Making the most of native bees

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Making the most of native bees

  1. 1. Making the most of native bees: hedgerow potential in agri-natural landscapes ofMediterranean climateGeorgia D. PollardAA School of Natural and Built Environments, University of South Australia, Adelaide, Mawson Lakes, 5095, AustraliaCorresponding author. Email: georgia.pollard@me.comAbstractAlthough Australia has over 1,500 species of native bee, agriculture depends on theintroduced honeybee, Apis millfera for pollination. Pests and diseases that are likelyto reach Australia are currently decimating honeybee populations worldwide. Nativebees can meet pollination requirements if sufficient support is given. Hedgerowswhen managed properly can provide valuable foraging habitat and a shift inpollination dependency to native bee species is both practical and viable.IntroductionPollination is an essential ecosystem service. Honeybees, Apis millfera are the mostimportant managed pollinator in the world (Southwick and Southwick 1992) and canenhance agricultural seed production and yield (Moradin and Winston 2006). InAustralia we depend on the introduced honeybee for honey and agriculturalpollination (Dollin et al. 2000). The honeybee is experiencing crisis in other parts ofthe world because of pests such as the varroa mite, Varroa destructor, diseases likeColony Collapse Disorder and insecticide use. Any one of these reaching Australiawill cause problems to industries dependant on honeybees, as in the US and Germany(Cunningham et al. 2000). A solution entails changes in agricultural practise toinclude use of native bees. Native bees require supportive foraging habitat, such as 1    
  2. 2. hedgerows. In this review, ‘hedgerow‘ is defined as, “a linear vegetation feature,including field margins, windbreaks and roadsides” and ‘agri-natural landscapes’ as,“land consisting of agricultural use and natural vegetation.” The potential for use andmanagement of native bees in agri-natural landscapes such as the Yorke Peninsula isexamined.Native bee requirementsAustralia has over 1,500 species of native bee, which have adapted to every type ofhabitat available (Dollin et al. 2000). In South Australia there are many species ofmining bee, mainly Colletines and Halictines (Edwards 2010). All bees requiresources of pollen, nectar, floral oils, nest sites and nesting material to live (Westrich1996; Hannon and Sisk 2009). Bee habitats can be separated into partial habitats ofeither foraging or nesting habitat. They can be separate areas within a largerlandscape (Westrich 1996; Kleijn et al. 2006; Hopwood 2008; Smallbone andSpooner 2008; Hannon and Sisk 2009). A study from Western USA found that the understorey vegetation is mostimportant when assessing whether the foraging habitat is resource rich or poor(Hannon and Sisk 2009). Native plants are beneficial and tend to attract higherabundance and variety of bee species (Kremen et al. 2002; Hopwood 2008; Edwards2010), but flowering crops also make suitable foraging habitat (Heard 1999) wheninsecticides do not affect bee numbers (Steffan-Dewenter and Tsharntke 1999;Kremen et al. 2002; Moradin and Winston 2006; Hannon and Sisk 2009). The miningspecies of native bee common to South Australia require nest sites that are open to thesun but somewhat sheltered with vegetation cover not exceeding 50% (Edwards2010). Both kinds of partial habitats can be provided in agri-natural landscapes under 2    
  3. 3. the right circumstances (Westrich 1996; Kremen et al. 2002; Kleijn et al. 2006;Moradin and Winston 2006; Hopwood 2008; Hannon and Sisk 2009; Edwards 2010).Hedgerow valueWhen comparing hedgerow value to remnant native vegetation there is some debate(Westrich 1996). Although remnant vegetation may provide a wider variety ofresources, the avaliability of such vegetation must be considered. Ninety four percentof Yorke Peninsulas native vegetation had been clear by 1989 (Malcolm and Wigan1989). For mining bees, hedgerows do tend to be more heavily vegetated than issuitable for nest sites but hedgerows can be valuable foraging habitat if theunderstorey is rich in flowering shrubs and native ground cover (Westrich 1996;Kremen et al. 2002; Hopwood 2008; Edwards 2010). Such hedgerows could link theremnants left and help reduce the chance of regional extinction of surviving nativebee species (Westrich 1996). Hedgerows regulate surrounding air temperature, soilwater content and organic carbon (Bunce et al. 2009) as well as being beneficial toother species such as birds and small mammals (Campi and MacNally 2001; Gellinget al. 2007).Viability of agricultural pollination by native beesBees provide pollination services in both natural and agricultural environments(Heard 1999; Steffan-Dewenter and Tscharntke 1999; Kremen et al. 2002; Kleijn etal. 2006; Moradin and Winston 2006; Hannon and Sisk 2009; Edwards 2010) andenhance seed production and yield (Steffan-Dewwenter and Tsharntke 1999; Kremenet al. 2002; Moradin and Winston 2006). The distance bees can fly for pollencollection is positively correlated with body size (Steffan-Dewwenter and Tsharntke 3    
