Sanitary and nutritional characterization of honeybee colonies in Eucalyptus grandis plantations

Abstract

SUMMARYIn Uruguay, many beekeepers transport their colonies to Eucalyptus grandis plantations at the end of the summer and autumn, obtaining important honey harvests. However, at the end of the flowering period the colonies become extremely weakened undergoing high levels of mortality. Nutritional and health problems could explain the weakening of colonies. In order to find out the causes for this weakening, colonies of the same size were taken to an E. grandis plantation, split up in three groups differentiated by the availability of pollen. Throughout the flowering period we registered: the botanical origins and crude protein content of the incoming pollen, the body protein of the bees, the infection by Nosema ceranae and the infestation of Varroa destructor, the brood area and the production of honey. The most important findings were: i) the sustained decline in botanical diversity of pollen as the flowering period of E. grandis advanced until only pollen from this species remained; ii) pollen from E. grandis presented crude protein values close to 30%, but these gradually diminished reaching values lower than 20% towards the end of the flowering period; iii) those colonies which initially counted on pollen reserves presented bees with higher body protein a few days after settling in the plantation and lower levels of infection with N. ceranae during most of the flowering period; iv) pollen availability did not affect levels of infection by V. destructor, size of the brood area or honey production. Bee's nutritional deficit during E. grandis flowering could generate adequate conditions for the multiplication of N. ceranae. At the end of the Eucalyptus' flowering period colonies presented on average more than 90% of foraging workers infected with N. ceranae and 12% infection of adult bees with V. destructor. Incidence of both pathogens in weakened bees could explain colony losses. RESUMENEn Uruguay muchos apicultores trasladan sus colonias a las forestaciones de Eucalyptus grandis al final del verano y en otoño obteniendo importantes cosechas de miel. Sin embargo, cuando finaliza la floración las colonias se encuentran muy debilitadas, sobreviniendo una elevada mortalidad. Problemas nutricionales y sanitarios podrían explicar el debilitamiento de las colonias. Para averiguar las causas del debilitamiento se llevaron colonias de igual tamaño a una forestación de E. grandis, separadas en tres grupos diferenciados por la disponibilidad de polen. A lo largo del periodo de floración se registró: el origen botánico y el contenido de proteína cruda del polen que ingresaba en las colmenas, la proteína corporal de las abejas, la infección por Nosema ceranae y la infestación por Varroa destructor, el área de cría y la producción de miel. Los resultados más importantes hallados fueron: i) la sostenida disminución de la diversidad botánica del polen a meArchivos de zootecnia vol. 60, núm. 232, p. 1304. INVERNIZZI, SANTOS, GARCÍA, DANERS, DI LANDRO, SAADOUN AND CABRERA dida que transcurría el periodo de floración de E. ...

Pharmacophagy and pharmacophory: mechanisms of self-medication and disease prevention in the honeybee colony (Apis mellifera)

“…On the contrary, nutritional enrichment by protein feeding seems to be linked with an expansion of the bees' midgut, facilitating an increase in Nosema spore production (Beutler and Opfinger 1950;Rinderer and Elliot 1977). However, colonies fed with pollen from diverse botanical origins had lower levels of N. ceranae spores compared to colonies fed only with monofloral pollen (Invernizzi et al 2011). Again, this result remains inconclusive regarding a Basualdo et al 2014 differentiation between potential malnutrition and true self-medication.…”

Honeybee colony losses in Uruguay during 2013–2014

“…Other bee pathogens, such as Paenibacillus larvae , the causative agent of American foulbrood, Melissococcus pluton , the causative agent of European foulbrood, and Ascosphaera apis , the causative agent of Chalkbrood disease, are also present. Clinical infections with these pathogens occur relatively infrequently and are not thought to represent an important threat to the beekeeping industry (Antunez et al 2012;Invernizzi et al 2011). Additionally, there have been documented cases of pesticide kills, specifically from fipronil and imidacloprid exposure (Pareja et al 2011).…”

Nosema ceranae (Microsporidia), a controversial 21st century honey bee pathogen

“…Given the direct relationship between N. ceranae and colony losses in Spain (Higes et al, 2009a;, Spanish research groups have actively sought to develop strategies to minimize the economic losses inflicted upon the professional sector by this microsporidium. Some studies have suggested a link between this pathogen and bee colony depopulation/loss in other countries with similar climatic conditions (Higes et al, 2005;Bacandritsos et al, 2010;Borneck et al, 2010;Hatjina et al, 2011;Invernizzi et al, 2011;Soroker et al, 2011). By contrast, in countries from colder climates, the role for this microsporidium in colony loss has been ruled out (Gisder et al, 2010;Hedtke et al, 2011;Stevanovic et al, 2011;Dainat et al, 2012a,b), suggesting that specific conditions are required to promote these pathogenic effects of N. ceranae.…”