Resistance to American foulbrood in honey bees IX. Effects of honey-bee larval food on the growth and viability of Bacillus larvae

Abstract

Experiments were designed to learn whether there are any differences between honey-bee ( Apis mellifera) larval food from American-foulbrood-resistant and American-foulbrood-susceptible lines of bees in regard to antimicrobial action on Bacillus larvae, the pathogenic agent of American foulbrood, cultured in vitro. To test for inhibition of germination, spores were exposed to various concentrations of brood food from both genetic lines in culture medium, heat-shocked to kill vegetable cells, and then plated for germination of those spores which were inhibited from germinating. Results indicated that brood food, from an American-foulbrood-resistant line (Brown) of bees was more effective in inhibiting spore germination than brood food from a disease-susceptible line (Van Scoy). Tests for effects of brood food on vegetable cells involved their exposure for different periods of time to various concentrations of the food in an aqueous medium. It was found that brood food from the resistant line was more effective in reducing the number of viable vegetable cells than brood food from the susceptible line.