Gilson Rudinei Pires Moreira

Absence of Learning and Local Specialization on Host Plant Selection by Heliconius erato

There is considerable interspecific variation in larval host plants (Passifloraceae) used among Heliconius erato (Lepidoptera: Nymphalidae) populations. This study evaluates the role of learning and the influence of interspecific variation in host plant attributes on such local specialization in H. erato host plant choices. Experiments were conducted under laboratory, insectary, and field conditions, with the two most widely used host plants in southern Brazil (Passiflora suberosa Linnaeus and Passiflora misera Humbold, Bonpland et Kunth). Larval feeding preference and induction were evaluated through choice tests for all instars. Oviposition was evaluated in relation to host plant preference, Hopkins host-selection principle, and conditioning time (for 3, 7, 11, or 15 days). Also, oviposition choice was tested regarding density, intemode length, and presence of intact terminal bud on P. suberosa and P. misera shoots. Both larvae and adults of H. erato phyllis showed preference for P. misera compared to P. suberosa, under all conditions. Larval feeding preference could not be induced for most instars. The Hopkins’ effect was not detected and oviposition choice could not be conditioned. Females alternated use of host plant species as a function of variation in either density or presence of terminal buds on shoots. Thus, our data indicate host plant preference in H. erato phyllis is not learned but innate. Therefore, we concluded that variation in local use of host plant by this butterfly in southern Brazil results from qualitative and quantitative variation of the passion vine species.

Geographical variation in larval host-plant use by Heliconius erato (Lepidoptera: Nymphalidae) and consequences for adult life history

Adult body size, one of the most important life-history components, varies strongly within and between Heliconius erato phyllis (Lepidoptera: Nymphalidae) populations. This study determines if this variation is caused by geographical changes in host-plant used by the larval stage, whose reproductive parameters are influenced by female body size, with estimates of the corresponding heritability. The variation in adult body size was determined together with a survey of passion vine species (Passifloraceae) used by the larvae in seven localities in Rio Grande do Sul State: three located in the urban area of Porto Alegre and Triunfo Counties, two within Eucalyptus plantations (Barba Negra Forest, Barra do Ribeiro County, and Aguas Belas Experimental Station-Viamão County), one in a Myrtaceae Forest (Itapuã State Park-Itapuã County) and one in the Atlantic Rain Forest (Maquiné Experimental Station-Maquiné County). Effects of female body size on fecundity, egg size and egg viability were determined in an outdoor insectary. Size heritability was estimated by rearing in the laboratory offspring of individuals maintained in an insectary. The data showed that adults from populations where larvae feed only upon Passiflora suberosa are smaller than those that feed on Passiflora misera. The larvae prefer P. misera even when the dominant passion vine in a given place is P. suberosa. Fecundity increases linearly with the increase in size of females, but there is no size effect on egg size or viability. Size heritability is null for the adult size range occurring in the field. Thus, the geographical variation of H. erato phyllis adult size is primarily determined by the type, corresponding availability and quality of host-plants used by the larval stage. Within the natural size range of H. erato phyllis, the variation related to this character is not genetically based, thus being part of H. erato phyllis phenotypic plasticity.

Genome-wide introgression among distantly related Heliconius butterfly species

BackgroundAlthough hybridization is thought to be relatively rare in animals, the raw genetic material introduced via introgression may play an important role in fueling adaptation and adaptive radiation. The butterfly genus Heliconius is an excellent system to study hybridization and introgression but most studies have focused on closely related species such as H. cydno and H. melpomene. Here we characterize genome-wide patterns of introgression between H. besckei, the only species with a red and yellow banded ‘postman’ wing pattern in the tiger-striped silvaniform clade, and co-mimetic H. melpomene nanna.ResultsWe find a pronounced signature of putative introgression from H. melpomene into H. besckei in the genomic region upstream of the gene optix, known to control red wing patterning, suggesting adaptive introgression of wing pattern mimicry between these two distantly related species. At least 39 additional genomic regions show signals of introgression as strong or stronger than this mimicry locus. Gene flow has been on-going, with evidence of gene exchange at multiple time points, and bidirectional, moving from the melpomene to the silvaniform clade and vice versa. The history of gene exchange has also been complex, with contributions from multiple silvaniform species in addition to H. besckei. We also detect a signature of ancient introgression of the entire Z chromosome between the silvaniform and melpomene/cydno clades.ConclusionsOur study provides a genome-wide portrait of introgression between distantly related butterfly species. We further propose a comprehensive and efficient workflow for gene flow identification in genomic data sets.

