Zakardjian Marie, Geslin Benoît, Mitran Valentin, Franquet Evelyne, Jourdan Hervé
IMBE, Aix Marseille Univ, Avignon Université, CNRS, IRD, 13000 Marseille, France.
IMBE, Aix Marseille Univ, Avignon Université, CNRS, IRD, Nouméa 98800, New Caledonia.
Insects. 2020 Nov 9;11(11):773. doi: 10.3390/insects11110773.
Land-use changes through urbanization and biological invasions both threaten plant-pollinator networks. Urban areas host modified bee communities and are characterized by high proportions of exotic plants. Exotic species, either animals or plants, may compete with native species and disrupt plant-pollinator interactions. These threats are heightened in insular systems of the Southwest Pacific, where the bee fauna is generally poor and ecological networks are simplified. However, the impacts of these factors have seldom been studied in tropical contexts. To explore those questions, we installed experimental exotic plant communities in urban and natural contexts in New Caledonia, a plant diversity hotspot. For four weeks, we observed plant-pollinator interactions between local pollinators and our experimental exotic plant communities. We found a significantly higher foraging activity of exotic wild bees within the city, together with a strong plant-pollinator association between two exotic species. However, contrary to our expectations, the landscape context (urban vs. natural) had no effect on the activity of native bees. These results raise issues concerning how species introduced in plant-pollinator networks will impact the reproductive success of both native and exotic plants. Furthermore, the urban system could act as a springboard for alien species to disperse in natural systems and even invade them, leading to conservation concerns.
城市化导致的土地利用变化和生物入侵都对植物-传粉者网络构成威胁。城市地区拥有经过改变的蜜蜂群落，其特点是外来植物比例很高。外来物种，无论是动物还是植物，都可能与本地物种竞争并扰乱植物-传粉者之间的相互作用。在西南太平洋的岛屿系统中，这些威胁更为严重，那里的蜜蜂种类通常较少，生态网络也较为简单。然而，在热带环境中，这些因素的影响很少得到研究。为了探究这些问题，我们在新喀里多尼亚这个植物多样性热点地区的城市和自然环境中设置了外来植物实验群落。在四周的时间里，我们观察了本地传粉者与我们的外来植物实验群落之间的植物-传粉者相互作用。我们发现城市中外来野生蜜蜂的觅食活动明显更高，并且两种外来物种之间存在很强的植物-传粉者关联。然而，与我们的预期相反，景观环境（城市与自然）对本地蜜蜂的活动没有影响。这些结果引发了关于引入植物-传粉者网络的物种将如何影响本地和外来植物繁殖成功率的问题。此外，城市系统可能成为外来物种扩散到自然系统甚至入侵自然系统的跳板，从而引发保护问题。
