Betina Blochtein

Bees for development: Brazilian survey reveals how to optimize stingless beekeeping.

Stingless bees are an important asset to assure plant biodiversity in many natural ecosystems, and fulfill the growing agricultural demand for pollination. However, across developing countries stingless beekeeping remains an essentially informal activity, technical knowledge is scarce, and management practices lack standardization. Here we profited from the large diversity of stingless beekeepers found in Brazil to assess the impact of particular management practices on productivity and economic revenues from the commercialization of stingless bee products. Our study represents the first large-scale effort aiming at optimizing stingless beekeeping for honey/colony production based on quantitative data. Survey data from 251 beekeepers scattered across 20 Brazilian States revealed the influence of specific management practices and other confounding factors over productivity and income indicators. Specifically, our results highlight the importance of teaching beekeepers how to inspect and feed their colonies, how to multiply them and keep track of genetic lineages, how to harvest and preserve the honey, how to use vinegar traps to control infestation by parasitic flies, and how to add value by labeling honey containers. Furthermore, beekeeping experience and the network of known beekeepers were found to be key factors influencing productivity and income. Our work provides clear guidelines to optimize stingless beekeeping and help transform the activity into a powerful tool for sustainable development.

Morphology of the Head Salivary and Intramandibular Glands of the Stingless Bee Plebeia Emerina (Hymenoptera: Meliponini) Workers Associated with Propolis

ABSTRACT Plebeia emerina (Friese) (Hymenoptera: Meliponini), like other stingless bees, collect large amounts of vegetal resin and store these materials, called propolis, in individualized clusters inside the nest that remain in a viscous state. The development of intramandibular and head salivary glands in P. emerina workers was studied in different life stages, aiming to relate gland functionality with the age in which they work at propolis maceration, biting the propolis clusters with the mandibles. The morphology of intramandibular and head salivary glands from newly emerged, 20–30 d old, and forager bees was analyzed. The greatest size of the head salivary glands occurred in 20–30-d-old worker bees, and the ultrastructure of this gland showed the presence of rough endoplasmic reticulum and lipid droplets. The intramandibular glands were of two types: glandular units (class 3 glands), present throughout the worker bee life span, and the secretory epithelium (class 1 glands), which hypertrophies in 20–30-d-old and forager bees. The development of the head salivary glands and the mandibular epithelium suggest that their products are added to the propolis clusters, supporting the hypothesis that they may serve in maintaining its viscous state.

Honey bee contribution to canola pollination in Southern Brazil

Although canola, (Brassica napus L.), is considered a self-pollinating crop, researchers have indicated that crop productivity increases as a result of honey bee Apis mellifera L. pollination. Given this crops growing importance in Rio Grande do Sul State, Brazil, this work evaluated the increase in pod and seed productivity with respect to interactions with anthophilous insects and manual pollination tests. The visiting frequency of A. mellifera was correlated with the crops blooming progression, and productivity comparisons were made between plants visited by insects, manually pollinated plants (geitonogamy and xenogamy) and plants without pollination induction. Pod set and seed production per plant were determined for each treatment. Among the 8,624 recorded flower-visiting insects, Hymenoptera representatives were the most prevalent (92.3%), among which 99.8% were A. mellifera. The correlation between these bees and blooming progression was positive (r = 0.87; p = 0.002). Pollination induction increased seed productivity from 28.4% (autogamy) to 50.4% with insect visitations, as well as to 48.7 (geitonogamy) and to 55.1% (xenogamy) through manual pollination.

