Systemic effects of phytoecdysteroids on the cabbage aphid Brevicoryne brassicae (Sternorrhyncha: Aphididae)
Pavela, R.(Vyzkumny Ustav Rostlinne Vyroby, Prague (Czech Republic))E-mail:pavela@vurv.cz | Harmatha, J.(Akademie Ved, Prague (Czech Republic). Ustav Organicke Chemie a Biochemie)E-mail:harmatha@uochb.cas.cz | Barnet, M.(Vyzkumny Ustav Rostlinne Vyroby, Prague (Czech Republic)) | Vokac, K.(Akademie Ved, Prague (Czech Republic). Ustav Organicke Chemie a Biochemie)
The systemic effects of 20-hydroxyecdysone (20E), ajugasterone C (ajuC) and polypodine B (polyB) in two concentrations (0.07 and 0.007 mg/mL) were investigated by applying these phytoecdysteroids to the roots of Brassica napus. Fertility, development rate, longevity and mortality of Brevicoryne brassicae feeding on treated and untreated plants were compared. We also investigated the systemic effects of a special Lc-Ecdy 8 fraction containing 20E, ajuC and polyB and at least six other minor compounds. HPLC analysis of the Lc-Ecdy 8 fraction indicated the presence of makisterone A and inokosterone in minor quantities. All ecdysteroids tested, with the exception of 20E, decreased the fertility of cabbage aphids. The mortality of both larvae and adults significantly increased with the Lc-Ecdy 8 fraction, and with ajuC or polyB compounds containing structural substituents in rather unusual positions. The phytoecdysteroid 20E was the best tolerated.
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