Eunice Enríquez

Morphometric and genetic differentiation in isolated populations of the endangered Mesoamerican stingless bee Melipona yucatanica (Hymenoptera: Apoidea) suggest the existence of a two species complex

The stingless bee Melipona yucatanica is a rare species only found in preserved forests across Mesoamerica. Morphometric and molecular analyses (DNA barcoding of the cytochrome oxidase (cox1) and microsatellites) were combined to characterize and compare populations from Mexico and Guatemala. We aim to test the hypothesis predicting that populations from these two geographic regions could be considered as distinct taxonomic units. Morphometric analyses revealed geographic differences, Guatemalan bees being larger than Mexican specimens. Bayesian analyses of the mitochondrial cox1 region and the microsatellite loci demonstrated that M. yucatanica form two clades corresponding to the Mexican and Guatemalan populations. These results suggest that M. yucatanica from Mexico and Guatemala could represent two distinct species. However, more studies are needed on their ecology and behavior to determine the possibility of gene flow between them.

The number of families of Triatoma dimidiata in a Guatemalan house

Triatoma dimidiata is an important vector of Chagas disease in Guatemala. To help understand the biology and population dynamics of the insect, we estimated the number of full sibling families living in one house. Forty one families with an average size of 2.17 individuals were detected using random amplification of polymorphic DNA-polymerase chain reaction genetic markers. This result suggests high levels of migration of the vector, polyandry, and a significant capability for spreading the disease.

Fragmentation in the clouds? The population genetics of the native bee Partamona bilineata (Hymenoptera: Apidae: Meliponini) in the cloud forests of Guatemala

Habitat fragmentation and loss are important drivers of genetic differentiation, often leading to a decrease in genetic diversity. Yet, natural populations of tropical bees often show a lack of differentiation, even in fragmented landscapes, suggesting resilience to deal with unfavourable land use. It is not clear what leads to this lack of differentiation, but large population sizes, high rates of dispersal and stable demography likely play important roles. Here, we investigate the population genetic structure and infer the present and historic demography of the eusocial stingless bee Partamona bilineata from tropical montane cloud forests in Guatemala. We used microsatellites and mitochondrial DNA to test for genetic differentiation, to infer migration rates, and to evaluate the effects of landscape. We also used demographic modelling to trace population sizes over time. We found that six populations of P. bilineata exhibited only subtle differentiation, with the exception of one site at the edge of the cloud forest, which was clearly distinct from all others. Effective population sizes (number of colonies) appeared to be rather small (18 ± 6 colonies) compared to the original sample size (N = 51 ± 9), but stable over time, and inferred rates of gene flow were low; yet, no genetic bottleneck was detected. A statistical model including elevation was the best in explaining the observed pattern of differentiation. We find that P. bilineata does not exhibit strong genetic structure, making it a resilient species for provision of pollination services. But, at the same time, our data point to the potential vulnerability of this and similar species, as effective population sizes appear to be low and hence populations may be easily affected by future environmental change. As such, P. bilineata may be representative of many other tropical stingless bees, for which lack of differentiation has been invoked.

Intraspecific variation in the stingless bee Melipona beecheii assessed with PCR-RFLP of the ITS1 ribosomal DNA

