A study by ophthalmologists from University College London (UCL) suggests that infrared light therapy can reverse the deadly effects of insecticides on bees. The simple treatment has also shown promise in improving retinal function in patients with AMD.
Neonicotinoid pesticides are linked to a widespread decline of pollinating insects. Most infamously, these chemicals are believed to be the cause of Colony Collapse Disorder – a phenomenon that has drastically reduced honey bee populations. Several insecticides in this class, including Imidacloprid, are commonly used on crops in the U.S., but have been banned in the European Union.
When ingested by an insect, Imidacloprid causes nerve cell overstimulation by irreversibly binding to acetylcholine receptors. The subsequent cell depolarization inhibits mitochondrial production of adenosine triphosphate (ATP). Without adequate ATP, the organism becomes lethargic, immobile and eventually dies.
However, experiments in flies have shown that mitochondrial function can be boosted with exposure to 670 nm (infrared) light, which activates the enzyme cytochrome c oxidase on the electron transport chain.
To evaluate whether light therapy could benefit neonicotinoid-poisoned bees, the team from UCL created 4 treatment groups: bees fed 10nM Imidacloprid in 50% sucralose solution, bees fed Imidacloprid and exposed to 670 nm light 2x/daily for 15 minutes, bees exposed to light with normal feed, and a control group with no light or pesticide exposure.
After 10 days of intervention and a 22-day recovery period, bees that were fed Imidacloprid showed a 25% decline in ATP levels compared with controls (p<0.05). Yet the Imidacloprid+670 group showed final ATP levels close to the control group (p<0.05), suggesting that ATP functionality was restored with light therapy.
The mortality rates of the groups were also significantly different in favor of the light treatment. The Imidacloprid group showed a rapid death rate of 20% by day 3 of intervention, reaching 70% by day 10. This was substantially higher than the control group (P<0.001). Conversely, the Imidacloprid+670 group survivorship was comparable to that seen in the control, and bees in the light-only group had a prolonged life span (P<0.01). The light therapy also had a positive impact on the bees’ mobility and visual function and reversed the deficits induced by Imidacloprid.
Following these promising results, the authors have begun developing an inexpensive light-generating device that could be placed in hives to protect colonies from the effects of neonicotinoid pesticides.
Decline in ATP levels is also hypothesized to be the underlying mechanism in age-related macular degeneration. As the eye ages, chronic inflammation from reactive oxygen species, retinal tissue degradation and accumulation of mitochondrial DNA mutations reduce the organelle’s activity, ultimately leading to photoreceptor death. So, the UCL team has also created a simple device that could be used in humans. The prototype, which looks like a normal flashlight, is placed directly over the eye for 1 to 2 minutes a day. Initial tests have demonstrated an increase in low-light (rod-cell) visual function.