Parasitic interactions between nosema spp. and varroa destructor in apis mellifera colonies

MARIANI F; MAGGI M; PORRINI M; FUSELLI S; CARABALLO G; BRASESCO C; BARRIOS C; PRINCIPAL J; EGUARAS M

ZOOTECNIA TROPICAL

Fondo Nacional de Investigaciones Agropecuarias (FONAIAP)

Año: 2012 vol. 30 p. 81 - 90

0798-7269

The European honey bee Apis mellifera is affected by many parasites and pathogens that modify its immune system being the most destructive ectoparasitc mite Varroa destructor. The parasitic disease caused by this mite results in high mortality levels in honeybee colonies without acaricide treatment. In addition, the microsporidium Nosema apis and Nosema ceranae produce serious damages to the colonies. Taking into account that the sporulation dynamics of the microsporidium can be affected by several factors the objective of this investigation was to analyze if there are parasitic interactions between V. destructor and Nosema spp. when both parasites co-infect A. mellifera colonies. Studies were carried out in an apiary in the Entre Ríos province, Argentina. The apiary was sampled for a 10 month period. Parameters recorded per hive in fi eld examination were: (a) adult bee population(estimated as number of combs covered with adult bees); (b) brood area (estimated as number of combs coveredby at least a 50 % of brood cells); (c) number of honey combs; (d) the V. destructor presence (a colony was considered parasitized by V. destructor when phoretic mite infestation was higher than 1 %) and (e) number of Nosema spp. spores (parasite abundance). Abundance of Nosema (ANij) per colony was analyzed using themixed general additive model (GAM) with variable intercept. The fi nal data modeling confi rmed that Nosema abundance is explained by the time and by the interaction between the month and the V. destructor infestation. Possible causes explaining this ecological relationship between V. destructor and Nosema spp. populations were discussed.