Determination of pesticide residues in honey bees, pollen and beeswax: assessing pesticide hazard in spanish apiaries

Pollinator decline is an emerging worldwide problem with serious repercussions on agriculture and environment. Around one third of human food relies on insect pollination, and most of the flowering plants need pollinators to survive. Honey bee is the main pollinator in environments where anthropogenic pressure has reduced the number of native pollinators, like urban, rural and agricultural areas. The main cause of beekeeping crisis is parasite Varroa destructor and secondary infections associated with the mite. Pesticide contamination and nutritional deficiencies, combined with the parasite, can act synergistically and reduce survival of bee colonies. Honey bees patrol extensive areas when foraging for nectar and pollen. These foraging flights expose them to compounds applied to crops like insecticides, fungicides, nematicides and herbicides through different routes. They are also in contact with pesticides applied inside the hive against varroa mite by beekeepers. As a result, honey bees are exposed to cocktails of pesticides inside and outside their colonies. Multiresidue methods for the screening, identification and quantitation of pesticides require a high sensitivity and reliability. The LC-MS/MS is a rugged technique that can cover the majority of the challenges involved in that task. Prior to the determination of the pesticides, it is necessary an efficient extraction procedure as comprehensive as the equipment used in the identification. The QuEChERS procedure followed by HPLC-MS/MS provided appropriate results in terms of accuracy, precision, sensitivity and quickness, and therefore was a suitable method for the determination of the selected pesticides in honey bees, pollen and beeswax. Miticides used in beekeeping were the most frequently detected pesticides in beeswax, pollen and live bees, whereas insecticides were the most frequent compounds found in dead honey bees. Beeswax is the most contaminated hive compartment regarding levels of pesticides detected, whereas pollen revealed the highest number of different pesticide residues detected in the samples. Live honey bees were remarkably less contaminated in both quantities and number of pesticides detected. Pesticide poisoning episodes took place only in apiaries located near agricultural settings, and dead honey bees revealed high levels of chlorpyrifos, dimethoate and imidacloprid insecticides, used in the surrounding crops. Beeswax was the beekeeping matrix with the highest pesticide hazard to honey bees and acrinathrin was the most important contributor to the HQ scores. The pesticide hazard of pollen was considered relevant for bees, and the main contributors to HQ scores were acrinathrin and chlorpyrifos. Pesticide hazard in live bees was considered low. The results obtained showed the widespread occurrence of pesticides used in plant protection in pollen and dead bees samples, pointing out that the reliance on pesticides of modern agriculture should be reconsidered.

Topic: Insect and Pesticide Research
Subfield: Insect Science
Field: Agricultural and Biological Sciences
Domain: Life Sciences