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The causes and consequences of pest population variability in agricultural landscapes

Citation

Paredes, Daniel; Rosenheim, Jay; Karp, Daniel (2022), The causes and consequences of pest population variability in agricultural landscapes, Dryad, Dataset, https://doi.org/10.25338/B86S6J

Abstract

Variability in population densities is key to the ecology of natural systems but also has great implications for agriculture. Farmers’ decisions are heavily influenced by their risk-aversion to pest outbreaks that result in major yield losses. However, the need for long-term pest population data across many farms has prevented researchers from exploring the drivers and implications of pest population variability. Here, we demonstrate the critical importance of population variability for sustainable farming by analyzing 13-yrs of pest densities across >1300 Spanish olive orchards and vineyards. Variable populations were more likely to cause major yield losses, but also occasionally created temporal windows when densities fell below insecticide spray thresholds. Importantly, environmental factors regulating pest variability were very distinct from factors regulating mean density, suggesting variability needs to be uniquely managed. Finally, we found diversifying landscapes may be a win-win for conservation and farmers, as diversified landscapes promote less abundant and less variable pest populations. Therefore, we encourage agricultural stakeholders to increase complexity of the landscapes surrounding their farms through conserving/restoring natural habitat and/or diversifying crops.

Methods

The Andalusian Government provides this large database containing pest and field management data for 13 years (2006-2018) across Andalusia, Spain. This is an unusually rich data resource, as it contains detailed, long-term, and well-replicated pest observations. Specifically, personnel within the RAIF network (Red de Información y Alerta Fitosanitaria) monitor pest populations on privately-owned fields across the Andalusian region of Spain and advise farmers about when and how to manage pests based on economic injury thresholds and integrated pest management rules. Farmers in the RAIF network are encouraged to use integrated management criteria, such that insecticides are only applied when pest populations exceed economic injury thresholds (described below). The RAIF database also records several pest management practices, including applications of insecticides, herbicides, and fungicides, as well as tillage events. Finally, the database includes the identities of the crop cultivars, the cooperatives in which farmers are members, and the regions in which the fields are located.