Urbanization alters the spatiotemporal dynamics of plant-pollinator networks in a tropical megacity.

Urbanization is a major driver of biodiversity change but how it interacts with spatial and temporal gradients to influence the dynamics of plant-pollinator networks is poorly understood, especially in tropical urbanization hotspots. Here, we analysed the drivers of environmental, spatial and temporal turnover of plant-pollinator interactions (interaction ß-diversity) along an urbanization gradient in Bengaluru, a South Indian megacity. The compositional turnover of plant-pollinator interactions differed more between seasons and with local urbanization intensity than with spatial distance, suggesting that seasonality and environmental filtering were more important than dispersal limitation for explaining plant-pollinator interaction ß-diversity. Furthermore, urbanization amplified the seasonal dynamics of plant-pollinator interactions, with stronger temporal turnover in urban compared to rural sites, driven by greater turnover of native non-crop plant species (not managed by people). Our study demonstrates that environmental, spatial and temporal gradients interact to shape the dynamics of plant-pollinator networks and urbanization can strongly amplify these dynamics.

Functional diversity of farmland bees across rural-urban landscapes in a tropical megacity.

Urbanization poses a major threat to biodiversity and food security, as expanding cities, especially in the Global South, increasingly compete with natural and agricultural lands. However, the impact of urban expansion on agricultural biodiversity in tropical regions is overlooked. Here we assess how urbanization affects the functional response of farmland bees, the most important pollinators for crop production. We sampled bees across three seasons in 36 conventional vegetable-producing farms spread along an urbanization gradient in Bengaluru, an Indian megacity. We investigated how landscape and local environmental drivers affected different functional traits (sociality, nesting behavior, body size, and specialization) and functional diversity (functional dispersion) of bee communities. We found that the functional responses to urbanization were trait specific with more positive than negative effects of gray area (sealed surfaces and buildings) on species richness, functional diversity, and abundance of most functional groups. As expected, larger, solitary, cavity-nesting, and, surprisingly, specialist bees benefited from urbanization. In contrast to temperate cities, the abundance of ground nesters increased in urban areas, presumably because larger patches of bare soil were still available beside roads and buildings. However, overall bee abundance and the abundance of social bees (85% of all bees) decreased with urbanization, threatening crop pollination. Crop diversity promotes taxonomic and functional diversity of bee communities. Locally, flower resources promote the abundance of all functional groups, and natural vegetation can maintain diverse pollinator communities throughout the year, especially during the noncropping season. However, exotic plants decrease functional diversity and bee specialization. To safeguard bees and their pollination services in urban farms, we recommend (1) preserving seminatural vegetation (hedges) around cropping fields to provide nesting opportunities for aboveground nesters, (2) promoting farm-level crop diversification of beneficial crops (e.g., pulses, vegetables, and spices), (3) maintaining native natural vegetation along field margins, and (4) controlling and removing invasive exotic plants that disrupt native plant-pollinator interactions. Overall, our results suggest that urban agriculture can maintain functionally diverse bee communities and, if managed in a sustainable manner, be used to develop win-win solutions for biodiversity conservation of pollinators and food security in and around cities.

A new species of the genus Discoelius Latreille, 1809 (Hymenoptera: Vespidae: Eumeninae) from India.

Discoelius vasukii Pannure & Carpenter, sp. nov. is described and illustrated from Tamil Nadu, India.        Discoelius Latreille, 1809 is a small genus of solitary wasp with ten species and one subspecies described, of which D. aurantiacus Nguyen, D. emeishanensus Zhou & Li, D. esakii Yasumatsu, D. longinodus Yamane, D. nigriclypeus Zhou & Li, D. turneri (Meade-Waldo), D. wangi Yamane and D. zonalis (Panzer) are recorded from Oriental Region (Zhou et al. 2013; Nguyen 2016). Only a single species, D. turneri described from Shillong (Meghalaya) (Meade-Waldo, 1910) and later recorded from Sikkim (Giordani Soika 1960) has been previously known from India. In this study, we describe a new species of Discoelius from India based on a single female specimen collected at Valparai (Tamil Nadu), India.

Taxonomic studies on potter wasps (Hymenoptera: Vespidae: Eumeninae) of south India.

The family Vespidae is represented in India by four subfamilies: Vespinae, Polistinae, Stenogastrinae, and Eumeninae. The subfamily Eumeninae is the most species rich among the Vespidae. The potter wasps of south India are reviewed for the first time to comprise 31 valid genera. The genera Discoelius Latreille, 1809, Coeleumenes van der Vecht, 1963, Euodynerus Dalla torre, 1904, and Pseudonortonia Giordani Soika, 1936 are newly reported from south India. Diagnoses and a key to south Indian eumenine genera are given. A total of 72 species and subspecies are listed, 15 of them are newly reported from Karnataka and two species from Kerala.