The range of hosts exploited by a parasite is determined by several factors, including host availability, infectivity and exploitability. Each of these can be the target of natural selection on both host and parasite, which will determine the local outcome of interactions, and potentially lead to coevolution. However, geographical variation in host use and specificity has rarely been investigated. Maculinea (= Phengaris ) butterflies are brood parasites of Myrmica ants that are patchily distributed across the Palæarctic and have been studied extensively in Europe. Here, we review the published records of ant host use by the European Maculinea species, as well as providing new host ant records for more than 100 sites across Europe. This comprehensive survey demonstrates that while all but one of the Myrmica species found on Maculinea sites have been recorded as hosts, the most common is often disproportionately highly exploited. Host sharing and host switching are both relatively common, but there is evidence of specialization at many sites, which varies among Maculinea species. We show that most Maculinea display the features expected for coevolution to occur in a geographic mosaic, which has probably allowed these rare butterflies to persist in Europe. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

The taxonomic status of Alcon Blues living in Central and Western Europe (conventionally: Maculinea alcon and Maculinea rebeli) is quite confused. Some authors distinguish them as separate species of the M. alcon species group, while others consider them as subspecies or simply ecological forms. Our aim was to study the pattern of genetic differentiation among several populations of these taxa with reference to their taxonomic position.Imagoes were collected from 27 localities in Central Europe between 1999 and 2003. Samples originated from four regions: northern Hungary, central Hungary, Romania: Transylvania and Slovenia. Enzyme polymorphism was analysed using polyacrylamide gel electrophoresis. In all samples 16 enzyme loci were studied. In the analysis of the data, F-statistics was computed and the total genetic variation was partitioned into within and between population components. Nei's genetic distances were calculated and UPGMA dendrogram was constructed on the basis of the distance matrix. Hierarchical F-statistics and amova was computed to study the pattern of genetic differentiation among the samples. Principal component analysis (PCA) was also carried out using the allele frequencies of the samples.The results of all analyses indicated a high level of differentiation among the samples. The differences among the samples collected in different years from the same population accounted for a considerable amount of the between sample variation. The distribution of the between sample variation did not exhibit a species pattern. The results of amova and PCA indicated that the geographic pattern was slightly more expressed in the between sample variation compared with the species pattern of it. These results seem to contradict with the conventional taxonomical subdivision.

The present study aimed to analyse the level of genetic variation in the eastern Central European (Slovenia, Hungary, and Romania/Transylvania) populations of the Large Blues (Maculinea) to analyse the pattern of differentiation both between and within the species. One objective was to compare the level of differentiation between the two disputed species (Maculinea alcon and Maculinea rebeli) with that among the other species. Imagos were collected from 23 localities in eastern Central Europe in 2002. Enzyme polymorphism was analysed using polyacrylamide gel electrophoresis. Fourteen enzyme loci were studied in all samples. In the analysis of the data, F‐statistics and Nei’s genetic distances were calculated and a dendrogram (unweighted pair group method with arithmetic mean) was constructed on the basis of the distance matrix. A multivariate analysis of variance was performed to study the pattern of genetic differentiation among the samples. Principal component analysis analysis was also carried out using the allele frequency data of the samples. Our results indicated that the large blues are generally less polymorphic than other European lycaenid butterflies studied. At the same time, the level of genetic differentiation was high, even among local populations within the species. A low level of genetic variation within the populations coupled with strong differentiation among them implies the effect of genetic drift. Strong genetic differentiation of four Maculinea species (M. alcon, Maculinea teleius, Maculinea nausithous, and Maculinea arion) was confirmed. Significant differentiation was not found between M. alcon and M. rebeli. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 11–21.

The movement of butterflies within habitat patches is usually assumed to be random, although few studies have shown this unambiguously. In the case of the highly specialized genus Maculinea, two contradictory hypotheses exist to explain the movement and distribution of imagos within patches: (1) due to the high spatial variance of survival rates among caterpillars, the "risk-spreading" hypothesis predicts that females will tend to make linear flight paths in order to maximize their net displacement and scatter the eggs as widely as possible; and (2) recent mark-release-recapture (MRR) data suggest that within-habitat displacement of some Maculinea species is constrained and that adults may establish home ranges. We tested both hypothesis by analysing the movement pattern of individuals. We also investigated whether egg laying is time constrained, which would enhance the trade-off between flying and egg laying. Thirty females of Maculinea rebeli (Lepidoptera: Lycaenidae) were tracked within a single population in Central Hungary. Their egg-laying behaviour and individual patterns of movement were recorded, and the latter were compared with random walk model predictions. The population was also sampled by MRR to estimate survival rates, and four non-mated, freshly eclosed females were dissected to assess their potential egg load. Net squared displacement of females was significantly lower than predicted by the random walk model and declined continuously after the 15th move. The ratio of net displacement and cumulative move length decreased with the number of moves, supporting the hypothesis that Maculinea butterflies establish home ranges. We found that low survival and a low rate of egg laying prevented females from laying their potential number of eggs within their lifespan. Time limitation increased the cost of movement, providing another possible explanation for the restricted movement of females.

As part of a major transformation of the EU agriculture in the last few decades, traditional land-use types disappeared due to either intensification or abandonment. Grasslands are highly affected in this process and are consequently among the most threatened semi-natural habitats in Europe.However, experimental evidence is scarce on the effects of management types on biodiversity.Moreover, management types need to be feasible within the recently changed socio-economic circumstances in Hungary. We investigated the effects of timing and frequency of mowing on the abundance of the scarce large blue butterfly (Phengaris teleius), on the abundance of its host plant and on the frequency of its host ant species. In each of four study meadows, we applied four types of management: one cut per year in May, one cut per year in September, two cuts per year (May and September) and cessation of management. After three years of experimental management, we found that adult butterflies preferred plots cut once in September over plots cut twice per year and abandoned ones, while plots cut once in May were also preferred over abandoned plots. Relative host plant abundance remarkably increased in plots cut once in September. Management did not affect the occupancy pattern of Myrmica host ants. Invasive goldenrod was successfully retained by two cuts per year. To our knowledge, this is the first attempt to test management effects on the whole community module of a socially parasitic butterfly, its host plant and host ants. Based on the results, we provide recommendations on regional management of the scarce large blue's habitats.