Gabriella Kovács1, Riina Kaasik1, Marjolein E Lof2, Wopke van der Werf2, Tanel Kaart3, John M Holland4, Anne Luik1, Eve Veromann1. 1. Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, Estonia. 2. Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University and Research, Wageningen, The Netherlands. 3. Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia. 4. Game & Wildlife Conservation Trust, Fordingbridge, UK.
Abstract
BACKGROUND: This study investigated how infestation rates of an important oilseed rape pest, the cabbage seed weevil (Ceutorhynchus obstrictus) and rates of parasitization by its parasitoids are affected by land use, up to 1000 m from 18 focal fields. RESULTS: The mean proportion of C. obstrictus-infested pods per plant was 8% (2-19.5%). Infestation rates were higher if the adjacent habitat was a herbaceous semi-natural habitat than if it was either another crop or a woody habitat. Infestation rates were positively related to the area of herbaceous semi-natural vegetation, permanent grassland and wheat (which followed oilseed rape in the crop rotation) at a spatial scale of at least 1 km. The mean parasitism rate of C. obstrictus larvae was 55% (8.3-87%), sufficient to provide efficient biocontrol. Parasitism rates were unrelated to adjacent habitats, however, they were positively related to the presence of herbaceous linear elements in the landscape and negatively related to permanent grasslands at a spatial scale of 200 m. CONCLUSION: Proximity of herbaceous elements increased both infestation rates and parasitism, while infestation was also related to landscape factors at larger distances. The findings provide an empirical basis for designing landscapes that suppress C. obstrictus, at both field and landscape scales.
BACKGROUND: This study investigated how infestation rates of an important oilseed rape pest, the cabbage seed weevil (Ceutorhynchus obstrictus) and rates of parasitization by its parasitoids are affected by land use, up to 1000 m from 18 focal fields. RESULTS: The mean proportion of C. obstrictus-infested pods per plant was 8% (2-19.5%). Infestation rates were higher if the adjacent habitat was a herbaceous semi-natural habitat than if it was either another crop or a woody habitat. Infestation rates were positively related to the area of herbaceous semi-natural vegetation, permanent grassland and wheat (which followed oilseed rape in the crop rotation) at a spatial scale of at least 1 km. The mean parasitism rate of C. obstrictus larvae was 55% (8.3-87%), sufficient to provide efficient biocontrol. Parasitism rates were unrelated to adjacent habitats, however, they were positively related to the presence of herbaceous linear elements in the landscape and negatively related to permanent grasslands at a spatial scale of 200 m. CONCLUSION: Proximity of herbaceous elements increased both infestation rates and parasitism, while infestation was also related to landscape factors at larger distances. The findings provide an empirical basis for designing landscapes that suppress C. obstrictus, at both field and landscape scales.
Authors: Jonathan Willow; Liina Soonvald; Silva Sulg; Riina Kaasik; Ana Isabel Silva; Clauvis Nji Tizi Taning; Olivier Christiaens; Guy Smagghe; Eve Veromann Journal: Commun Biol Date: 2021-04-06
Authors: Baltazar J Ndakidemi; Ernest R Mbega; Patrick A Ndakidemi; Steven R Belmain; Sarah E J Arnold; Victoria C Woolley; Philip C Stevenson Journal: Insects Date: 2022-06-23 Impact factor: 3.139