High level methoprene resistance in the mosquito Ochlerotatus nigromaculis (Ludlow) in Central California

Abstract

In the summer of 1998, failures of methoprene field applications to control the mosquito Ochlerotatus nigromaculis (Ludlow) were noticed in several pastures in the outskirts of Fresno, California, USA. Effective control with methoprene had been achieved for over 20 years prior to this discovery. Susceptibility tests indicated that the Fresno Oc nigromaculis populations had developed several thousand-fold higher LC50 and LC90 tolerance levels to methoprene compared with methoprene-naïve populations. The synergists piperonyl butoxide (PBO), S,S,S-tributyl phosphorotrithioate and 3-octylthio-1,1,1-trifluoro-2-propanone had little synergistic effect, suggesting that the mechanism of methoprene tolerance was not mediated by P450 monooxygenase or carboxylesterase enzyme degradation. As part of initiating a resistance management strategy, partial reversion back to methoprene susceptibility was achieved in a resistant population after six consecutive applications of Bacillus thuringiensis israelensis Goldberg & Marga coupled with two oil and two pyrethrum + PBO applications.

Drosophila melanogaster Methoprene-tolerant (Met) gene homologs from three mosquito species: Members of PAS transcriptional factor family

“…taeniorhynchus (Dame et al, 1998) and Oc. nigromaculis (Cornel et al, 2002), but the resistance mechanism is unknown. Identifying the mechanisms of resistance to methoprene in mosquitoes will aid in mosquito control.…”

Molecular Evolution of Juvenile Hormone Signaling

“…Reports of methoprene resistance in mosquito populations (Dame et al, 1998;Cornel et al, 2000;Cornel et al, 2002) (Wang et al, 2007). Retrotransposition, or retroposition is a mechanism of gene duplication that proceeds through an mRNA intermediate.…”

Development of a HPLC/Tandem-MS Method for the Analysis of the Larvicides Methoprene, Hydroprene, and Kinoprene at Trace Levels Using Diels−Alder Derivatization

“…Before methoprene was applied to the pasture, 1st and 2nd stage larvae were collected and reared in the laboratory to the 4th stage for bioassays (11). In addition, to compare mortality observed in the laboratory assays, pupae were collected from several locations at the same pasture including the five pools of water from which water samples were taken for methoprene quantification.…”