Potential host range of myrmecophilous Arhopala butterflies (Lepidoptera: Lycaenidae) feeding on Macaranga myrmecophytes

“Plant-ants”, i.e. those symbiotic with myrmecophyte plants, defend their hosts against herbivores. Plant-ants are expected to affect the host-plant ranges of herbivores that feed on myrmecophytes. This study aimed to experimentally determine whether anti-herbivore defences by plant-ants restrict the larval host-plant ranges of four Arhopala (Lycaenidae) butterflies that feed on Macaranga (Euphorbiaceae) trees, some of which are myrmecophytes. We fed Arhopala larvae with the leaves of five Macaranga species under ant-excluded conditions to examine their potential host-plant ranges. Under ant-excluded conditions, three Arhopala species survived to the pupal stage when fed species not used in the field as well as their normal host species. Our data suggested that the aggressive behaviours of plant-ants towards leaf-feeding insects restrict the potential host-plant ranges of some Macaranga-feeding Arhopala butterflies.     

Afrotropical mistletoe butterflies: Larval food plant relationships of Mylothris Hübner (Lepidoptera: Pieridae)

A detailed list of larval food plants of Mylothris based on review of published records in the literature is presented. Food plants have been reported for some 23 species (40%), although in only eight species (14%) of butterflies have plants been identified to species level. The food plants represent two unrelated orders, Santalales and Polygonales, although nearly all records (93%) are from four closely related families in the former group. Within the Santalales, the family Loranthaceae, a diverse group of aerial stem‐parasitic shrubs (mistletoes), is most frequently exploited. Only two species of Mylothris, M. bernice (Hewitson) and M. rubricosta (Mabille), which are closely related and possibly comprise a single species, are associated with Polygonaceae (Polygonales). Comparison of the morphology of the early stages of M. bernice, and other evidence, clearly indicates that M. bernice/rubricosta belong to Mylothris and do not represent a separate genus or sister group. Comments are made on these diverse food plant relationships within the context of a modern phylogeny of the Santalales and the evolution of parasitic plant feeding in butterflies in general. It is suggested that Mylothris had its major period of evolution and adaptive radiation on the Loranthaceae, probably sometime after the differentiation of most of the families or lineages in the Santalales (rather than on an earlier ancestral branch at or near the root of the Santalales evolutionary tree), and that this association has facilitated host switching multiple times. While more field data are clearly needed to ascertain the full extent of host specificity and range of mistletoe species exploited by Mylothris, this is unlikely to significantly change the patterns of food plant utilization seen at the higher taxonomic (ordinal and familial) levels. Mylothris represents one of only a few diverse groups of Lepidoptera, and insects in general, known to feed predominantly on African mistletoes.     

Patterns of host-plant utilization by leafhoppers in the genus Eupteryx (Hemiptera: Cicadellidae) in Britain

Known host-plant associations are listed for the 16 species of Eupteryx occurring in Britain. A total of 77 species in 17 plant families are exploited. The most frequently represented plant family is the Labiatae. Degrees of specificity range from strict monophagy (four spp.) to broad polyphagy (five spp.). In general, host-plant overlap between species is low. The detailed relationships between three Eupteryx species and three members of the Urticaceae were explored using field populations and laboratory feeding experiments, survival tests and examination of patterns of oviposition. Eupteryx urticae, E. cyclops and E. aurata all utilized Urtica dioica as their primary host plant. However, the only regularly recorded association with other members of the Urticaceae was the host range expansion of E. urticae onto Parietaria judaica in the second generation. These findings were supported by the laboratory experiments. The spatial distributions of E. urticae oviposition sites and levels of attack by mymarid parasitoids were similar in populations on the two plant species. The implications of these results are discussed.     

