Effects of Wetland Presence and Upland Land Use on Wild Hymenopteran and Dipteran Pollinators in the Rainwater Basin of

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ECOSYSTEM SERVICES OF WETLANDS

Effects of Wetland Presence and Upland Land Use on Wild Hymenopteran and Dipteran Pollinators in the Rainwater Basin of Nebraska, USA Angela Begosh 1 & Loren M. Smith 1 & Cynthia N. Park 2 & Scott T. Mcmurry 1 & Ted G. Lagrange 3 Received: 11 July 2019 / Accepted: 6 November 2019 # The Author(s) 2019

Abstract Pollination is an ecosystem service that is in jeopardy globally. Decreasing trends in wild pollinator populations are primarily attributed to habitat loss and degradation. These concerns are especially apparent in the Rainwater Basin of Nebraska, USA where more than 90% of the land has been cultivated and 90% of the wetlands have been lost. We compared hymenopteran and dipteran pollinator abundance, richness, and diversity in 28 wetlands and their adjacent uplands within 3 dominant land-condition types: cropped, restored, and reference state. We used vane traps to capture local pollinator insects and sweep nets to collect insect pollinators on flowers. Vane-trap captures revealed a greater abundance, richness, and diversity of hymenopteran pollinators in uplands as compared to wetlands over the entire growing season in all land-condition types. However, net collections showed that hymenopterans foraged more in wetlands than in uplands, especially in restored wetlands. The exception was September when hymenopterans were captured in uplands more than wetlands while feeding on late season forbs. Dipteran vane-trap and sweepnet captures primarily consisted of hoverflies (Syrphidae). Hoverflies were more abundant in wetlands than uplands. All pollinators used both wetlands and uplands for resources. Thus, insect-pollinator conservation can be enhanced by promoting native forb communities and pollinator habitat through wetland restoration and the planting of buffer strips. Keywords Diptera . Ecosystem services . Hymenoptera . Pollinators . Restoration ecology

Introduction Global pollinator declines can jeopardize agricultural production as well as wild-plant populations and their associated biota (Potts et al. 2010). There are myriad issues that contribute to pollinator declines in wild pollinator populations. Interrelated factors include pesticides, pathogens, exotic species, climate change, and habitat loss and degradation (Biesmeijer et al. 2006; Winfree et al. 2009; Potts et al. 2010). In this paper, we focus on habitat loss and degradation,

* Angela Begosh [email protected] 1

Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74059, USA

2

Coos Watershed Association, Coos Bay, OR, USA

3

Nebraska Game and Parks Commission, Lincoln, NE, USA

which is the primary threat to native bee populations (Winfree et al. 2009). Although the domestic honeybee (Apis mellifera L.) is the most important commercial pollinator (Calderone 2012b), research has documented that wild pollinators are more effective pollinators of several important crops such as sweet cherry (Holzschuh et al. 2012; Eeraerts et al. 2017), almonds (Alomar et al. 2018), apples (Mallin