Effects of Lactobacillus johnsonii AJ5 metabolites on Apis mellifera nutrition, immunity and their toxicity against Varroa destructor

DE PIANO FG; MITTON GIULIA; MAGGI MD; LORA MARCHETTI DA; RAMOS F; QUINTANA S; AUDISIO C M; RUFFINENGO SR.

Congreso; Reunión Conjunta de Sociedades de BioCiencias; 2017

Apis mellifera L. is an essential pollinator affected by severalstressors linked with colony losses and the disturbance of their ecologicalfunction. Among this, Varroa destructor, an ectoparasitic miteaffects seriously the colonies. The relationship between stressorsand bee symbionts is being studied to enhance bee health. Thegoal of this study was to evaluate the effect of cell-free supernatants(CFS) produced by Lactobacillus johnsonii AJ5, a bee bacterial symbiont,on A. mellifera nutrition, immunity and their toxicity against V.destructor. Bees in cages were fed ad libitum with a solution of 40%v/v (CFS/sugar syrup) for 6 days. Two controls were performed:one with sugar syrup (50% w/v) and the other with a solution ofMRS broth and syrup (6.25 % v/v). Assays were performed by triplicate.Soluble protein was assessed in samples of 20 abdomensper treatment. Samples of each replicate were used to analyze byquantitative real-time PCR (qRT-PCR) the expression of immunitygenes: Vitellogenin (Vg), Insulin-like peptides 2 (Ilp2), Domeless(Dom), Hymenoptesin (Hym) and Propheniloxidase (Ppo), usingbeta actin as housekeeping gene. Toxicity against V. destructor wasassayed in glass Petri dishes (n=5) feeding 3 bees ad libitum asmentioned above. After three days, six female mites were incorporatedper dish, and their mortality was registered at 24, 48, and 72h. Results were analyzed by ANOVA and means were comparedwith the Tukey test. Soluble protein in bees fed with the CFS wassignificant different respect to controls (p