Influence of crop management and landscape diversity on Meligethes aeneus and its biological control


Abstract: Pest management strategies have traditionally focused on the field scale and often relyon the use of broad-spectrum pesticides. Recent studies have pointed out the importance of takinginto account larger scales to understand pest and natural enemy population dynamics. Enhancing thenatural regulation function in agroecosystems therefore appears to be a promising way to increasecrop production sustainability.In this study, we examined the relative influence of crop management and landscape context ona serious winter oilseed rape (OSR) pest (Meligethes aeneus) and its parasitoids. Landscapevariables were assessed in 8 different buffers ranging from 250m to 2000m radius in order toidentify the most relevant spatial scale. We used multimodel inference methods to identify and rankthe relative importance of the explanatory variables. The most relevant spatial scale and predictorswere determined examining their relative importance based on the sum of Akaike weights.We found that large buffers (from 1500m to 2000m) were the most adapted scales to explainpest abundance and subsequent crop damage. Proportion of forest is positively correlated withpollen beetle abundance and injuries and is the most significant explanatory variable. Nitrogennutrition index appears to have an important influence on crop damage, with high nitrogen contentplants supporting the lowest proportions of destroyed buds. Non-crop areas and the proximity toprevious year oilseed rape crop in the 250m buffer around the fields appear to be the most importantvariables for explaining parasitism rates of pollen beetle larvae. These results are discussed inrelation to the design of innovative crop protection strategies.

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