[Pollinator] (no subject)

[Rufus Isaacs]

Insecticides Can Affect Wild Bee Populations, MSU Research Shows

Fruit and vegetable growers all over the country rely on pollinators --
mainly bees -- to produce crops from blueberries to almonds. In addition to
managed honey bees, wild bees that live in and around crop fields also
provide pollination services.

To help growers make pest control choices that conserve these valuable
native pollinators, Michigan Agricultural Experiment Station entomologist
Rufus Isaacs and entomology postdoctoral scientist Julianna Tuell studied
how wild bee populations are affected by pest management programs in
highbush blueberries. The research was published in the June issue of the
Journal of Economic Entomology.

During crop bloom, growers avoid using insecticides or use only bee-safe
products to ensure that pollinators are protected. After bloom, honey bee
colonies are removed from the fields, but wild bees stay in the fields.

"A rich wild bee community can be present before, during and after blueberry
bloom, with more than 100 species of wild bees found in these fields," Tuell
said. "Of these, approximately 10 species are present in high numbers and
consistently pollinate blueberries."

"Michigan is the leading producer of blueberries in the world, and this crop
is very dependent on pollination for good yields," Isaacs added. "It also
faces some important insect pest challenges. This provides a great
opportunity to test the hypothesis that insecticide applications made when
the crop is not in bloom affect the wild bee community present during the
bloom period -- when bees are most important to the crops and to the
growers."

Tuell and Isaacs developed a risk index to quantify the relative risk to
wild bees from insecticide applications to blueberry fields and then
analyzed the relationship between the index and the abundance, diversity and
species richness of wild bee communities over three growing seasons. The
study also evaluated the stability of the wild bee population.

In the first two years of the study, bee abundance and species richness
declined with increasing insecticide risk index values. Bee diversity
declined only in the first year.

"The results indicate that wild bee communities are negatively affected by
increasingly intensive chemical pest management activities in crop fields,"
Tuell said.

She said that studying wild bee populations is important because it can help
growers make informed decisions about their pest management program that
will result in more sustainable crop pollination.

"Most insecticides are applied after the crop is finished blooming," she
said. "Growers who rent honey bee hives know to avoid spraying insecticides
until after hives are removed. Many native bees live in the ground and nest
in crop fields or in field margins, where they are likely to come into
contact with post-bloom insecticides."

Using the scientists' results, growers can make more informed choices about
how to manage pests while continuing to get benefits from wild bees.

"Growers can reduce the toxicity and amount of insecticide they apply for
pest control, and they can make adjustments in application timing," Tuell
said. "More focused spraying that targets only pest-infested areas also is
expected to improve the overall farm environment for bees. Our data suggest
that reducing the risk of pest control programs to bees will help conserve
populations of these beneficial pollinating insects that are active during
crop bloom."

"With fruits and vegetables an increasing component of the nation's diet and
honey bee colonies continuing to face challenges, it makes good sense to
find strategies to help promote wild bees on farmland," Isaacs said.

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sonic.net/pipermail/pollinator/attachments/20100901/f0a4bc3b/attachment-0001.html>