SREL Reprint #3614

The direct and indirect effects of copper on vector-borne disease dynamics

Erik Neff1,2 and Guha Dharmarajan1

1Savannah River Ecology Lab, University of Georgia, Aiken, SC, 29801, USA
2Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA

Abstract: Metal pollution is a growing concern that affects the health of humans and animals globally. Copper is an essential insect micronutrient required for respiration, pigmentation and oxidative stress protection but can also act as a potentially toxic trace element. While several studies have focused on the negative fitness effects of copper on the aquatic larvae of mosquitoes, the effects of larval copper exposure on adult mosquito fitness (i.e., survival and fecundity) and their ability to transmit parasites (i.e., vector competence) remains unclear. Here, using a well-studied model vector-parasite system, the mosquito Aedes aegypti and parasite Dirofilaria immitis, we show that sublethal copper exposure in larval mosquitoes alters adult female fecundity and vector competence. Specifically, mosquitoes exposed to copper had a hormetic fecundity response and mosquitoes exposed to 600 mg/L of copper had significantly fewer infective parasite larvae than control mosquitoes not exposed to copper. Thus, exposure of mosquito larvae to copper levels far below EPA-mandated safe drinking water limits (1300 mg/L) can impact vector-borne disease dynamics not only by reducing mosquito abundance (through increased larval mortality), but also by reducing parasite transmission risk. Our results also demonstrated that larval copper is retained through metamorphosis to adulthood in mosquitoes, indicating that these insects could transfer copper from aquatic to terrestrial foodwebs, especially in urban areas where they are abundant. To our knowledge this is the first study to directly link metal exposure with vector competence (i.e., ability to transmit parasites) in any vector-parasite system. Additionally, it also demonstrates unequivocally that mosquitoes can transfer contaminants from aquatic to terrestrial ecosystems. These results have broad implications for public health because they directly linking contaminants and vector-borne disease dynamics, as well as linking mosquitoes and contaminant dynamics.

Keywords: Aedes aegypti, Dirofilaria immitis, Copper, Vectorial capacity, Vector competence

SREL Reprint #3614

Neff, E., and G. Dharmarajan. 2021. The direct and indirect effects of copper on vector-borne disease dynamics. Environmental Pollution 269(2021): 116213.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).