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 path-ogen 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 disap-pearance 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.