Mode of action of methoprene in affecting female reproduction in the African malaria mosquito, Anopheles gambiae.
BACKGROUND
One of the most studied actions of juvenile hormone (JH) is its ability to modulate ecdysteroid signaling during insect development and metamorphosis. Previous studies in mosquitoes showed that 20-hydroxyecdysone (20E) regulates vitellogenin synthesis. However, the action of JH and its mimics, e.g. methoprene, on female reproduction of mosquitoes remains unknown.


RESULTS
Here, a major malaria vector, Anopheles gambiae Giles, was used as a model insect to study the action of methoprene on female reproduction. Ecdysteroid titers and expression profiles of ecdysone-regulated genes were determined before and after a blood meal. An ecdysteroid peak was detected at 12 h post blood meal (PBM). The maximum expression of ecdysone-regulated genes, such as ecdysone receptor (EcR), hormone receptor 3 (HR3) and vitellogenin (Vg) gene, coincided with the ecdysteroid peak. Interestingly, topical application of methoprene at 6 h PBM delayed ovarian development and egg maturation by suppressing the expression of ecdysone-regulated genes in female mosquitoes.


CONCLUSIONS
The data suggest that ecdysteroid titers are correlated with Vg synthesis, and methoprene affects vitellogenesis by modulating ecdysteroid action in A. gambiae.
Bai
Hua
H
Department of Entomology, University of Kentucky, Lexington, KY 40546, USA.
Gelman
Dale B
DB
Palli
Subba R
SR
D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001769:Blood; D004032:Diet / Q000662:veterinary; D015536:Down-Regulation / Q000187:drug effects; D004440:Ecdysone / Q000378:metabolism; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D020869:Gene Expression Profiling; D007303:Insect Vectors / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008288:Malaria / Q000635:transmission; D008726:Methoprene / Q000494:pharmacology*; D010063:Ovum / Q000187:drug effects / Q000254:growth & development; D051381:Rats; D012098:Reproduction / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D014818:Vitellogenesis / Q000187:drug effects / Q000235:genetics; D014819:Vitellogenins / Q000235:genetics
D014819:Vitellogenins; D004440:Ecdysone; D008726:Methoprene