New insights into changing honey bee (Apis mellifera) immunity molecules pattern and fatty acid esters, in responses to Ascosphaera apis infection.

Monitoring of metabolite changes could provide valuable insights into disturbances caused by an infection and furthermore, could be used to define the status of an organism as healthy or diseased and define what could be defensive elements against the infection. The present investigation conducted a gas chromatography-mass spectrometry (GC/MS) for haemolymph of larval honey bees (Apis mellifera L.) infected with the fungal pathogen Ascosphaera apis in comparison with control haemolymph non-infected insects. Results revealed that the pathogen caused a general disturbance of metabolites detected in the haemolymph of the honey bee. The majority of metabolites identified before and after infection were fatty acid esters. The disease caused an elevation in levels of methyl oleate, methyl palmitate, and methyl stearate, respectively. Further, the disease drove to the disappearance of methyl palmitoleate, and methyl laurate. Conversely, methyl linolelaidate, and ethyl oleate were identified only in infected larvae. A high reduction in diisooctyl phthalate was recorded after the infection. Interestingly, antimicrobial activities were confirmed for haemolymph of infected honey bee larvae. In spite of the presence of some previously known bioactive compounds in healthy larvae there were no antimicrobial activities.

Detection Bioactive Metabolites of Fructobacillus fructosus Strain HI-1 Isolated from Honey Bee's Digestive Tract Against Paenibacillus larvae.

American foulbrood is a devastating disease of honey bee, causing economic loss in the beekeeping industry. The disease mainly causes reduction in honey bee populations which negatively affect the honey bee's major role as natural pollinators of significant crops and wildflowers. Thus, it is crucial to develop safe efficient strategies to control the disease and to improve bee colony health. Using lactic acid bacteria (LAB) as an alternative to chemical treatments is a promising novel technique for tackling honey bee diseases and improving their immunity. The endogenous LAB isolates were recovered from honey bee gut samples collected from different apiaries in two Egyptian governorates and screened for antagonistic activities against Paenibacillus larvae (pathogen of AFB disease). The results showed that 53.3% of tested LAB isolates (n = 120) exhibited antagonistic activities against P. larvae. The minimum inhibitory concentration and minimum bactericidal concentration of the most potent LAB isolate (with an inhibition zone of 44 mm) were 100 and 125 µL/mL, respectively. 16S rRNA sequencing identified the most potent isolate as Fructobacillus fructosus HI-1. The bioactive metabolites of F. fructosus were extracted with ethyl acetate and fractionated on thin-layer chromatography (TLC); also, bioactive fractions were detected. Heptyl 2-methylbutyrate, di-isobutyl phthalate, D-turanose, heptakis (trimethylsilyl), di-isooctyl phthalate, and hyodeoxycholic acid compounds were identified in the bioactive fractions. The result explores the promising administration of probiotic metabolites to control honey bee AFB disease, as a natural tool to substitute antibiotics and chemicals in disease-controlling strategies.