Effect of nitrogen on Passiflora suberosa L. (Passifloraceae) and consequences for larval performance and oviposition in Heliconius erato phyllis (Fabricius) (Lepidoptera: Nymphalidae)

The present study examines the influence of nitrogen on growth rates, morphological and nutritional characteristics of Passiflora suberosa L., and the corresponding consequences for Heliconius erato phyllis (Fabricius) growth and oviposition. The treatments consisted of different nitrogen doses (0, 150 and 300 mg L(-1)) applied to the soil. Newly emerged larvae were individually reared in the laboratory (25+/-1 degree C) on branches of P. suberosa obtained from plants grown under the three nitrogen levels, and field collected females were submitted to oviposition choice tests. P. suberosa growth rates, leaf area and internode length increased significantly when grown with nitrogen enriched soil. P. suberosa presented significantly greater leaf toughness when grown without nitrogen addition. Leaves of this species also presented lower water content and toughness. Nitrogen addition increased the concentration of nitrogen and potassium on plant leaf tissues. The greater nitrogen concentration on plants did not affect H. erato phyllis larval survival, but led to a reduction in larval development time and increased adult size. Females significantly preferred to lay eggs in plants cultivated in nitrogen enriched soil. This choice was positively correlated with larval performance, which could be a possible explanation for the maintenance of that behaviour, as well as the choice of larger branches as reported in previous studies.

Moving on hairy surfaces: modifications of Gratiana spadicea larval legs to attach on its host plant Solanum sisymbriifolium

Both larvae and adults of Gratiana spadicea (Klug) (Coleoptera: Chrysomelidae: Cassidinae) feed exclusively on leaves of Solanum sisymbriifolium Lamarck (Solanaceae), which have simple and stellate trichomes. The simple trichomes can be non‐glandular or glandular. The stellate trichomes present a long central ray that secretes a viscous exudate when broken. Trichome effects on movement of G. spadicea larvae were evaluated in the laboratory. Larval speed on intact petioles of S. sisymbriifolium was compared to those where the exudates and/or stellate trichomes were removed. Exudates had no effect on larval speed. Stellate trichomes mechanically slowed down first instar movement. Gratiana spadicea larval legs have a modified distal portion, the tarsungulus, whose rounded aperture shape matches that of the cylindrical pointed rays of S. sisymbriifolium stellate trichomes. The first three instars anchor the tarsungulus to the trichome rays, and get both attachment to the leaf surface and support to body impulsion. Morphological comparisons showed that the legs in the first larval instars are shorter than the central ray of the stellate trichome, so larvae have to walk above them. Fifth instar larvae have longer legs and walk by inserting the sharp tip of their tarsungulus directly into the leaf epidermis. The dimensions of the tarsungulus aperture vary in such a way that it can clasp every thickness of trichome ray for any larval instar. Contrary to other tarsungulus portions and larval body features, where growth is allometric, growth of the tarsungulus aperture is isometric throughout the larval stage. Thus, it is suggested that this G. spadicea leg structure is adapted for moving on hairy leaf surface of S. sisymbriifolium.

O Estágio de ovo dos Heliconiini (Lepidoptera, Nymphalidae) do Rio Grande do Sul, Brasil

Based upon light and scanning electron microscopy, the external morphology of the egg stage is described and illustrated for the following Heliconiini (Lepidoptera, Nymphalidae) from Rio Grande do Sul State, Brazil: Agraulis vanillae maculosa (Stichel, 1907), Dione juno juno (Cramer, 1779), Dione moneta moneta Hubner, 1825, Dryadula phaetusa (Linnaeus, 1758), Dryas iulia alcionea (Cramer, 1779), Philaethria wernickei (Rober, 1906), Eueides isabella dianasa (Hubner, 1806), Eueides aliphera aliphera (Godart, 1819), Heliconius ethilla narcaea Godart, 1819, Heliconius besckei Menetries, 1857, and Heliconius erato phyllis (Fabricius, 1775). A dichotomic key is provided for their identification, based upon differences at the levels of generic and ultrastructural morphology, and variation in host-plant use.

Size of and damage on shoots of Passiflora suberosa (Passifloraceae) influence oviposition site selection of Heliconius erato phyllis (Fabricius) (Lepidoptera, Nymphalidae)

Oviposition site selection of Heliconius erato phyllis (Fabricius, 1775) (Lepidoptera, Nymphalidae) was studied when size of and damage on shoots were variable in a natural population of Passiflora suberosa Linnaeus (Passifloraceae), and through sequential and simultaneous choice experiments performed under insectary conditions. Females showed marked oviposition preference for undamaged and largest shoots of P. suberosa. Eggs were mostly laid on the terminal buds of intact shoots under natural conditions. In simultaneous choice trials, females preferred to oviposit on shoots from which leaves (ten) were removed but the terminal bud maintained to those where leaves were kept but the terminal bud was cut out. In sequential choice trials, they did not lay eggs on shoots from which the terminal bud was removed. Females preferred to oviposit on large to short intact shoots in both sequential and simultaneous choice trials. Females laid eggs preferentially on shoots with the greatest leaf area when most plants were intact in the field during early spring. Later in fall, when mostly large, old shoots were damaged or in a reproductive stage (less desirable for oviposition), oviposition intensity was highest on the shortest, youngest shoots of P. suberosa. Thus, females might rank these quality attributes higher than size while selecting shoots for oviposition. The consequences of ovipositing selectively on intact, large shoots of P. suberosa are discussed from the view point of H. erato phyllis larval performance.

