Biology and conservation of <Emphasis Type="Italic">Zerynthia cassandra</Emphasis> (Lepidoptera,Papilionidae) in semi-natural environments and agricultural landscapes

The Southern festoon, Zerynthia polyxena, is a south-European butterfly listed in Annex IV of the Habitats Directive (92/43/EEC). Populations from most of the Italian territory have been recently recognized as belonging to a separate species, endemic to Italy: Zerynthia cassandra. In the province of Bologna (northern Italy), Z. cassandra is quite common. The territory of the province is densely inhabited and modified by man. Semi-natural environments are found almost exclusively in the hills, while the plain is almost entirely built-upon or cultivated. This study was based on data collected in the field in the province of Bologna, and aimed to investigate some biological and ecological aspects of Z. cassandra, with the purpose of identifying the factors that favour its presence and the most relevant issues for its conservation. In the area of study, the hostplant of Z. cassandra is Aristolochia rotunda, which is common in the plain, along the edges of drainage canals, where it supports a large Z. cassandra population. In the hills, A. rotunda is scarcer, and Z. cassandra is present in small separated nodes. Human activities such as mowing and canal maintenance are potentially damaging to Z. cassandra, particularly if carried out when eggs and larvae are present. However, if correctly timed and executed, such maintenance can preserve grassy areas that would otherwise be colonized by bushes and trees, and in which A. rotunda finds a suitable environment. Some level of disturbance can be beneficial for Z. cassandra habitats, favouring the species’ survival in the long term.     

Observations on the ecology of the endangered butterfly <Emphasis Type="Italic">Zerynthia cassandra</Emphasis> in a protected area of Northern Italy

Zerynthia cassandra is a butterfly endemic to the Italian peninsula. It was recently recognized as a sister species of Zerynthia polyxena. Z. cassandra is oligophagous as it feeds on a very restricted number of toxic plants belonging to the genus Aristolochia: Aristolochia pallida and A. rotunda. The paper reports the results of a research on the ecology of this species which was studied in the natural reserve "Stagni di Lungavilla" (Northern Italy) where the butterfly was living in a small patch of grassy vegetation bordered by a ditch at the margins of a pond. Z. cassandra develops one generation a year. Oviposition occurred in April. Eggs were mainly laid on the lower side of A. rotunda blades. The height of eggs from the ground depended on climatic trends, which affected the host plant phenology. Eggs mortality was mainly due to consumption of leaves by snails (Cepaea nemoralis) and slugs (Arion sp.). Larvae completed their development from April to May, while chrysalises were the aestivating and overwintering stage. Females did not lay eggs on host plants when they were part of the undergrowth. A decline of the butterfly due to habitat changes was recorded during the research (2001–2005). According to information coming from local butterfly watchers the butterfly used to be quite common in the natural reserve until 70’s. Its decline was caused by agricultural intensification and the natural evolution of vegetation towards woodlands, which gradually reduced the host plant density, so making the habitat unsuitable and causing the local extinction of the butterfly.     

Oviposition preferences of a threatened butterfly Leptidea morsei (Lepidoptera: Pieridae) at the western border of its range

The oviposition preferences of Leptidea morsei at the western border of its range (SE Slovenia) were studied with the aim of integrating this information into species habitat management recommendations. The characteristics of egg-laying habitat were examined at the landscape, patch, plant and leaf levels. Because sightings of adults in the field were infrequent, intensive searching for previously laid eggs on Lathyrus niger plants was chosen as the survey method. The main oviposition habitats of L. morsei in Slovenia were found to be the forest edges and light stands of thermophilous oak, oak-hornbeam and mesic beech forests (landscape level). The egg-laying sites were L. niger plants growing individually or in small stands, and oriented mostly towards W, SW, and S. The oviposition plants were between 33 and 120 cm high, with those growing in half to full shade preferred. Eggs were deposited singly, mainly on the underside of leaflets of terminal leaves, located mostly on the top quarter of plants irrespective of their height and growth form. The most important factors affecting egg-placement are sun exposure and the size of L. niger stands at ovipositing sites (patch level), leaf exposure on the plant in vertical and horizontal directions (plant level), leaf age and the leaf parts where the risk of leaf and egg desiccation is lower (leaf level). Management strategies for the main egg-laying habitats of the species are proposed.     

