Evolution of the health status in Apis mellifera L. hives under different management conditions and its relationship with the nutritional contribution of pollen

Abstract

Argentine Northeast beekeeping has a promising development, due to the favuorable conditions of the region. Apis mellifera L. colonies are affected by different biotic stressors, including Varroa destructor mite and microsporidian Nosema sp., which can seriously affect bee health and decrease hive production. Bees nutritional status can be influenced by foraged pollen and species visited by bees protein content. The study was carried out in "Tupá Rembiapo" Agricultural Family School AFS apiary. Six hives were assigned to the "treatment" group, to whom an organic acaricide based on oxalic acid was applied only once, and five to the "control" group. Monthly samplings were carried out (October/2020 - April/2021). The jar method was used to evaluate the prevalence of varroa in the phoretic state. At the same time, samples were taken from returning bees to evaluate nosema. Samples of corbicular loads were obtained with pollen traps, the qualitative analysis was carried out with microscopy techniques, and total nitrogen was determined (Kjeldahl method). In the treated hives, the Varroa population decreased in the immediate post-treatment samplings, and the dynamics of the parasitism was variable in the control group with infestation ranges from 0.74% to 6.71%. The Nosema sp. spores record was well marked in spring and fall. Despite this, no symptoms associated with Nosemosis that indicated risks and disease development were observed in the area. Regarding the collected pollen, native species (81%) predominated over exotic ones (19%). The largest volumes were collected in spring (October) and the dominant species were Senecio grisebachi and Enterolobium contortisiliquum. In the summer (January) Schinopsis balansae predominated and in autumn (April) the specific diversity increased, but the total volume decreased. Regarding the crude protein content, a range of 11% to 21.5% was determined.