Dl. Bull et Rw. Meola, INTERACTIONS OF THE INSECT GROWTH-REGULATOR PYRIPROXYFEN WITH IMMATURE AND ADULT STAGES OF THE STABLE FLY, The Southwestern entomologist, 19(3), 1994, pp. 257-263
Laboratory tests were conducted to evaluate the efficacy and posttreat
ment fate of the insect growth regulator (IGR) pyriproxyfen after trea
tment of different life stages of the stable fly, Stomoxys calcitrans
L. Direct treatment of newly laid eggs with pyriproxyfen had no effect
on hatch or subsequent development of larvae and pupae. When eggs wer
e placed on larval rearing medium treated with different concentration
s of the IGR there was a strong reduction in the yields of F1 adults c
ompared with untreated controls; probit regressions of data indicated
the concentration of the IGR needed for a 50% reduction in adult emerg
ence (IC50) was 12.8 parts per billion (ppb). Direct treatment of thir
d instars by immersing them for 1 min in aqueous solutions of pyriprox
yfen also caused a strong reduction in yields of F1 adults (IC50 of 2.
6 ppb). Exposure of mixed sexes of adults to different residual concen
trations of pyriproxyfen resulted in significant dose-dependent reduct
ions in yields of F1 pupae. Although there also appeared to be reducti
ons in the subsequent emergence of adults from those pupae, the data w
ere too variable to show a reliable concentration-response relationshi
p. Studies of the posttreatment distribution and fate of topically app
lied [C-14]pyriproxyfen in adult stable fly females indicated the IGR
penetrated the cuticle very rapidly (>90% after 8 h) and then was meta
bolized and excreted at a very slow rate. Because pyriproxyfen has goo
d stability in the environment, and is highly active against larval st
ages of the stable fly, its use as a treatment of breeding sites could
have good potential as a tactic to aid in managing field populations
of the pest.