Disentangling prey-handling efficiency of larval newts through multivariate prey trait analysis

Multivariate prey trait analysis is a functional approach to understand predator–prey relationships. In the present study, six prey macroinvertebrate ecological traits were used to identify several key factors in the handling efficiency of seven predatory larval newt species. The results revealed a remarkable similarity in the feeding behaviour among species, suggesting a foraging behaviour convergence among species in the prey-handling efficiency of larval newts. Nevertheless, larvae of some newt species showed clear preferences for particular categories of ecological trait; for example, Lissotriton vulgaris tended to feed on macroinvertebrate taxa with random trajectory, and Calotriton asper fed on macroinvertebrate taxa with high agility. In contrast, Mesotriton alpestris showed a clear ability to feed on prey with movable accessories (cases/tubes) and patterned concealment. This study shows how multivariate approaches can complement traditional diet analyses, and the method has wide applicability across life-stages and species.     

Diverse mechanisms of feeding and movement in Cyclorrhaphan larvae (Diptera)

Direct observation, filmed behaviour and morphological analysis were used to investigate mechanisms of larval feeding and movement in 20 species of Cyclorrhapha (Diptera). Feeding mechanisms refer to techniques of gathering food close to the pharynx entrance prior to sucking it in. A total of 12 mechanisms were recorded. Contrasting mechanisms were associated with saprophagy, phytophagy, mycophagy and zoophagy. Larvae had role-specific, compartmentalised bodies. The rear compartment grips substrates enabling the front ones to scan for food by sweeping from side to side or up and down. The front compartments extend or lunge to gather food or grip substrates during locomotion. Lower cyclorrhaphans had more disparate mechanisms than higher cyclorrhaphans. In the latter, the size, shape and movements of the thorax, pseudocephalon and head skeleton are diverse. Influences on this diversity are food quality and access conditions at development sites. Movement capabilities and functions were established for many components.     

Seasonal nutrient cycling in Potamogeton pectinatus of the lower Provo River

A common submersed aquatic plant of Great Basin wetland and riverine systems, Potamogeton pectinatus L. (sago pondweed) is a key waterfowl food. Nutritional qualities of submersed aquatics in the Great Basin are little understood. The purpose of this study was to determine the seasonal element cycling and nutritional qualities of P. pectinatus drupelet, leaf, and root tissues from the lower Provo River. Leaf tissues protein was 27% (dry weight) in July, but declined to 15% by December. Drupelet protein content was 9% in July and 6.5% in October. Lignocellulose in leaf tissue was lowest in July at 34% and increased as the season progressed. Percent fat was highest in leaf tissue at 12% in July. Sugars were highest in P. pectinatus leaf tissues in December and July. Calcium and magnesium concentrations increased in P. pectinatus tissues over the entire season. Leaf tissue zinc was 329 ppm (dry weight) in October. Leaf iron concentration was highest in September at 1184 ppm, while root tissue iron was 7166 ppm. Manganese content in leaf tissue peaked in October at 4990 ppm. Copper concentrations in leaves and roots were variable. High protein in leaf tissue would benefit local nesting and brooding waterfowl populations that feed on this aquatic. Trace metal concentrations in leaf and root tissues, from possible anthropogenic activities, appear very high during fall migratory months. Metal bioaccumulation by this species in other Great Basin wetlands and possible metal toxicity in waterfowl warrant further study.     

Contrasting modes of handling moss for feeding and case‐building by the caddisfly Scelotrichia willcairnsi (Insecta: Trichoptera)

Final‐instar larvae of the microcaddisfly, Scelotrichia willcairnsi sp. nov. (Trichoptera: Hydroptilidae) were discovered feeding on a moss, Platyhypnidium muelleri in north‐eastern Queensland. Not only do the larvae feed on the moss, but their cases are constructed from fragments of moss leaves. Microscopic examination of larval guts and cases showed a total contrast in the angle at which the moss leaves are cut for each purpose: for cases the moss leaves are cut longitudinally, in parallel with the length of the cells, whereas for feeding the leaves are cut perpendicular to the leaf margin, across the cells, presumably an adaptation that releases the cell contents for digestion. The new caddisfly species is described based on the adult males. Scelotrichia willcairnsi represents the first Australian record of the South‐east Asian‐New Guinean Stactobiini genus Scelotrichia.     

