PS 9-78 - Intensity of agricultural management impacts butterfly biodiversity

Background/Question/Methods

Insects are declining globally due to habitat loss, habitat fragmentation, pesticide use, and climate change — all of which are due in part to agriculture. Reluctance to protect pollinator populations permits an immense loss of biodiversity, and poses a threat to crop quality and yield. There is potential for farmers to protect pollinator biodiversity through the implementation of informed agricultural management; however, more research is needed to guide such practices and determine the effects on pollinator populations. In this study we focused on butterflies, which serve as an indicator of ecosystem health, to understand how regenerative agricultural practices can benefit insects in and around agricultural land. Prairie strips — a method of restoring habitat in row crop agriculture by sowing strips of native perennial vegetation within row crops — are one such practice that can support pollinators. In order to determine how agricultural management impacts butterfly abundance and species richness, we surveyed butterflies from May-October 2020 across a gradient of land use intensity from conventional farming to conservation land, including prairie strips.

Results/Conclusions

We found that butterfly abundance and species richness were greatest in prairie strips and plots that contained prairie strips (abundance: χ² = 128.7204, df = 7, p < 2e-16 ; richness: χ² = 376.99, df = 7, p < 2.2e-16). The abundance and species richness of butterflies in prairie strip treatments was comparable to that of restored prairie. There was significantly higher abundance of butterflies in reduced input and organic treatments than in no-till or conventional treatments. Plots treated with high inputs of pesticides had the lowest abundances and species richness of the eight treatments. Our results indicate that altering agricultural management to reduce pesticide use and increase prairie habitat on farms could increase pollinator abundance and richness. In the future, we look forward to examining the effect of prairie strips on butterfly presence as the three-year-old strips continue to mature.