Impact of Neonicotinoid Insecticide Use on Northern Bobwhite in Texas

The widespread use of neonicotinoid insecticides in recent years has led to increasing environmental concern, including impacts to avian populations. In Texas and across their range, Northern Bobwhite (Colinus virginianus; hereafter bobwhite) habitat frequently overlaps with agricultural areas of known neonicotinoid use. To address the impacts of neonicotinoids on bobwhites in Texas, we developed the following research objectives: (1) Conduct statistical analysis of bobwhite abundance and neonicotinoid use in Texas over the last 35 years, and (2) Analyze bobwhite samples collected from three field sites across the state for neonicotinoid residues and signs of tissue damage. Generalized linear, generalized additive, mixed-effects, zero-inflated, and hurdle models were used to analyze long-term data on bobwhite abundance, neonicotinoid use, and environmental variables from 1978-2012. Statewide analysis indicates that total neonicotinoid use is negatively correlated with quail abundance in the periods after neonicotinoid introduction (1994-2003) and after their widespread use (2004-2012). Analysis by ecoregion provided further support for the significant negative relationship between bobwhites and neonicotinoids in areas of high-use (e.g. High Plains, Rolling Plains, and Gulf Coast Prairies and Marshes). Approximately 10 bobwhites were collected from three field sites in Fall 2014 and Spring 2015, for a total of 61 birds. Neonicotinoid compounds were detected in trace amounts in the livers of seven quail, including samples from all three field sites and both collecting periods. Signs of testicular degeneration (n = 2) and lipid-type hepatocellular vacuolation (n=8) were consistent with known results of neonicotinoid intoxication. Overall, we identified evidence of bobwhite exposure to neonicotinoid insecticides, and our statistical analysis indicates that neonicotinoid use may be contributing to quail decline in some ecoregions in Texas.

Source:
Ertl, Hannah Mae Halie (2016). Impact of Neonicotinoid Insecticide Use on Northern Bobwhite (Colinus virginianus) in Texas. Master's thesis, Texas A & M University.
Available electronically from http : / /hdl .handle .net /1969 .1 /157102
http://oaktrust.library.tamu.edu/handle/1969.1/157102