Efeito da polinização por abelhas e outros insetos na produção de sementes de cebola

Pollinations deficit has been pointed as one of the causes of the low onion seed production. The objective of this work was to evaluate the relationship of the presence of bees and other insects in flowers of two cultivars of onion, Allium cepa L. (Alliaceae), with seed production. The diversity and frequency of insects in flowers of onion was registered and their pollinizing effect was tested. The behavior of Apis mellifera was directly observed in the flowers and the fidelity was testified from the presence of pollen in the corbiculas. Representatives of Hymenoptera and Diptera were the most abundant flower visitors. There was a correlation between frequency of A. mellifera and the number of umbels with flowers in both cultivars and of other insects in Crioula Alto Vale. The production of seeds with free insect visitation had an increase of more than 20% in relation to others without insects and with the visitation of one bee. A. mellifera transported more than 70% of onion pollen. The presence of A. mellifera is indispensable for the commercial production of onion seeds.

Atividades de vôo de Plebeia saiqui (Holmberg) (Hymenoptera, Apidae, Meliponini) durante o período de postura da rainha e em diapausa

The activities of four colonies of Plebeia saiqui (Holmberg, 1903), of Sao Francisco de Paula, Rio Grande do Sul, Brazil, were studied from October, 1998 to September. 1999, comparatively during the oviposition period and the diapause. The construction of the cells was monitored by direct observation of the nests. The duration of the diapause period varied from 76 to 168 days. Monthly, the bees that left and entered were counted for 10 minutes, at each hour, during the complete period of flight activity. Influence of meteorological factors on the activities of bees flight was analyzed through simple and multiple regressions. During the oviposition period was found that solar irradiation, temperature and relative humidity had a significant influence on bees flight activity. However, during the diapausa only solar irradiation and temperature played significant influence on bees flight activity. The wind never influenced in a significant way on the flight of the bees.

Atividades de coleta e origem floral do pólen armazenado em colônias de Plebeia saiqui (Holmberg) (Hymenoptera, Apidae, Meliponinae) no sul do Brasil

Four colonies of Plebeia saiqui (Holmberg, 1903), of Sao Francisco de Paula, were studied during the period from October/1998 to October/1999. The counting of the bees was proceeded monthly, differentiated workers that came back with and without pollen in the corbicula. Grains of pollen of pots previously marked were collected monthly and identified. The percentage of the pollen types of the samples was estimated: 20% of Asteraceae, 17% Myrtaceae, 15% type Meliaceae and 10% Euphorbiaceae. The remaining corresponds to other pollen types of small representation, besides those the were no identified. The climatic influence on the pollen collection was analyzed being used simple and multiple regressions. It was verified that in the spring and in the summer the temperature, the solar irradiation and relative humidity were significant for the pollen foraging. During autumn and winter the relative humidity had smaller influence in the pollen collection.

Queens become workers: pesticides alter caste differentiation in bees

Bees are important for the world biodiversity and economy because they provide key pollination services in forests and crops. However, pesticide use in crops has adversely affected (decreased) queen production because of increased mortality among larvae. Here, we demonstrated that in vitro-reared queens of a neotropical social bee species (Plebeia droryana) also showed high larval mortality after exposure to an organophosphate pesticide (chlorpyrifos) via larval food. Moreover, most of the surviving larvae that were destined to develop into queens became workers more likely because they ate less food than expected without pesticide skewing thus caste differentiation in this bee species. This adverse effect has not been previously reported for any other social insects, such as honeybees or bumblebees. Queens are essential for breeding and colony growth. Therefore, if our data are applicable to other pantropical social bee species across the globe, it is likely that these bees are at a serious risk of failure to form new colonies.

Seasonal flight and resource collection patterns of colonies of the stingless bee Melipona bicolor schencki Gribodo (Apidae, Meliponini) in an Araucaria forest area in southern Brazil