In previous works, significant variation in morphometric and molecular characteristics was detected among populations of M. beecheii. Here RFLP tests of the internal transcribed spacer 1 of the ribosomal gene were performed to confirm those results and to evaluate the intraspecific variability within the species. The complete ITS1 region and the flanking regions showed length variation (1720 to 1670) and also three different restriction patterns that allowed differentiation of three groups of colonies with different geographic distribution. Mexican colonies from Yucatán, Campeche and Chiapas, together with one colony from northern Guatemala formed one group, a second was composed of colonies from southern Guatemala, El Salvador and Costa Rica and a third one corresponded to one colony from San Marcos (Guatemala but close to the Mexican border). Such test could be used to characterize locally adapted ecotypes subject to conservation efforts.ZusammenfassungMolekulare Analysen an Melipona beecheii, einer in den amerikanischen Tropen einheimischen Stachellosen Biene, ermöglichten die Charakterisierung der Populationen über das gesamte Verbreitungsgebiet von Mexiko bis Costa Rica (Tab. I). Als molekularen Marker wählten wir die interne transkribierte Region 1 eines ribosomalen Gens. Dieser Marker wurde bereits zur populationsgenetischen Charakteri-sierung von drei brasilianischen Melipona-Arten eingesetzt (Fernandes-Salomão et al., 2005) und erwies sich auch als nützlich in intraspezifischen Untersuchungen der brasilianischen Art M. subnitida (Cruz et al., 2006). Die ITS1-Region der von uns untersuchten Art erwies sich als besonders komplex und lang (1670–1720 Basenpaare), so dass einfache Analysen zu Restriktionsfragment-Längenpolymorphismen (RFLP) möglich waren. Von den zehn verwendeten Restriktionsenzymen erwiesen sich vier als besonders geeignet und erlaubten die Trennung von drei RFLP-Mustern (Abb. 1 und 2). Die geographische Verteilung der Kolonien, von denen die Proben stammten, stimmte mit der Verteilung der unterschiedlichen RFLP-Muster überein und bestätigte damit die Unterschiedlichkeit von drei Populationen (Abb. 3). Diese können deshalb als an jeweils lokale Umweltbedingungen angepasste Ökotypen aufgefasst werden. Die Kolonien aus Mexiko (Yucatán, Campeche und Chiapas) bildeten zusammen mit den Kolonien des nördlichen Guatemala eine gemeinsame Gruppe, eine zweite umfasste Völker aus dem Süden Guatemalas, aus El Salvador und Costa Rica, und eine dritte Gruppe bildeten Völker aus San Marcos (eine nahe der mexikanischen Grenze gelegenen Region Guatemalas). Da wilde Melipona-Populationen von einer Habitatfragmentierung der Wälder stark betroffen sein können, bildet die genetische Information aus den RFLP-Analysen der ITS1 Region der M. beecheii Völker eine Grundlage für die Etablierung von Managementstrategien und Schutzmassnahmen für die Erhaltung dieser Art.

The Pot-Honey of Guatemalan Bees

In Guatemala there are 32 species of native stingless bees that produce pot-honey, some 15 of which are bred by the beekeepers. The most popular bees for their facility of breeding and their honey are Melipona beecheii, Tetragonisca angustula, Scaptotrigona pectoralis, and Scaptotrigona mexicana. Honey is an esteemed product as both food and medicine, used mostly by the beekeepers themselves, due to its scarcity. Only those who have many hives sell honey, but only locally. We studied the honey of nine species for antibacterial activity and pollen composition, eight for physicochemical properties, five for sensory attributes, and four for sanitary quality. The results show differences on the composition of the honey between species; for example, the honey of G. acapulconis with a strong acidity or the honey of Scaptotrigona with a high content of protein. There is also honey with great diversity on pollen composition like T. angustula or a high antibacterial activity as the honey of M. beecheii. This evidences that stingless bee honey is a great biological treasure in the tropics.

The incidence of three honey bee viruses in collapsing colonies in Guatemala

Patricia Landaverde*, Natalia Escobedo, Claudia Calderón, Eunice Enríquez and Carlota Monroy Laboratorio de Entomología Aplicada y Parasitología –LENAPEscuela de Biología, Facultad de Ciencias Químicas y Farmacia, Universidad de San Carlos de Guatemala. Unidad de Investigación para el Conocimiento, Uso y Valoración de la Biodiversidad. Departamento de Estudios y planificación -DEyP. Centro de Estudios Conservacionistas. CECON, Facultad de Ciencias Químicas y Farmacia. Universidad de San Carlos de Guatemala