Concerted evolution of male and female display traits in the European corn borer, Ostrinia nubilalis

BACKGROUND: Sexual reproduction entails the encounter of the sexes and the multiplicity of rituals is parallel to the diversity of mating systems. Evolutionary mechanisms such as sexual selection and sexual conflict have led to the elaboration of traits to gain attention and favours from potential partners. A paradox exists about how coordinated systems can evolve and diverge when there would seem to be a stabilising selection acting. Moth display traits - pheromones - constitute an advantageous model with which to address questions about the evolution of mating systems in animals. Both males and females can possess pheromones that are involved either in close- or long-range communication. Female and male pheromones appear to have different origins and to be under different evolutionary constraints, thus they might be envisioned as independently evolving traits. We conducted laboratory experiments to explore the role of scents released during courtship by males of the European corn borer, Ostrinia nubilalis. RESULTS: Information provided by the male pheromone appears critical for female acceptance. The composition of this male pheromone varies in an age-dependent manner and females show mating preference towards older males in choice experiments. Furthermore, male signals may allow species discrimination and reinforce reproductive isolation. Finally, we found evidence for a genetic correlation between male and female signals, the evolution of which is best explained by the constraints and opportunities resulting from the sharing of gene products. CONCLUSION: In this study we used an integrative approach to characterise the male sex pheromone in a moth. Interestingly, the male chemical signal is analogous to the female signal in that structurally similar compounds are being used by both sexes. Hence, in systems where both sexes possess display traits, the pleiotropy of genes generating the traits could influence the evolutionary trajectories of sexual signals and lead to their divergence, with speciation being the ultimate result

Journey in the Ostrinia world: from pest to model in chemical ecology.

The European corn borer Ostrinia nubilalis (ECB; Lepidoptera: Crambidae) is a widely recognized pest of agricultural significance over much of the northern hemisphere. Because of the potential value of pheromone-based control, there has been considerable effort devoted to elucidation of the ECB chemical ecology. The species is polymorphic regarding its female- produced pheromone. Partly because of this feature, over the years the ECB has become a model to study pheromone evolution. This review should assist in identifying new areas of pheromone research by providing an overview of the literature produced on this subject for the ECB since the late 1960's

Sex pheromone biosynthetic pathways are conserved between moths and the butterfly Bicyclus anynana

Although phylogenetically nested within the moths, butterflies have diverged extensively in a number of life history traits. Whereas moths rely greatly on chemical signals, visual advertisement is the hallmark of mate finding in butterflies. In the context of courtship, however, male chemical signals are widespread in both groups although they likely have multiple evolutionary origins. Here, we report that in males of the butterfly Bicyclus anynana, courtship scents are produced de novo via biosynthetic pathways shared with females of many moth species. We show that two of the pheromone components that play a major role in mate choice, namely the (Z)-9-tetradecenol and hexadecanal, are produced through the activity of a fatty acyl Δ11-desaturase and two specialized alcohol-forming fatty acyl reductases. Our study provides the first evidence of conservation and sharing of ancestral genetic modules for the production of FA-derived pheromones over a long evolutionary timeframe thereby reconciling mate communication in moths and butterflies

A moth pheromone brewery: production of (Z)-11-hexadecenol by heterologous co-expression of two biosynthetic genes from a noctuid moth in a yeast cell factory

Background: Moths (Lepidoptera) are highly dependent on chemical communication to find a mate. Compared to conventional unselective insecticides, synthetic pheromones have successfully served to lure male moths as a specific and environmentally friendly way to control important pest species. However, the chemical synthesis and purification of the sex pheromone components in large amounts is a difficult and costly task. The repertoire of enzymes involved in moth pheromone biosynthesis in insecta can be seen as a library of specific catalysts that can be used to facilitate the synthesis of a particular chemical component. In this study, we present a novel approach to effectively aid in the preparation of semi-synthetic pheromone components using an engineered vector co-expressing two key biosynthetic enzymes in a simple yeast cell factory. Results: We first identified and functionally characterized a ∆11 Fatty-Acyl Desaturase and a Fatty-Acyl Reductase from the Turnip moth, Agrotis segetum. The ∆11-desaturase produced predominantly Z11-16:acyl, a common pheromone component precursor, from the abundant yeast palmitic acid and the FAR transformed a series of saturated and unsaturated fatty acids into their corresponding alcohols which may serve as pheromone components in many moth species. Secondly, when we co-expressed the genes in the Brewer’s yeast Saccharomyces cerevisiae, a set of long-chain fatty acids and alcohols that are not naturally occurring in yeast were produced from inherent yeast fatty acids, and the presence of (Z)-11-hexadecenol (Z11-16:OH), demonstrated that both heterologous enzymes were active in concert. A 100 ml batch yeast culture produced on average 19.5 μg Z11-16:OH. Finally, we demonstrated that oxidized extracts from the yeast cells containing (Z)-11-hexadecenal and other aldehyde pheromone compounds elicited specific electrophysiological activity from male antennae of the Tobacco budworm, Heliothis virescens, supporting the idea that genes from different species can be used as a molecular toolbox to produce pheromone components or pheromone component precursors of potential use for control of a variety of moths. Conclusions: This study is a first proof-of-principle that it is possible to “brew” biologically active moth pheromone components through in vitro co-expression of pheromone biosynthetic enzymes, without having to provide supplementary precursors. Substrates present in the yeast alone appear to be sufficient

