and crop to another and are staged awaiting the next pollination, they must be fed since there aren’t enough naturally occurring plants in bloom to sustain the thousands of hives needed to pollinate a large crop. The feeding stops when the crop comes into bloom. Honeybee pollination in the U.S. is valued at about $15 billion annually.
In recent years, pollinators, including honeybees have been in decline. Beekeepers began discovering that their bees had left their hives. In 2007, we identified this phenomenon as Colony Collapse Disorder (CCD). Some researchers have found that not only are the pollinators in decline but the plants they depend on and thus the ecosystem are also in decline. CCD is the most recent manifestation of the general decline in pollinators.
With CCD we see a decline in the adult bee population. The beekeeper discovers that a strong colony of bees that produced a large number of cap brood cells for rearing young rather suddenly has far fewer adult bees than normal. In normal conditions there should be about two adults per one cap brood cell. The decline in adults continues until there are no adult bees left.
This phenomenon was first discovered by Dave Hackenberg, a beekeeper in Lewisburg, Pennsylvania. Experts formed a working group to study the problem. We don’t yet know the exact cause of CCD but we can point to several factors that are putting stress on the bees. Newly evolved pathogens, pesticides on crops, drought, moving bees long distances, poor nutrition and a narrowing of the genetic material that makes up our honeybee population are all suspected of contributing to CCD.
Because the honeybee genome is now known, we can isolate the “footprints” of diseases that are present in the bees. Researchers from Penn State and Columbia University found that the Israeli acute paralysis virus (IAPV) was common to colonies of bees that had suffered from CCD. There were also other diseases found to be common in CCD colonies. What this tells us is that the bees used in commercial operations are very sick. What we don’t know is if something is making them get the diseases and die. After two years of research, none of the groups is able to say they have found the one thing that is causing CCD. What we are thinking now is that it is a combination of factors that cause the disorder.
The team I work on is focusing on the role insecticides might play. We use insecticides a lot in agriculture and honeybees are insects. During summer when there are no alternative blooms for bees to visit they collect a lot of pollen from corn. Farmers use systemic pesticides that linger in the cells of corn. In addition, beekeepers have for years had to use pesticides in their colonies to control mites. Our team has analyzed 669 samples from colonies owned by all kinds of beekeepers. We are studying apple orchards and we’re following migratory beekeepers by following them when they move their colonies around the country. We have found a lengthy list of pesticides that have turned up in the pollen and in the bees.
Bees are very good a collecting what’s out there in the environment. On average, each sample of pollen we tested had six pesticides in it. One sample had 31. In essence the bees are feeding this pollen to their babies. Only three of the samples we tested lacked any pesticide. Pesticides are also in the beeswax and the bees themselves. We believe it’s likely that various combinations of pesticides can work to the disadvantage for bees just as combinations of drugs can work to the disadvantage of humans. They can work at sub-lethal levels, potentially degrading the ability of bees to learn and retain information. It is critical that bees be able to learn in order to navigate between fields and hives. We have evidence that pesticides are degrading the immune systems of bees. They may also be shortening the longevity of bees which is a problem in winter since bees have to live for five months in winter. CCD has led to greater public awareness of the need to protect our pollinators.
In an effort to provide wide-ranging views and perspectives regarding the practice of and issues surrounding agriculture, the Philadelphia Society for Promoting Agriculture (PSPA) seeks speakers representing a variety of perspectives. The statements and opinions they present are strictly their own and do not necessarily represent the views of PSPA.