Conservation management of coastal dunes for Orthoptera has to consider oviposition and nymphal preferences

Dune and heathland ecosystems can harbour a multitude of specialized insect species. To assess the habitat quality of these ecosystems, the presence of specialized insect species may act as a useful indicator. The Orthoptera species Myrmeleotettix maculatus, Decticus verrucivorus, and Platycleis albopunctata present such umbrella species. Because knowledge of oviposition and nymphal habitats of these species is insufficient, we conducted a combined study consisting of an outdoor oviposition experiment and a field survey analyzing nymphal habitat preferences during summer 2009 on the Baltic island of Hiddensee, Germany. The oviposition experiment showed, that all three species mostly avoid oviposition under lichens (= mature grey dunes). M. maculatus preferred bare ground for oviposition, D. verrucivorus favoured both bare ground and mosses, and P. albopunctata laid most eggs into mosses. Young nymphs of both M. maculatus and P. albopunctata preferred initial grey dunes with a high proportion of bare ground and moss-rich grey dunes. Old nymphs were related to moss-rich and lichen-rich grey dunes with more dense vegetation. Based on our results, early seral stages of dune succession with bare ground and mosses as keystone structures are crucial for the conservation of the three studied umbrella species. Because old nymphs and adults additionally require more dense grey dune vegetation or adjacent heath stands, practical dune and heathland management measures should aim to maintain a mosaic-like pattern of different grey dune and dwarf-shrub vegetation stands.     

When the Rule Becomes the Exception. No Evidence of Gene Flow between Two Zerynthia Cryptic Butterflies Suggests the Emergence of a New Model Group

There is increasing evidence that most parapatric cryptic/sister taxa are reproductively compatible across their areas of contact. Consequently, the biological species concept, which assumes absence of interbreeding, is becoming a not so effective criterion in evolutionary ecology. Nevertheless, the few parapatric sister taxa showing complete reproductive barriers represent interesting models to study speciation processes and the evolution of reproductive isolation. In this study, we examined contact populations in northwestern Italy of two butterfly species, Zerynthia polyxena and Z. cassandra, characterized by different genitalic morphotypes. We studied levels of divergence among 21 populations distributed from Sicily to France using three genetic markers (the mitochondrial COI and ND1 genes and the nuclear wingless gene) and genitalic geometric morphometrics. Moreover, we performed species distribution modelling to estimate different climatic requirements of Z. polyxena and Z. cassandra. We projected climatic data into glacial maximum scenarios in order to verify if and to which extent glacial cycles could have contributed to speciation processes. Genetic and morphometric analyses identified two main groups. All specimens showed a concordant pattern of diversification, including those individuals sampled in the contact area. Haplotype distribution and climatic models showed that during glacial maxima both species experienced a strong range contraction and presumably remained separated into different microrefugia in southern France, in the Italian Peninsula and on the islands of Elba and Sicily. Long term separation was probably favoured by reduced dispersal ability and high phylopatry, while genitalic diversification probably favoured interbreeding avoidance. Conversely, the aposematic wing pattern remained almost identical. We compared our results with those obtained in other species and concluded that Z. polyxena and Z. cassandra represent a valuable model in the study of speciation.     

