Dynamics of mate-searching behaviour in a hilltopping butterfly, Lasiommata megera (L.): the effects of weather and male density

By studying a hilltopping population of the satyrine Lasiommata megera in southern Sweden, the effects of density and meteorological conditions on mate-searching behaviour were investigated. Lasiommata megera males switched between stationary and vagrant behaviour, and the behaviour adopted was correlated to meteorological conditions; more males were stationary at low temperatures, low irradiation levels and high wind speeds than vice versa. Body temperature measurements indicated that these factors were important in deciding the body temperature and thereby the flight activity of males. Male density did not significantly influence mate-locating behaviour. The tendency of males to hilltop and their distribution around the hill were strongly influenced by weather. The hilltopping behaviour of this species did not adhere to an all-or-none pattern, but instead males, as well as the stations they used, were found at increasingly higher elevations on the hill with increasing temperatures and decreasing wind speeds. Moreover, males tended to use the lee side and sun-exposed side of the hill. Females, of which the majority were already mated, also showed this distribution around the hill, but preferred lower elevations than males. Release experiments did not reveal any propensity of mated females to fly uphill. Such a propensity was shown by released virgin females.     

Geometric morphometrics reveal male genitalia differences in the Lasiommata megera/paramegaera complex (Lepidoptera, Nymphalidae) and the lack of a predicted hybridization area in the Tuscan Archipelago

The recognition of specific demarcation between allopatric populations, as for island endemics, is particularly difficult according to the Biological Concept of Species. However, the recognition of the specific status of island taxa is decisive in evaluating important areas of endemism for conservation purposes. The recent taxonomic inflation of European butterfly species calls into question the validity and objectivity of taxonomic practices, and of databases dependent on them, which are used in biogeography and conservation. In this paper I applied rigorous morphometric analyses instead of visual evaluation to solve the long debated question of whether Lasiommata paramegaera butterfly from Sardinia and Corsica should be considered as a separated entity from the widespread Lasiommata megera . First, I carried out analyses of male genitalia shape comparing the populations from Corsica and Tuscany. Thereafter, I also searched for possible hybridization evidence in the sole area where it is strongly predicted: the Tuscan Archipelago. These islands are located between Tuscany and Corsica and there is large evidence of a continuous immigration of butterflies from these two main sources. I found that Corsican L. paramegaera and Tuscan L. megera can be clearly distinguished on the basis of genitalia shape. Furthermore, the Lasiommata population of each islet clearly maintains the characteristics of one of the two species without evidence of intermediate individuals. In conclusion, I suggest that the two entities should be considered as separate species maintaining their homogeneity by a reduced gene flow across sea, mating avoidance and/or by some depletion of F1 hybrids in developmental or mating success.     

Allozyme variability in central, peripheral and isolated populations of the scarce heath (Coenonympha hero: Lepidoptera, Nymphalidae); implications for conservation

Genetic drift tends to lower geneticvariability in peripheral and isolatedpopulations. These populations also tend todiverge from more central populations if thedegree of isolation is high enough. Theseprocesses could have opposite effects on thevalue of the respective populations in thespecies conservation context. On the basis ofallozyme polymorphism data, we compare geneticvariability and differentiation between core,peripheral and isolated populations of thescarce heath, a butterfly endangered inNorthern and Central Europe. Genetic variationwas lowest in populations that were bothperipheral and isolated(P = 16.5%, Hobs = 0.017),and highest in the central populations(P = 35%,Hobs = 0.052). However, overall variability waslow also in the core area compared to that ofclosely related butterfly species. Theperipheral region was more differentiated fromthe other regions than the isolated region(F_PC = 0.118, F_PI = 0.257,F_IC = 0.068). This study indicated thatisolation in combination with marginality havecaused an erosion of the gene pool. Theobserved patterns may be caused both by thecontemporary population structure of thespecies, as well as by the colonisationhistory. Both genetic and ecological evidencesuggests that the species is likely to followthe stepping-stone model of dispersal.     

Distribution and Morphological Variations in Coenonympha leander (Lepidoptera,Satyridae) Populations from the Urals

Entomological Review - The modern distribution of the Western Eurasian subboreal butterfly Coenonympha leander (Esper, 1784) was studied in the Urals region, with its northeastern range limits...     

