Androconial Organs Research Articles

Redescription of Centronia melanitis Hübner, 1818 (Lepidoptera: Arctiinae: Arctiini: Ctenuchina) with notes on androconial organs

The Neotropical genus Centronia Hübner, 1818 is monotypic and represented by the species Centronia melanitis Hübner, 1818. Individuals of this species display diurnal habits and are attracted by plant bait of Heliotropium sp.. Specimens of Centronia are very rare in museum collections. The present study, notes are provided for the male specimens and the first time the female is mentioned in the scientific literature. The presence of androconial organs in Centronia melanitis and other species of Ctenuchina is hypothesized to be related to the visits to pyrrolizidine sources and their role in the pheromones production and the sexual attraction for mating.

Asturodes Amsel (Lepidoptera: Crambidae: Spilomelinae): Three New Species from the Western Hemisphere and Food Plant Records from Area de ConservaciÓn Guanacaste, Costa Rica

AsturodesAmsel, 1956, a Neotropical genus of distinctive pyraloid moths (Lepidoptera: Crambidae) with dark brown lines and silver scales on a yellow ground color on the wings and abdomen, is revised. As defined herein, the genus includes four species: A. fimbriauralis Guenee, the type species, A. bioalfae Solis, new species, A. encisoensis Solis, new species, and A. junkoshimurae Solis, new species. During this study, a petaloid scale formed by a group of coalesced setae in the abdominal androconial organs of the male genitalia was discovered and illustrated for the first time. Androconial organs in the Pyraloidea are briefly discussed. The type species and two new species, A. junkoshimurae, new species and A. bioalfae, new species, were reared from larvae feeding on the leaves of Rhamnaceae in the Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica representing 913 rearing events. This contribution is part of a long-term inventory of ACG caterpillars, their food plants, and their parasitoids, that includes COI DNA barcoding of specimens for discovery and identification.

Physical and behavioral adaptations to prevent overheating of the living wings of butterflies

The wings of Lepidoptera contain a matrix of living cells whose function requires appropriate temperatures. However, given their small thermal capacity, wings can overheat rapidly in the sun. Here we analyze butterfly wings across a wide range of simulated environmental conditions, and find that regions containing living cells are maintained at cooler temperatures. Diverse scale nanostructures and non-uniform cuticle thicknesses create a heterogeneous distribution of radiative cooling that selectively reduces the temperature of structures such as wing veins and androconial organs. These tissues are supplied by circulatory, neural and tracheal systems throughout the adult lifetime, indicating that the insect wing is a dynamic, living structure. Behavioral assays show that butterflies use wings to sense visible and infrared radiation, responding with specialized behaviors to prevent overheating of their wings. Our work highlights the physiological importance of wing temperature and how it is exquisitely regulated by structural and behavioral adaptations.

'Crystal Macrosetae': Novel Scales and Bristles in Male Arctiine Moths (Lepidoptera: Erebidae: Arctiinae) Filled with Crystallizing Material.

Scales, exoskeletal features characteristic of the Lepidoptera, occur in enormous structural and functional diversity. They cover the wing membranes and other body parts and give butterflies and moths their often stunning appearance. Generally, the patterns made by scales are visual signals for intra- and interspecific communication. In males, scales and/or bristles also make up the androconial organs, which emit volatile signals during courtship. Here, a structurally and putative functionally novel type of scales and bristles is reported: ‘crystal macrosetae’. These lack trabeculae and windows, are made up by a very thin and flexible envelope only and contain crystallizing material. In ‘crystal scales’, there is a flat surface ornamentation of modified ridges, while ‘crystal bristles’ often show large protrusions. Crystal macrosetae usually cannot be reliably recognized without destruction. Apparently, they serve as containers for large amounts of material that is viscous in living moths, highly hygroscopic, crystallizes when specimens dry up, and can be visualized by scanning electron microscopy. Crystal macrosetae occur in males only, always associated with or making up androconial organs located on various parts of the body, and have numerous forms with diverse surface ornamentation across many species and genera. The newly identified structures and the discovery of crystallizing material in scales and bristles raise many questions and could shed new light on ontogenetic development of macrosetae, and on the biology and physiology as well as the evolution and systematics of Arctiinae. There is evidence that crystal macrosetae occur in other moths too.

