Saturday, February 19, 2011

Some Buzz On Native Bees

Rutgers entomologist Rachael Winfree gave an information-packed talk on native bees at DR Greenway this past Thursday. Here is some of the information I packed for the trip home, with apologies for any bruising of the truth that might have occurred in-transit. Rachael has a very useful downloadable brochure on the subject of native bees and the sort of plants and nesting habitat they need (link below).
  • Bees are some of the most beautiful animals on earth.
  • They're descended from wasps. Wasps feed animals--other insects, I suppose--to their young, while bees are vegetarian, raising their young on pollen. Bees are also better pollinators, being more hairy.
  • There are about 400 species of native bees in NJ (I was guessing around 100), out of about 4000 native species in the U.S.
  • The natives are grouped into the Mellitidae, Andrenidae, Halictidae, Colletidae, and Megachilidae. Honey bees, which are not native to America, are in the Apidae.
  • The peak diversity of most kinds of animals and plants can be found in the tropics, but peak diversity of bees is in xeric (dry) temperate zones, such as Arizona. They are most diverse in unwooded areas.
  • A "univoltine" bee produces only one generation per year, while multivoltine bees have multiple generations.
  • Bees, depending on species, can overwinter in any stage, from egg to adult.
  • Most adults live only a few weeks.
  • Some bees come out in early spring and then go dormant through summer, fall and winter. Those may be the ones that are specialized to feed off of spring ephemerals (woodland wildflowers that sprout early to take advantage of the sunlight before the trees leaf out).
  • Pollen supplies protein, nectar provides sugar.
  • Female bees are better pollinators than males, which are smaller and less hairy.
  • Just as there are parasitic birds like cowbirds that leave their eggs in other bird species nests for raising, there are also parasitic bees that use the same strategy.
  • The blueberry bee specializes in pollinating blueberry flowers. (Turns out they are one of the single generation per year bees. An interesting description of their pollination technique can be found here.)
  • A heterogeneous landscape, such as can be found in towns and suburbs, helps provide a progression of flowers throughout the growing season (whereas our dense woods may only provide flowers in the spring, if the spring wildflowers are intact.)
  • That honeybees are proving susceptible to various maladies is not surprising, given that they are part of a monoculture approach to farming. Honeybees are trucked all over the States to pollinate crops, be they almonds in California or cranberries in the northeast. Huge expanses of one crop create locally a boom and bust cycle, in which flowers are abundant for only a brief period each year, making it impossible for a resident bee population to survive. Trucking in honeybees is the only way to insure pollination. 
  • Community Collapse Disorder, in which the adult honeybees disappear from a hive, leaving only the young, first appeared in 2006. The cause remains unknown, though it may be a combination of stresses caused by the varroa mites that first reached this continent in 1990, pesticides such as imidacloprid, miticides, a virus or bacterium, and poor nutrition. 
  • It's not clear if honeybees have affected native bee populations in the U.S, though some evidence suggests their competition can reduce native bee numbers.
  • There is no monitoring of native bee populations in the U.S, so it's hard to tell if there are any trends in native bee populations.
  • There are some endangered bee species in NJ, but it wasn't clear if there's anything that can be done locally, such as grow particular plants, to help them recover.
  • She suggested a couple websites. To plant bee-friendly habitats, check out her brochure called Native Bee Benefits. For bee identification, DiscoverLife is a popular website. BugGuide is another helpful site for getting identifications.

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