Effects of pesticides at field-detected concentrations on nursing behavior of honey bee, Apis mellifera

Honey bees play an important role in pollination in both agricultural and natural ecosystems. However, honey bees are recently facing population decline worldwide, and pesticides are considered one of the main factors of colony collapse. In addition to forager bees, nurse bees are also potentially exposed to pesticides through pollen and honey. Therefore, it is essential to investigate the effects of pesticides on nurse bees. In this study, nurse bees were treated for ten days with eight pesticides (carbaryl, carbofuran, fluvalinate, fenitrothion, coumaphos, flupyradifurone, thiamethoxam, and cypermethrin) at field-detected concentrations and monitored the nursing behaviors using queen cells for thirty minutes. In measuring the duration of nursing per session, all pesticides, except for flupyradifurone, led to a decrease in nursing time. When the total duration of nursing behavior was observed over a period of thirty minutes, nurse bees showed negative responses to all pesticides. Furthermore, a reduction in the number of visits to queen cell was investigated in nurses exposed to all pesticides, except for coumaphos. In general, with some exceptions, nurse bees exhibited negative effects on their nursing behavior when exposed to low concentrations of pesticides, suggesting that accidental exposure to pesticides can be a cause of colony collapse due to behavioral disturbances.