Production and sex-pheromonal activity of alkaloid-derived androconial compounds in the danaine butterfly,Parantica sita(Lepidoptera: Nymphalidae: Danainae)

Close associations of certain lepidopteran taxa with pyrrolizidine alkaloids (PAs), a typical class of plant secondary metabolites, have been well documented from the perspective of evolutionary ecology. Male danaine butterflies are thought to utilize PAs as precursors for the production of dihydropyrrolizines [e.g. danaidone (DO) and hydroxydanaidal (HD)] in their two distinct androconial organs, viz. alar scent organs (sex brands) and abdominal hairpencils. However, little is known about the quantitative profiles of these compounds in danaines, the mechanism for their formation in the androconial organs, or their biological functions, particularly in mating behaviour. The present study addressed these unanswered questions posed for males of the danaine butterfly, Parantica sita. Chemical analyses of androconial extracts revealed considerable seasonal/regional and individual variations of the amounts of DO (the major dihydropyrrolizine produced) and 7R-HD (the 7R-enantiomer of HD detected in this study) found in the two organs. These variations seemed to depend primarily on the age of the male and the phenological traits of PA-containing plants available. Males were found to acquire an adequate capability to produce DO ~1 week after eclosion. DO was shown to be produced exclusively in the sex brand and subsequently physically transferred to the hairpencil through a contact behaviour between the two organs, here termed ‘perfuming behaviour’. The results of behavioural experiments with PA-fed and PA-unfed males that were allowed to compete for mates, combined with the positive electroantennographic (EAG) responses of the female, to both DO and 7R-HD, led to the conclusion that either or both of these compounds can act as the sex pheromone. Oral administration of PAs to males indicated that DO can be biosynthesized from various PA precursors, while 7R-HD, unlike in arctiid moths, is derived only from PAs with the 7R-configuration. The putative biosynthetic pathways of DO and 7R-HD, and the evolutionary provenance of the binate androconial system in the Danainae are also discussed.

Phylogenetic evidence for loss of sound production and a shift in sexual recognition signals in Hamadryas butterflies (Nymphalidae: Biblidinae)

The neotropical butterfly genus Hamadryas Hübner comprises 20 species that exhibit an intriguing variation in their natural history traits. Although revised in 1983, no phylogenetic hypothesis was presented: the first phylogenetic hypothesis is estimated here based on 93 characters and including species from the three other genera in the tribe Ageroniini. The phylogeny is used to test the monophyly of the genus, establish the sister group of Hamadryas and identify its apomorphies. The tree allows the inference of patterns of character change in sound production and sexual dimorphism. Implied weights show that Hamadryas is monophyletic and corroborate Ectima Doubleday as a sister genus. Previously suggested subgenera for Hamadryas were non‐monophyletic, with the exception of the laodamia clade, supported by the presence of a complete sterigma. Sound production is inferred to be a derived condition in Hamadryas that has been lost in the laodamia clade. This, plus the presence of androconial organs and sexual dimorphism in the laodamia clade, suggests a shift in sexual recognition signalling. Furthermore, the phylogeny indicates that the colour pattern of males in the laodamia clade is novel, supporting a Darwinian origin of sexual dimorphism.

Neotropical Blepolenis butterflies: wing pattern elements, phylogeny, and Pleistocene diversification (Lepidoptera, Nymphalidae)

This study re-describes and provides a phylogeny for the Brassolini genus Blepolenis, which includes three species from the Brazilian Atlantic forest. A diagnosis and illustrations of habitus and genitalia are given for each species. We compare variation in wing color pattern among the genera Blepolenis, Opsiphanes, Orobrassolis and Mielkella, and discuss the repeated loss of male wing androconial organs within Blepolenis. DNA sequence (nuclear and mitochondrial genes) provided the strongest signal for phylogeny reconstruction, given that Blepolenis species are morphologically homogeneous. Estimated time of divergence between Blepolenis and Opsiphanes dates from the Mid Miocene (ca. 15 million years ago), and was followed by an apparent period of stasis. Extant Blepolenis species seem to have diverged in the Pleistocene (ca. 2.5 mya).

Pungent odor of the adult skipper butterfly Erynnis montanus (Lepidoptera: Hesperiidae)

Adults of some butterfly species have odors, several components of which are known to have pheromonal or defensive functions. Little is known about the odors of hesperiid butterflies, however. Erynnismontanus (Hesperiidae), especially male adults, emit a pungent odor that is detectable by the human nose. Chemical analysis has revealed that crude extracts of wild individuals contained 10 volatile substances, of which docosane and heneicosane were the main components. Because males contain a significantly larger amount of p-cresol than females, this aromatic compound is characterized as a strong male odor. At the end of the adult occurrence period, p-cresol decreased substantially in each male. Benzothiazole, identified for the first time in lepidopteran adults, was present in both sexes in almost equal amounts. Among the 10 volatile substances detected in males, biased distribution in the wings rather than the body was observed for benzothiazole, heptanal, and p-cresol. Male adults have androconial organs in the costal part of the forewing on which benzothiazole and p-cresol tended to concentrate. However, these compounds were detected not only in other parts of the forewing but also in the hindwing and body, suggesting the presence of undiscovered scent-producing organs.