First records of the Z-Race of European Corn Borer Ostrinia nubilalis (Hübner 1796) from Scandinavia

Der Maiszünsler (Ostrinia nubilalis) ist einer der bedeutendsten Schädlinge im Mais in Europa und in den Gebieten seiner Einschleppung. Er tritt in 2 Pheromonrassen (E und Z) mit in Mitteleuropa derzeit unterschiedlichen Hauptwirtspflanzen auf. Die E-Rasse ist häufig in Beifuß (Artemisia vulgaris) zu finden, während die hauptsächlich im Mais auftretende Z-Rasse in Deutschland den ökonomisch bedeutenden Schaden verursacht. Beide Ras­sen können jedoch auch andere Pflanzen befallen. So kann beispielsweise die E-Rasse auch am Mais auftreten. Eine morphologische Unterscheidung der Rassen ist nicht möglich. Für Skandinavien lagen bisher zwar Daten über das Vorkommen des Maiszünslers vor, jedoch keine Berichte über das Auftreten in Mais. In 2010 wurden Maiszünsler-Larven an einem Standort im Mais auf der Insel Sjaelland (Seeland), Dänemark, gefunden. Ein Moni­toring in Dänemark 2011 mit Pheromonfallen für die Z-Rasse erbrachte keine weiteren Funde. 2011 wurden jedoch in Südschweden am Mais an 3 Standorten Befall durch Maiszünsler-Larven festgestellt. Mittels PCR wurden Larven von 2 Standorten untersucht und als zur Z-Rasse gehörig bestätigt. Unabhängig davon wurden in 2010 Falter von der schwedischen Ostseeinsel Gotland ebenfalls als Tiere der Z-Rasse bestätigt. Dies sind die ersten Nachweise der Z-Rasse für Skandinavien und in Europa bislang die nördlichsten belegten Funde dieser Rasse. Implikationen für den Pflanzenschutz werden diskutiert.    European Corn Borer (ECB, Ostrinia nubilalis) is among the main pests of maize in Europe and throughout its intro­duced range. Two morphologically indistinguishable phero­mone races of the species exist, the so-called E-race and Z-race. In Germany the E-race is most common in mugwort (Artemisia vulgaris) whereas the Z-race occurs mainly in maize and is responsible for the main proportion of the economic damage. But both races have several alternative host plants. For example, the E-race can also occur in maize. The species has been known from Scandinavia already for a considerable time period, but no occurrence in maize was reported until recently. In 2010 larvae were found in maize at one site on the isle of Sealand, Denmark. A monitoring with Z-race pheromone traps in Denmark in 2011 did not result in any catches of ECB. In the same year however, ECB larvae were found in maize at 3 sites in southern Sweden. Larvae from 2 sites were assigned to Z-race via PCR. Independently from these finds, adult moths caught on the isle of Gotland in 2010 were also confirmed to be Z-race by PCR. This is the first evidence of the occurrence of the Z-race in Scandinavia and the northernmost find of the Z-race in Europe so far. Implications for plant protection are discussed.   &nbsp

A novel enhancer of Agouti contributes to parallel evolution of cryptically colored beach mice

Identifying the genetic basis of repeatedly evolved traits provides a way to reconstruct their evolutionary history and ultimately investigate the predictability of evolution. Here, we focus on the oldfield mouse (Peromyscus polionotus), which occurs in the southeastern United States, where it exhibits considerable coat-color variation. Dorsal coats range from dark brown in mice inhabiting mainland habitat to near white on the white-sand beaches of the southeastern US, where light pelage has evolved independently on Florida’s Gulf and Atlantic coasts as an adaptation to visually hunting predators. To facilitate genomic analyses in this species, we first generated a high-quality, chromosome-level genome assembly of P. polionotus subgriseus. Next, in a uniquely variable mainland population that occurs near beach habitat (P. p. albifrons), we scored 23 pigment traits and performed targeted resequencing in 168 mice. We find that variation in pigmentation is strongly associated with a ~2 kb region approximately 5 kb upstream of the Agouti-signaling protein (ASIP) coding region. Using a reporter-gene assay, we demonstrate that this regulatory region contains an enhancer that drives expression in the dermis of mouse embryos during the establishment of pigment prepatterns. Moreover, extended tracts of homozygosity in this region of Agouti indicate that the light allele has experienced recent and strong positive selection. Notably, this same light allele appears fixed in both Gulf and Atlantic coast beach mice, despite these populations being separated by >1,000km. Given the evolutionary history of this species, our results suggest that this newly identified Agouti enhancer allele has been maintained in mainland populations as standing genetic variation and from there has spread to, and been selected in, two independent beach mouse lineages, thereby facilitating their rapid and parallel evolution

