Cabbage seedpod weevil (Ceutorhynchus obstrictus) susceptibility monitoring in Estonia
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Kuupäev
2026
Kättesaadavus
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Estonian University of Life Sciences
Abstrakt
The present study provides insight into the dynamics of pyrethroid susceptibility in cabbage seedpod weevil (Ceutorhynchus obstrictus) populations in commercial winter oilseed rape fields in Estonia during 2021−2023 and 2025. Bioassays followed the IRAC method No. 031 and included four pyrethroid active ingredients: lambda-cyhalothrin, deltamethrin, gamma-cyhalothrin, and tau-fluvalinate. Mortality to lambda-cyhalothrin and deltamethrin remained 100% across all study years, indicating stable susceptibility. Gamma-cyhalothrin also provided complete mortality in nearly all populations, although one population showed reduced sensitivity. In contrast, tau-fluvalinate showed a pronounced and progressive decline in efficacy. Tau-fluvalinate LD50 values increased from 0.96 g a.i. ha-1 in 2021 to 3.84 g a.i. ha-1 in 2025, corresponding to a four-fold reduction in susceptibility. The rise in LD90 was even more pronounced, increasing from 1.73 g a.i. ha-1 in 2021 to 25.7 g a.i. ha-1 in 2025, indicating that substantially higher concentrations are required to achieve efficient pest management in the field. These results provide clear evidence of emerging resistance to tau-fluvalinate in cabbage seedpod weevil populations, while other pyrethroids remain fully effective. The results highlight the need for continued resistance monitoring and careful selection of insecticides with different modes of action to maintain effective control of cabbage seedpod weevils in the field.
Kirjeldus
Received: January 29th, 2026 ; Accepted: April 14th, 2026 ; Published: June 12th, 2026 ; Correspondence: liina.kann@metk.agri.ee
Märksõnad
Ceutorhynchus obstrictus, insecticide resistance, pyrethroid resistance, susceptibility monitoring, articles
Viide
Kann, L., & Mäe, A. (2026). Cabbage seedpod weevil (Ceutorhynchus obstrictus) susceptibility monitoring in Estonia. Estonian University of Life Sciences. https://doi.org/10.15159/AR.26.048