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Bumble bees are an ecologically and economically important group of pollinating insects worldwide. Global climate change is predicted to affect bumble bee ecology including habitat suitability and geographic distribution. Our study aims to estimate the impact of projected climate change on 18 Mesoamerican bumble bee species. We used ecological niche modeling (ENM) using current and future climate emissions scenarios (representative concentration pathway 4.5, 6.0, and 8.5) and models (CCSM4, HadGEM2-AO, and MIROC-ESM-CHEM). Regardless of the scenario and model applied, our results suggest that all bumble bee species are predicted to undergo a reduction in their potential distribution and habitat suitability due to projected climate change. ENMs based on low emission scenarios predict a distribution loss ranging from 7% to 67% depending on the species for the year 2050. Furthermore, we discovered that the reduction of bumble bee geographic range shape will be more evident at the margins of their distribution. The reduction of suitable habitat is predicted to be accompanied by a 100-500 m upslope change in altitude and 1-581 km shift away from the current geographic centroid of a species' distribution. On average, protected natural areas in Mesoamerica cover ~14% of each species' current potential distribution, and this proportion is predicted to increase to ~23% in the high emission climate change scenarios. Our models predict that climate change will reduce Mesoamerican bumble bee habitat suitability, especially for rare species, by reducing their potential distribution ranges and suitability. The small proportion of current and future potential distribution falling in protected natural areas suggests that such areas will likely have marginal contribution to bumble bee habitat conservation. Our results have the capacity to inform stakeholders in designing effective landscape management for bumble bees, which may include developing restoration plans for montane pine oak forests habitats and native flowering plants.

Climate oscillations have left a significant impact on the patterns of genetic diversity observed in numerous taxa. In this study, we examine the effect of Quaternary climate instability on population genetic variability of a bumble bee pollinator species, Bombus huntii in western North America. Pleistocene and contemporary B. huntii habitat suitability (HS) was estimated with an environmental niche model (ENM) by associating 1,035 locality records with 10 bioclimatic variables. To estimate genetic variability, we genotyped 380 individuals from 33 localities at 13 microsatellite loci. Bayesian inference was used to examine population structure with and without a priori specification of geographic locality. We compared isolation by distance (IBD) and isolation by resistance (IBR) models to examine population differentiation within and among the Bayesian inferred genetic clusters. Furthermore, we tested for the effect of environmental niche stability (ENS) on population genetic diversity with linear regression. As predicted, high‐latitude B. huntii habitats exhibit low ENS when compared to low‐latitude habitats. Two major genetic clusters of B. huntii inhabit western North America: (a) a north genetic cluster predominantly distributed north of 28°N and (b) a south genetic cluster distributed south of 28°N. In the south genetic cluser, both IBD and IBR models are significant. However, in the north genetic cluster, IBD is significant but not IBR. Furthermore, the IBR models suggest that low‐latitude montane populations are surrounded by habitat with low HS, possibly limiting dispersal, and ultimately gene flow between populations. Finally, we detected high genetic diversity across populations in regions that have been climatically unstable since the last glacial maximum (LGM), and low genetic diversity across populations in regions that have been climatically stable since the LGM. Understanding how species have responded to climate change has the potential to inform management and conservation decisions of both ecological and economic concerns.

