Tetrapedia australis (Apidae: Tetrapediini),

Use of reed stalk trap nests by insects within the reed beds and in nearby steppic habitats

Obtaining colonies of stingless bees in the wild for the formation or expansion of meliponaries and other purposes is permitted by law in Brazil using bait containers or trap nests, and other non-destructive methods. We tested the efficiency of trap nests made from plastic bottles for attraction and nesting of stingless bees in the central Brazilian Amazon. We used 2-L and 5-L bottles and three types of attractants (cerumen and geopropolis from Melipona seminigra, M. interrupta and a mix of the two). We used 216 trap nests distributed in three experimental areas during 13 months. Visitation by six species of stingless bees in 58 (26.9%) trap nests, and nesting by three species in 12 (5.6%) trap nests in two areas near meliponaries was recorded. There was no significant difference between trap-nest size, nor among attractants for visitation or nesting, suggesting that the availability of cavities or hollows is more important than odor for nesting. Monthly pooled visitation and nesting events were not correlated with monthly rainfall. Based on our results, we can conclude that, despite the low capture rate, the acquisition of swarms through nest traps is a viable alternative to obtain new colonies of stingless bees for meliponaries.

Habitat structure components are effective predictors of trap-nesting Hymenoptera diversity

Simple SummaryMany bees and wasps are important pollinators and natural pest controllers. Habitat loss is a major threat to bee and wasp conservation, but little is known about how this impacts tropical bees and wasps. This study aimed to determine how habitat loss affects solitary bees and wasps in tropical agricultural landscapes and how they change with the seasons. Solitary bees and wasps can be monitored using trap nests, popularly known as “bee hotels”. We installed bee hotels in forests and orchards and checked them every season over two years. We found 41 species of bees and wasps nesting in bee hotels. Importantly, five species of bees and 14 species of wasps were found only in forests, mostly species with particular food or nesting requirements. More species of bees and wasps used the hotels in the wet season (spring-summer). Our study suggests that solitary bees and wasps with special resource requirements are vulnerable to habitat loss in tropical agricultural landscapes.(1) Background: Landscape simplification is a major threat to bee and wasp conservation in the tropics, but reliable, long-term population data are lacking. We investigated how community composition, diversity, and abundance of tropical solitary bees and wasps change with landscape simplification (plant diversity, plant richness, distance from forest, forest cover, and land use type) and season. (2) Methods: We installed 336 timber and cob trap nests in four complex forests and three simplified orchards within the subtropical biodiversity hotspot of south-east Queensland, Australia. Trap nests were replaced every season for 23 months and all emergents identified. (3) Results: We identified 28 wasp species and 13 bee species from 2251 brood cells. Bee and wasp community composition changed with landscape simplification such that large, ground-nesting, and spider-hunting species were present in all landscapes, while those with specialist resource requirements and (clepto) parasitoids were present only in complex landscapes. Abundance and diversity of bees and wasps were unaffected by landscape simplification but increased with rainfall. (4) Conclusions: This study highlights the need for multi-year studies incorporating nuanced measures such as composition with a focus on functional diversity to detect changes bee and wasp populations.

Bee pollinators are currently recorded with many different sampling methods. However, the relative performances of these methods have not been systematically evaluated and compared. In response to the strong need to record ongoing shifts in pollinator diversity and abundance, global and regional pollinator initiatives must adopt standardized sampling protocols when developing large‐scale and long‐term monitoring schemes.We systematically evaluated the performance of six sampling methods (observation plots, pan traps, standardized and variable transect walks, trap nests with reed internodes or paper tubes) that are commonly used across a wide range of geographical regions in Europe and in two habitat types (agricultural and seminatural). We focused on bees since they represent the most important pollinator group worldwide. Several characteristics of the methods were considered in order to evaluate their performance in assessing bee diversity: sample coverage, observed species richness, species richness estimators, collector biases (identified by subunit‐based rarefaction curves), species composition of the samples, and the indication of overall bee species richness (estimated from combined total samples).The most efficient method in all geographical regions, in both the agricultural and seminatural habitats, was the pan trap method. It had the highest sample coverage, collected the highest number of species, showed negligible collector bias, detected similar species as the transect methods, and was the best indicator of overall bee species richness. The transect methods were also relatively efficient, but they had a significant collector bias. The observation plots showed poor performance. As trap nests are restricted to cavity‐nesting bee species, they had a naturally low sample coverage. However, both trap nest types detected additional species that were not recorded by any of the other methods.For large‐scale and long‐term monitoring schemes with surveyors with different experience levels, we recommend pan traps as the most efficient, unbiased, and cost‐effective method for sampling bee diversity. Trap nests with reed internodes could be used as a complementary sampling method to maximize the numbers of collected species. Transect walks are the principal method for detailed studies focusing on plant–pollinator associations. Moreover, they can be used in monitoring schemes after training the surveyors to standardize their collection skills.

