Infestation by phorid flies disrupts behavior and immune function in honey bees monitored by radio-frequency identification

Honey bees (Apis mellifera Linnaeus) and global food security face increasing threats from diverse biotic and abiotic stressors. A. mellifera, known for its remarkable adaptability, thrives across varied environments while encountering novel challenges. In this study, we examined the effect of phorid fly infestation on A. mellifera under field conditions. We recorded the daily activity of honey bees, both incoming and outgoing records, in healthy and infested hives. This monitoring involved the use of radio-frequency identification (RFID) tags on individual worker bees to assess the effects of fly infestations on bee performance weekly. We also analyzed worker bee survival, additional coinfections, and immune responses including humoral and cellular parameters. Our findings revealed: (1) reduced frequency and duration of foraging trips, (2) increased nocturnal activity, and (3) elevated immune activity due to fly invasion. Here, we highlight the detrimental consequences that a phorid fly invasion can have on the health and colony performance. Although specific outcomes may vary depending on hive management practices, it is evident that colonies in which bees must allocate significant resources to safeguard their nests from intruders exhibit reduced vigor and performance. Furthermore, knowledge of phorid flies and their invasion impact on honey bees could help prevent their spread to beehives that may be easily susceptible to attack.