COMPARISON BETWEEN DIFFERENT FUMAGILLIN DOSAGE AND EVALUATION METHOD IN THE APIARY CONTROL OF NOSEMOSIS TYPE C

SARLO, E. G.; SANDRA K. MEDICI; MARTÍN P. PORRINI; GARRIDO P, M.; IGNAZIO FLORIS; EGUARAS M, J.

Redia

Research centre for agrobiology and pedology (ABP)

Lugar: Florencia; Año: 2011 vol. XCIV p. 39 - 44

0370-4327

Fumagillin (dicyclohexylammonium) is an antibiotic with well-known microsporicidal activity widely used tocontrol Nosema disease caused by Nosema apis in honeybees. Its use is permitted by law in Argentine and USA, butnot in the EU countries, apart from specific cases under veterinary authorization. So far, the optimal dosage of thisactive ingredient in controlling Nosema ceranae has not been determined. The aim of the present work was to assessthe efficiency of different fumagillin dosages on Apis mellifera colonies affected by different N. ceranae intensity. Forthis purpose, during April and May of 2007, in an apiary located near the Mar del Plata city (Buenos Aires Province,Argentine), forty eight A. mellifera colonies reared in Langhstroth hives, each containing 8 to 10 adult bee combs,were used in order to evaluate the effectiveness of different doses of fumagillin. The colonies were divided into thosewith mild or semi-severe disease intensity, based on the number of Nosema spores estimated in a sample of 60 returningbees (arb, spores abundance in returning bee). Then the colonies were randomly distributed forming 6 experimentalgroups (3 with mild intensity: one untreated left as control and the other two treated with 102 mg of fumagillinin two and three doses, respectively; 3 with semi-severe intensity: treated with 102 mg of fumagillin in two andthree doses, and with 120 mg of fumagillin in four doses, respectively). Each dose was administered at intervals of 7days. Before and during each administration, for a period of 35 days, the number of frames covered with adult beeswas recorded in each hive and a sample of 100 workers per colony was collected from the hive entrance in order todetermine the abundance (arb) and prevalence (prb) of spores. This alternative parameter (prb) was calculated byexamining a sub-sample of 10 bees, crushing the propodeum of the bees in 0.5 ml distilled water, taking a drop ofsuspension and observing 20 fields under a optic microscope (450x) for spore absence (0) or presence (1); then theestimation of spores prevalence (prb) was recorded as percentage of spore presence in the 20 observed fields, andthe average of two estimates were used. Moreover, spores from 5 randomly selected colonies were molecularly characterizedto confirm the Nosema species. The sequencing results showed a 98% of homology with N. ceranae. Theresults obtained allow to establish that the efficiency of fumagillin in controlling Nosemosis type C caused by N. ceranaeis affected by the intensity of the disease rather than from dosage or way of application. The best result wasobtained when colonies were affected by a mild intensity and the drug was administered in two weekly doses of 51mg per hive.