Population patterns in relation to food and nesting resource for two cavity-nesting bee species in young boreal forest stands

Small-scale area effect on species richness and nesting occupancy of cavity-nesting bees and wasps. The research was conducted in an urban forest remnant in southeast Brazil. We tested the predictions of the following hypotheses: (1) larger areas present higher species richness of bees and wasps, (2) solitary bees and wasps occupy more nests in larger areas, (3) rare species occupy more nests in smaller areas. We sampled Aculeate bees and wasps using trap nests from February to November 2004. We placed trap nests in sampling units (SU) with different size (25, 100 and 400 m2) located in 6 ha of secondary mesophytic forest. One hundred and thirty-seven trap nests were occupied by seven species of bees and four species of wasps. We found an increase in wasp, but not bee species richness following increase in SU size. Hymenoptera richness (i.e. bees plus wasps) was also greater in larger SU. Both the number and density of occupied nests increased with SU size. The wasp Trypoxylon lactitarse responded significantly to area size, larger SU having more occupied nests. The same pattern was exhibited by the wasp Auplopus militaris, the Megachile bee species, and the bee Anthodioctes megachiloides. Only Trypoxylon sp. was not affected by SU size. Our results show that cavity-nesting bee and wasps respond differently to the area effects. Such findings must be complemented by information on the frequency and dynamics of area colonization and nest occupancy by species of solitary Hymenoptera.

Trap nests for aculeate Hymenoptera were exposed during 15 years (2002–2016) in 80 localities of Crimea. A total of more than 500 trap nests containing about 25 000 cavities were used. As a result, 6 895 nests of 97 species from 9 families of Hymenoptera were obtained: Pompilidae (5 species / 118 nests), Vespidae (27/1201), Ampulici-dae (1/6), Sphecidae (2/8), Crabronidae (10/591), Colletidae (7/202), Megachilidae (37/4619), Apidae (3/9), and Formicidae (5/141). The rate of trap nest colonization by different species and groups of aculeate Hymenoptera is discussed. Attractiveness of trap nests to these insects is discussed in relation to their bionomics (nest structure, nesting substrate choice, number of generations per year, trophic relations, and philopatry). A strong correlation between the rate of colonization of trap nests and the amount of rains fallen at the beginning of the corresponding season in the given locality was observed. Nests of some unusual inhabitants of the trap nests, including Eumenes papillarius (Christ) and Eumenes sp., are reported. The number of obtained nests of species of the family Megachilidae was compared with the number of museum specimens of the corresponding species; the correlation between these parameters exists but it is relatively low. Two species of wasps and 9 species of bees are considered as suitable for breeding.

Summary Habitat requirements of solitary bees include nesting sites, food resources and nesting material. We used translocation experiments to establish foraging distances and measured foraging trip duration to analyse how solitary bees cope with the distance between nesting sites and suitable food plants in different habitat types. Maximum foraging distance between nesting site and food patch was 150–600 m for the 16 bee species examined. Foraging distance was correlated positively with body length. Mean foraging trip duration, measured for seven bee species, ranged from 6 to 28 min and was also correlated with body length. In a study of the polylectic species Osmia rufa , we found a significant decrease in foraging trip duration with increasing number of plant species. Logistic regressions showed that the oligolectic Megachile lapponica nested in trap nests with a probability of 50% if the distance between trap nest and food patch was less than 250 m. The oligolectic Chelostoma rapunculi utilized trap nests when the distance to the nearest food patch was less than 300 m. These experiments showed that solitary bees have a rather small foraging range so local habitat structure appears to be of more importance than large‐scale landscape structure. All requirements for sustaining viable populations must be within this range. Therefore, it is necessary to maintain and restore a dense network of habitat patches in landscapes to ensure long‐term sustainability of wild bee diversity and their ecological function as pollinators.