Summary Traditional tropical agriculture often entails a form of slash‐and‐burn land management that may adversely affect ecosystem services such as pollination, which are required for successful crop yields. The Yucatán Peninsula of Mexico has a >4000 year history of traditional slash‐and‐burn agriculture, termed ‘milpa’. Hot ‘Habanero’ chilli is a major pollinator‐dependent crop that nowadays is often grown in monoculture within the milpa system.We studied 37 local farmers’ chilli fields (sites) to evaluate the effects of landscape composition on bee communities. At 11 of these sites, we undertook experimental pollination treatments to quantify the pollination of chilli. We further explored the relationships between landscape composition, bee communities and pollination service provision to chilli.Bee species richness, particularly species of the family Apidae, was positively related to the amount of forest cover. Species diversity decreased with increasing proportion of crop land surrounding each sampling site. Sweat bees of the genus Lasioglossum were the most abundant bee taxon in chilli fields and, in contrast to other bee species, increased in abundance with the proportion of fallow land, gardens and pastures which are an integral part of the milpa system.There was an average pollination shortfall of 21% for chilli across all sites; yet the shortfall was unrelated to the proportion of land covered by crops. Rather, chilli pollination was positively related to the abundance of Lasioglossum bees, probably an important pollinator of chilli, as well indirectly to the proportion of fallow land, gardens and pastures that promote Lasioglossum abundance. Synthesis and applications. Current, low‐intensity traditional slash‐and‐burn (milpa) agriculture provides Lasioglossum spp. pollinators for successful chilli production; fallow land, gardens and pasture therefore need to be valued as important habitats for these and related ground‐nesting bee species. However, the negative impact of agriculture on total bee species diversity highlights how agricultural intensification is likely to reduce pollination services to crops, including chilli. Indeed, natural forest cover is vital in tropical Yucatán to maintain a rich assemblage of bee species and the provision of pollination services for diverse crops and wild flowers., Current, low‐intensity traditional slash‐and‐burn (milpa) agriculture provides Lasioglossum spp. pollinators for successful chilli production; fallow land, gardens and pasture therefore need to be valued as important habitats for these and related ground‐nesting bee species. However, the negative impact of agriculture on total bee species diversity highlights how agricultural intensification is likely to reduce pollination services to crops, including chilli. Indeed, natural forest cover is vital in tropical Yucatán to maintain a rich assemblage of bee species and the provision of pollination services for diverse crops and wild flowers.

International audience; The conservation of pollinator diversity is fundamental to maintaining sustainable agricultural systems and food security. Some agricultural systems support pollinator diversity, while others may lead to their decline. Previous studies have evaluated the impacts of agricultural intensification on pollinators in temperate climates regions, but in tropical regions these impacts have been evaluated by only very few studies. We conducted a study in southeastern Mexico, in order to understand the effects of three agricultural systems on bee diversity in a tropical landscape. We compared 18 sites at two different scales (plot scale and landscape scale). We found a link between agricultural system intensity level at the plot scale and forest proportion at the landscape scale: land use intensity was low at both scales in 7 polycultures, low at plot scale and high at landscape scale in 4 pastures, and high at both scales in 7 monocultures. We collected bees at all sites, and found an overall high bee richness, with a total of 127 species. Bee richness was compared across agricultural systems using diversity accumulation curves with iNEXT package. Both polycultures and pastures had significantly higher richness as monocultures. We constructed bee species guilds according to ecological and life-history traits (i.e. size, sociality and nesting) and found that whatever the trait considered, the species richness in the different agricultural systems was most often affected in the same way than the complete community richness. Our results show, for the first time in tropical conditions that agricultural systems with low-intensity farming practices and forested landscape allow the preservation of a significantly higher diversity of bees than agricultural systems with high-intensity farming practices and highly deforested landscape. Considering that bee diversity is key to maintaining crop productivity, these findings can help scientists, policy-makers, and community members design policies that support both agricultural production and biodiversity conservation in the tropics.

