Blood Cholinesterase Activity in Northern Bobwhite (Colinus virginianus) Quail in the Rolling Plains Ecoregion of Texas and Oklahoma, USA

Editorial

Austin J Environ Toxicol. 2017; 3(1): 1020.

Blood Cholinesterase Activity in Northern Bobwhite (Colinus virginianus) Quail in the Rolling Plains Ecoregion of Texas and Oklahoma, USA

Pappas SA, Turaga U, Kumar N and Kendall RJ*

Wildlife Toxicology Laboratory, The Institute of Environmental and Human Health, Texas Tech University

*Corresponding author: Kendall RJ, Wildlife Toxicology Laboratory, Texas Tech University USA

Received: June 13, 2017; Accepted: October 20, 2017; Published: October 27, 2017

Abstract

In an effort to identify factors contributing to the population decline of Northern bobwhites (Colinus virginianus) in the Rolling Plains ecoregion of Texas and Oklahoma, blood samples were collected from quail during the summer (August) and fall (October) of 2013. The blood cholinesterase activity in the samples was evaluated to investigate the exposure of wild bobwhites to cholinesterase inhibiting chemicals. Baseline blood cholinesterase activity in quail was established by evaluating cholinesterase activity in pen-raised quail. Significant differences in the blood cholinesterase activities of pen-raised and wild bobwhites were observed. Additionally, significantly higher blood cholinesterase activity was observed in wild bobwhites captured during August compared to those captured in October. A significantly lower blood cholinesterase activity in the wild bobwhites, particularly in October, suggests a potential for exposure to cholinesterase inhibiting chemicals in the Rolling Plains ecoregion.

Keywords: Northern Bobwhites, Rolling Plains ecoregion, Cholinesterase, Cholinesterase Inhibiting Chemicals

Abbreviations

Cholinesterase: (ChE); Dried Blood Spot (DBS); The Institute of Environmental and Human Health (TIEHH); Ethylene Diamine tetracartic Acid (EDTA)

Introduction

Data from the US Geological Survey’s Breeding Bird Survey revealed that Northern bobwhite (Colinus virginianus) populations have been on the decline for several decades in the Rolling Plains ecoregion of Texas and Oklahoma, with a more severe decline observed over the last decade [1]. Considering the economic and ecological significance of bobwhites to the Rolling Plains ecoregion [2], it is important to investigate the potential factors causing the decline. The decline in bobwhite populations could be attributed to many different factors such as the quality of habitat [3], weather [4, 5], predation [6, 7], and parasites [8-10]. Another important factor to be considered is the exposure of bobwhites to environmental contaminants.

Previous studies have revealed that bobwhites in the ecoregion are being exposed to neurotoxic chemicals like organochlorines, lead, mercury, and neonicotinoids [11, 12]. The widespread use of chemically treated seeds is a common agricultural practice not only in the Rolling Plains ecoregion, but also across the United States [13]. Because wild bobwhites frequently feed near agricultural fields, there is an increased possibility of ingesting these chemically treated seeds [14]. Considering the many direct and indirect behavioral effects these neurotoxic chemicals exert on avian species [15-17], it is important to monitor the exposure of bobwhites to neurotoxic/Cholinesterase (ChE) inhibiting chemicals.

The objective of the present study is to non-destructively monitor the exposure of wild bobwhites to ChE inhibiting chemicals such as insecticides, herbicides, fungicides, etc. in the ecoregion. A non-destructive assessment of exposure to chemicals necessitates the selection of suitable biomarkers, and an often-used biomarker to assess the exposure of avian species to ChE inhibiting chemicals is blood ChE [18]. Here, we evaluate blood ChE levels in wild bobwhite in the Rolling Plains using a Dried Blood Spot (DBS) technique [19].

Materials and Methods

Trapping of Wild Bobwhites

Northern bobwhites were trapped on 35 ranches spread out over 24 counties in Texas and nine counties in Oklahoma (Figure 1).

Quail were collected under Texas Parks and Wildlife permit SPR-1098-984, Texas Tech University Institutional Animal Care and Use protocol 11049-07, and Texas A&M University Acceptable Use Policy (2011-93). A total of 233 bobwhites were trapped during the months of August and October. Because widespread cotton and wheat planting activity happens across the ecoregion during these months, collecting samples from wild bobwhites during these months provided the best opportunity to assess the exposure of bobwhites to ChE inhibiting chemicals. In all, 109 male and 90 female bobwhites were captured, and the gender of the remaining 34 bobwhites could not be determined. Of the 109 male bobwhites, there were 80 juveniles, 28 adults, and 1 that age could not be determined. Similarly, the 90 female bobwhites consisted of 65 and 23 juveniles and adults, respectively. The age of the remaining two bobwhites could not be determined. Lastly, 33 of the 34 bobwhites with undetermined gender were found to be juveniles, and the age of the remaining bobwhite could not be determined. Additional details about the bobwhites are presented in (Table 1).