Impact of local and landscape complexity on the stability of field-level pest control

Agricultural production has increased dramatically in the past 50 years, supported, in part, by the simplification of agricultural landscapes. While the benefits of increased food production are difficult to dispute, simplification, at both the local and landscape level, has fuelled declines in biodiversity and ecosystem services. In addition to the concerns that this loss of complexity necessitates higher levels of pesticide use in general, local and landscape simplification may also increase pest outbreaks and, consequently, infrequent but particularly high pesticide use with potentially damaging consequences for the environment and human health. We find that increasing cropland in the landscape—and larger fields generally—increase the level and variability of pesticide use while crop diversity has the opposite effect, as predicted by ecological theory. In all cases, accounting for non-random planting decisions and farmer-specific behaviour strongly influences the magnitude of the estimated statistical relationships. This suggests that, while complexity increases stability and reduces high deviations in insecticide use, accounting for crop and farmer-specific characteristics is crucial for statistical inference and sound scientific understanding.