Nosema ceranae development in italian and africanized honeybees

MENDOZA YAMANDÚ ; PORRINI M. P.; SEBASTIÁN DÍAZ-CETTI; GUSTAVO RAMALLO; EGUARAS MARTÍN J.; INVERNIZZI CIRO

KIEV

Congreso; 43º International Apicultural congress Apimondia; 2013

Apimondia

 Responses to Nosema ceranae infection of Italian honeybees(descendants of Apis mellifera ligustica)and Africanized honeybees (descendants of European and Apis mellifera scutellata bees) were compared in a laboratoryassay. Combs obtained in summer 2011 from 3 colonies of each race were placedon incubator until imagoes emergence. Seventy two hours bees were dosedindividually with 1.3x104 N. ceranaespores and placed in cages (3 replicates of 30 bees per colony). Uninfectedcontrol was also established. Diet consisted on sugar syrup available ad libitum. Dosed individuals wereremoved at 4, 8 and 12 days post infection (p.i.) and midgut dissected and examinedunder microscope to measure intensity of spores. Spores development showeddifferences between races only on day 4 p.i., with an average of 3.7x103spores per bee (14% of individuals infected) in Italian honeybees and 12.7x103spores per bee (50% of individuals infected) in africanized honeybees (Wilcoxontest: W= 1166; P< 0.001). At day 8 p.i. 93% of bees from both races wereinfected. At day twelve p.i., the highest intensity values were recorded withan average of 3.2x106 spores per bee. Control bees showed a slightamount of spores on day twelve, possibly due to contamination of the comb withspores. The obtained results constitute an important report about the responseof these two races to N. ceranaeinfection and suggest differences on sensitivity at the beginning of theinfective process. Histopathology analysis can provide interesting informationto enlarge the discussion. Also, field assays measuring parasitosis indicators arenecessary to study the susceptibility at colony level.