Limitation of complementary resources affects colony growth, foraging behavior, and reproduction in bumble bees

Resource availability in agricultural landscapes has been disturbed for many organisms, including pollinator species. Abundance and diversity in flower availability benefit bee populations; however, little is known about which of protein or carbohydrate resources may limit their growth and reproductive performance. Here, we test the hypothesis of complementary resource limitation using a supplemental feeding approach. We applied this assumption with bumble bees (Bombus terrestris), assuming that colony growth and reproductive performance should depend on the continuous supply of carbohydrates and proteins, through the foraging for nectar and pollen, respectively. We placed wild‐caught bumble bee colonies along a landscape gradient of seminatural habitats, and monitored the colonies’ weight, foraging activity, and reproductive performance during the whole colony cycle. We performed supplemental feeding as an indicator of landscape resource limitation, using a factorial design consisting of the addition of sugar water (carbohydrate, supplemented or not) crossed by pollen (protein, supplemented or not). Bumble bee colony dynamics showed a clear seasonal pattern with a period of growth followed by a period of stagnation. Higher abundance of seminatural habitats resulted in reducing the proportion of pollen foragers relative to all foragers in both periods, and in improving the reproductive performance of bumble bees. Interestingly, the supplemental feeding of sugar water positively affected the colony weight during the stagnation period, and the supplemental feeding of pollen mitigated the landscape effect on pollen collection investment. Single and combined supplementation of sugar water and pollen increased the positive effect of seminatural habitats on reproductive performance. This study reveals a potential colimitation in pollen and nectar resources affecting foraging behavior and reproductive performance in bumble bees, and indicates that even in mixed agricultural landscapes with higher proportions of seminatural habitats, bumble bee populations face resource limitations. We conclude that the seasonal management of floral resources must be considered in conservation to support bumble bee populations and pollination services in farmlands

The economic cost of losing native pollinator species for orchard prodution

The alarming loss of pollinator diversity world‐wide can reduce the productivity of pollinator‐dependent crops, which could have economic impacts. However, it is unclear to what extent the loss of a key native pollinator species affects crop production and farmer's profits. By experimentally manipulating the presence of colonies of a native bumblebee species Bombus pauloensis in eight apple orchards in South Argentina, we evaluated the impact of losing natural populations of a key native pollinator group on (a) crop yield, (b) pollination quality, and (c) farmer's profit. To do so, we performed a factorial experiment of pollinator exclusion (yes/no) and hand pollination (yes/no). Our results showed that biotic pollination increased ripe fruit set by 13% when compared to non‐biotic pollination. Additionally, fruit set and the number of fruits per apple tree was reduced by less than a half in those orchards where bumblebees were absent, even when honeybees were present at high densities. Consequently, farmer's profit was 2.4‐fold lower in farms lacking bumblebees than in farms hosting both pollinator species. The pollination experiment further suggested that the benefits of bumblebees could be mediated by improved pollen quality rather than quantity. Synthesis and applications. This study highlights the pervasive consequences of losing key pollinator functional groups, such as bumblebees, for apple production and local economies. Adopting pollinator‐friendly practices such as minimizing the use of synthetic inputs or restoring/maintaining semi‐natural habitats at farm and landscape scales, will have the double advantage of promoting biodiversity conservation, and increasing crop productivity and profitability for local farmers. Yet because the implementation of these practices can take time to deliver results, the management of native pollinator species can be a provisional complementary strategy to increase economic profitability of apple growers in the short term.info:eu-repo/semantics/acceptedVersio

Estudios sobre el comportamiento de aprendizaje de la abeja revelan su capacidad para discriminar tipos de polen

Cuando las abejas perciben una solución azucarada (Ej. néctar), extienden su probóscide para absorberla. Esta reacción se llama reflejo de extensión de la probóscide (REP). Si un estímulo inicialmente neutro (color, forma, olor) antecede la percepción de solución azucarada, la abeja asociará los dos estímulos (condicionamiento). Luego, el primer estímulo provocará el REP. Si bien las abejas se alimentan con néctar y/o polen de diversas plantas, prefieren recolectar siempre de una misma especie mientras tenga flores disponibles (constancia floral). En el curso del año, las flores disponibles son diferentes, por lo tanto la abeja prefiere recolectar en flores percibidas similares a las ya conocidas (generalización).Estación Experimental Agropecuaria BarilocheFil: Pietrantuono, Ana Laura. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Requier, Fabrice. CONICET. CCT Patagonia Norte; ArgentinaFil: Fernández-Arhex, Valeria Cristina. Instituto Nacional de Tecnología Agropecuaria (INTA).Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Winter, Josefina. INTI. Sede Neuquén; ArgentinaFil: Huerta, Guillermo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Sistemas de Producción y Territorios; ArgentinaFil: Guerrieri, Fernando. Université de Tours. Institut de Recherche sur la Biologie de l’Insecte; Franci

