Beporzók, beporzás, élelmiszertermelés – az IPBES első tematikus tanulmányának fő üzenetei

A Biológiai Sokféleség és Ökoszisztéma-szolgáltatás Kormányközi Testület (Intergovernmental Platform on Biodiversity and Ecosystem Services, IPBES) első tematikus tanulmányának témájául 2014-ben a beporzók, az általuk biztosított növényi beporzás (pollináció) és ennek élelmiszertermelésben játszott szerepének értékelését választotta. A háziméhek és vad beporzók nyújtotta beporzásra a vadon élő és termesztett növények zömének szüksége van, ezáltal a pollináció kiemelkedő ökológiai, gazdasági, szociális és kulturális értékkel bír. A 2016-ban elkészült tanulmány, és az IPBES plenárisa által elfogadott, a főbb üzeneteket összefoglaló dokumentum szerint a beporzókra az emberi tevékenységek egyre fokozódó nyomást gyakorolnak, ideértve a tájhasználat változást, a természetközeli élőhelyek területének csökkenését, feldarabolódását, intenzív mezőgazdasági termelést, fokozott vegyszerhasználatot, klímaváltozást. Miközben a beporzó rovarok számos faja kihalással veszélyeztettet, illetve csökkenő trendeket mutat, a beporzásra való igény egyre nő a rovarbeporzást igénylő termesztett növénykultúrák területének kiterjedésével. A pollináció hatékony, hosszútávú fenntartása azonnali és többrétű cselekvéssorozatot igényel nemcsak a mezőgazdálkodás, hanem az emberi hozzáállás, mentalitás és a környezetünkhöz való viszonyulás terén is. Az IPBES beporzókat célzó tanulmánya megjelenése óta számos nemzeti és nemzetközi stratégia kidolgozását, beporzók védelmét célzó kezdeményezés elindulását segítette elő

Flower visiting preferences of bumblebees (Apidae: Bombus spp.) in grasslands of the Velyka Dobron' Game Reserve (Transcarpathia, Ukraine)

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Flower visiting preferences of bumblebees (Apidae: Bombus spp.) in grasslands of the Velyka Dobron’ Game Reserve (Transcarpathia, Ukraine)

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Landscape configuration of crops and hedgerows drives local syrphid fly abundance

Summary 1. Human-dominated landscapes are characterized by a mosaic of natural and managed eco- systems, affecting arthropod communities on different spatial scales. Effective landscape man- agement for functionally important organisms suffers from little understanding of organism spillover between semi-natural habitats and adjacent crops, and of how it is affected by the surrounding landscape. 2. We examined syrphid abundance (Diptera: Syrphidae) in three types of linear semi-natural habitats, differing in connectedness to annual crops and forest [forest edges ( n = 12), forest- connected hedges ( n = 11) and isolated hedges ( n = 12)], as well as in the adjacent oilseed rape or winter wheat fields (i.e. altogether n = 70 sites in 35 landscapes). The landscape cir- cles with 1 km radius around the study sites differed in the proportion of oilseed rape (rang- ing from 0% to 35% oilseed rape) enabling us to test landscape-scale effects of oilseed rape. 3. Aphidophagous syrphids were more abundant in forest-connected hedgerows than in for- est edges (with isolated hedges being intermediate), and more abundant in crop fields adjacent to hedgerows than adjacent to forest edges, indicating spillover from semi-natural habitats to the adjacent crop fields. Aphidophagous syrphid abundance was higher in semi-natural habi- tats adjacent to oilseed rape fields than adjacent to wheat fields if the proportion of oilseed rape in the landscape was low (indicating local concentration). 4. Synthesis and applications. This study highlights the potential of hedgerows to enhance the abundances of beneficial syrphids and their spillover to adjacent crop fields, especially when they are connected with forests. We provide evidence that this local exchange is moderated by the extent of mass-flowering crops in the surrounding landscapes due to local concentration. There- fore, measurements for the improvement in local biological functioni ng should be evaluated by simultaneously investigating local and regio nal aspects of crop configurations to allow for region-specific management recommendations. Increasing the total amount of hedgerows in the agricultural matrix under moderate landscape- scale proportions of mass-flowering crops may serve best for the conservation of biodiversity and augmentation of i mportant ecosystem services such as biological control and pollination in lands capes dominated by agricultural cultivations

Contrasting effects of mass-flowering crops on bee pollination of hedge plants at different spatial and temporal scales

Landscape-wide mass-flowering of oilseed rape (canola Brassica napus) can considerably affect wild bee communities and pollination success of wild plants. We aimed to assess the impact of oilseed rape on the pollination of wild plants and bee abundance during and after oilseed-rape bloom, including effects on crop-noncrop spillover at landscape and adjacent-field scales. We focused on two shrub species (hawthorn Crataegus spp., dog rose Rosa canina) and adjacent herb flowering in forest edges, connected hedges, and isolated hedges in Lower Saxony, Germany. We selected 35 landscape circles of 1 km radius, differing in the amount of oilseed rape; 18 were adjacent to oilseed rape and 17 to cereal fields, and we quantified bee density via pan traps at all sites. Adjacent oilseed rape positively affected fruit mass and seed number per fruit of simultaneously flowering hawthorn (no effect on dog rose, which flowers after the oilseed rape bloom). At the landscape scale, oilseed rape had a negative effect on bumble bee density in the hedges during flowering due to dilution of pollinators per unit area and the consequently intensified competition between oilseed rape and wild shrubs, but a positive effect after flowering when bees moved to the hedges, which still provided resources. In contrast, positive landscape-scale effects of oilseed rape were found throughout the season in forest edges, suggesting that edges support nesting activity and enhanced food resources. Our results show that oilseed rape effects on bee abundances and pollination success in seminatural habitats depend on the spatial and temporal scale considered and on the habitat type, the wild plant species, and the time of crop flowering. These scale-dependent positive and negative effects should be considered in evaluations of landscape-scale configuration and composition of crops. Food resources provided by mass-flowering crops should be most beneficial for landscape-wide enhancement of wild bee populations if seminatural habitats are available, providing (1) nesting resources and (2) continuous flowering resources during the season

Nesting activity of cavity-nesting bees and wasps is lower in small-scale apple orchards compared to nearby semi-natural habitats

Commercially reared cavity-nesting bees have been studied mainly in large, intensively managed orchards. However, knowledge on wild cavity-nesting bee and wasp communities and their potential limitations in smaller orchards remain insufficient. We compared the colonization rate of trapnests, nesting success, parasitism and response to flower resources of cavity-nesting bees and wasps between apple orchards and nearby semi-natural habitats (SNHs). Trapnests were placed in orchards and neighbouring SNHs. Colonization dynamics were studied and herbaceous flower resources were estimated. Furthermore, nest and brood cell quantity, number of alive offspring and nest parasitism rate were assessed. We found a higher colonization rate in the SNHs than in the orchards. Both bees and wasps made more nests, completed more brood cells and had a higher number of alive offspring in the SNHs. The number of bee nests in the orchards showed a positive correlation with the species richness of the flowering plants. The nest parasitism of wasps was higher in the SNHs. Apple orchards in the studied small-scale system were generally less colonized by cavity-nesting hymenopterans than nearby SNHs that can be important reservoirs of these ecosystem service provider hymenopterans. Our results highlight the importance of diverse flowering herbaceous vegetation in the understory that increased the number of bee nests in orchards and that could have a positive effect on the nesting activity of the bee species active in summer. Therefore, management practices that support flowering plant species in the understory vegetation are highly recommended in such orchards