Mexico and Central America are among the most biodiverse regions on Earth, harboring many species with high levels of interpopulation morphological and genetic diversity. The mountainous topography of this region contains isolated sky island habitats that have the potential to promote speciation. This has been studied in vertebrates, yet few studies have examined the phylogeographic and genetic structure of insect species encompassing this region. Here we investigate geographic patterns of genetic and morphological divergence and speciation among widespread populations of the highly polymorphic bumble bee Bombus ephippiatus and its closest relative B. wilmattae. We used DNA sequences from a fragment of cytochrome oxidase I (COI), genotypes for twelve microsatellite markers, and morphometric data from wings to construct a well-supported inference of the divergences among these taxa. We have found complex patterns of genetic isolation and morphological divergence within B. ephippiatus across its geographic range and present evidence that B. ephippiatus comprises multiple independent evolutionary lineages. The pattern of their diversification corresponds to geographic and environmental isolating mechanisms, including the Mexican highlands, the lowlands of the Isthmus of Tehuantepec in southern Mexico, the Nicaraguan Depression, the patchily distributed volcanic ranges in Nuclear Central America and Pleistocene glacial cycles. These results have important implications for the development and distribution of B. ephippiatus as a commercial pollinator in Mexico and Central America.

When coffee is grown under shade trees, as in Mexico and Guatemala, coffee landscapes are complex and offer a high diversity of plants to the bees. This study focuses on the manner in which bees adapt their foraging behavior as a function of variation in tree coverage on a landscape scale. Study sites were characterized by satellite images and categorized according to percentage of tree cover: low (50–62%), medium (63–77%), and high (77–83%). Honey samples were collected from several apiaries in each landscape. In order to identify resources used by Apis mellifera, samples were analyzed according to melissopalynology. A random forest model analysis performed to compare different honeys did not show significant differences between honeys in any given landscape. Nevertheless, percentage of tree cover was positively correlated, in a significant manner, with the relative proportion of pollen from trees and from shrubs present in honey samples. These analyses, along with physical–chemical and sensory analyses ...

"Se aportan nuevos registros a la fauna de abejas sin aguijón (tribu Meliponini) para los estados de Oaxaca y Chiapas. Para ello, se hicieron muestreos intensivos de estas abejas, con lo cual se reunieron registros de distribución, incluyendo las aportadas por investigadores, las presentes en colecciones y los reportados en la literatura. Se tienen 12 registros nuevos de especies de abejas sin aguijón para Oaxaca y se confirma la presencia en Chiapas de Paratrigona opaca. Adicionalmente, se discute sobre la distribución de estas abejas en estos estados y el país. Se espera que la información sobre la fauna y la distribución de las abejas sin aguijón ayude en los esfuerzos de conservación regional, uso de estas abejas en la meliponicultura y la polinización."

Despite their relevant contribution to the conservation of tropical ecosystems and crop productivity through pollination, the stingless bees (Apidae: Meliponini) can be considered a group of neglected species in the assessment of pesticides upon nontarget organisms. In this article, we evaluated the effect of aerial sprays of the spinosad-based fruit fly toxic bait GF-120 upon colonies of the stingless bee Scaptotrigona mexicana Guerin (Hymenoptera: Apidae), an economically important and abundant species in some landscapes of Mexico, located in mango orchards. Colonies of the honey bee Apis mellifera L. (Hymenoptera: Apidae) were used for comparison. Eight colonies (four of A. mellifera and four of S. mexicana) were moved into each of two mango orchards, one was used as a control, with no insecticide application, and other received five weekly aerial sprays of GF-120. Foraging activity and strength of colonies of both species were measured nine times over the fruiting season, previous, during and after insecticide application. We did not find a significant difference in foraging activity and strength between exposed and control colonies of A. mellifera during the observation period. However, colonies of S. mexicana seemed to be affected by the exposure, as revealed by a reduction in colony strength. However, 1 yr later, with no insecticide applications, the colonies of both species were evaluated and found to be in good conditions. Our results showed that weekly aerial sprays of GF-120 are unlikely to generate acute poisoning in both species, even if in acute toxicity tests this product has been found to be highly active.

In this study, drone congregations of the stingless bee Scaptotrigona mexicana Guerin were genetically analyzed at 5 microsatellite loci to estimate the number of colonies of this species in the La Sepultura Biosphere Reserve, in Chiapas, Mexico. A total of 216 drones from 3 congregations were analyzed. We found that the 3 congregations had enough genetic differences to be considered as coming from different populations. The average number (± SD) of colonies per congregation was 19.8 ± 0.63, 17.6 ± 0.70 and 12. A similar result was reported for areas where stingless beekeeping occurs. We discuss the implications of our findings in a conservation framework in which stingless beekeeping might play a significant role.