Host plant use by the Heath fritillary butterfly, Melitaea athalia: plant habitat, species and chemistry

We present a study of habitat use, oviposition plant choice, and food plant suitability for the checkerspot butterfly Melitaea athalia Rottemburg (Lepidoptera: Nymphalidae) in Åland, Finland. We found that in Åland, unlike in the mainland of Finland and many parts of its range, M. athalia flies mainly in open meadows. When offered an array of plants in a large (32 × 26 m) field cage, they predominately oviposited upon Veronica chamaedrys L., V. spicata L. and Plantago lanceolata L. (Plantaginaceae), which grow in open meadows. The relative abundance of the butterfly in Åland, and its habitat and host plant use there, may reflect local adaptation to land use practices and geology that maintain clusters of small open meadows with little successional change. At the scale of a plant patch, preferred species were used as frequently in mixed species patches as in mono-specific patches, and more oviposition occurred in open than in grassy patches. All of the host plants used by M. athalia are defended by iridoid glycosides (IGs). However, oviposition choice among species and among individual plants within species was largely independent of IG concentration. This contrast with the more discerning congener, M. cinxia, supports the idea that host discrimination decreases with increasing host range. Finally, although the adult butterflies chose specific plant species for oviposition, as larvae they performed well on twelve out of thirteen species of plants, including both known hosts and related novel plants that occur in Åland, indicating a much wider range of larval food plant species than adult oviposition species.     

A first step towards successful conservation: understanding local oviposition site selection of an imperiled butterfly, mardon skipper

Lack of basic biological information is a key limiting factor in conservation of at-risk butterflies. In the Puget prairies of Washington State little is known about the habitat requirements of mardon skipper (Polites mardon, federal candidate, WA endangered). We investigated oviposition site selection and used our results to assess oviposition habitat quality at a restored site with reintroduction potential. During the 2009 flight season we marked eighty-eight eggs and sampled vegetation at oviposition and random locations, measuring habitat variables with respect to the oviposition plant, vegetation structure, and vegetation cover. Eighty-six of the eighty-eight eggs were laid on Festuca roemeri, a native, perennial bunchgrass. Discriminant function analysis revealed selection of oviposition sites based on habitat structure; females laid eggs in small F. roemeri tufts in sparsely vegetated areas of the prairie. These results are contrary to results from a previous study in the Cascade Mountains of WA where females are generalists and selected densely vegetated areas, suggesting that the species has geographically specific habitat requirements. To assess oviposition habitat at a potential reintroduction site we measured the six variables most important for oviposition at the occupied site and a proposed reintroduction site. Results revealed differences in habitat quality between locations and suggest a need for further habitat management at the reintroduction site. Our results highlight the importance of understanding the local habitat use of a rare species where restoration activities occur and increase our ability to target habitat management where it is most needed for the persistence of the species.     

Differences in larval nutritional requirements and female oviposition preference reflect the order of fruit colonization of Zaprionus indianus and Drosophila simulans

Species coexist using the same nutritional resource by partitioning it either in space or time, but few studies explore how species-specific nutritional requirements allow partitioning. Zaprionus indianus and Drosophila simulans co-exist in figs by invading the fruit at different stages; Z. indianus colonizes ripe figs, whereas D. simulans oviposits in decaying fruit. Larvae feed on yeast growing on the fruit, which serves as their primary protein source. Because yeast populations increase as fruit decays, we find that ripe fruit has lower protein content than rotting fruit. Therefore, we hypothesized that Z. indianus and D. simulans larvae differ in their dietary requirements for protein. We used nutritional geometry to assess the effects of protein and carbohydrate concentration in the larval diet on life history characters in both species. Survival, development time, and ovariole number respond differently to the composition of the larval diet, with Z. indianus generally performing better across a wider range of protein concentrations. Correspondingly, we found that Z. indianus females preferred to lay eggs on low protein foods, while D. simulans females chose higher protein foods for oviposition when competing with Z. indianus. We propose the different nutritional requirements and oviposition preference of these two species allows them to temporally partition their habitat.     