Effects of large-scale anthropogenic development on juvenile lemon shark (Negaprion brevirostris) populations of Bimini, Bahamas

The waters around Bimini (25° 43.70′ N, 79° 18.00′ W) provide an ideal nursery location for juvenile lemon sharks, Negaprion brevirostris, but this habitat is threatened by the development of a large resort. Since 1999 the North Sound (NS) has been subjected to intermittent periods of dredging, the most intensive of which was in March 2001. Possible effects from the development up to June 2006 were investigated by: comparing growth rates of juvenile lemon sharks in the NS, Sharkland (SL) and South Bimini (SB) nurseries between 1995-2005 using before-after, control-impact (BACI) analysis; analyzing survival of juvenile lemon sharks in the NS and SL between 1995–2006; and by comparing habitat structures in the NS and SB nurseries in 2003 and 2005. BACI analysis detected no statistically significant difference between the growth rates of juvenile lemon sharks in the three nurseries before and after the impact date of March 2001. However, a reduction in the survival rate of juvenile lemon sharks in the NS after March 2001 was statistically significant, including a 23.5% decline in first-year survival. Habitat structure of the NS in 2003 and 2005 also varied with the mean percentage cover of the seagrass Thalassia testudinum declining by 17.7% since 2003. Our results indicate a correlation between the development thus far and a decline in the survival rates of juvenile lemon sharks and changes in the habitat structure of the NS. To elucidate further information regarding potential effects of the resort development on juvenile lemon sharks in the NS nursery, we suggest several future research directions.     

Patch occupancy in Coenonympha tullia (Muller, 1764) (Lepidoptera: Satyrinae): habitat quality matters as much as patch size and isolation

Patch occupancy by Coenonympha tullia has been surveyed in 166 sites in Northumberland, UK. It was found in 117 of them and absent in 37. Weather conditions were too poor to determine its presence at a further 12 sites. Differences in habitat quality among sites account for patch occupancy as successfully (R2 = 48%) as isolation and patch size jointly (R2 = 46%). This finding has relevance for metapopulation studies as it demonstrates that greater attention should be given to differences in habitat quality among patches beyond their size and distance from one another. Together, habitat quality, patch size and isolation account for 61% of the variation in C. tullia occupancy of sites and discriminant analysis produces a correct classification for > 88% of sites. Habitat quality and patch size jointly account for much the same variance, and result in the same classification of the twelve sites excluded from analysis, as they do in conjunction with patch isolation. This result suggests that there is potential for predicting changes in occupancy of sites from site specific data in the face of changes to biotopes, such as planned exploitation and deterioration of sites from other causes including climate change and management practices.     

Phenotypic variability of eye-spots in natural populations of <Emphasis Type="Italic">Coenonympha pamphilus</Emphasis> L. (Lepidoptera,Satyridae)

Variation of eye-spots in the wing pattern of Coenonympha pamphilus (Linnaeus, 1758) was studied in the Urals with adjacent territories and in Dzhelal-Abad Province of Kyrgyzstan. Discriminant analysis of the wing length and eye-spot diameter and the phenetic distances calculated by the Hartman’s method revealed clinal variation of the characters. The butterflies in the northern parts of the range (Sverdlovsk and Kurgan Provinces) are smaller than those in the south (Orenburg and Chelyabinsk Provinces) and have fewer eye-spots which themselves are smaller. The Kyrgyzstan specimens differ significantly from the Ural ones (the nominotypical subspecies) in both quantitative and qualitative characteristics of the wing pattern, and should probably be assigned to the subspecies C. pamphilus marginata Heyne, 1894. As in most Satyridae, females of C. pamphilus are larger than males and on the average possess more eye-spots on the wings. The degree of phenotypic variation in natural populations was studied using the method of variation spectra (Kovalenko, 1996a, 1996b, 2007, etc.). The arrangement of phenotypic combinations within the theoretical spectrum (St) matrix allows one to describe the actual (Sr) and potential (Sp) spectra for either sex and for the species as a whole. The actual spectrum was found to be considerably broader in males than in females. With minor variations, Sr and Sp showed the same general trends in different samples of both sexes. In all the samples, phenetic combinations with one spot on the fore wing (in cell M ₁-M ₂) were predominant. The hind wing had either no spots (which was typical of males, especially in the northern parts of the range) or the maximum possible number, six (mostly in females, more often in the southern parts of the range). The phenetic combinations with the maximum (4) number of spots on the fore wing and the minimum number (0) on the hind wing are prohibited for C. pamphilus.     

