Re: NANFA-L-- screw worm fly and gambusia
Tue, 16 May 2006 10:28:20 -0500

A few days ago I posted a reply to a question about introducing
sterile mosquitofish to control wild mosquitofish reproduction in
infested locations. In that post, I stated that the new world screw
worm, an agricultural and wildlife pest that was controlled by this
method in the SW U.S., had rebounded to its former status.

Thanks to an alert fellow list member, who questioned me on that via a
private email, I investigated more fully. It turns out that the screw
worm infestations that now occur in the SW U.S. are more isolated and
sporadic occurances, some due to importation of cases in infected
animals, and some due to native infections. I'd gained the impression
from scattered reports I'd heard, and from a rancher friend who
probably never experienced the devastation of this pest prior to its
near elimination. However, eradicated is probably not a proper term
to use, since cases do occur, and some herds and some wildlife do
suffer substantial loss in Texas, Arizona, and Mexico.

It remains the case that release of sterile mosquitofish to control
mosquitofish reproduction has no basis in life history. The technique
works for screw worms, and for some other insects, because an
individual female mates only one time. Saturate the environment with
sterile males and the chance that she will find and mate with a
fertile male is very small.

David L. McNeely, Ph.D., Professor of Biology
Langston University; P.O. Box 1500
Langston, OK 73050; email:
telephone: (405) 466-6025; fax: 405) 466-3307
home page

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