Molecular diagnosis of Apicystis bombi (Apicomplexa: Neogregarinorida) parasitizing Apis mellifera in Argentina

PLISCHUK, S.; MEEUS, I.; SMAGGHE, G.; LANGE, C. E.

Buenos Aires

Congreso; 42º Congreso Internacional de Apicultura - Apimondia; 2011

Federación Internacional de Asociaciones de Apicultura

The neogregarine Apicystis bombi is a parasite of Bombus bumblebees. Prior to our work it has only once been detected in the Western honeybee Apis mellifera, in Finland, parasitizing a single specimen. This contribution confirms with molecular techniques the presence of A. bombi in A. mellifera at a site located 8 km West of San Carlos de Bariloche (41°07´33"S; 71°23´55"W), north-western Patagonia, Argentina. Workers of A. mellifera were collected during January 2009 (n = 79) and January-April 2010 (n = 59) while foraging. Insects were frozen (-32° C) until processing. Dissection and homogenization techniques were used for prospection and isolation of pathogens. Observations and morphological identification of neogregarines were conducted in fresh preparations under compound microscopy (x400, x1000). Infection intensity was estimated using a haemocytometer. To confirm the presence of A. bombi with molecular techniques, purified oocyst suspensions were prepared from 14 Apicystis-like cases as determined by microscopy. DNA extraction, PCR amplification of 18S rDNA, and sequencing were performed. The consensus sequence was deposited at NCBI-Genbank (accession number HQ619890). Although statistical differences between oocysts measurements were seen, no mutations were found after alignment with A. bombi isolates obtained from B. terrestris (Argentina) and B. pratorum (Ireland). Prevalence of A. bombi in honeybees of Bariloche was 7.6% in 2009, and 13.6% in 2010. The average intensity of infections was 8.96 ± 2.78 x 105 (n = 7) oocysts per insect. Due to its high virulence showed in several species of Bombus in the Northern hemisphere and its multihost nature, A. bombi should be closely monitored in A. mellifera and in Bombus spp. in Argentina. The role of A. mellifera as reservoir of this neogregarine should not be ruled out.