Impacts of pests and diseases on the decline of managed bees in Brazil: a beekeeper perspective

Abstract

Brazilian beekeepers have experienced massive colony losses in recent years. Possible causes include bee pests and diseases, although there have been few relevant studies in the country and no official data are available. The aim of this work was to assess, from a beekeeper's perspective, the incidence of pests and diseases in colonies, and their impact on the decline of bee populations in Brazil. The research used two online questionnaires that included disease symptoms to facilitate participant identification of diseases. A total of 674 valid responses were obtained from beekeepers of Apis mellifera (49% of the total) and stingless bees (51%), distributed among 24 of the 27 Brazilian states. Most beekeepers observed pests (average 78.1%) and disease symptoms (65.5%) in their colonies. Based on beekeepers' responses, pests and diseases affect beehive losses in Brazil. Colony loss percentage for A. mellifera was higher in apiaries with ants (19.8% of colony losses) and wasps (46.7%) than in those without pests (p < 0.001). While for stingless bees, meliponaries with robber bees (15.8% of colony losses), ants (14.7%), and phorid flies (12.5%) had higher colony losses than those without pests (p < 0.001). Apiaries and meliponaries with worker bee deaths had higher losses than those without symptoms. The results also indicate that monitoring can reduce colony losses in apiaries and meliponaries that have some kind of pests and diseases. Using a beekeeper perspective, this study provides information about the impact that pests and pathogens have on bee losses that can be used to guide improved management practices.