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Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bee (Apis mellifera) diseases cause great economic losses and are considered the main cause of the high loss of colonies. In this study, the frequency and infestation levels of Varroa destructor and Acarapis woodi were determined. Likewise, the frequency and infection levels of Nosema spp. in colonies of honeybees from Tabasco, Mexico, were determined. During October to November 2020, bee samples were collected in 112 colonies in the five subregions of Tabasco. The frequency and levels of infestation of V. destructor were diagnosed using the capped brood comb fragment technique, as well as the washing of adult bees. The quantification of spores of Nosema spp. was performed by macerating abdomens and visual identification of A. woodi in tracheas using a stereoscopic microscope. At the state level, it was found a frequency of V. destructor in capped brood (FVCO)= 69.64%; level of infestation of V. destructor in capped brood (NIVCO)= 13.86% (p= 0.419), likewise, it was observed a frequency of V. destructor in adult bees (FVAA)= 92.86%; level of infestation of V. destructor in adult bees (NIVAA)= 3.88% (p= 0.944). It was observed a frequency of Nosema spp. (FN)= 91.96%; infection level of Nosema spp. (NIN)= 133 738 ±156 221 spores/bee. All samples were negative for A. woodi. The results indicate that the presence of V. destructor and Nosema spp. are more frequent in the subregions studied, the levels of infestation of V. destructor and the levels of infection of Nosema spp. are low. However, extreme values that exceed the tolerable limits were found in various communities, which could represent foci of attention before possible dissemination of these pathogens. [ABSTRACT FROM AUTHOR]

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: A study was carried out in the Ingenio Santa Rosalía sugar mill supply area with the aim of identifying the soil subunits cultivated with sugar cane and to quantify the degree of mycorrhization of Saccharum officinarum. Design/Methodology/Approach: Rhizosphere samples were collected at a depth of 0-30 cm and root segments with diameters of ≤1 mm and 1-2.0 mm were studied. The intersect method and the fungal structures method were comparatively analyzed to determine the mycotrophic state of the roots. The study also quantified the number of spores in the soils and classified the morpho-species of vesicular-arbuscular mycorrhiza (VAM). Results: The results show that seven soil subunits exist in the area, but the intersect method did not detect differences in colonization by root diameter or by root colonization (X=68.5%). For its part, the fungal structures method showed differences in colonization between soil subunits (X=69.5%), being higher in thin roots, and statistical differences wer found for vesicles and spores. At the sites, an average of 696 spores was quantified per 100 g of soil, which indicates a high presence of vesicular-arbuscular mycorrhizal fungi in the study area. Finally, six species of mycorrhizae were identified, of which four are present in various soil subunits: Glomus aff. deserticola, Glomus etunicatum, Glomus viscosum, and Paraglomus occultum. Study Limitations/Implications: This was an exploratory study that indicates the potential of VAM on sugarcane. Findings/Conclusions: The presence of hyphae, vesicles, arbuscules, and spores indicates that there is an active mycotrophic process between VAM and sugarcane cultivation in the soils of the study area. [ABSTRACT FROM AUTHOR]

The diversity, structure, genetic flow, and evolutive relationships within and among three wild-weedy-domesticated complexes and a wild population isolated from crops of common bean (Phaseolus vulgaris L.) were analyzed under traditional agriculture, within a region of the Mesoamerican center of domestication. Their diversity was compared with the diversity of a local commercial variety and a breeding line. A morphological marker and 37 polymorphic ISSR loci were used. Total genetic diversity within the wild, weedy, and domesticated populations across the complexes was very similar (0.24, 0.22, and 0.26, respectively). Weedy populations within each complex were more closely related to the domesticated than to the wild populations, suggesting they originated from introgression of wild-type alleles into the domesticated populations or predominant gene flow from domesticated to wild populations. The wild population in closest proximity to the crop within its complex was more similar to the domesticated and weedy populations of its complex than to the rest of the wild populations, suggesting displacement of the wild genetic diversity by gene flow from the domesticated population within its complex. The high values of differentiation among wild, weedy, and domesticated populations within each complex suggest high autogamy or genetic drift. However, the values of gene flow among populations within the complexes were close to one, theoretically sufficient to counteract genetic drift and/or autogamy. We therefore assume that human selection is the most important evolutionary mechanism for maintaining the high wild-domesticated differentiation by negative farmer selection of cultivated plants with morphological characters that suggest introgression. Farmers may influence the magnitude and characteristics of gene flow among populations within each complex by the management of the distance between the crops and the wild populations, the diversity within the landraces sown, and the tolerance and harvesting of weedy populations. The high geographic differentiation of the wild populations, together with the local differences in human selection practices and agronomic management, could have generated multiple evolutionary lineages after domestication. Domesticated populations within complexes were between two and four times more diverse than the local commercial variety and four and nine times more diverse than the breeding line. New conservation and breeding strategies are suggested to maintain and use the gene pools from these complexes. [ABSTRACT FROM AUTHOR]

Beekeeping in Mexico is based on subspecies of European ( Apis mellifera L) and Africanized bees. Due to the difficulty in the morphological differentiation of the European (E) and Africanized (A) populations of A. mellifera, the objective of this work was to perform a comparative analysis between the FABIS morphometric technique, against the diagnosis using the restriction fragment length polymorphism (RFLP) of mitochondrial DNA (mtDNA). Samples of bees from 135 commercial colonies (CC), 15 breeding colonie s (BRC) and 3 wild colonies (WC), located in different municipalities of the state of Tabasco (N= 153), were used. Both diagnostic methods identified BRCs as European and WCs as Africanized, but in CCs, the FABIS method could not define 9 colonies, conside ring them as suspicious (S) and another 50 did not coincide with the result of the molecular method, so, in total, both methods coincided in 94 identifications (61.44 %). The Bayesian grouping based on the analysis of the twelve morphometric variables show ed that the categories A - CC and E - CC form a group close to the category E - BRC; while the category A - WC presented the greatest distance, forming an isolated group. Therefore, CC bees have morphometric characteristics tending to E - BRC bees. This work is also intended to be a contribution to the lack of records on Africanization in the state of Tabasco. It is recommended to use the molecular method to discriminate between E/A bees, as it is not affected by environmental factors. [ABSTRACT FROM AUTHOR]