Control of marine bacterioplankton populations: Measurement and significance of grazing

A variety of methods have been used to estimate the degree of control exercised upon marine bacterioplankton by grazing organisms. These include filtration or dilution of samples to reduce grazers, the use of specific inhibitors to prevent growth or grazing, and the use of artificial particles or radio-labelled bacteria as tracers for the natural bacterioplankton. Each of these techniques has drawbacks which may lead to under- or overestimates of grazing. In addition, they tell us little about which organisms are doing the grazing or the degree to which viruses or lytic bacteria compete with grazers for bacterial production. Because measurements of grazing and bacterioplankton growth rates are uncertain, exact comparisons are not presently possible. Thus measurements of bacterial and bacterivore abundance, concentrated on comparisons between seasons, on diel cycles and on spatial variations, have been used to evaluate mechanisms controlling bacterial populations. These give an idea of the degree of coupling between bacterial growth and bacterivore activity and of the time scales over which growth and grazing balance. Combined with laboratory studies of grazing, they currently provide the best insight into what controls populations of bacteria in the sea.     

Effects of stock grazing on the ground invertebrate fauna of woodland remnants

Habitat fragmentation can leave formerly widespread habitat types represented by only small habitat ‘islands’, and the conservation of these remnants is frequently compromised by ongoing disturbance. In northern Victoria, grazing of woodland remnants by sheep and cattle has profound effects on the vegetation structure of the woodland by removing understorey and ground vegetation. To investigate the effects of grazing pressure on remnant grey box Eucalyptus microcarpa woodland in northern Victoria, we surveyed the ground invertebrate fauna in ungrazed woodland remnants, grazed woodland remnants, and grazed pasture. The number of invertebrates caught increased from ungrazed woodland to grazed woodland to pasture, but this increase was due primarily to the most abundant orders (Hymenoptera, Coleoptera and Aranaea), and two abundant taxa characteristic of pasture (Orthoptera and Dermaptera). In contrast, most of the less abundant orders followed the opposite pattern, and were caught in higher numbers (and as a higher proportion of the total catch) in ungrazed woodland. Ungrazed woodland had a more diverse ground invertebrate fauna, most likely due to the greater diversity of food and habitat resources provided by the less disturbed vegetation. The differences in invertebrate communities corresponded to differences in vegetation and litter layers. The reduction in biodiversity of remnants due to grazing has implications for conservation management of remnant woodland in agricultural landscapes.     

Effects of livestock grazing on aboveground insect communities in semi-arid grasslands of southeastern Arizona

Despite the importance of invertebrates in grassland ecosystems, few studies have examined how grassland invertebrates have been impacted by disturbances in the southwestern United States. These grasslands may be particularly sensitive to one common disturbance, livestock grazing, because they have not recently evolved in the presence of large herds of bison, an important mammalian herbivore. This study examined how livestock grazing influenced vegetation-associated insect communities in southeastern Arizona. Insect abundance, richness, diversity, community composition, and key environmental variables were compared between sites on active cattle ranches and sites on a 3160 ha sanctuary that has not been grazed by cattle for over 25 years. Vegetation-associated insect communities were found to be sensitive to livestock grazing. Overall abundance of these insects was lower on grazed grasslands, and certain insect orders appeared to be negatively affected by livestock grazing; beetles were less rich, flies were less diverse, and Hymenoptera were less rich and diverse on grazed sites. Conversely, Hemiptera were more diverse on grazed sites. Species composition of vegetation-associated insect communities also differed and was significantly correlated with percent vegetation cover and number of shrubs. Insect species responsible for these differences were taxonomically diverse, and included herbivores and predators/parasites. When compared to other studies conducted in areas of the United States that fall within the historic range of bison, this study suggests that invertebrates in areas outside this range may be more sensitive to grazing pressure.     

