Introduction Honeybee ( Apis mellifera L.) larvae are susceptible to Paenibacillus larvae , a spore-forming, Gram-positive bacterium that causes American Foulbrood (AFB), a destructive honeybee brood diseases. Current antibiotic treatments are inadequate because of rising pathogen resistance and residue accumulation in hive products, driving interest in biological and other natural strategies for AFB control. Most candidate biocontrol agents, however, have been evaluated only for their ability to inhibit P. larvae or protect larvae, with less attention to their effects on adult bees. Methods Here we assessed the biocontrol potential of hive-associated Bacillus species against P. larvae infection. Bacteria isolated from AFB-infected combs were sequenced and screened for antagonistic activity, and active isolates, their lysates, and lysate-derived protein fractions were tested for their ability to improve larval survival during P. larvae challenge. To evaluate effects on adult bees, newly emerged workers were caged and fed the B. licheniformis lysate (ASx), and their survival and gut microbiome were compared with untreated controls and with bees fed Terra-Pro, a Terramycin-based AFB treatment. Results Several Bacillus species – including B. zhangzhouensis, B. subtilis, B. amyloliquefaciens, B. licheniformis , and B. mojavensis – inhibited one or more P. larvae strains . The B. licheniformis lysate (ASx) and its 30 -50 kDa protein fraction improved larval survival during P. larvae challenge. In caged adults, survival of lysate-fed bees differed from untreated controls but was comparable to that of Terra-Pro-fed bees, and their gut microbiome remained similar to that of untreated controls. Discussion Together, these results indicate that hive-associated Bacillus species – and B. licheniformis -derived proteins in particular – are promising candidates for AFB management that improve larval survival without harming adult bees more than an existing antibiotic treatment.
- Biocontrol potential of hive-associated Bacillus species against American Foulbrood disease in honeybees (Apis mellifera L.)
- A Shrestha - Department of Animal, Veterinary and Food Science, University of IdahoY Eline - University of IdahoK Sundstrom - University of IdahoJT Van Leuven - Department of Animal, Veterinary and Food Science, University of Idaho
- Frontiers in Insect Science, Vol.6, 1870750
- Frontiers Media SA
- National Institute of General Medical Sciences; National Institute of Food and Agriculture
- 997015751701851
- Animal, Veterinary, and Food Sciences
- English
- Journal article