Chemical Composition, Antimicrobial Activity, and Mode of Action of Essential Oils against Paenibacillus larvae , Etiological Agent of American Foulbrood on Apis mellifera

This study aimed to characterize the chemical composition of Aloysia polystachia , Acantholippia seriphioides , Schinus molle , Solidago chilensis , Lippia turbinata , Minthostachys mollis , Buddleja globosa , and Baccharis latifolia essential oils ( EO s), and to evaluate their antibacterial activities and their capacity to provoke membrane disruption in Paenibacillus larvae , the bacteria that causes the American Foulbrood ( AFB ) disease on honey bee larvae. The relationship between the composition of the EO s and these activities on P .  larvae was also analyzed. Monoterpenes were the most abundant compounds in all EO s. All EO s showed antimicrobial activity against P .  larvae and disrupted the cell wall and cytoplasmic membrane of P .  larvae provoking the leakage of cytoplasmic constituents (with the exception of B .  latifolia EO ). While, the EO s’ antimicrobial activity was correlated most strongly to the content of pulegone, carvone, ( Z )‐ β ‐ocimene, δ ‐cadinene, camphene, terpinen‐4‐ol, elemol, β ‐pinene, β ‐elemene, γ ‐cadinene, α ‐terpineol, and bornyl acetate; the volatiles that better explained the membrane disruption were carvone, limonene, cis ‐carvone oxide, pentadecane, trans ‐carvyl acetate, trans ‐carvone oxide, trans ‐limonene oxide, artemisia ketone, trans ‐carveol, thymol, and γ ‐terpinene (positively correlated) and biciclogermacrene, δ ‐2‐carene, verbenol, α ‐pinene, and α ‐thujene (negatively correlated). The studied EO s are proposed as natural alternative means of control for the AFB disease.