Promising antimicrobial activity against the honey bee parasiteNosema ceranaeby methanolic extracts from Chilean native plants and propolis

Propolis Consumption Reduces Nosema ceranae Infection of European Honey Bees (Apis mellifera)

“…The propolis used in our bioassays effectively halted the proliferation of N. ceranae spores in the bee gut, as previously reported by [54][55][56][57]. This is an important finding because resin chemical composition can vary with geographical area of origin and, consequently, so can its antimicrobial activity [83,84].…”

“…In these studies, only the propolis extract and not ethanol showed positive effects on Nosema-infected bees, causing an increase in survival and a decrease in spore load. Similar effects of propolis on workers of A. mellifera infected by Nosema have also been reported by Arismendi et al [57], but a different solvent was used to extract the active ingredients from propolis (methanol instead of ethanol) and the study lacked a positive control (infected bees treated with the solvent alone). In our experiments, a single administration of 2 µL of a sugar solution containing 17.5% ethanol did not cause any increase in mortality of uninfected bees nor did it change Nosema load in experimentally infected bees.…”

“…Nevertheless, several ethanolic plant extracts have shown significant anti-Nosema activity [57,89], probably due to their polyphenolic compound content [57,90]. Arismendi et al [57], who chemically characterised two types of propolis that enhanced the survival of N. ceranae-infected bees, found many flavonol compounds (rutin, myricetin, querecetin, kaempferol and galangin) as well as phenolic acids, such as apigenin, pinocembrin and caffeic acid phenethyl ester in their propolis. Many of these compounds show broad-spectrum antimicrobial activity [91].…”

“…Recently, the therapeutic properties of propolis extracts against N. ceranae were assayed in the Asiatic honey bee species Apis florea [54,55], Apis cerana [56] and the Western Apis mellifera [57]. In the Asiatic Apis species, propolis used in the bioassays was obtained from the stingless bee Trigona apicalis, whereas in A. mellifera the propolis tested was produced by honey bees themselves.…”

“…In the Asiatic Apis species, propolis used in the bioassays was obtained from the stingless bee Trigona apicalis, whereas in A. mellifera the propolis tested was produced by honey bees themselves. In all these studies, an improvement in bee survival and a decrease in the N. ceranae spore load were observed in experimentally infected bees [54][55][56][57]. For the Asiatic Apis species, these results leave open the question of whether the honey bee's own propolis has a similar beneficial effect in reducing Nosema pathogenesis.…”