A multiple-scale analysis of host plant selection in Lepidoptera

Lepidoptera play an important role in terrestrial ecosystems as pollinators, as components of the food chain and as indicators for healthy ecosystems due to their sensitivity to change. Heterogeneous landscapes with variability of topographical features, vegetation structure combined with food sources for all life stages are the basis for successful lepidopteran oviposition. A multiple-scale analysis is proposed to understand the hierarchical relationships between selected site to plant characteristics and oviposition preferences for the dingy skipper (Erynnis tages). To achieve this goal, factors driving oviposition at the plant and patch scale were identified and scale dependencies at the site scale were assessed. At the plant scale, tallest host plants were used for oviposition; however relative egg height upon each plant was similar in both host plant species [bird’s-foot trefoil (Lotus corniculatus) and horseshoe vetch (Hippocrepis comosa)]. The main factors preferred by E. tages in L. corniculatus patches were sward height and percent of bare ground, and in H. comosa host plant density patches. Selected patches had slopes of greater gradients (mostly facing south) than patches with no selected host plants. At the site scale, oviposition patches were clustered at small scales and oviposition sites were dispersed at larger scales. Our study suggests that oviposition selection in E. tages is a hierarchical process varying from the site to the plant scale. Our study provides empirical evidence useful to inform landscape management strategies. These can be expanded to assess larger scale vegetation and habitat suitability beyond individual sites for systematic conservation planning.     

The impact of two non-native plant species on native flora performance: potential implications for habitat restoration

Both Impatiens glandulifera and Fallopia japonica are highly invasive plant species that have detrimental impacts on native biodiversity in areas where they invade and form dense monocultures. Both species are weakly dependent on arbuscular mycorrhizal fungi (AMF) for their growth and, therefore, under monotypic stands, the AMF network can become depauperate. We evaluated the impact of I. glandulifera and F. japonica on the performance (expressed as shoot biomass) of three UK native species (Plantago lanceolata, Lotus corniculatus and Trifolium pratense) grown in soil collected from under stands of both invasive plants and compared to plants grown in soil from under stands of the corresponding native vegetation. All native species had a higher percentage colonisation of AMF when grown in uninvaded soil compared to the corresponding invaded soil. P. lanceolata and L. corniculatus had a higher biomass when grown in uninvaded soil compared to corresponding invaded soil indicating an indirect impact from the non-native species. However, for T. pratense there was no difference in biomass between soil types related to I. glandulifera, suggesting that the species is more reliant on rhizobial bacteria. We conclude that simply managing invasive populations of non-native species that are weakly, or non-dependent, on AMF is inadequate for habitat restoration as native plant colonisation and establishment may be hindered by the depleted levels of AMF in the soil below invaded monocultures. We suggest that the reintroduction of native plants to promote AMF proliferation should be incorporated into future management plans for habitats degraded by non-native plant species.     

Restoration action and species response: oviposition habits of Plebejus icarioides fenderi (Lepidoptera: Lycaenidae) across a restoration chronosequence in the Willamette Valley, Oregon, USA

Habitat restoration is critical to the conservation of rare species. However, restoration efforts often proceed without knowledge of their effects on these species. We investigated the reproductive response of federally endangered Fender’s blue butterfly (Plebejus icarioides fenderi) to prairie restoration in Willamette Valley, Oregon, USA. In 2009 and 2010, we quantified availability of larval host plant, Kincaid’s lupine (Lupinus oreganus), and butterfly oviposition in three restored areas (1–10 years old) and adjacent intact habitat. Oviposition measures in restored areas reached or exceeded intact habitat (0.1 eggs/leaf of host plant and 12 % of time ovipositing) within five years post-restoration. However, none of the restorations provided an equivalent host plant density to intact areas (55 leaves/m²). The different response time of host plants and butterflies to restoration highlights the importance of monitoring both vegetation and oviposition over an ecologically relevant timescale (at least 10 years). For imperiled species, quantifying reproductive response to restoration is critical for adaptive management and successful conservation of the species which restoration efforts are intended to benefit.     