Developmental pathway from leaves to galls induced by a sap-feeding insect on Schinus polygamus (Cav.) Cabrera (Anacardiaceae)

Galling sap-feeding insects are presumed to cause only minor changes in host plant tissues, because they usually do not require development of nutritive tissues for their own use. This premise was examined through comparison of the histometry, cytometry and anatomical development of non-galled leaves and galls of Calophya duvauae (Scott) (Hemiptera: Calophyidae) on Schinus polygamus (Cav.) Cabrera (Anacardiaceae). Cell fates changed from non-galled leaves to galls during the course of tissue differentiation. C. duvauae caused changes in dermal, ground, and vascular systems of the leaves of S. polygamus. Its feeding activity induced the homogenization of the parenchyma, and the neoformation of vascular bundles and trichomes. The histometric and cytometric data revealed compensatory effects of hyperplasia and cell hypertrophy in the epidermis, with hyperplasia predominating in the adaxial epidermis. There was a balance between these processes in the other tissues. Thus, we found major differences between the developmental pathways of non-galled leaves and galls. These changes were associated with phenotypic alterations related to shelter and appropriate microenvironmental conditions for the gall inducer. The nondifferentiation of a typical nutritive tissue in this case was compared to other non-phylogenetically related arthropod gall systems, and is suggested to result from convergence associated with the piercing feeding apparatus of the corresponding gall-inducer.

Conspecific mimics and low host plant availability reduce egg laying by Heliconius erato phyllis (Fabricius) (Lepidoptera, Nymphalidae)

Oviposition response of Heliconius erato phyllis (Fabricius, 1775) (Lepidoptera, Nymphalidae) to variation in host plant availability, Passiflora suberosa Linnaeus (Passifloraceae), and to presence of conspecific eggs and larvae was determined through choice experiments performed under insectary conditions. Freeze dried, painted eggs and larvae were used as mimics for testing presence of conspecific effects. Females laid more eggs on intact P. suberosa shoots without conspecifics than on those with H. erato phyllis egg and first instar mimics in both simultaneous and sequential choice trials. Oviposition response to variation in host plant availability was determined through no-choice trials, under host plant densities varying from 0.3 to 8.3 plants per female. Number of eggs laid per plant decreased exponentially with an increase in plant availability. On the contrary, daily oviposition rates (eggs /female/day) increased with an increase in plant number, and levelled off when the number of plants available for oviposition was greater than potential fecundity of females. Thus, it is inferred from the results that females assess egg and larval load and prefer to lay eggs on shoots free from conspecifics. It is also inferred that they are able to recognize plant abundance and are unwilling to lay more than one egg per shoot even when host availability is scarce, as judged by reduction in daily oviposition rates under low host plant number. The consequences of laying isolated eggs on P. suberosa shoots are discussed from the viewpoint of intraspecific competition in the larval stage of H. erato phyllis.

A new Brazilian Passiflora leafminer: Spinivalva gaucha, gen. n., sp. n. (Lepidoptera, Gracillariidae, Gracillariinae), the first gracillariid without a sap-feeding instar.

Abstract Male, female, pupa, larva and egg of a new genus and species of Gracillariidae (Gracillariinae), Spinivalva gaucha Moreira and Vargas from southern Brazil are described and illustrated with the aid of optical and scanning electron microscopy. A preliminary analysis of mitochondrial DNA sequences including members of related lineages is also provided. The immature stages are associated with Passiflora actinia, Passiflora misera and Passiflora suberosa (Passifloraceae), and build mines on the adaxial leaf surface. Initially the mines are serpentine in shape, but later in larval ontogeny become a blotch type. Although the larvae are hypermetamorphic as in other Gracillariidae, there is no sap-feeding instar in Spinivalva gaucha; the larva feeds on the palisade parenchyma, thus producing granular frass during all instars. Pupation occurs outside the mine; prior to pupating, the larva excretes numerous bubbles that are placed in rows on the lateral margins of the cocoon external surface. This is the second genus of gracillariid moth described for the Atlantic Rain Forest, and the second gracillariid species known to be associated with Passifloraceae.