There are several varieties of Bt available. The varieties usually used against mosquitos and other flies are Bt var. israelensis and Bt var. sphaericus (known as Bti and Bts, respectively). The Bt variety that seems to be most widely used as a control for lepidopteran insects is Bt var. kurstaki (Btk), although Bt var. aizawai (Bta) may also be used.

The use of Btk, in particular, seems to be less devastating to the ecology of the application area when used to control caterpillars than previous pesticides, but still causes concern. For example, Fenitrothion was used in New Brunswick forests to control the 1969-71spruce budworm outbreak, and lead to the loss of pollination services to the blueberry growers of the region. Btk is better targeted in that it will not damage bees, but research indicates it has the capacity to kill up to 85% of nontarget lepidoptera individuals. Sadly, many nontarget species appear to be more susceptible to the control measures than the target pest species.

Given the known impacts of Btk on nontarget lepidopteran species, it seems sensible to be aware of the potential impacts on nontarget species of the application of other Bt varieties.

Matthew Shepherd

*********** REPLY SEPARATOR  ***********

On 3/20/00 at 10:03 AM [log in to unmask] wrote:

>Anyone know if the widespread application of the BT mosquito larvicide will
>have an effect on wax mothes and other lepidopterous insects?


_______________________________________________

Matthew Shepherd
Director, Publications and Pollination Programs
The Xerces Society
4828 SE Hawthorne Boulevard, Portland, OR 97215-3252
Tel: 503-232 6639   Fax: 503-233 6794
Email: [log in to unmask]
_______________________________________________