The preimaginal stages of Minotetrastichus frontalis (Nees) and Chrysocharis laomedon (Walker) (Hymenoptera: Eulophidae), parasitoids associated with Phyllonorycter issikii (Kumata) (Lepidoptera,Gracillariidae)

The biology and morphology of the early larval instars of Minotetrastichus frontalis (Nees) are redescribed and the morphology of the preimaginal stages of Chrysocharis laomedon (Walker) (Hymenoptera: Eulophidae) are described in detail for the first time. Both species are larval-pupal parasitoids of Phyllonorycter issikii (Lepidoptera, Gracillariidae), which is associated with Tilia sp. The female of M. frontalis lays her egg beside the host larva and the newly hatched first instar larva moves and has to find the host larva. The larva of P. issikii tries to continue its feeding but never pupates after paralysis. The female of C. laomedon lays its egg inside the cuticle of the larva of P. issikii, but the newly hatched parasitoid larva vacates the host larva and develops externally on its surface as an ectoparasitoid. Such behaviour might be facilitated by the constant temperature and humidity inside the mine. Some peculiarities of parasitoid–host relationships are described and discussed.     

Studies on Gasteroclisus rhomboidalis (Boheman.) (Coleoptera: Curculionidae)—a pest of the African ‘spinach’

Summary

Eggs of G. rhomboidalis are usually laid singly in separate excavations made with the snout of the beetle in either leaf petioles or tender portions of shoots of host plants, Amaranthus sp. At field temperatures fluctuating between 19°C and 30°C and in contact with water, eggs hatched in a mean of 2·8 days while unmoistened ones shrivelled up.

Beetle larvae bore and feed on the stele of host plants where development, up to adulthood, is completed in self-made larval galleries. On the average, the larvae are capable of consuming 40% and above of the cross-sectional areas of stems of infected host plants. In nature, multiple infection of host plants was quite common with 1–16 beetle larvae/plant rather usual. Consequently, the stem of virtually every healthy-looking host plant is internally traversed by larval galleries, at times even below ground level.

Adults bite their way out of the stem after a mean of 36·37 days from date of oviposition.

Larval damages to host plants are the gravest and bring about premature breakage and/or death of crops, stunted growth and reduced yield of the wanted leaf products.     

Description of the biology and immature stages of Pagyris ulla (Hewitson) (Lepidoptera: Nymphalidae: Ithomiini) in the Colombian Andes

The biology and immature stages of Pagyris ulla (Hewitson, [1857]) (Lepidoptera: Nymphalidae: Ithomiini) are described for the first time. The species’ host plant is established to be Brugmansia candida Pers. (Solanaceae). The life cycle from eggs to adult under laboratory conditions and ambient temperature took approximately 47 days, and the larvae passed through five instars. The larvae are gregarious, feed at night, and rest during the day in nests made by joining leaves near the apex of the plant stem.     

Morphology of Eogystia sibirica (Alphéraky) (Lepidoptera: Cossidae) attacking Asparagus officinalis in northern China with descriptions of its immature stages

The carpenter moth Eogystia sibirica (Alphéraky) (Lepidoptera: Cossidae) is a serious pest of the garden asparagus Asparagus officinalis (family Liliaceae) in northern China, with its larvae boring in the stem and roots, frequently causing significant damage to the plant. All the life stages of the pest, including egg, larva, pupa and adult, are described and illustrated in detail. The ovoid egg is covered with a reticulate meshwork of ridges on the chorion. The eruciform larva possesses only three stemmata on each side of the head; the reduced abdominal prolegs on segments III–VI each bear 35–55 uniordinal crochets arranged in two transverse bands; the short anal prolegs each bear five to seven uniordinal crochets in a transverse band. The pupa is adecticous and obtect, without cremaster. The reduction of larval stemmata and the invagination of the adult pterosterna are briefly discussed.     

