A field-based quantitative analysis of sublethal effects of air pollution on pollinators

Abstract

While the impact of air pollution on human health is well studied, mechanistic impacts of air pollution on wild systems, including those providing essential ecosystem services, are largely unknown, but directly impact our health and well-being. India is the world’s largest fruit producer, second most populous country, and contains 9 of the world’s 10 most polluted cities. Here, we sampled Giant Asian honey bees, Apis dorsata, at locations with varying air pollution levels in Bangalore, India. We observed significant correlations between increased respirable suspended particulate matter (RSPM) deposition and changes in bee survival, flower visitation, heart rate, hemocyte levels, and expression of genes related to lipid metabolism, stress, and immunity. Lab-reared Drosophila melanogaster exposed to these same sites also exhibited similar molecular and physiological differences. Our study offers a quantitative analysis on the current impacts of air pollution on insects, and indicates the urgency for more nonhuman studies to accurately assess the effects of pollution on our natural world.

Foraging trip duration of honeybee increases during a poor air quality episode and the increase persists thereafter

“…In a recent study conducted in India where there are many of the world most polluted cities, significant correlations between PM10 increases and physiological changes of Giant Asian honeybees ( Apis dorsata ) were found (Thimmegowda et al., 2020). Giant Asian honeybee samples from severely polluted areas (in Bangalore, India) showed significantly lower rates of survival.…”

“…More importantly, colony‐level chronic impacts through gene expression could also be predicted. For example, vitellogenin, associated with survival of worker bees, was found depleted in bees sampled from the highly polluted site compared with those from the low polluted site (Thimmegowda et al., 2020). This is important because the reduced fitness of individual foragers and their colony due to degraded foraging performance may have detrimental impacts on pollination services.…”

Effects of air pollution exposure on social behavior: a synthesis and call for research

“…Honeybees have been used as biomonitors of air pollutants, and a limited number of studies have examined pollutant effects on olfactory learning and memory [ 155 ]. Effects on social behavior from air pollutants have yet to be investigated, however a recent study found an association between particulate matter air pollution and flower visitation, expression of stress-related genes, and survival in the Giant Asian honeybee, Apis dorsata [ 156 ]. Given the ability to track and monitor individual interactions at high spatial and temporal resolution [ 157 ], honeybees could become a powerful model system to examine effects of air pollution.…”

Exposure to low doses of pesticides induces an immune response and the production of nitric oxide in honeybees

“…Indeed, CYP9E2 has been shown to metabolize thiacloprid efficiently in honeybees, whereas other CYPs cannot fulfil this function 73 . Moreover, a recent analysis of the sublethal effects of air pollution, a chemically complex stressor, also showed that cyp9e2 was strongly upregulated in honeybee heart tissue 74 . Our data indicate that biotic and abiotic stressors induce the preferred expression of genes encoding UGTs and catalase, respectively, whereas CYP9E2 appears to fulfil a universal detoxification function.…”