Melipona bicolor schencki ocorre no Sul e em regioes de altitude elevada no Sudeste do Brasil. Encontra-se vulneravel a extincao no Rio Grande do Sul e possui potencial para meliponicultura, entretanto o conhecimento de sua ecologia e escasso. Desenvolveu-se o estudo sazonal das atividades de voo de colonias em ambiente natural, com vistas a subsidiar acoes conservacionistas e manejo. Amostrou-se o ingresso de polen, nectar/agua e resina/barro em cinco colonias, durante o periodo de atividades externas, em cada estacao do ano. Analisou-se tambem a influencia do horario e de fatores meteorologicos sobre o voo. Os voos foram similarmente mais intensos durante a primavera e verao, com estimativa diaria de 2100 e 2333, enquanto no outono e inverno reduziram-se respectivamente para 612 e 1104. O transporte de nectar/agua foi maior, seguido de cargas de polen e de materiais de construcao. Esta situacao ocorreu similarmente nas quatro estacoes, porem com variacoes de intensidade. A amplitude diaria de voo foi de 14 horas na primavera, reduzindo-se nas demais estacoes e atingindo 8 horas no inverno. Os fatores meteorologicos exerceram influencia de 40,2% no voo das abelhas. Este resultado indica que outros fatores, nao mensurados neste estudo, como as necessidades das colonias determinadas por fatores fisiologicos e a disponibilidade de recursos florais, exercem forte influencia sobre a intensidade de coleta de recursos.

Bionomia de Monoeca xanthopyga Harter-Marques, Cunha & Moure (Hymenoptera, Apidae, Tapinotaspidini) no Planalto das Araucárias, Rio Grande do Sul, Brasil

A study of the life history of the solitary bee Monoeca xanthopyga, was conducted at the Araucaria Plateau, at the state of Rio Grande do Sul. The study focused the seasonality, sexual behavior, females activity during nest building, the exploited plant resources and the associated parasitoids. Three nest aggregations of M. xanthopyga built in clay soil with few plant cover or none at all, were studied on the Parque Nacional dos Aparados da Serra, located in Cambara do Sul, Rio Grande do Sul State. The nests were randomly distributed in areas up to eight square meters in size and reach a maximum density of 57 nests per square meter. The only one generation occurred from January to April. The immature stayed in diapausa in the prepupa stage during eight to 11 months. Males emerged a few days before females, and disappeared from the aggregations four days before the end of females activities. The search for females to mate occurred at nests from the previous year, where many males struggled for a single emergent female. It is suggested that males perceive smells emitted by females. Copulations lasted, on average, 26 seconds and, immediately after it, the couple separated. Nest building females were not attractive to males. Mating tests, at artificial environments showed the occurrence of copulation with both virgin and fertilized females. After mating, the females returned to the aggregations and established new nests by digging new tunnels, or by using abandoned nests. The bees flying activities began around 6 A.M. and lasted up to 6 P.M. The females did, on average, eight trips per day, each one lasting 31,4 minutes. They returned from the trips carrying pollen and/or floral oils. These resources were obtained from flowers of Malpighiaceae and Fabaceae species. Pollinaria from orchids of the genus Oncidium Sw. were carried accidentally by males and females. Mutilid parasitoids were present at the aggregations of M. xanthopyga during all the period of the activities. One species of Traumatomutilla Andre, 1903 was related to the immature of these bees, composing the first registration of inhabitant of this Mutillidae.

Consumption of the neonicotinoid thiamethoxam during the larval stage affects the survival and development of the stingless bee, Scaptotrigona aff. depilis

In Brazil, where the use of neonicotinoids is allowed in bee-attracting flowering crops, we investigated whether thiamethoxam intake during the larval stage of the native bee species Scaptotrigona aff. depilis affects the survival and development by exposing larvae to contaminated food. Our results indicated that the larvae exposed to the dose at a field-realistic level and to the doses ranging around it had their survival rates significantly impaired. At the highest doses, we observed larvae and pupae with shorter and longer development times, respectively, and the formation of smaller and asymmetric specimens. Evidently, we need to consider that thiamethoxam reaches the pollen and nectar at residual levels, and that they are processed by nurse bees before destined for offspring. Nevertheless, our findings suggest a warning, since the individuals had their biological parameters affected by thiamethoxam, when exposed to doses at field-realistic levels.