The use of chemical and visual cues in female choice in the butterflyBicyclus anynana

Investigating the relative importance of multiple cues for mate choice within a species may highlight possible mechanisms that led to the diversification of closely related species in the past. Here, we investigate the importance of close-range pheromones produced by male Bicyclus anynana butterflies and determine the relative importance of these chemical cues versus visual cues in sexual selection by female choice. We first blocked putative androconial organs on the fore- and hindwings of males, while also manipulating the ability of females to perceive chemical signals via their antenna. We found that male chemical signals were emitted by both fore- and hindwing pairs and that they play an important role in female choice. We subsequently tested the relative importance of these chemical cues versus visual cues, previously identified for this species, and found that they play an equally important role in female choice in our laboratory setting. In addition, females will mate with males with only one signal present and blocking both androconial organs on males seems to interfere with male to male recognition. We discuss the possible functions of these signals and how this bimodal system may be used in intra- and interspecific mate evaluation.

If you've got it, flaunt it: ingested alkaloids affect corematal display behavior in the salt marsh moth, Estigmene acrea.

Plant-derived pyrrolizidine alkaloids play an important role in the biology of the salt marsh moth, Estigmene acrea (Lepidoptera: Arctiidae). They are phagostimulants for larvae and they stimulate the growth and development of adult male androconial organs called coremata. In this study, we have shown that the pyrrolizidine alkaloid monocrotaline N-oxide (MNO) fed to larvae also affects the courtship behavior of adult males. Males fed a diet containing MNO display their coremata while males fed on the same diet without alkaloid rarely display. This explains why it has been difficult to replicate field observations of the "lekking" behavior of this species in the laboratory where animals are frequently raised on commercially available diets devoid of alkaloids. Corematal inflation was observed in isolated males and in laboratory leks. The effect of larvae feeding on pyrrolizidine alkaloid on the reproductive behavior of adults suggests that this substance may modify the development of the moth's nervous system and contribute to their unusual dual mating strategies. MNO was also shown to be an adequate precursor for the production of the courtship pheromone hydroxydanaidal.

If you've got it, flaunt it: ingested alkaloids affect corematal display behavior in the salt marsh moth, Estigmene acrea.

Plant-derived pyrrolizidine alkaloids play an important role in the biology of the salt marsh moth, Estigmene acrea (Lepidoptera: Arctiidae). They are phagostimulants for larvae and they stimulate the growth and development of adult male androconial organs called coremata. In this study, we have shown that the pyrrolizidine alkaloid monocrotaline N-oxide (MNO) fed to larvae also affects the courtship behavior of adult males. Males fed a diet containing MNO display their coremata while males fed on the same diet without alkaloid rarely display. This explains why it has been difficult to replicate field observations of the "lekking" behavior of this species in the laboratory where animals are frequently raised on commercially available diets devoid of alkaloids. Corematal inflation was observed in isolated males and in laboratory leks. The effect of larvae feeding on pyrrolizidine alkaloid on the reproductive behavior of adults suggests that this substance may modify the development of the moth's nervous system and contribute to their unusual dual mating strategies. MNO was also shown to be an adequate precursor for the production of the courtship pheromone hydroxydanaidal.

Niaviolides, New Macrocyclic Sesquiterpenes Secreted by Males of the African Butterfly Amauris niavius.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Niaviolides, New Macrocyclic Sesquiterpenes Secreted by Males of the African Butterfly Amauris niavius

AbstractThe abdominal androconial organs (“hairpencils”) of the African butterfly Amauris niavius (Danainae) emit a complex scent bouquet consisting of previously described aromatic compounds, terpenoids, fatty acids, and hydrocarbons. This work reports the identification of two major sesquiterpenes, each possessing a unique 13‐membered macrolide ring, originating from an α,ψ‐oxidation pattern of the sesquiterpene backbone. To the best of our knowledge, sesquiterpene macrolides have not been found before in nature. The structure elucidation of the two compounds, which we propose to call niaviolide (3) and epoxyniaviolide (4), by NMR and GC/MS experiments is presented, together with their subsequent synthesis. Finally, the absolute configuration of natural 4 was determined to be (S,S) by stereoselective synthesis and chiral gas chromatography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Dietary alkaloids and the development of androconial organs in Estigmene acrea

