Changes in host ant communities of Alcon Blue butterflies in abandoned mountain hay meadows

Abstract

Land use intensification is a general threat to biodiversity, but many species depend on low‐intensity agricultural ecosystems. One example is European mountain meadow ecosystems, traditionally managed by hay harvesting or livestock grazing. Abandoning management often causes population declines, local extinctions and biotic homogenisation in these meadows. We studied changes in the Myrmica host ant communities of the xerophilic form of the ant‐parasitic Alcon Blue butterfly (Maculinea alcon) in four hay meadows in the Bükk mountains of Hungary between 2000–2007 and 2018. Abandonment started in this region in the 1970s, accelerated in the 1980s, and culminated in the 1990s. We found that the Myrmica ant community has changed substantially in less than two decades. Diversity of the ant community always decreased, and species composition became more homogeneous at two sites. Habitat suitability for Maculinea butterflies decreased at three sites and increased at only one site, where management was restarted 20 years after abandonment. The number of M. alcon caterpillars and pupae, the rate of infestation of ant nests and the mean number of caterpillars and pupae per ant nest decreased between the two periods, whereas host ant specificity did not differ from random in either period. We conclude that the unfavourable changes in the host ant community due to abandonment have negative consequences for the persistence of Maculinea populations. Our study highlights the need for detailed monitoring, and the maintenance of low‐intensity management by mowing or grazing to avoid the decline of biodiversity dependent on low‐intensity agriculture.

A Unique Population in a Unique Area: The Alcon Blue Butterfly and Its Specific Parasitoid in the Białowieża Forest

“…Other meadows were still open but encroachment of the invasive Lupinus was observed and goldenrods could be problematic in the future, taking into consideration that they were widespread in the vicinity. It is known that long term abandonment may lead to adverse changes in ant species composition in the habitats of P. alcon [ 71 ], and indeed we noticed that M. scabrinodis became less frequent in unmanaged patches in higher vegetation.…”

Inter-Parasitic Interactions in Myrmica Ants: Ectoparasitic Fungus Affecting the Success of Socially Parasitic Caterpillars

“…When the number of prepupal caterpillars and pupae was divided by the number of nests, this index of infection level 33 was higher in uninfected (10.12) than in infected (4.69) nests.…”

Host Ant Change of a Socially Parasitic Butterfly (Phengaris alcon) through Host Nest Take-Over

“…The study population belongs to the xerophilic ecotype of P. alcon [ 16 ]. This population inhabits a small meadow at Bükkszentkereszt (Hungary, 48°04′ N, 20°38′ E, 563 m above sea level; see [ 17 ] for a detailed description and history of this site), uses Gentiana cruciata L. as host plant and both Myrmica sabuleti Meinert, 1861 and M. scabrinodis Nylander, 1846 as host ants [ 4 , 17 , 18 ].…”

“…Altogether 12 M. sabuleti and 14 M. scabrinodis (det. by A.T. using a Leica MZ125 10-160× magnification microscope, according to the key of Radchenko and Elmes [ 19 ]) source colonies were collected ( Table 1 ) from meadows inhabited by P. alcon at Bükkszentkereszt and at the nearby Kecskeláb-rét [ 17 ] on the 15th and 16th of July 2019. The ants were collected from nests more than 10 m distance from G. cruciata plants to avoid potential disturbance of the P. alcon population and to work with, presumably, naïve colonies which have not met with P. alcon caterpillars before.…”