Environmental quality and agrochemical exposure in honey bee colonies: a comparative case study of two contrasting...

Environmental quality associated with agricultural intensification alters the availability and nutritional quality of floral resources, with consequences for pollinator health. Here, we evaluated honey bee (Apis mellifera) colonies as environmental sentinels in two contrasting agroecosystems of the Argentine Pampas: a crop-dominated landscape and a livestock-dominated landscape. Within each setting, colonies received either protein supplementation or no supplementation. An integrative approach combining biological, pathological, toxicological, and environmental indicators was applied to assess colony responses across seasons. Colony condition was characterized using hemolymph protein concentration, prevalence of Varroa destructor and Nosema spp., brood area development, survival probability, and herbicide residues (glyphosate, glufosinate, and 2,4-D) in hive products. After accounting for year, supplementation, and Varroa treatment, colonies located in the livestock-dominated landscape exhibited higher hemolymph protein levels, greater survival probability, and lower herbicide residues. In contrast, colonies from the crop-intensive landscape showed reduced protein concentrations, increased Nosema prevalence, and detectable herbicide residues in honey and pollen. Principal component analysis identified glufosinate concentration in honey and reduced hemolymph protein levels as the main variables discriminating between environments. Together, these results indicate patterns consistent with an association between landscape composition, herbicide exposure, and honey bee physiology and survival within the studied agroecosystems, highlighting the potential role of environmental quality and floral diversity in shaping pollinator health.