Artificial trap nesting of bees will help in their conservation in situ and utilizing them for enhancing pollination service in cropping systems. The present study was undertaken to study the nesting behavior and rate of acceptance of pithy stems for nesting by the different bee species at ICAR-NBAIR Yelahanka Campus (13.096792N, 77.565976E). Fifteen nests comprising of pithy stems of Caesalpinia pulcherrima each made into three bundles containing five nests each were placed at three places in two sites viz. , Site 1 (Pollinator Garden) and Site 2 (Vegetable block). The days taken by the bees to accept the trap nests placed in the pollinator garden and vegetable field were found to be 5.87 and 11.53 days with a percent acceptance of 80 and 66.67 per cent, respectively. The average number of cells built by the bees in the nests obtained from the pollinator garden and vegetable ecosystem were found to be 6.00 and 5.33 respectively. Ceratina binghami, C. hieroglyphica, Megachile lerma and predatory sphecid wasps were found to emerge out from the trap nests. Diversity of the stem nesting bees was found to be higher in the nests placed in the pollinator garden as compared to vegetable block.

The rate of deforestation of primary tropical forests due to agricultural expansion is higher in Southeast Asia compared to all other world's tropical regions. Deforestation in tropical forests is a major threat for global biodiversity, because estimated 50-90 % of the world's species are living in tropical forests. Therefore, human dominated landscapes and forested land-use systems such as agroforestry become increasingly important as a storage reservoir of global biodiversity. Biodiversity is related to ecosystem functioning, with complementarity in resource use as a major mechanism. Pollination is essential for plant-derived ecosystem services such as food production, and pollinators are one of the major functional groups for human well-being. Agroforestry systems often include coffee (Coffea sp. L.) and cacao (Theobroma cacao L.) as important cash crops, traditionally crown under a canopy of shade trees and with fruit set depending on pollination. Because of the variety of planted shade and fruit trees, agroforestry systems resemble primary forests more than any other agricultural habitat type and have great but little explored potential to offer substitute habitats for many tropical forest species. My aim was to evaluate the importance of agricultural systems for conservation of trap-nesting Hymenoptera and the pollinator community. I analyzed a land-use gradient in a tropical forested landscape, from primary forests, agroforestry systems differing in diversity of the shade trees and openland such as grassland and fallow land. I assessed the relative importance of different strata for species richness with trap nests, which offer standardized nesting resources for different guilds of above-ground nesting Hymenoptera and their antagonists. Furthermore, I linked pollinator richness to habitat modification and final crop yield and analyzed species-specific differences in resource use. I also assessed the contribution of agroforestry system for the maintenance of high densities of a pest predating wasp species over the course of one year. This study took place in Central Sulawesi (Indonesia) in the surrounding of the village Toro at the margin of a primary tropical forest (Lore Lindu National Park). The results show that total bee species richness in the herb layer increased with increasing land-use intensity and was highest in openland. However, species richness estimation and additive partitioning of biodiversity revealed higher overall bee species richness, presumably due to high management diversity, in agroforestry systems compared to primary forests and openland. Agroforestry systems offer higher floral diversity in the understorey, due to the richer herb layer and cash crops, than primary forests and provide more nesting sites for cavity-nesting bee species than openland. The canopy in primary forests was far more important for trap-nesting bee and wasp richness than the understorey. This pattern reversed with intensification in agroforestry systems where highest richness was found in the understorey. Food resource availability and microclimatic conditions appeared to make the canopy in primary forests a more suitable habitat for most species and might cause underestimation of species richness when only lower strata are sampled. In addition, agroforestry habitats showed high beta diversity due to high land-use diversity and between-plot community dissimilarity, showing that agricultural management can be crucial for conservation plannings on a landscape scale. I used standardized pumpkin plantations in different habitat types to test the effect of pollinator diversity on crop yield. Bee pollinators showed species specific differences in flower visiting traits, such as height, time and body size-related flower visiting behaviour. I provide the first empirical evidence of the relation between spatiotemporal and behavioural complementarity in resource use of a pollinator community causing increased crop yield. Furthermore, I show that the native bee community can sustain pollination services in absence of managed honey bees. Using the highly abundant wasp species Rhynchium haemorrhoidale (F.) (Eumenidae, Hymenoptera), I show that agroforestry systems can maintain high insect densities of a pest predator, even under intense land-use management. Tropical regions experience lower climatic fluctuations between the seasons compared to temperate zones. However, R. haemorrhoidale undergoes seasonal changes in density and body size, due to a complex combination of potential reasons (e.g. climate, food supply, parasitism) independent of habitat type. In conclusion, agroforestry systems can play a crucial role in the conservation of the understorey pollinator communities and densities of pest predators, whereas the importance of the canopy for species richness is increasing with decreasing land-use intensity and is highest in primary forests. Furthermore, I show that the ecosystem service of pollination and crop yield strongly depends on the bees' functional diversity. Low-intensity land-use and a complex shade-tree canopy appear to increase local and regional Hymenoptera richness and to sustain important ecosystem services, showing the necessity to include such agricultural systems in landscape-wide conservation programs.

