02820nas a2200325   4500008004100000245012600041210006900167260001200236300001200248490000600260520192500266653001202191653001602203653001702219653001802236653002202254653001002276653001202286653001202298653001702310653001602327653001502343653000902358653002002367653001302387653001402400100001702414700001902431856004402450       2001                        eng d00aCauses and extent of declines among native North American invertebrate pollinators: Detection, evidence, and consequences0 aCauses and extent of declines among native North American invert  c2001///  a17 - 260 v53 aEcosystem health and agricultural wealth in North America depend on a particular invertebrate fauna to deliver pollination services. Extensive losses in pollinator guilds and communities can disrupt ecosystem integrity, a circumstance that today forces most farmers to rely on honey bees for much fruit and seed production. Are North America’s invertebrate pollinator faunas already widely diminished or currently threatened by human activities? How would we know, what are the spatiotemporal scales for detection, and which anthropogenic factors are responsible? Answers to these questions were considered by participants in a workshop sponsored by the National Center for Ecological Analysis and Synthesis in October of 1999, and these questions form the nucleus for the papers in this special issue. Several contributors critically interpret the evidence for declines of bee and fly pollinators, the pollination deficits that should ensue, and their economic costs. Spatiotemporal unruliness in pollinator numbers, particularly bees, is shown to hinder our current insights, highlighting the need for refined survey and sampling designs. At the same time, two remarkable studies clearly show the long-term persistence of members of complex bee communities. Other authors offer new perspectives on habitat fragmentation and global warming as drivers of pollinator declines. Bees and lepidopterans are contrasted in terms of their natural genetic variation and their consequent resilience in the face of population declines. Overall, many ecologists and conservation biologists have not fully appreciated the daunting challenges that accompany sampling designs, taxonomy, and the natural history of bees, flies, and other invertebrate pollinators, a circumstance that must be remedied if we are to reliably monitor invertebrate pollinator populations and respond to their declines with effective conservation measures10aApoidea10aCOMMUNITIES10aCONSERVATION10aFRAGMENTATION10aGENETIC VARIATION10aGUILD10aHABITAT10aINSECTA10aLIFE HISTORY10aPOLLINATION10aPOLLINATOR10aSEED10aSEED PRODUCTION10ataxonomy10aVARIATION1 aCane, J., H.1 aTepedino, V.J.  uhttps://apoidea.myspecies.info/node/12702640nas a2200265   4500008004100000245006400041210006200105260001200167300001400179490000600193520195900199653001202158653001602170653001702186653001202203653001402215653001802229653001202247653001602259653001502275653001402290653000902304100001702313856004402330       2001                        eng d00aHabitat fragmentation and native bees: a premature verdict?0 aHabitat fragmentation and native bees a premature verdict  c2001///  a149 - 1610 v53 aFew studies directly address the consequences of habitat fragmentation for communities of pollinating insects, particularly for the key pollinator group, bees (Hymenoptera: Apiformes). Bees typically live in habitats where nesting substrates and bloom are patchily distributed and spatially dissociated. Bee studies have all defined habitat fragments as remnant patches of floral hosts or forests, overlooking the nesting needs of bees. Several authors conclude that habitat fragmentation is broadly deleterious, but their own data show that some native species proliferate in sampled fragments. Other studies report greater densities and comparable diversities of native bees at flowers in some fragment size classes relative to undisrupted habitats, but find dramatic shifts in species composition. Insightful studies of habitat fragmentation and bees will consider fragmentation, alteration, and loss of nesting habitats, not just patches of forage plants, as well as the permeability of the surrounding matrix to interpatch movement. Inasmuch as the floral associations and nesting habits of bees are often attributes of species or subgenera, ecological interpretations hinge on authoritative identifications. Study designs must accommodate statistical problems associated with bee community samples, especially non-normal data and frequent zero values. The spatial scale of fragmentation must be appreciated: bees of medium body size can regularly fly 1-2 km from nest site to forage patch. Overall, evidence for prolonged persistence of substantial diversity and abundances of native bee communities in habitat fragments of modest size promises practical solutions for maintaining bee populations. Provided that reserve selection, design, and management can address the foraging and nesting needs of bees, networks of even small reserves may hold hope for sustaining considerable pollinator diversity and the ecological services pollinators provide10aApoidea10aCOMMUNITIES10aCONSERVATION10aDENSITY10aDIVERSITY10aFRAGMENTATION10aHABITAT10aPOLLINATION10aPOLLINATOR10aSELECTION10aSIZE1 aCane, J., H.  uhttps://apoidea.myspecies.info/node/128