In this paper, we show the results of investigating the presence of organochlorine pesticides in honey and pollen samples from managed colonies of the honey bee, Apis mellifera L. and of the stingless bee Scaptotrigona mexicana Guérin. Three colonies of each species were moved into each of two sites. Three samples of pollen and three samples of honey were collected from each colony: the first collection occurred at the beginning of the study and the following ones at every six months during a year. Thus the total number of samples collected was 36 for honey (18 for A. mellifera and 18 for S. mexicana) and 36 for pollen (18 for A. mellifera and 18 for S. mexicana). We found that 88.44% and 93.33% of honey samples, and 22.22% and 100% of pollen samples of S. mexicana and A. mellifera, respectively, resulted positive to at least one organochlorine. The most abundant pesticides were Heptaclor (44% of the samples), γ-HCH (36%), DDT (19%), Endrin (18%) and DDE (11%). Despite the short foraging range of S. mexicana, the number of pesticides quantified in the honey samples was similar to that of A. mellifera. Paradoxically we found a small number of organochlorines in pollen samples of S. mexicana in comparison to A. mellifera, perhaps indicating a low abundance of pollen sources within the foraging range of this species.

The Latin American subcontinent contains some of the world’s major honey producing and exporting countries, but the status of bee health in this part of the world has not been clearly documented. There have been no reports of massive colony losses in Latin America, at least from the symptoms of CCD (colony collapse disorder) or in the proportion and extent of the situations in the US and Europe. We examine possible reasons for the difference, and develop hypotheses that this prevailing good bee health could be due to: (1) the management of generally unselected bees with a certain natural resistance to diseases (tropical regions) or the selection of disease resistant bees (temperate regions); (2) a lower proportion of cropland over the total land area, resulting in more abundant or higher-quality pollen resources for bees; (3) the generally small-scale, low-income and little subsidized agriculture, and concomitant lower use of insecticides compared to industrialized countries. These general parameters may act synergistically, resulting in a large number of configurations across the tremendous ecological, social and economic diversity of Latin America. We suggest that the health of honey bees in Latin America may be ultimately due to the practices of low-income agriculture and beekeeping in the region, leading to more sustainable conditions for the bees. However the increasing trend of land use intensification in some parts of Latin America could lead to declines in honey bee health and population size.

As a general rule, within an ecological guild, there is one species that is dominant and is commonly the most abundant. The aim of this work was to investigate if such pattern occurs intraspecifically, among colonies of the stingless bee Scaptotrigona mexicana Guerin. Through behavioral and molecular techniques, we found preliminary evidence that apparently colonies of this species do not monopolize resources, instead they seem to share food; however, some colonies had more foragers in a food patch or in a feeder, so some type of exclusion could be at work, though we could not determine the final output of such interaction, i.e., if underrepresented colonies were eventually excluded, developed slower or were overrepresented in other food patches. Our results give evidence that resource partitioning within this species occurs peacefully; however, further studies are necessary to determine if threatening behavior or aggressions appear when resources are scarce and competition becomes harsher.

Bumblebees are highly valued for their pollination services in natural ecosystems as well as for agricultural crops. These precious pollinators are known to be declining worldwide, and one major factor contributing to this decline are infections by parasites. Knowledge about parasites in wild bumblebee populations is thus of paramount importance for conservation purposes. We here report the geographical distribution of Crithidia and Nosema, two common parasites of bumblebees, in a yet poorly investigated country: Mexico. Based on sequence divergence of the Cytochrome b and Glycosomal glyceraldehyde phosphate deshydrogenase (gGPDAH) genes, we discovered the presence of a new Crithidia species, which is mainly distributed in the southern half of the country. It is placed by Bayesian inference as a sister species to C. bombi. We suggest the name Crithidia mexicana for this newly discovered organism. A population of C. expoeki was encountered concentrated on the flanks of the dormant volcanic mountain, Iztaccihuatl, and microsatellite data showed evidence of a bottleneck in this population. This study is the first to provide a large-scale insight into the health status of endemic bumblebees in Mexico, based on a large sample size (n=3,285 bees examined) over a variety of host species and habitats.