Natural history of an ant–plant–butterfly interaction in a Neotropical savanna

Non-myrmecophilous lepidopteran larvae using plants bearing ant attractants such as extrafloral nectaries are good models for studying morphological and behavioural mechanisms against ant predation. Udranomia spitzi (Hesperiidae) is a butterfly whose larvae feed on leaves of Ouratea spectabilis (Ochnaceae), a plant with extrafloral nectaries. We described the early stages of U. spitzi, and used field observations and experiments to investigate the defensive strategies of caterpillars against predatory ants. Larvae pass through five instars and pupation occurs inside larval leaf shelters. Ant-exclusion experiments revealed that the presence of ants did not affect significantly caterpillar survival. Predation experiments showed that vulnerability to ant predation decreased with increase in larval size. The present study showed that predatory ants are not as relevant as demonstrated for other systems, and also illustrates how observational data and field experiments can contribute to a better understanding of the biology and ecology of a species of interest.     

Strategies for size and growth in butterflies (Insecta: Lepidoptera): counterintuitive trends and unique solutions to achieving maturity

Larger organisms are expected to take longer to develop, depressing overall growth rates. An examination of relationships between size, development times and growth rates in British and northwest European butterflies has revealed a reversal of this relationship with large species developing rapidly and small species developing slowly, especially in subsets of species that complete their development in a single season and have multiple broods. Distinctive life history associations are found to be linked to rapid development (daytime and gregarious feeding) and enhanced defence (larval spines, aposematism) from the resulting increased exposure to enemies. Taxonomic bias is evident in development-size patterns linked to overwintering strategy and voltinism. Different strategies exist for faster growth in the larger Pieridae and non-satyrine Nymphalidae. Larval host plant contrasts for food quantity and quality underlie distinctions for size and development times.     

Natural history of a South African insect pollinator assemblage (Insecta: Coleoptera,Diptera, Hymenoptera,Lepidoptera): diagnostic notes,food web analysis and conservation recommendations

We describe activity patterns, relative abundances and pollen transport by insect floral visitors in the Skukuza Ranger District, Kruger National Park, Republic of South Africa, based on field surveys conducted during the early rainy seasons of years 2006 to 2012 (inclusive). Diagnostic notes, illustrations and natural history observations are provided for species in the families Buprestidae, Cerambycidae, Cleridae, Lycidae and Scarabaeidae (Coleoptera), Muscidae, Platystomatidae and Tabanidae (Diptera), Apidae, Halictidae, Megachilidae, Sphecidae and Vespidae (Hymenoptera), and Pieridae and Thyrididae (Lepidoptera) that transported pollen of tree or shrub species. Observations on floral phenology and pollination syndrome are presented for 27 flowering tree or shrub species. To provide a foundation for studies of the effects of drought and climate change on pollination services in the Kruger National Park, we applied methods of food web analysis to characterise this plant-pollinator assemblage. The food web analysis shows moderate levels of redundancy in plant-pollinator interactions (with connectance values averaging 0.19 for plant species and 0.20 for pollinator species), suggesting that pollination services in this system may exhibit some resilience to environmental perturbations. Possible conservation strategies for maintaining pollination services in this ecological system are discussed, including habitat management to conserve larval or nesting areas for social and solitary bees and scarab beetles, as well as further inventories and long-term monitoring of pollinator species.     

