The effect of diet on Apis mellifera larval susceptibility to Paenibacillus larvae

Abstract

Honey bees are threatened by changes in food resources. American Foulbrood (AFB), caused by Paenibacillus larvae, affects Apis mellifera larvae which progressively become more resistant to the disease with age. It has been suggested that nutritional limitations could result in increased susceptibility upon exposure to pathogens. This research, conducted on laboratory-reared honey bee larvae, aimed to analyze the effects of diet quality on the susceptibility of Apis mellifera larvae to P. larvae infections. The values of the lethal dose that killed 50% of the inoculated larvae (LD₅₀) were determined for five strains of P. larvae (ERIC I). Virulence ranged from 2 spores/μl for the N15 strain to 906 spores/μl for the Miramar strain. Different groups of larvae infected with half of the LD₅₀ doses of P. larvae strains were fed Aupinel diet (with daily increases of glucose, fructose, yeast extract and royal jelly) and four different modifications thereof. The results show that the absence of a diet component tends to cause an increase in mortality associated with the infection, depending on the virulence of the strain and the component suppressed. Glucose and fructose suppression, and mainly royal jelly deprivation, affect larval susceptibility to AFB and their survival.

Keywords:

• Honey bee larvae
• in vitro rearing
• Paenibacillus larvae
• Apis mellifera

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financed by CONICET (PIP Project 0804/2014-2016 by LG) and the Universidad Nacional de Mar del Plata (15/E818-EXA 860/18).