Spot distribution in the meadow brown butterfly, Maniola jurtina L. (Lepidoptera: Satyridae): South Welsh populations

Meadow brown butterflies, Maniola jurtina , were studied on Skokholm Island, off the Pembrokeshire coast, from 1976 to 1978 and at six other sites in south Wales from 1973 to 1977.
Daily survival of butterflies on Skokholm was estimated by capture-recapture data to be 0.70–0.84, but these values may be low because in the year of detailed study, 1976, dispersal rates between study sites were high and increased through the emergence period.
The butterflies were scored for the number and placing of the hind wing spots (Ford, 1975). Female populations in the east of our study area resembled English populations for they were unimodal at 0 spots. Spotting increased westwards until on Skokholm and the adjacent mainland the females caught were roughly equally likely to have 0, 1 or 2 spots. The Skokholm male populations had many 3-spotted individuals and so the mode of 2 in the spot-frequency distribution was less clear cut that in English populations. The trends in south Wales therefore resemble those found along the Cornish peninsula and on the Isles of Scilly. We suggest the increasingly maritime climate and the fragmentation of habitat on the coastal fringes of the species range are factors which may selectively favour butterflies with high flying and dispersal ability. Brakefield (1983) has offered evidence that more highly spotted meadow browns indeed have such an ability.     

Effects of restoration with cattle grazing on plant species composition and richness of semi-natural grasslands

Restoration of semi-natural grasslands by cattle grazing is among the most practical options for reversing the decline of northern European floristic diversity, but no studies on this subject are available. In this work the success of restoration of abandoned, privately owned mesic semi-natural grasslands by farmers receiving support from the EU agri-environmental support scheme was studied in southwestern Finland. Three kinds of grasslands were compared: old (continuously cattle grazed), new (cattle grazing restarted 3–8 years ago) and abandoned pastures (grazing terminated >10 years ago). Plant species composition of the three pasture types was floristically different in multivariate analyses (non-metric multidimensional scaling). Total species richness, richness of grassland plants, indicator plants and rare plants were highest in old and lowest in abandoned pastures in all studied spatial scales (0.25–0.8 ha, 1 and 0.01 m²). The results were congruent with different scales and species list definitions, suggesting that species density scale (1 m²) can be used as a partial surrogate for large scale species richness. Species richness of new pastures was 20% higher on 0.25–0.8 ha, 40–50% higher on 1 m² and 30% higher on the 0.01 m² scale compared to abandoned grasslands. Rare species showed insignificant response to resumed grazing. Despite problems in management quality, this study showed promising results of restoration of abandoned grasslands by cattle grazing on private farms. However, populations of several rare grassland plants may not recover with present cattle grazing regimes. Management regulations in the agri-environmental support scheme need to be defined more precisely for successful restoration.     

Effects of patch characteristics and isolation on relative abundance of the scarce heath butterfly <Emphasis Type="Italic">Coenonympha hero</Emphasis> (Nymphalidae)

The scarce heath (Coenonympha hero) is an internationally threatened butterfly in Western Europe, where it occurs primarily on hay fields and abandoned arable land in a small-scale agricultural landscape of south-central Scandinavia. Due to afforestation, this habitat is becoming increasingly fragmented in Sweden, and it can be expected that the scarce heath will decline abruptly when threshold conditions for metapopulation persistence are no longer met. We used stepwise polychotomous logistic regression to compare habitat characteristics and isolation measures for patches that harbour large, small or no populations, respectively, in an area of south-western Sweden. We found that patch area, distance to the nearest large population and amount of Galium spp. explained a significant part of the variation in relative abundance among patches. Distance to nearest large population resulted in a better model to predict occupancy than both distance to the nearest inhabited patch and connectivity, which suggests that primarily large populations act as sources for small satellite populations. Today, sites of three of the eight larger populations in the study area have been planted with spruce or pine and will disappear within 20 years. We argue that the disappearance of these patches may very well lead to rapid extinction of the whole metapopulation system.     

Rampant drift in artificially fragmented populations of the endangered tidewater goby (Eucyclogobius newberryi)

Habitat fragmentation and its genetic consequences are a critically important issue in evaluating the evolutionary penalties of human habitat modification. Here, we examine the genetic structure and diversity in naturally subdivided and artificially fragmented populations of the endangered tidewater goby (Eucyclogobius newberryi), a small fish restricted to discrete coastal lagoons and estuaries in California, USA. We use five naturally fragmented coastal populations from a 300‐ km spatial scale as a standard to assess migration and drift relative to eight artificially fragmented bay populations from a 30‐ km spatial scale. Using nine microsatellite loci in 621 individuals, and a 522‐base fragment of mitochondrial DNA control region from 103 individuals, we found striking differences in the relative influences of migration and drift on genetic variation at these two scales. Overall, the artificially fragmented populations exhibited a consistent pattern of higher genetic differentiation and significantly lower genetic diversity relative to the naturally fragmented populations. Thus, even in a species characterized by habitat isolation and subdivision, further artificial fragmentation appears to result in substantial population genetic consequences and may not be sustainable.     