The number and distribution of vascular plant species in island forest communities in the northern part of the West Carpathian foothills

Phytosociological records were made in 80 stands lying in 50 small woodland islands in the Wierzbanówka valley. The types of communities were distinguished on the basis of numerical classification of records. These were mainly fragments of theTilio-Carpinetum association. For all the stands and for two groups of stands connected with various soils and localized mainly in the eastern or western part of the valley the statistical relationships between ten independent variables were examined (area of record, area of woodland island, its shape, distance to the nearest large woodland, mean distance to the three nearest woodland islands and others) and 10 dependent variables (number of species of trees, shrubs, herbaceous plants, species characteristic of the classesQuerco-Fagetea, Vaccinio-Piceetea, Molinio-Arrhenatheretea, Rudero-Secalietea and others). It was found that the floristic composition of the communities investigated was connected primarily with the isolation of the woodland islands. With increasing isolation the total number of species decreased, as did the number of herbaceous plants and that of herbaceous plants of the classesQuerco-Fagetea andVaccinio-Piceetea, while the number of species of the classesMolinio-Arrhenatheretea andRudero-Secalietea increased. Conditions of the habitat such as the inclination of slopes, shading, and soil fertility were less important.     

Charophyte occurrence in Ceratophyllum demersum stands

The hornwort Ceratophyllum demersum is a loosely attached to the bottom or free-floating vascular macrophyte, which builds dense stands in nutrient-rich waters. The hornwort stands are usually monospecific communities with a negligible contribution of other aquatic plants. However, some published literature data and our own observations evidenced the co-occurrence of densely growing Ceratophyllum and other macrophytes, including charophytes, which by contrast to hornwort are indicative of clear and less productive waters. Thus, the aim of this study was to identify the charophyte species growing in C. demersum stands and to define the environmental conditions promoting this co-occurrence. In 18 natural lakes of Western Poland, 60 stands of Ceratophyllum demersum were studied in the years 2001–2005. A total of 25 species built the studied stands. As many as eight charophyte species, 13 vascular plants, two moss species and one filamentous alga co-occurred with C. demersum. Among charophytes rare to Poland Chara polyacantha and Nitella gracilis were identified. Nitellopsis obtusa and Chara globularis revealed the highest frequencies along with Myriophyllum spicatum. Morphology of lakes combined with water quality, particularly transparency, appeared to regulate the coexistence of charophytes and C. demersum, macrophytes usually competing with each other.     

The Duke of Burgundy butterfly and its dukedom: larval niche variation in <Emphasis Type="Italic">Hamearis lucina</Emphasis> across Central Europe

In order to improve our understanding of habitat preferences and optimal management of open woodland insects, we analyse patch occupancy and oviposition electivity of the endangered Duke of Burgundy butterfly, Hamearis lucina, in three regions across German habitat types. Some newly available forest clearings created by a severe winter storm in the Schönbuch region were colonised within 2 years, whereas some suitable patches remained unoccupied for several years. We discuss how small population sizes, limited patch connectivity, and habitat quality may contribute to such an intermediate colonisation power. Across study regions, we document differences in oviposition site electivity. On calcareous grassland in the Diemeltal, shaded Primula plants on western slopes were preferentially used, probably to avoid desiccation of the natal food plant. To the contrary, sun-exposed Primula stands were preferred in forest clearings in the Schönbuch and calcareous fens in the Allgäu. In these regions, the risk of desiccation is low, but the overall cool and moist microclimate conditions may hamper larval development in shaded conditions, favouring oviposition at sites with maximum exposition to solar radiation. Optimal management strategies depend on the abiotic and biotic conditions and conservation priorities for the given region and habitat type, and we suggest management regimes that promise to sustain suitable H. lucina habitat at a landscape-level.     