Nous avons mene une etude afin d'evaluer la croissance de la population de Varroa destructor dans des colonies d'abeilles africanisees et dans deux types de colonies mixtes (europeenne hygienique x africanisee et europeenne commerciale x africanisee) au Mexique. La contribution relative des trois mecanismes qui conferent aux abeilles la resistance a l'acarien a ete estimee toutes les cinq semaines durant une annee. Sur les 46 colonies d'origine, 18 colonies, dont six de chaque type, ont survecu jusqu'a la fin de l'etude avec leur reine d'origine. Les mesures des mecanismes de resistance ont ete evalues par les protocoles suivants : (i) comportement hygienique (pourcentage de couvain tue par le froid elimine), (ii) comportement de toilettage (proportion d'acariens mutiles sur un plateau de fond enduit de matiere grasse), (iii) capacite de reproduction du parasite par la fertilite (proportion d'acariens qui se reproduisent), (iv) fecondite (nombre total de descendants par fondatrice) et (v) nombre de descendants femelles fecondees produites par fondatrice (Wr). Les populations d'abeilles et d'acariens des 18 colonies ont varie de facon significative en fonction du temps et des trois types d'abeilles (Figs. 1 et 2). Des changements significatifs au cours de l'annee ont ete observes pour Wr, la fertilite et la mutilation des acariens (Figs. 3 et 4). Ces changements correspondaient aux variations du nombre estime d'acariens par colonie. Des differences significatives en fonction de la periode de l'annee et du type d'abeilles ont ete trouvees pour le comportement hygienique (Fig. 3), bien qu'aucune des colonies n'ait pu etre consideree comme fortement hygienique, puisque l'elimination du couvain mort a toujours ete inferieure a 95 %. Le comportement hygienique ne correspondait aux fluctuations des populations d'abeilles ou d'acariens. Nous emettons l'hypothese que si les mecanismes de resistance ont un effet sur la croissance de la population d'acariens, l'effet se fera sentir dans la periode d'echantillonnage suivante (cinq semaines plus tard) et pas immediatement. L'analyse factorielle a montre que les deux mecanismes rendaient compte de la variation d'acariens par colonie au cours du temps : Wr (r 2 = 0,732 ; P = 0,003 ; n = 9 ; Fig. 5a) et de la proportion d'acariens mutiles (r2 = 0,506 ; P = 0,032 ; n = 9 ; Fig. 5c). Quand on inclut ces deux mecanismes, on trouve un modele multi-factoriel significatif (r2 = 0,973 ; P = 0,0001 ; n = 9). Aucune difference n'a ete observee entre les abeilles africanisees et les colonies d'abeilles croisees dans le degre d'expression des mecanismes de resistance.

The case of a host-parasite relationship may provide a good model to evaluate the costs and bene- fits of some behaviors, an area in which field data a currently lacking. European (EHB) and Africanized (AHB) honey bees are two Apis mellifera subspecies that coexist in Mexico, the former highly compatible with Varroa destructor, the latter less compatible. Here we examine two mechanisms that could explain the low compatibility between AHB and V. destructor in Mexico: (1) grooming behavior appeared significantly more intensive in AHB colonies, but was nevertheless ineffective; (2) EHB removed 8.03% of the infested brood, while AHB removed 32.46%, especially between 5 and 7 days post-capping. Though the cost of re- moving infested brood was not different between subspecies, the result, in terms of the amount of removed in- fested brood, was significantly higher for AHB. For both bees, there is thus a real cost, since removing a pupa results in a lower number of adult bees. We discuss the possibility that the removal of infested brood corre- sponds with a threshold above which the cost of removal becomes greater than the benefit. Apis mellifera / Varroa destructor / parasitology / costs and benefits / behavioral resistance