Investigation of genetic diversity in fragmented geometric tortoise (Psammobates geometricus) populations

Microsatellite DNA was used to investigatelevels of genetic variability in severelyfragmented populations of the geometrictortoise, Psammobates geometricus, themost endangered tortoise on mainland Africa.Eight microsatellite markers were used toassess genetic variability within and betweenthree naturally occurring populations of P. geometricus. These populations areseparated by the Cape Fold mountain ranges inthe western Cape region of South Africa. Levels of variability were quantified usingallelic diversity, genotypic frequencies andheterozygosity. Evidence for populationsub-structuring was examined using Fstatistics, R_st and ².High levels of variability were found in allthree populations. Low levels of populationdifferentiation were found suggestingsignificant gene flow between the populations.     

Effects of stable flies (Diptera: Muscidae) on weight gains of grazing yearling cattle.

Differences in weight gains caused by stable flies, Stomoxys calcitrans (L.), on grazing yearling steer/calves averaged 0.2 kg per steer in a 3-yr study on canyon range pastures in West Central Nebraska, Stable fly numbers averaged 0.85 per front leg on treated calves and 3.64 per front leg on control calves. In 2 of the 3 yr after the grazing trials were completed, the calves were placed in a feedlot and fed a finishing ration. Compensatory gain did not occur in the feedlot after the stable fly stress was removed.     

Note on the life history of the magpie moth,Nyctemera annulata (Lepidoptera: Arctiidae)

Nyctemera annulata Boisduval was reared in the laboratory at 26±1°C and 50 ±5% RH on a host plant, ragwort (Senecio jacoboea L.), and on an artificial diet. On ragwort the average life cycle of 34 days embraced a larval period of 24 days, with up to 6 larval instars, and a pupal period of 9–11 days, depending on whether pupation occurred at the 5th or 6th instar. On the artificial diet the larval period of 56 days, involving up to 10 instars, was followed by a pupal period of 9 days, for an average life cycle of 65 days.     

Dung Beetle Conservation: Effects of Habitat and Resource Selection (Coleoptera: Scarabaeoidea)

There is increasing concern about the conservation of dung beetles which are threatened by several peculiar dangers world-wide, both at the population and community level. A noticeable threat in Europe is the dramatic reduction in the number of cattle and sheep grazing in the open, which is associated with both intensive agriculture and the progressive reforestation of previously pastured areas. We studied dung beetle habitat and resource preferences at La Mandria Park (north-west Italy) which is a mosaic of open and wooded patches where domestic (cows and horses) and wild ungulates (deer and wild boar) co-exist. Scarabaeidae were numerically dominant, accounting for 61.5% of the approximately 3000 individuals sampled (Aphodiidae accounted for 32.5% and Geotrupidae for only 6%). However, when species richness was considered, Aphodiidae were dominant, with 17 of the 27 species found (Scarabaeidae with eight and Geotrupidae with two). Assuming a null hypothesis of equal probability of colonizing any habitat or faeces, we found that most species were significantly associated with one of the four dung types or with one of the two habitats considered. On average, Scarabaeidae preferred cattle dung and open habitats whereas most Aphodiidae used deer lumps and wooded habitats. In spite of the precise ecological choices observed at La Mandria, surveys from other European areas suggest that both habitat and food selection are quite flexible. From a conservation viewpoint, the ability of coprophagous beetles to choose herbivore faeces according to their availability and to select habitats that satisfy their own microclimate requirements may certainly be useful in preserving biodiversity. Agroecology, which implies some woodland and hedgerow management practices associated with pastoralism, could be the right approach to the management of the agricultural landscape. Conversely, in reforested areas, while wild ungulate populations should be preserved, some form of human disturbance, particularly clearings used for pastoralism, should also be maintained.