Body Size Influences Stingless Bee (Hymenoptera: Apidae) Communities Across a Range of Deforestation Levels in Rondônia, Brazil

Ethno-medicinal uses and cultural importance of stingless bees and their hive products in several ethnic communities of Bhutan

BACKGROUND

Indigenous and non-indigenous people in subtropical and temperate areas of Bhutan share an intricate relationship with stingless bees for diverse purposes including ethno-medicinal uses. Stingless bees hold significant importance in the realms of social, economic, cultural, and spiritual aspects. Bhutan's cultural traditions demonstrate a strong bond with the environment, exemplified by the regular use of honey from stingless bees for remedies such as treating the common cold, cough, and sore throat.

METHODS

Ethnographic research was conducted to document the ethno-medicinal uses and cultural importance of stingless in Bhutan. We deployed semi-structured interviews with stingless beekeepers and honey collectors including traditional healers who perform religious rituals for curing and preventing physical and mental illness.

RESULTS

We documented 22 different uses of stingless bee honey in food, medicine, veterinary medicine, crafts, beliefs, and religious purposes. The relative cultural importance (RCI) of stingless bees among Bhutan's ethnic communities was assessed through our calculations. It was determined that these bees hold notably greater significance for the Lhotshampa communities compared to other ethnic groups in Bhutan. This finding demonstrates the dependence of Hindu ethnic communities on natural resources in their everyday life. All participant communities largely exploit these bees through destructive extraction practices. They often find the natural nests in nearby forests, transfer them as a log hive to their backyards, and practice traditional meliponiculture.

CONCLUSION

The ethnic communities of Bhutan use stingless bees for various purposes and the local knowledge are persistent. However, significant efforts should be made to address the ethno-medicinal, ecological, biological, and commercial perspectives of meliponiculture in Bhutan.

Route of exposure to veterinary products in bees: Unraveling pasture's impact on avermectin exposure and tolerance in stingless bees

Deforestation rapidly increases in tropical regions, primarily driven by converting natural habitats into pastures for extensive cattle ranching. This landscape transformation, coupled with pesticide use, are key drivers of bee population decline. Here, we investigate the impact of pasture-dominated landscapes on colony performance, pesticide exposure, and insecticide sensitivity of the stingless bee Tetragonisca angustula. We monitored 16 colonies located in landscapes with varying proportions of pasture. We collected bee bread for pesticide and palynological analysis. We found a positive correlation between pollen diversity and colony growth, with no effect of the proportion of pasture in the landscape. In contrast, we detected prevalent and hazardous concentrations of the insecticide abamectin (9.6-1,856 µg/kg) in bee bread, which significantly increased with a higher proportion of pasture. Despite the abamectin exposure, the bee colonies displayed no adverse effects on their growth, indicating a potential tolerance response. Further investigations revealed that bees from sites with higher proportions of pasture showed significantly reduced mortality when exposed to a lethal concentration of abamectin (0.021 µg/µL) after 48 h. Since abamectin is scarcely used in the study area, we designed an experiment to track ivermectin, a closely related antiparasitic drug used in cattle. Our findings uncovered a new exposure route of bees to pesticides, wherein ivermectin excreted by cattle is absorbed and biotransformed into abamectin within flowering plants in the pastures. These results highlight that unexplained exposure routes of bees to pesticides remain to be described while also revealing that bees adapt to changing landscapes.

Forests are critically important to global pollinator diversity and enhance pollination in adjacent crops

Although the importance of natural habitats to pollinator diversity is widely recognized, the value of forests to pollinating insects has been largely overlooked in many parts of the world. In this review, we (i) establish the importance of forests to global pollinator diversity, (ii) explore the relationship between forest cover and pollinator diversity in mixed-use landscapes, and (iii) highlight the contributions of forest-associated pollinators to pollination in adjacent crops. The literature shows unambiguously that native forests support a large number of forest-dependent species and are thus critically important to global pollinator diversity. Many pollinator taxa require or benefit greatly from resources that are restricted to forests, such as floral resources provided by forest plants (including wind-pollinated trees), dead wood for nesting, tree resins, and various non-floral sugar sources (e.g. honeydew). Although landscape-scale studies generally support the conclusion that forests enhance pollinator diversity, findings are often complicated by spatial scale, focal taxa, landscape context, temporal context, forest type, disturbance history, and external stressors. While some forest loss can be beneficial to pollinators by enhancing habitat complementarity, too much can result in the near-elimination of forest-associated species. There is strong evidence from studies of multiple crop types that forest cover can substantially increase yields in adjacent habitats, at least within the foraging ranges of the pollinators involved. The literature also suggests that forests may have enhanced importance to pollinators in the future given their role in mitigating the negative effects of pesticides and climate change. Many questions remain about the amount and configuration of forest cover required to promote the diversity of forest-associated pollinators and their services within forests and in neighbouring habitats. However, it is clear from the current body of knowledge that any effort to preserve native woody habitats, including the protection of individual trees, will benefit pollinating insects and help maintain the critical services they provide.

