Pollinator richness and abundance in Northeast Estonia: bumblebees, butterflies and day-flying moths

Abstract

We studied diversity and abundance of three groups of pollinators: bumblebees, butterflies and day-flying moths, in Ida-Viru County, Estonia. The field work was done during the summers of 2008 and 2009, in 22 semi-natural meadows located across Northeast Estonia. In total, we found 22 species of bumblebees (gen. Bombus ), including 5 species of cuckoo bumblebees, 56 species of butterflies and 42 species of day-flying moths. We recorded 597 individuals of bumblebees, 768 individuals of butterflies and 330 individuals of day-flying moths in our study sites. We analysed differences between years (2008 and 2009) for the species richness and abundance of bumblebees, butterflies and day-flying moths; the relationships between insect species richness and area of meadow, the total number of species per meadow and the local abundance of each species separately. We found significant differences between bumblebee richness and abundance in 2008 and 2009, and between butterfly abundance at the same years. These differences may be due to more favourable conditions: warmer and dryer weather in the second year. We found no significant relationships between area of meadow and species richness of bumblebees, butterflies and day-flying moths; however, when we analysed the abundance of each species separately, we found that two species of bumblebees, i.e. B. pascuorum and B. schrencki , and one species of day-flying moths, i.e. Chiasmia clathrata , were negatively related with area of meadow. Although, Northeast Estonia is a region that has been environmentally affected by mining activities and the presence of power plants, it could be considered an important area that supports a significant richness and abundance of pollinators across its territory. Töö eesmärgiks oli uurida kolme tolmeldajate rühma: kimalased, päevaliblikad ja päeval aktiivsed hämarikuliblikad, liigirikkust ja arvukust Ida-Virumaal. Välitööd tehti aastatel 2008 ja 2009 22-1 poollooduslikul niidul. Kimalasi leiti 22 liiki (gen. Bombus ), sealhulgas 5 liiki kägukimalasi (subgen. Psithyrus ), 597 isendit. Kõige arvukamad liigid olid B. pascuorum, B. lucorum and B. ruderarius . Päevaliblikaid leiti 56 liiki ja 768 isendit, kõige arvukamad liigid olid Coenonympha glycerion, Aphantopus hyperantus ja Thymelicus lineola . Päeval aktiivseid hämarikuliblikaid leidsime 42 liiki ja 330 isendit, kõige arvukamad liigid olid Siona lineata ja Scopula immorata. Kimalaste liigirikkus ja arvukus ning liblikate arvukus erinesid statistiliselt oluliselt aastatel 2008 ja 2009. See võis olla põhjustatud erinevate aastate ilmastikutingimuste erinevustest, kuivõrd 2009. aasta oli kuivem ja soojem. Elupaiga suurus ei avaldanud statistiliselt usaldusväärset mõju uuritud tolmeldajate rühmade liigirikkusele. Samas omas elupaiga suurenemine negatiivset mõju mõningate liikide, nagu B. pascuorum, B. schrencki ja Chiasmia clathrata arvukusele.