Decline in wild bee species richness associated with honey bee (Apis mellifera L.) abundance in an urban ecosystem

The effects of meliponicultural use of Tetragonula laeviceps on other bee pollinators and pollination efficacy of lemon

The augmentation of pollination success in lemon (Citrus limon Eureka) flowers remains contingent on the involvement of bee pollinators. With wild bee pollinator populations declining in agroecosystems, meliponiculture has emerged as a potential option in Indonesia. This study aimed to investigate the effects of meliponicultural use of Tetragonula laeviceps on diversity, foraging behavior, and monthly population of bee pollinators, as well as lemon pollination efficacy with and without meliponiculture treatment during two periods. Using scan and focal sampling methods in first and second periods, the study found that the diversity of wild bee pollinators was six species (Apis cerana, Lasioglossum albescens, Megachile laticeps, Xylocopa confusa, Xylocopa latipes, and Xylocopa caerulea), and T. laeviceps when using meliponiculture. The relative abundance and daily foraging activity of wild bee pollinators were initially reduced in the first period (March-June) and then maintained in the second period (July-October). T. laeviceps foraged on the flowers, involving specific sequences for 72 s with highest visitation rate of 0.25 flowers/h from 10:00-13:00. Light intensity was observed to be the most influential factor for bee pollinator density. Pollination efficacy results showed that meliponiculture usage has greater benefit compared to meliponiculture absence across various parameters, including fruit sets, fruit weight, yield, and estimated productivity. The effects of meliponicultural use of T. laeviceps can enhance lemon pollination efficacy while preserving the diversity of wild insect pollinators. This suggests that meliponiculture stingless bees could be a beneficial practice in agroecosystems, especially in tropical regions where wild bee populations and diversity are declining.

Drivers of flower visit and resource sharing between the honeybee and native bees in Neotropical coastal sand dunes

The honeybee (Apis mellifera) is one of the most important pollinator species because it can gather resources from a vast variety of plant species, including both natives and introduced, across its geographical distribution. Although A. mellifera interacts with a large diversity of plants and shares resources with other pollinators, there are some plant species with which it interacts more frequently than others. Here, we evaluated the plant traits (i.e., plant length, abundance of bloomed individuals, number of open flowers, and stamen length) that would affect the honeybee visit frequencies to the flowers in a coastal environment in the Gulf of Mexico. Moreover, we evaluated which native bee species (and their body size) overlap floral resource with A. mellifera. We registered 998 plant-bee interactions between 35 plant species and 47 bee species. We observed that plant species with low height and with high abundances of bloomed individuals are positively related to a high frequency of visits by A. mellifera. Moreover, we found that A. mellifera tends to share a higher number of plant species with other bee species with a similar or smaller body size than with bigger species, which makes them a competitor for the resource with honeybees. Our results highlight that the impacts of A. mellifera on plants and native bees could be anticipated based on its individual's characteristics (i.e., plant height and abundance of bloomed individuals) and body size, respectively.

Drivers of arthropod biodiversity in an urban ecosystem

Our world is becoming increasingly urbanized with a growing human population concentrated around cities. The expansion of urban areas has important consequences for biodiversity, yet the abiotic drivers of biodiversity in urban ecosystems have not been well characterized for the most diverse group of animals on the planet, arthropods. Given their great diversity, comparatively small home ranges, and ability to disperse, arthropods make an excellent model for studying which factors can most accurately predict urban biodiversity. We assessed the effects of (i) topography (distance to natural areas and to ocean) (ii) abiotic factors (mean annual temperature and diurnal range), and (iii) anthropogenic drivers (land value and amount of impervious surface) on the occurrence of six arthropod groups represented in Malaise trap collections run by the BioSCAN project across the Greater Los Angeles Area. We found striking heterogeneity in responses to all factors both within and between taxonomic groups. Diurnal temperature range had a consistently negative effect on occupancy but this effect was only significant in Phoridae. Anthropogenic drivers had mixed though mostly insignificant effects, as some groups and species were most diverse in highly urbanized areas, while other groups showed suppressed diversity. Only Phoridae was significantly affected by land value, where most species were more likely to occur in areas with lower land value. Los Angeles can support high regional arthropod diversity, but spatial community composition is highly dependent on the taxonomic group.

Insect-Mediated Pollination of Strawberries in an Urban Environment

Pollination services provided by a diversity of pollinators are critical in agriculture because they enhance the yield of many crops. However, few studies have assessed pollination services in urban agricultural systems. We performed flower-visitor observations and pollination experiments on strawberries (Fragaria × ananassa) in an urban area near Paris, France, in order to assess the effects of (i) insect-mediated pollination service and (ii) potential pollination deficit on fruit set, seed set, and fruit quality (size, weight, and malformation). Flower-visitor observations revealed that the pollinator community solely comprised unmanaged pollinators, despite the presence of beehives in the surrounding landscape. Based on the pollination experiments, we found that the pollination service mediated by wild insects improved the fruit size as a qualitative value of production, but not the fruit set. We also found no evidence of pollination deficit in our urban environment. These results suggest that the local community of wild urban pollinators is able to support strawberry crop production and thus plays an important role in providing high-quality, local, and sustainable crops in urban areas.