GIMÉNEZ MARTÍNEZ Pablo Darian
Valorization of hop leaves for development of eco-friendly bee pesticides
IGLESIAS, AZUCENA; GIMÉNEZ MARTÍNEZ PABLO DARIAN; RAMIREZ, CRISTINA; MITTON GIULIA; FANGIO FLORENCIA; CHURIO SANDRA; FUSELLI SANDRA; FANOVICH ALEJANDRA; EGUARAS MARTIN; MAGGI MATIAS
EDP SCIENCES S A
Lugar: Paris; Año: 2020
The bacterium Paenibacillus larvae and the mite Varroa destructor are the mostsevere biotic stressors affecting honeybees. To control these pathogens, beekeepersapply synthetic acaricides or antibiotics inside the hive. Nevertheless, its continuousmisuse over time generates resistant bacteria strains and resistant mite populations,and residual contamination of bee products. In this context, the development ofalternative and effective control methods of bee diseases is crucial. In recent years,natural substances from vegetable extracts have emerged as the basis of suitablecontrol methods to treat bee colonies parasitized by P. larvae and V. destructor . Ouraim was to evaluate the bioactivity of ethanolic and methanolic hop leaves extractsagainst P. larvae, V. destructor and A. mellifera . To assess the bactericide activityagainst P. larvae , the broth microdilution method was used. Topical administrationprotocols were used to determine the bioactivity of hop extracts on V. destructor andA. mellifera . Total polyphenols, flavonoids, saponines and antioxidant capacity were determined for each hop leaves extract tested. Our results indicate that Victoria extractpresent the highest concentration of phenolic compounds and Cascade and Victorialeaves presented the highest values of saponine concentration. All hop extractspresent low toxicity against bees after 48h of topical administration (a maximum of 36%of bee mortality for Cascade ethanolic extract). Minimum Inhibitory Concentration(MIC) and Minimum Bacteridicidal Concentrations (MBC) values ranged from 0.69 to2.75 ppm for the Cascade variety; 1.38 to 5.5 ppm for the Spalt variety and 5.5 to 11ppm for the Victoria variety. After 48h, the acaricidal activity for an ethanolic extract ofthe Victoria variety reached values close to 80%, while the methanolic extract ofCascade showed an acaricidal activity close to 70%. The results reported in this studysupport the potential use of methanolic and ethanolic extracts of hop leaves fromArgentina as promising natural alternatives for varroosis and american foulbroodcontrol.