Random Forest Analysis of Impact of Abiotic Factors on Culex pipiens and Culex quinquefasciatus Occurrence

Arinder K Arora,David W Severson,David S Kang,Cheolho Sim

doi:10.3389/fevo.2021.773360

Abstract

The Culex pipiens complex of mosquitoes are significant vectors of several pathogens resulting in infectious human diseases in North America, including but not limited to West Nile encephalitis, Rift Valley Fever, and Lymphatic filariasis. Among this complex are C. pipiens form pipiens and Culex quinquefasciatus. While morphologically similar, the mosquitoes exhibit unique life histories that suit them uniquely to divergent niches, wherein C. pipiens can thrive despite the cold winters of the northern United States and C. quinquefasciatus is able to survive periods of drought typical in the southern states. Here, Random Forests machine-learning algorithms were employed to model and explore which environmental parameters best explain mosquito occurrence in historical trapping data across the continental United States of America, and test correlation with abundance data. The models explained between 71 and 97% of the presence or absence of the two mosquitoes based on historical climatic data. The results of this study will improve vector management programs by explaining which environmental variables will provide the most accurate predictions of mosquito presence at a given site.

Highlights

Culex pipiens complex mosquitoes are major vectors of several pathogens that cause human diseases such as West Nile encephalitis, Rift Valley Fever, and Lymphatic filariasis (Meegan et al, 1980; Monath, 1988; Lai et al, 2000; Diamond, 2009)
The absence of the diapausing phenotype would cull the southern mosquitoes from C. pipiens populations, yet fails to fully explain the low level of introgression of C. pipiens into the southern C. quinquefasciatus populations in North America
The collection data from Vectorbase was comprised of 642,812 C. pipiens and 209,658 C. quinquefasciatus collected from various locations in the United States

Summary

Introduction

Culex pipiens complex mosquitoes are major vectors of several pathogens that cause human diseases such as West Nile encephalitis, Rift Valley Fever, and Lymphatic filariasis (Meegan et al, 1980; Monath, 1988; Lai et al, 2000; Diamond, 2009). Diapause is an anticipated, preprogrammed response of insects to the shortening of days and lower temperatures at the onset of winter and is characterized by a developmental arrest resulting in reduced metabolism, enhanced stress tolerance, and fat hypotrophy (Mori et al, 2007; Sim and Denlinger, 2013; Kang et al, 2014, 2016; Sim et al, 2015). This reallocation of resources toward survival is a critical adaptation for the northern house mosquito, C. pipiens. The absence of the diapausing phenotype would cull the southern mosquitoes from C. pipiens populations, yet fails to fully explain the low level of introgression of C. pipiens into the southern C. quinquefasciatus populations in North America

Methods

Results

Discussion

Conclusion