Automated tracking reveals the social network of beach mice and their burrows

Evolutionary biologists have long sought to understand the selective pressures driving phenotypic evolution. While most experimental data come from the study of morphological evolution, we know much less about the ultimate drivers of behavioral variation. Among the most striking examples of behavioral evolution are the long, complex burrows constructed by oldfield mice (Peromyscus polionotus ssp.). Yet how these mice use burrows in the wild, and whether burrow length may affect fitness, remains unknown. A major barrier to studying behavior in the wild has been the lack of technologies to continuously monitor – in this case, nocturnal and underground – behavior. Here, we designed and implemented a novel radio frequency identification (RFID) system to track patterns of burrow use in a natural population of beach mice. We combine RFID monitoring with burrow measurements, genetic data, and social network analysis to uncover how these monogamous mice use burrows under fully natural ecological and social conditions. We first found that long burrows provide a more stable thermal environment and have higher juvenile activity than short burrows, underscoring the likely importance of long burrows for rearing young. We also find that adult mice consistently use multiple burrows throughout their home range and tend to use the same burrows at the same time as their genetic relatives, suggesting that inclusive fitness benefits may accrue for individuals that construct and maintain multiple burrows. Our study highlights how new automated tracking approaches can provide novel insights into animal behavior in the wild

Adaptive tail-length evolution in deer mice is associated with differential Hoxd13 expression in early development

Variation in the size and number of axial segments underlies much of the diversity in animal body plans. Here, we investigate the evolutionary, genetic, and developmental mechanisms driving tail-length differences between forest and prairie ecotypes of deer mice (Peromyscus maniculatus). We first show that long-tailed forest mice perform better in an arboreal locomotion assay, consistent with tails being important for balance during climbing. The long tails of these forest mice consist of both longer and more caudal vertebrae than prairie mice. Using quantitative genetics, we identify six genomic regions that contribute to differences in total tail length, three of which associate with vertebra length and the other three with vertebra number. For all six loci, the forest allele increases tail length, consistent with the cumulative effect of natural selection. Two of the genomic regions associated with variation in vertebra number contain Hox gene clusters. Of those, we find an allele-specific decrease in Hoxd13 expression in the embryonic tail bud of long-tailed forest mice, consistent with its role in axial elongation. Additionally, we find that forest embryos have more presomitic mesoderm than prairie embryos, and that this correlates with an increase in the number of neuromesodermal progenitors (NMPs), which are modulated by Hox13 paralogs. Together, these results suggest a role for Hoxd13 in the development of natural variation in adaptive morphology on a microevolutionary timescale

Sex pheromone biosynthesis in the sugarcane borer Diatraea saccharalis: paving the way for biotechnological production.

peer reviewed[en] BACKGROUND: The sugarcane borer Diatraea saccharalis (Lepidoptera) is a key pest on sugarcane and other grasses in the Americas. Biological control as well as insecticide treatments are used for pest management, but economic losses are still significant. The use of female sex pheromones for mating disruption or mass trapping in pest management could be established for this species, provided that economical production of pheromone is available. RESULTS: Combining in vivo labelling studies, differential expression analysis of transcriptome data and functional characterisation of insect genes in a yeast expression system, we reveal the biosynthetic pathway and identify the desaturase and reductase enzymes involved in the biosynthesis of the main pheromone component (9Z,11E)-hexadecadienal, and minor components hexadecanal, (9Z)-hexadecenal and (11Z)-hexadecenal. We next demonstrate heterologous production of the corresponding alcohols of the pheromone components, by expressing multiple steps of the biosynthetic pathway in yeast. CONCLUSION: Elucidation of the genetic basis of sex pheromone biosynthesis in D. saccharalis, and heterologous expression in yeast, paves the way for biotechnological production of the pheromone compounds needed for pheromone-based pest management of this species

The European Corn Borer Ostrinia nubilalis: exotic pest and model system to study pheromone evolution and speciation

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