Honeybee impact on plants and wild bees in natural habitats

La abeja melífera (Apis mellifera L.) es una especie que, por su utilidad, se ha expandido gracias al Hombre por todo el globo, siendo la principal especie de abeja invasora. A pesar de ser considerada una especie benéfica, existe controversia en torno a los impactos que puede provocar su alta densidad en hábitats naturales. Aquí revisamos los principales efectos y mecanismos atribuidos a un incremento en la abundancia de la abeja melífera sobre plantas y abejas silvestres. Encontramos que los impactos pueden ser positivos y negativos, jugando un papel importante el contexto ecológico (disponibilidad de recursos, comunidad de polinizadores silvestres) como también la densidad de la abeja melífera. Los efectos ocurren a escala de individuo, población y comunidad afectando las redes planta-polinizador mientras que las consecuencias para el funcionamiento de los ecosistemas son inciertas. Recientemente se ha demostrado que la abeja melífera puede actuar como agente de selección afectando la evolución de plantas en un lapso relativamente breve de tiempo. La transmisión de parásitos y patógenos de la abeja melífera a otras especies de abejas ha ganado relevancia en este último tiempo. Si bien la abeja melífera puede beneficiar la polinización de plantas silvestres, al ser los impactos en abejas casi puramente negativos es necesario ser cautelosos con la introducción de colmenas en áreas naturales; particularmente hasta no determinar las consecuencias de la transmisión de parásitos y patógenos.The honey bee (Apis mellifera L.) has been spread all over the world by humans and is now the most widespread bee invasive species. In spite of being considered a beneficial species, there is a controversy around its impact on natural habitats caused by its high densities. Here we review the most important effects and mechanisms attributed to an increase in honey bee abundance on plants and wild bees. We found that the impacts can be negative and positive as well, playing an important role the ecological context (resource availability, wild pollinator community, etc.) and the honey bee density. Effects occur at the individual, population, and community level, affecting plant-pollinator networks, while the consequences for ecosystem functioning and crop pollination are still uncertain. It has been recently shown that the honey bee can also act as a selective force affecting plant evolution in a relative short time. The parasite and pathogen transmission from honey bees to wild pollinators has become a relevant issue in the last years. Although honey bees can benefit wild plants pollination, because impacts in other bees are primary negative, we should be careful with hives introduction at natural sites. Especially until we can determine the parasites and pathogen transmission consequences.Fil: Agüero, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Rollin, Orianne. Universidad Nacional de Río Negro; ArgentinaFil: Torretta, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Aizen, Marcelo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Requier, Fabrice. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de Río Negro; ArgentinaFil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de Río Negro; Argentin

The conservation of native honey bees is crucial

Recent studies have emphasized the role of the western honey bee, Apis mellifera, as a managed agricultural species worldwide, but also as a potential threat to endangered wild pollinators. This has resulted in the suggestion that honey bees should be regulated in natural areas to conserve wild pollinators. We argue that this perspective fails to appreciate the multifaceted nature of honey bees as native or introduced species with either managed or wild colonies. Wild populations of A. mellifera are currently imperiled, and natural areas are critical for the conservation of local subspecies and genotypes. We propose that a differentiation between managed and wild populations is required and encourage integrated conservation planning for all endangered wild bees, including A. mellifera.http://www.cell.com/trends/ecology-evolution/home2020-09-01hj2020Zoology and Entomolog

Écologie des abeilles mellifères en paysage agricole intensif : le prix caché d’une ressource florale fluctuante

Honeybee ecology in intensive farmland habitats : the hidden cost of a fluctuating floral resource. The agricultural intensification is considered as a major cause of biodiversity decline, causing a typical disturbance in resource dynamics for many species. Surprisingly, this disturbance is few investigated yet on the global decline of honeybee populations. This study, carried out on free-ranging honeybees, confirms the negative impact of floral resource dynamic on honey bee ecology in intensive cereal farming system. Indeed, the three major crops, i. e. rapeseed, sunflower and maize have created a temporal resource dynamic which causes a strong temporal lack in pollen and nectar. By a priori adaptive mechanisms, colonies and individuals adapt their behaviours and life histories in response to the food-lack. However, these trade-off mechanisms in resource allocation have a significant cost and generate a weakening of colonies that increases overwintering mortality. These results bring up the need to enhance the floral resource availability in agricultural landscapes in order to stop the widespread decline of honeybees populations. These results are discussed so as to build conservation measures on the honeybee, beekeeping and pollination service in intensive agricultural landscapes.L’intensification de l’agriculture est désignée comme une cause majeure dans le déclin de la biodiversité, causant en particulier une perturbation dans la dynamique des ressources pour de nombreuses espèces. De façon surprenante cette cause n’est que très peu explorée à l’heure actuelle sur l’effondrement généralisé des populations d’abeilles mellifères. Cette étude, menée en plein champ, confirme l’impact négatif de la dynamique des ressources florales sur l’écologie de l’abeille mellifères en paysage céréalier intensif. En effet, la dynamique des ressources dominées par trois cultures majeures que sont le colza, le tournesol et le maïs, provoque l’apparition d’une pénurie alimentaire en pollen et nectar. Par des mécanismes a priori adaptatifs, les individus et les colonies régulent leurs comportements et histoires de vie en réponse à cette pénurie. Cependant, ces mécanismes de compromis d’allocation des ressources ont un coût important et peuvent aboutir à un affaiblissement des colonies, se traduisant par une surmortalité hivernale. Ces résultats évoquent la nécessité de reconsidérer l’importance du manque de ressources florales en céréaliculture intensive dans le déclin de l’abeille mellifère. Ces travaux se tournent vers la conception de mesures de conservation de l’abeille domestique, de l’apiculture et du service de pollinisation en paysages agricoles intensifs.Requier Fabrice. Écologie des abeilles mellifères en paysage agricole intensif : le prix caché d’une ressource florale fluctuante. In: Bulletin de la Société entomologique de France, volume 120 (2),2015. pp. 121-127