A Pine Is a Pine and a Spruce Is a Spruce – The Effect of Tree Species and Stand Age on Epiphytic Lichen Communities

With an increasing demand for forest-based products, there is a growing interest in introducing fast-growing non-native tree species in forest management. Such introductions often have unknown consequences for native forest biodiversity. In this study, we examine epiphytic lichen species richness and species composition on the trunks of non-native Pinus contorta and compare these to the native Pinus sylvestris and Picea abies in managed boreal forests in northern Sweden across a chronosequence of age classes. Overall, we recorded a total of 66,209 lichen occurrences belonging to 57 species in the 96 studied forest stands. We found no difference in species richness of lichens between stands of P. contorta and P. sylvestris, but stands of P. abies had higher total species richness. However, species richness of lichens in stands of P. abies decreased with increasing stand age, while no such age effect was detected for P. contorta and P. sylvestris. Lichen species composition progressively diverged with increasing stand age, and in 30-year-old stands all three tree species showed species-specific assemblages. Epiphytic lichen assemblages in stands of 30-year-old P. contorta were influenced by greater basal area, canopy closure, and average diameter at breast height, P. abies stands by higher branch density and canopy closure, and stands of P. sylvestris by greater bark crevice depth. Differences in lichen species richness and composition were mainly explained by canopy closure and habitat availability, and the greater canopy closure in mature P. abies stands promoted the colonization and growth of calicioid lichen species. Our results indicate that the non-native P. contorta have similar species richness as the native P. sylvestris. The main difference in lichen species richness and composition is between P. abies and Pinus spp. in managed forests of boreal Sweden.     

Better Hosts Dive: Detachment of Ectoparasitic Water Mites (Hydrachnellae: Arrenuridae) from Damselflies (Odonata: Coenagrionidae)

Water mite larvae parasitizing damselflies must detach while the host is in a suitable reproduction habitat for both parasites and itself. They should do so during the host's oviposition. In this paper I present experimental data for the detachment rate of water mite larvae (Arrenurus cuspidator) from different host species, Coenagrion hastulatum and C. puella, in relation to the host's oviposition behavior. C. hastulatum oviposits submerged, whereas C. puella oviposits at the water surface and aggregates with conspecifics. It was found that mite larvae detach at a significantly higher ratio from hosts with submerged oviposition. Experimental tests showed that this is not a species-specific effect. It is caused mainly by the oviposition behavior. The results are discussed in the light of different oviposition systems in damselflies.     

Microhabitat selection in a grassland butterfly: a trade-off between microclimate and food availability

Understanding the factors that determine habitat quality is vital to ensuring appropriate habitat management. The main objective of this study was to assess the microhabitat preferences of egg-depositing females of the Grizzled Skipper (Pyrgus malvae) in calcareous grasslands of the Diemel Valley (Central Germany) for defining habitat quality. Based on this knowledge, we make management recommendations for the conservation of this threatened species. P. malvae generally preferred open and warm oviposition sites. However, there were considerable differences in the environmental conditions, depending on the selected host plant. On the small Potentilla tabernaemontani plants that grew in sparse vegetation with low-growing turf, mostly only one egg was found per plant. In contrast, occupied Agrimonia eupatoria host plants were larger and more prominent, regularly having more than one egg, and grew at sites with a taller and denser vegetation. The observed oviposition pattern reflects a trade-off between microclimate and food availability: Usually, occupied P. tabernaemontani plants grow under favourable microclimatic conditions. However, during hot years the risk of desiccation is high, leading to food shortage. In contrast, A. eupatoria generally provides more biomass, thrives on deeper soils and the vegetation has a cooler microclimate: hence, food shortage is somewhat unlikely. To meet the described habitat requirements of P. malvae, traditional rough grazing by sheep and goats seemed to be the most appropriate land management strategy. The re-introduction of coppicing in woodlands, particularly adjacent to calcareous grasslands, would also be beneficial.     