La relation dose de fluvalinate-mortalite de l'acarien a ete construite a partir de parasites preleves sur trois types de ruchers : i) ruchers ou l'apiculteur n'observe pas de parasites apres traitement; ii) ruchers ou l'apiculteur ne remarque que quelques parasites apres traitement ou ruchers places a proximite de ruchers dans lesquels le traitement au fluvalinate a ete inefficace ; iii) ruchers ou la varroose demeure grave malgre la repetition des traitements avec cet acaricide. Sept dilutions de la formulation commerciale Klartan (240g/L de fluvalinate), espacees selon une progression geometrique de raison deux (figs 1, 2 et 3 en abscisse), ont ete pulverisees sur le fond de boites de Petri pour obtenir un depot de 1,5 a 2 mg par cm 2 . Soixante parasites, extraits du couvain, ont ete mis en contact avec chaque dilution, pour une colonie. La mortalite a ensuite ete relevee apres 24 et 48 h d'incubation a 33 °C et 50 % d'humidite relative. Le type de la regression dose-letalite a ete choisi en fonction du meilleur ajustement aux donnees experimentales puisque la population parasitaire d'une colonie est vraisemblablement composee des deux phenotypes resistant et sensible. Dans un cas (figs 3 et 4), nous avons applique la regression segmentaire d'Otto. Les CL50 a 24 h varient entre 0,73 et 131,54 ng de fluvalinate par cm 2 et les CL90 a 24 h entre 2,83 et 259,52 ng/cm 2 (tableau I). Lorsqu'on utilise la regression segmentaire d'Otto, la CL50 des parasites les plus sensibles est de 2 ng/cm 2 et de 128 ng/cm 2 pour les resistants (fig 4). L'hypothese de l'existence des deux phenotypes (resistant et sensible) dans la population parasitaire d'une colonie est donc confortee. Le coefficient de resistance le plus eleve est de 182,7 (tableau I), ce qui rend inutile toute augmentation de dose therapeutique lors d'une baisse d'efficacite du traitement. L'emergence de la resistance serait soupconnee si des parasites provenant d'une meme colonie et soumis 24 h a la concentration de 10 ng/cm 2 , demeuraient vivants.

International audience; The number of colonies in feral and managed honeybee populations (Apis mellifera) was determined for various sampling locations in Chiapas and Yucatan (Mexico) to assess the impact of apiculture on feral honeybee populations. We used a comparative sampling approach determining the number of colonies in similar habitats and landscapes but with different intensity of beekeeping. Sampling sites included nature reserves, and mango and shaded coffee plantations. The agricultural sites were all set in high-diversity landscapes with plenty of surrounding secondary forest. The number of colonies was determined by genotyping drones caught on drone congregation areas and assigning the drone genotypes to mother queens each heading a colony. We used three sets of linked markers each to achieve sufficient resolution for a precise colony assignment. The estimated colony numbers ranged from 34 to 54 colonies, with an average of 38.3 ± 6.9 colonies in areas with high and 43.5 ± 6.6 colonies in areas with low beekeeping activity. There was no significant difference in colony numbers between the sites with high and low beekeeping activity suggesting that the managed honeybee populations do not substantially add to the overall number of honeybee colonies supported in the wild. This might indicate that restrictions on apicultural activities to prevent any potential conservation conflict with native pollinators might not be useful, since honeybee colonies are very abundant in many different landscapes in Southern Mexico independent of apiculture.