A estrutura da comunidade das especies de abelhas que nidificam em cavidades pre-existentes foi sistematicamente investigada por um periodo de dois anos (maio/97 a abril/99), em um fragmento de dunas litorâneas na Area de Protecao Ambiental das Lagoas e Dunas de Abaete, Salvador, Bahia (12o56'S; 38o21'W). A tecnica de amostragem utilizada foi a de ninhos-armadilha, distribuidos no campo ao acaso, em blocos com 16 ninhos, com diâmetros variaveis, a altura de 1,5 m do solo. Os ninhos eram inspecionados quinzenalmente. Foram fundados 62 ninhos pertencentes a sete especies de abelhas. Duas especies predominaram na area, Centris (Hemisiella) tarsata Smith (58% do total de ninhos fundados), seguida por Euplusia musitans Fabricius (31%). Em geral, houve flutuacao sazonal nas abundâncias de abelhas e variacao nas frequencias totais de nidificacao entre os dois anos de amostragem. As duas especies predominantes apresentaram diferentes padroes sazonais. Houve sempre ninhos-armadilha disponiveis no campo para as abelhas, que usaram apenas 14% do total oferecido.

Bees are important components of mutualistic interactions with plants, playing a key role as pollinators of both wild and crop plants. In this context, studies on the plants visited by bees are important to determining conservation strategies. We investigated the use of floral resources by the trap-nesting bee species sampled in a semideciduous forest fragment. Trap nests were set in the forest fragment in three different zones: forest edge, 250 m away from the edge and 500 m away from the forest edge. Pollen analysis of the residual pollen content removed from the nests of 12 bee species revealed a total of 63 pollen types from 16 botanical families. The bee community showed specialized populations with no overlap in diet. Within the community, the diet overlap was higher in closely related species, the two Tetrapedia species and the two Centris (Heterocentris) species, than in the other sampled species. Although the studied bee community is composed of widespread bee species, our data showed a low niche overlap among them, suggesting the occurrence of food niche partitioning at our study site. The asymmetry in the period of nesting activities and floral preferences among the bee species are factors that might have contributed to the low niche overlap observed.

Landscapes with high amounts of mass-flowering fruit crops reduce the reproduction of two solitary bees

During a two year trap nest study in the forest reserve of the La Selva Biological Station, a total of 450 males, 288 females, and 455 nests from 16 species of solitary bees were collected. Trap nests were set up in six dead and six live trees, at canopy level and at 1.5 m height. Comparison of the phenology among species indicated a general seasonality pattern across two bee families, with peak abundance of nests and adults between May and August and lowest values between December and February. Contrary to an original hypothesis, adult and nest abundance was never negatively correlated with monthly rainfall. The occurrence of maximum values for males, females, or nests coincided with flowering peaks of trees at La Selva found in another study. The more sun-exposed canopy trap nests in dead trees were preferred by most species, but not Centris labrosa, which is assumed to be a rainforest specialist. According to this result, the protection of dead but standing canopy emergent trees for bee conservation in commercially managed forests is emphasized. Egg to adult development periods indicated that multiple generations per year might be common for the species investigated in this study.