Local and landscape predictors of herbivory on subsistence croplands in Brazilian dry forests

Abstract

ABSTRACT Understanding the impact of herbivores on croplands is critical to developing sustainable agricultural landscapes. Here, we test the hypothesis that field size and landscape structure modulate the levels of herbivory in cowpea and maize subsistence croplands in Brazilian drylands. We conducted the study in nine small-scale farms with varying levels of landscape structure and field sizes (0.10–1.67 ha). In each farm, we haphazardly sampled 20 plants of maize and cowpea. The frequency of foliar herbivory was high for both crops (0.45–0.72), but the average magnitude of damage was low (<3% of leaf surface in both crops), indicating that herbivory is not an ecosystem disservice. Nonetheless, the field size and level of human impact on the landscape matrix were positively related to the frequency and magnitude of damage on maize foliage and cowpea foliage and pods. Landscape composition (proportion of woodland/forest surrounding the field) and configuration (number of surrounding woodland/forest patches) had weaker effects on herbivory levels, mixing positive and negative effects on both crops. Our findings indicate that herbivory attack is not concerning in the agricultural fields studied, but suggest that maize and cowpea should be preferably grown in small fields surrounded by an environmental-friendly matrix and patches of conserved ecosystems.