Increasing neonicotinoid use and the declining butterfly fauna of lowland California

Biol Lett. 2016 Aug;12(8):20160475. doi: 10.1098/rsbl.2016.0475.


The butterfly fauna of lowland Northern California has exhibited a marked decline in recent years that previous studies have attributed in part to altered climatic conditions and changes in land use. Here, we ask if a shift in insecticide use towards neonicotinoids is associated with butterfly declines at four sites in the region that have been monitored for four decades. A negative association between butterfly populations and increasing neonicotinoid application is detectable while controlling for land use and other factors, and appears to be more severe for smaller-bodied species. These results suggest that neonicotinoids could influence non-target insect populations occurring in proximity to application locations, and highlights the need for mechanistic work to complement long-term observational data.

Keywords: butterflies; global change; insecticide; long-term ecological data; neonicotinoids.

MeSH terms

  • Animals
  • Butterflies*
  • California