International audience; So far, nearly all studies concerning the mating frequency of bumblebees have been conducted with temperate species, showing that single mating seems to be the predominant pattern in bumblebees. Studies involving tropical species, however, are still scarce. Here, we determined the mating frequency of queens of the tropical bumblebee species, Bombus wilmattae by using microsatellite genotyping based on a sample of nine colonies from Chiapas, Southern Mexico. A total of 204 workers were genotyped with microsatellite markers to infer the queen genotype and the number of males with which each queen had mated. Two of the nine queens were doubly mated and seven singly mated. In the colonies with the double-mated queens, the distribution of the patrilines was not even, resulting in effective mating frequencies of 1.34 and 1.70, respectively, and an average relatedness of g = 0.58 ± 0.06.

International audience; The Africanization of the honeybee (Apis mellifera) in South America is one of the most spectacular examples of biological invasions. In this study, we analyzed the Africanization process in Central Mexico along an altitudinal transect from 72 to 2800 m, using both mitochondrial and nuclear DNA markers. The mitochondrial analysis revealed that the two high-altitude populations had a significantly greater percentage of African mitotypes (95%) than the three lowland populations (67%), indicating successful spreading of Africanized swarms to these altitudes. All populations (highland and lowland) had a similar overall proportion of African alleles at nuclear loci (58%). Thus, all populations showed an asymmetric introgression of African nuclear and mtDNA. Colonies with African mitotypes had, on average, significantly more African nuclear alleles (60%) than those with European mitotypes (51%). Furthermore, the three lowland populations showed clear signs of linkage disequilibrium, while the two high-altitude populations did not, indicating recent genetic introgression events into the lowland populations.; L'africanisation des abeilles Apis mellifera en Amérique du sud est l'un des plus spectaculaires exemples d'invasion biologique. Nous avons analysé le processus d'africanisation dans des populations d'abeilles du Mexique central, au long d'un gradient altitudinal de 72 à 2800 mètres, sur la base de marqueurs de l'ADN nucléaire et mitochondrial. Au niveau mitochondrial, les deux populations d'altitude avaient un pourcentage de mitotypes Africains plus élevé (95%) que les trois populations de basse altitude, montrant une colonisation effective a haute altitude. Au niveau nucléaire, la proportion de gènes Africains étaient relativement constante (58%), quelque soit l'altitude. Toutes les populations présentaient donc une introgression asymétrique de gènes Africains. Cependant, les colonies au mitotype Africain présentaient plus d'allèles nucléaires Africains (60%) que les colonies au mitotype Européen (51%), et il y avait une différenciation significative entre ces populations. De plus, les populations de basse altitude montraient des signes clairs de déséquilibre de liaison, montrant des introgressions plus récentes

International audience; Abstract Recruitment precision, i.e. the proportion of recruits that reach an advertised food source, is a crucial adaptation of social bees to their environment. Studies with honeybees showed that recruitment precision is not a fixed feature, but it may be enhanced by factors like experience and distance. However, little is known regarding the recruitment precision of stingless bees. Hence, in this study, we examined the effects of experience and spatial distance on the precision of the food communication system of the stingless bee Scaptotrigona mexicana. We conducted the experiments by training bees to a three-dimensional artificial patch at several distances from the colony. We recorded the choices of individual recruited foragers, either being newcomers (foragers without experience with the advertised food source) or experienced (foragers that had previously visited the feeder). We found that the average precision of newcomers (95.6±2.61%) was significantly higher than that of experienced bees (80.2±1.12%). While this might seem counter-intuitive on first sight, this “loss” of precision can be explained by the tendency of experienced recruits to explore nearby areas to find new rewarding food sources after they had initially learned the exact location of the food source. Increasing the distance from the colony had no significant effect on the precision of the foraging bees. Thus, our data show that experience, but not the distance of the food source, affected the patch precision of S. mexicana foragers.; La précision du recrutement, c'est à dire la proportion de recrues trouvant une ressource alimentaire communiquée, est une adaptation cruciale des abeilles sociales à leur environnement. Les études avec les abeilles Apis mellifera ont montré que la précision n'est pas fixe, mais peut être améliorée par l'expérience ou la distance. Cependant, peu est connu à ce sujet chez les abeilles sans aiguillon. Nous avons donc examiné l'effet de l'expérience et de la distance sur la précision chez l'abeille sans aiguillon Scaptotrigona mexicana. Nous avons entraîné les abeilles sur un nourrisseur tri-dimensionnel à différentes distances de leur colonie, puis enregistré les choix des butineuses. Les butineuses novices choisissaient le nourrisseur communiqué avec une plus grande précision (95.6% ± 2.61%) que les butineuses expérimentées (80.2% ± 1.12%). Cette perte de précision pourrait s'expliquer par une tendance des butineuses expérimentées à explorer des nouvelles ressources autour d'une ressource connue. Par contre, l'augmentation de la distance à la colonie n'affecte pas la précision.