Distribution and dispersal ecology of Lobaria pulmonaria in the largest primeval beech forest of Europe

Occupancy and density of the epiphytic lichen L. pulmonaria were studied in the mountains of Uholka–Shyrokyi Luh (Ukraine), which include the largest primeval beech forest in Europe. The lichen occupancy was assessed on 314 plots laid out on a systematic grid. Additional data on population density were collected from 483 trees growing both, on and between these plots. The trees harbouring L. pulmonaria were distributed very sparsely within Uholka–Shyrokyi Luh, and occupy nearly 10 % of the studied perimeter. The generalized linear models showed that area of occupancy of L. pulmonaria was significantly influenced by altitude and canopy cover, whereas the species’ density was explained by habitat types and slope exposition. Population density is higher at the timberline than in the interior forest or on lowland meadows. We found a bimodal altitudinal distribution of L. pulmonaria, with maxima below and above 900 m a.s.l., where it prefers forest stands with loose or scattered canopy. The preferred position of L. pulmonaria on host tree trunks depends on stand density and allows the species to get the necessary level of insolation also in shaded sites where it grows higher up on the trunk than in open stands. While L. pulmonaria occupied trees with various diameters, juvenile individuals are more frequent on small trees, but mature lichen individuals are predominantly found on trees of average or large sizes. Fertile individuals require specific environmental conditions, which are available at intermediate altitudes, related with sheltered light, and horizontal terraces on slopes with eastern exposition. In general, the primeval beech forest of Uholka–Shyrokyi Luh harbours a high percentage of juvenile thalli of L. pulmonaria, which lack vegetative propagules. Mature individuals have a low frequency of fruit bodies and reproduce mainly with vegetative diaspores. We interpret this as an indication of a currently growing population of L. pulmonaria within the area. We hypothesize that transboundary air pollution has decreased the lichens’ population frequency and density and has altered the ratio of developmental stages in L. pulmonaria during earlier decades.     

Host associations of <Emphasis Type="Italic">Coenonympha hero</Emphasis> (Lepidoptera: Nymphalidae) in northern Europe: microhabitat rather than plant species

Understanding ecological requirements of endangered species is a primary precondition of successful conservation practice. Regrettably, we know surprisingly little about the life history of numerous threatened insects, and about their use of larval host plants in particular. The brown butterflies (Nymphalidae: Satyrinae) have traditionally been considered polyphagous on grasses and indiscriminatory in their oviposition behavior. However, detailed studies on several species have revealed local specialization in host plant use as well as the decisive role of microlimatic conditions as determinants of habitat quality. The present study addresses host plant relationships in the endangered brown butterfly Coenonympha hero (L.) at the northern limit of its European distribution. We combine laboratory-based host preference and performance tests with an analysis of microhabitat use by adult butterflies in the field. Both lines of evidence suggest that C. hero is polyphagous enough not to be associated with one particular host species. Oviposition choices of C. hero are not driven by host plant species but rather by structural characteristics of the substrate. The preferred rigid needle-like structures may serve as cues of ‘transparent’ vegetation which allows the larvae to benefit from sunlight reaching the lower strata of the tuft. Our results suggest that conservation efforts should prioritize microclimatic parameters, rather than the presence of any particular host plant species, as decisive determinants of habitat quality in C. hero.     

Host range of a newly introduced parasitoid, Binodoxys communis among common aphid species in Hawaii

Binodoxys communis (Gahan) (Hymenoptera:Braconidae), a parasitoid of aphids originally from China, was introduced into Hawaii and evaluated in the laboratory for its ability to detect, accept, oviposit and develop in Aphis gossypii reared on two host plants, plus five other common aphid species. The parasitoid was able to detect all six aphid species and to successfully sting five species, with highest preference for those in the genus Aphis. Aphis species were highly suitable for parasitoid development. Other species were only marginally suitable. Parasitoids spent less time searching on plants of less acceptable aphids. Aphid defensive behaviors did not affect oviposition success, but did lengthen the parasitoid’s handling time of several aphid species. Host acceptance was positively correlated with host suitability, yet one unsuitable host was readily accepted for oviposition.