  4. 4. 1999) unless nectar is available along the way (Westrich 1996). Native mining beeshave been reported travelling an average of 500 m for pollen, although one hive wasspotted in the centre of a canola field in South Australia (Edwards 2010). Having 30% of uncultivated land within 750 m from field edges maximized crop yield andprofit (Moradin and Winston 2006). Full pollination requirements were met by just native bees on organicallymanaged farms near natural habitat in California, but they were insufficient on non-organic farms, with extensive use of insecticides and lack of supplementary habitatdetrimental to the bees (Moradin and Winston 2006). Although the main crops grownon the Yorke Peninsula are wheat and barley and so wind pollinated, other cropsgrown there including canola, peas, lentils, beans, sunflowers and tomatoes wouldbenefit from bee pollination (Heard 1999; Steffan-Dewwenter and Tsharntke 1999;Cunningham et al. 2000; Kremen et al. 2002; Moradin and Winston 2006).Practical support of native bees in agri-natural landscapesRecommendations on how to provide nesting habitat for native bees have been madein a study from England (Kleijn et al. 2006), by widening field edges to 6 m or byidentifying small linear areas to be set aside from production for at least three yearswith at least one such area per square kilometre (Edwards 2010). This land is suitableas nesting habitat for mining bees. Supplementary foraging habitat needs to be available when crops are notflowering (Kremen et al. 2002). Managed hedgerows along field edges and roadsidesclose to fields, with understoreys of native shrubs and ground flora would providerich foraging habitat (Kremen et al. 2002; Hannon and Sisk 2009; Edwards 2010).Fields retired from crop production but still being used as grazing land result in poor 4    
  5. 5. foraging habitat (Hannon and Sisk 2009) but I did not find studies on the impacts ofgrazing on nest habitats of native mining bees. Extensive use of insecticides on fields adversely affects visiting bees.Lessening their use and enhancing hedgerows can also increase abundance of otherbeneficial insects (Kremen et al. 2002). To gain the full benefits from native beepollinators, the enhancement of foraging habitat and creation of nest habitats, as wellas minimised use of insecticides are recommended (Kremen et al. 2002; Hannon andSisk 2009; Edwards 2010).ConclusionPests and diseases such as Colony Collapse Disorder or the varroa mite, reachingAustralia, are likely to have adverse effects our honeybee populations. A shift inreliance on species of native bee for agricultural pollination is suggested as bothpossible and viable (Cunningham et al. 2000) because bees have the potential tocompliment or meet the full pollination requirements of agricultural crops (Kremen etal. 2002). Agriculture on the Yorke Peninsula can mitigate the risk of agriculturalpollination loss by changes to agricultural practise to encourage growth of native beespecies by implementing nesting and foraging habitats within hedgerows and fieldedges.References 5    
  6. 6. Bunce, R. G. H., Lassaletta, L., McCollin, D., and Sanchez, I. A. (2009). The effect of hedgerow loss on microclimate in the Mediterranean region: an investigation in Central Spain. Agroforestry Systems 78, 13-25. doi:10.1007/s10457-099-9224-zCampi, M. J., and MacNally, R. (2001). Birds on edge: avian assemblages along forest-agricultural boundaries of central Victoria, Australia. Animal Conservation 4, 121-132.Cunningham, S. A., FitzGibbon, F., and Heard, T. A. (2000) The future of pollinators for Australian agriculture. Australian Journal of Agricultural Research 53, 893- 900.Dollin, A., Batley, M., Robinson, M., and Faulkner, B. (2000). Native bees of the Sydney region. Australian Native Bee Research Centre. http://www.aussiebee.com.au/fieldguide.html Accessed; April 2nd 2011.Gelling, M., MacDonald, D. W., and Mathews, F. (2007). Are hedgerows the route to increased farmland small mammal density? Use of hedgerows in British pastoral habitats. Landscape Ecology 22, 1019-1032.Edwards, M. (2010). Draft report – Assessment of native pollinators of crops in South Australia. (NRM: South Australia.)Hannon, L. E., and Sisk, T. D. (2009). Hedgerows in an agri-cultural landscape: Potential habitat value for native bees. Biological Conservation 142, 2140-2154.Heard, T. A. (1999). The role of stingless bees in crop pollination. Annual Review of Entomology 44, 186-206.Hopwood, L. J. (2008). The contribution of roadside grassland restorations to native bee conservation. Biological Conservation 141, 2632-2640. 6    
  7. 7. Kleijn, D., Marshall, E. J. P., and West, T. M. (2006). Impacts of an agri-environment field margin prescription on the flora and fauna of arable farmland in different landscapes. Agriculture, Ecosystems & Environment 113, 36-44.Kremen, C., Thorp, R. W., and Williams, N. M. (2002). Crop pollination from native bees at risk from agricultural intensification. Proceedings of the National Academy of Sciences of the United States of America 99, 16812-16816.Malcolm, I., and Wigan, A. (1989). Report to Yorke Peninsula roadside vegetation steering group on roadside management plans for Yorke Peninsula.Morandin, L. A., and Winston, M. L. (2006). Pollinators provide economic incentive to preserve natural land in agroecosystems. Agriculture, Ecosystems & Environment 116, 289-292.Smallbone, L., and Spooner, P. G. (2008). Effects of road age on the structure of roadside vegetation in south-eastern Australia. Agriculture, Ecosystems & Environment 129, 57-64.Steffan-Dewenter, I., and Tscharntke, T. (1999). Effects of habitat isolation on pollinator communities and seed set. Oecologia 121, 432-440.Westrich, P. (1996). Habitat requirements of central European bees and the problems of partial habitats. The conservation of Bees 1-6. 7    

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