Hemato-biochemical and Antioxidant Changes Induced by PM2.5 Exposure in Apis mellifera

Abstract

Fine particulate matter (PM_2.5), an increasingly serious environmental contaminant, has been shown to negatively impact ecological systems and health of pollinators, thereby making it one of the most important environmental stressors. This study evaluated changes in hemato-biochemical and antioxidant status of the honey bee (Apis mellifera) resulting from exposure to PM_2.5. Honey bees were exposed to controlled amounts of PM_2.5 in laboratory conditions. The hemolymph of the exposed bees was analysed for total hemocyte count (THC), differential hemocyte count (DHC), biochemical parameters and indicators of oxidative stress. The data showed that THC was significantly reduced and that hemocyte populations showed changes in the number of plasmatocytes and granulocytes, indicating modulation of the immune system. In addition, the results of biochemical analyses showed that glucose, ALT, AST and ALP were all increased in the exposed groups, while total protein levels were remarkably decreased, indicative of metabolic stress and tissue damage. Oxidative stress indicators showed a significant increase in LPO and a significant decrease in GSH, indicating that there was an increase in ROS production and a decrease in antioxidant capacity. The results support previous research that has found that particulate pollutants produce oxidative damage, immune suppression and metabolic disruption to honey bee populations. The research indicates that honey bees are very sensitive to PM_2.5 exposure and affords the opportunity to use honey bees as bio indicators of environmental pollution.