A review of stingless bees' bioactivity in different parts of the world

Stingless bees, also known as meliponines, live in beehives. However, reports on the distribution of stingless bees are scattered, resulting in a lack of precision. Honey and propolis are the main components that can be harvested from their beehive, with a great commercial value of up to 610 million USD. Despite the enormous potential profits, discrepancies in their bioactivities have been observed worldwide, leading to a lack of confidence. Therefore, this review provided oversight on the potential of stingless bee products and highlighted the differences between stingless bees in Asia, Australia, Africa, and America. The bioactivity of stingless bee products is diverse and exhibits great potential as an antimicrobial agent or in various diseases such as diabetes, cardiovascular disease, cancers, and oral problems.

Survival Rate of the Neotropical Stingless Bees Nannotrigona perilampoides and Frieseomelitta nigra after Exposure to Five Selected Insecticides, under Controlled Conditions

Insecticides used in agricultural pest management pose survival risks to the stingless bees that forage on crops in tropical and subtropical regions. In the present study, we evaluated, under laboratory conditions, the acute oral toxicity of five selected insecticides (dinotefuran, imidacloprid, flupyradifurone, spirotetramat, and cyantraniliprole) to two species of neotropical stingless bees: Nannotrigona perilampoides and Frieseomelitta nigra. At field recommended doses, dinotefuran, imidacloprid, and flupyradifurone caused the highest mortality in both bee species. These insecticides also caused the largest decrease in the survival rate when exposed to a 10-fold dilution of the field recommended doses. Notably, dinotefuran exerted a high effect even at 100-fold dilution (100% mortality). In contrast, cyantraniliprole had a low effect and spirotetramat was virtually nontoxic. These results suggest that some insecticides used to control sap-sucking insects may have a significant negative impact on the communities of stingless bees.

Spatial resolution and sensitivity of the eyes of the stingless bee, Tetragonula iridipennis

Stingless bees are important pollinators in the tropics. The tremendous variation in body size makes them an excellent group to study how miniaturization affects vision and visual behaviours. Using direct measurements and micro-CT, we reconstructed the eye structure, estimated anatomical spatial resolution and optical sensitivity of the stingless bee Tetragonula iridipennis. T. iridipennis is similar in size to the Australian stingless bee Tetragonula carbonaria and is smaller than honeybees. It has correspondingly small eyes (area = 0.56 mm²), few ommatidia (2451 ± 127), large inter-facet (3.0 ± 0.6°) and acceptance angles (2.8°). Theoretical estimates suggest that T. iridipennis has poorer spatial resolution (0.17 cycles degree^-1) than honeybees, bumblebees, and T. carbonaria. Its optical sensitivity (0.08 µm² sr), though higher than expected, is within the range of diurnal bees. This may provide them with greater contrast sensitivity, which is likely more relevant than the absolute sensitivity in this diurnal bee. Behaviourally determined detection thresholds for single targets using y-maze experiments were 11.5° for targets that provide chromatic contrast alone and 9.1° for targets providing chromatic and achromatic contrast. Further studies into microhabitat preferences and behaviour are required to understand how miniaturization influences its visual ecology.

Disentangling the effects of local resources, landscape heterogeneity and climatic seasonality on bee diversity and plant-pollinator networks in tropical highlands

Land-use alteration and climate seasonality have profound effects on bee species diversity by influencing the availability of nesting and floral resources. Here, using twelve sites embedded in an agriculture-forest mosaic in the tropical highlands of Guatemala, we investigated the relative effects of climate seasonality and landscape heterogeneity on bee and floral-resource community structure and on their mutualistic network architecture. We found that climate seasonality affected bee diversity, which was higher in the wet season and associated positively with the availability of floral resources across both seasons. Bee community composition also differed between seasons and it was mainly driven by floral-resource richness and the proportion of agricultural, semi-natural and forest cover. In addition to the effects on bee diversity, climate seasonality also affected flower-bee visitation networks. We documented higher relative (null model corrected) nestedness in the dry season compared to the wet season. Niche partitioning as a result of competition for scarce resources in the dry season could be the process driving the differences in the network structure between seasons. Furthermore, relative nestedness was consistently smaller than zero, and relative modularity and specialization were consistently larger than zero in both seasons, suggesting the existence of isolated groups of interacting partners in all our flower-bee visitation networks. Our results highlight the effect of climatic seasonality and the importance of preserving local floral resources and natural heterogeneous habitats for the conservation of bee communities and their pollination services in tropical highlands.