L'acarien Varroa jacobsoni Oudemans a ete signale pour la premiere fois au Mexique en 1992. Puisque le Mexique a des abeilles africanisees et des conditions climatiques semblables a celles du Bresil, il est important de savoir si la croissance des populations d'acariens dans les colonies d'abeilles se maintiendra a de faibles taux, comme c'est le cas au Bresil. Les resultats des etudes specifiques qui ont porte sur la tolerance des colonies d'abeilles a V. jacobsoni au Mexique sont passes en revue et compares avec la situation au Bresil. Plusieurs etudes ont montre que la croisssance des populations d'acariens varie significativement d'une colonie a l'autre. Le genotype et le climat sont parmi les facteurs responsables de cette variation. Ceci est conforme avec ce qui a ete observe au Bresil. Pourtant les resultats suggerent aussi que la tolerance a V. jacobsoni au Mexique est plus faible que celle mentionnee au Bresil. Les taux d'infestation trouves au Mexique sont beaucoup plus eleves (taux estimes a 45 % ou a 9 000 acariens/colonie) que ceux du Bresil (1-3 %). Deux etudes independantes [17, 35] ont montre que le couvain d'abeilles europeennes etait deux fois plus attractif que celui des abeilles africanisees. Dans l'une des etudes [17] le couvain europeen etait 1,95 fois plus sensible a l'infestation par V. jacobsoni que le couvain africanise (figure 1). Au Mexique les taux de fertilite des acariens dans les colonies europeennes et africanisees n'ont pas montre de variation dans aucune des etudes realisees jusqu'a present et ils semblent se situer dans la fourchette des valeurs trouvees au Bresil et dans d'autres regions du globe (42-89 %). On n'a donc pas encore retrouve au Mexique le faible taux de fertilite de l'acarien qui semble expliquer la tolerance des colonies d'abeilles au Bresil. Dans l'une des etudes [17] neanmoins, la fertilite de l'acarien a ete significativement plus elevee dans le couvain hybride que dans le couvain europeen ou africanise, mais aucune difference n'a ete trouvee entre les couvains africanise et europeen (figure 2). Comme au Bresil, les colonies africanisees du Mexique ont un comportement hygienique (elles eliminent significativement plus de couvain infeste) plus developpe que les colonies europeennes situees au meme endroit (figure 3). Dans une autre etude, le comportement de toilettage, que l'on a pu deduire des acariens mutiles tombes sur le plancher, explique en grande partie la difference de croissance des populations d'acariens trouvees parmi les colonies (r 2 = 0,54, figure 4). Les abeilles mexicaines semblent relativement moins tolerantes a V. jacobsoni que les abeilles bresiliennes. Les abeilles africanisees sont presentes au Bresil depuis plus de 40 ans et les acariens les parasitent depuis plus de 20 ans, alors que les abeilles africanisees sont au Mexique depuis 17 ans et V. jacobsoni depuis 7 ans seulement. Cette difference de duree pourrait expliquer des eventuelles differences de sensibilite des colonies mexicaines et bresiliennes a V. jacobsoni.