Red light corrects neonicotinoid induced immunodeficiency and impaired respiration in poisoned bumblebees

Abstract

Neonicotinoid pesticides undermine mitochondrial function in insects including bumblebees, reducing ATP, mobility and leading to death. They also reduce bumblebee immunocompetency leaving them vulnerable to pathogen attack. This undermines key pollinators critical in the agricultural economy. However, 670nm light exposure improves mitochondrial function undermined by age or disease, increasing respiratory chain efficiency, improving ATP production, mobility and survival in bumblebees and fruit flies. Here we show that 670nm restores immunocompetence, improving hemocyte counts and hemolymph anti-microbial action. Additionally, we measure whole body respiration in vivo in individual bumblebees revealing that it is a functional metric of both neonicotinoid impact and light induced mitochondrial protection. Critically we show that only 1 min 670nm exposure is sufficient to correct respiratory deficits induced by pesticide and restore normal immune ability. Longer exposures are not more effective. Further, single 1 min exposure protects respiration and immunity for approximately 3-6 days. Hence, 670nm impact is not dose dependent but switch like. These data provide a compelling rational for 670nm application to protect pollinators on which a major part of the agro economy is based and who are being challenged by aggressive pesticide application.