Morphology and feeding behaviour of the leaf-mining larva of Cheilosia semifasciata (Diptera: Syrphidae)

In North Wales the larva of Cheilosia semifasciata (Diptera: Syrphidae) makes full-depth blotch mines in leaves of Umbilicus rupestris. Mines occur mostly on shaded plants with one larva per plant. Each larva mines several leaves to complete development and initiates new mines by curling round the leaf margin and puncturing the epidermis under the leaf. Unlike other dipteran leaf-miners which feed on their sides, only the thorax is turned sideways when feeding. The larva uses a grasping organ on the anal segment to grip the substrate when moving externally on the food-plant. Inside leaf mines, position is further secured by the integumental vestiture which grips the epidermis above the larva. The morphology and behaviour of the larva of C. semifasciata differs markedly from larvae of three congeneric species that tunnel in stems and roots.     

Improving knowledge of the cyclorrhaphan larva (Diptera)

A significant factor in the evolution of the Cyclorrhapha (Diptera), the most biodiverse of higher dipteran taxa, is the larva. The larva also has wide-ranging trophic and environmental relationships, including positive and negative impacts on human health and wealth. Despite its importance, the larva is neglected and a low proportion of species are known in this stage. In this paper, factors contributing to larval neglect are reviewed, including: poor attitudes leading to cycles of neglect and shallow treatment; taxonomy that uses adult not larval stages; lack of material in collections; rearing barriers, and presumptions of morphological similarity suggesting that characters will be problematic to acquire and analyse. Neglect is pervasive and affects many subjects; those considered here are: species inventories and rarity assessments for biodiversity and conservation, in which larvae are usually ignored although they can be more cost-effective to sample and a richer source of environmental data; determining larval feeding modes where controversies due to conflicting evidence persist unresolved; and reliance on a limited pool of increasingly old publications whose data are repeated rather than tested and updated with new research. In an attempt to reinvigorate interest, which is the main aim of this paper, poorly assessed larval features possibly significant to cyclorrhaphan diversification are also considered. These include: change facilitated by independently evolvable modules; rapid change enabled by labile trophic morphology; shifts between saprophagy and phytophagy due to opportunities provided by angiosperm evolution; and enhanced adaptive potential resulting in derived more than basal taxa developing adaptations that enable access to new and little used resources. Apart from the need to rear more larvae, a major conclusion from this review is that knowledge will improve when the movement capabilities of larvae are used to inform morphological and taxonomic analyses.     

The relative exploitation of annuals as larval host plants by European butterflies

Theoretically, Lepidoptera should be able to adapt to using annuals as larval host plants through increased development rates and migration capacity. Even so, we show that annuals are used less frequently as host plants than expected among British and continental European butterflies. In particular, no example has been found of a European butterfly monophagous on an annual plant over its entire range. Use of annuals is proportionately greater among species that exploit increasing numbers of host plants and among subsidiary host plants than among primary (main) host plants. Annuals as host plants change status as habitat components with changes in species' spatial dynamics. The statistical findings point to perennials as providing host plant refuges, whereas the few case examples of site monophagy suggest that annuals can become valuable complementary resources during range extensions such as those currently associated with climatic warming. Annuals are more likely to be used in highly restricted circumstances, when environmental conditions allow the plants to persist over prolonged periods (i.e. when they are behaving like biennials) or when their spatial predictability is high because of low seed dispersal.     

Natural history and behaviour of the primitively eusocial wasp Ropalidia marginata (Hymenoptera: Vespidae): a comparison of the two sexes

We report the natural history and behaviour of the primitively eusocial wasp Ropalidia marginata with a special reference to the males. We found that just as nests of this species are found throughout the year, so are the males. Females spend all their life in their nests but males stay in their natal nests only for 1–12 days and leave to lead a nomadic life. Males maintained in the laboratory can live for up to 140 days. Like all eusocial hymenopteran males, R. marginata males also do not perform any colony maintenance activities. We found that males did not forage or feed larvae. Compared with females, males showed fewer dominance and subordinate behaviours and being solicited behaviour and more feeding self and soliciting behaviours. By comparing males with young females, we found similar differences, except that the males showed similar rates of feeding self and higher rates of subordinate behaviour.