Male salt marsh moths, Estigmene acrea (Lepidoptera: Arctiidae), possess inflatable androconial organs called coremata. Prior to mating males form aggregations and inflate their coremata en masse. The communal display attracts additional males and females for the purpose of mating. The coremata are known to carry the plant-derived dihydropyrrolizine, hydroxydanaidal. This pheromonal substance is derived from secondary plant chemicals called pyrrolizidine alkaloids found in the larval diet. When E. acrea larvae were raised on semi-synthetic diets containing different levels of the pyrrolizidine alkaloid precursors the alkaloids triggered a pronounced morphogenetic effect. Adult males that fed on high levels of the pyrrolizidine alkaloid monocrotaline N-oxide (2500 microg) developed the largest coremata. Males that fed on lower levels of monocrotaline N-oxide (500 microg) or no alkaloid, while normal in body weight, had coremata that were progressively smaller and less robust. The size of the coremata and their commensurate pheromonal charge may have behavioral consequences in the unusual mating system of this species.

Dietary alkaloids and the development of androconial organs in Estigmene acrea

Male salt marsh moths, Estigmene acrea (Lepidoptera: Arctiidae), possess inflatable androconial organs called coremata. Prior to mating males form aggregations and inflate their coremata en masse. The communal display attracts additional males and females for the purpose of mating. The coremata are known to carry the plant-derived dihydropyrrolizine, hydroxydanaidal. This pheromonal substance is derived from secondary plant chemicals called pyrrolizidine alkaloids found in the larval diet.When E. acrea larvae were raised on semi-synthetic diets containing different levels of the pyrrolizidine alkaloid precursors the alkaloids triggered a pronounced morphogenetic effect. Adult males that fed on high levels of the pyrrolizidine alkaloid monocrotaline N-oxide (2500 µg) developed the largest coremata. Males that fed on lower levels of monocrotaline N-oxide (500 µg) or no alkaloid, while normal in body weight, had coremata that were progressively smaller and less robust. The size of the coremata and their commensurate pheromonal charge may have behavioral consequences in the unusual mating system of this species.

A survey of androconial organs in the Riodinidae (Lepidoptera)

A comprehensive survey of the occurrence and morphology of alar, abdominal and appendage androconial organs in the Riodinidae is presented based on light microscopy and scanning electron microscopy. Although historically poorly studied, the group actually possesses among the greatest diversity of androconial organs in the butterflies, including coremata, reported here for the first time outside the Lycaenidae and Nymphalidae, and hindleg hairpencils, reported here for the first time in the true butterflies. Twenty-five percent of riodinid species are reported to have androconial organs. The mode of function of these organs and their role in courtship is discussed where known, based on field observations. A number of taxonomic changes are made at the tribal, generic and species level, predominantly in the Symmachiini, based on the occurrence and structure of androconia.

Miriamica, a New Genus of Milkweed Butterflies with Unique Androconial Organs (Lepidoptera: Nymphalidae)

Results of microscopical (SEM) investigations of the androconial organs of Parantica sita and P. weiskei are presented. Such is the structural novelty of the patch scales in P. weiskei that, in combination with other morphological characters, it is proposed that a new genus Miriamica is established to accommodate this species, together with a second species, M. thalassina, until now regarded as a subspecies of weiskei, separate from Parantica and other members of the subtribe Amaurina.

Specific mixtures of secretions from male scent organs of African milkweed butterflies (Danainae)

The abdominal androconial organs (hairpencils: male scent glands) of samples of ten African milkweed butterfly species (Lepidoptera: Danainae) belonging to Danaus, Tirumala and Amauris , including all nine species commonly encountered in Kenya, have been analysed by gas chromatography and mass spectrometry. A total of 214 compounds have been identified, belonging to 14 chemical classes: hydrocarbons, alcohols, aldehydes, ketones, esters, lactones, carboxylic acids, oxidized carboxylic acids, aromatics, derivatives of pyrrolizidine alkaloids (PAs), monoterpenes, sesquiterpenes, other terpenoids and tetrahydrofurans. Various compounds only rarely or never found in insects before, including some previously unknown in nature, are present in the hairpencils. Excluding the numerous tetrahydrofurans, which were not investigated systematically, the number of compounds ranges from 12-59 per species. All ten species have distinct mixtures of volatiles, including, in all cases, species-specific compounds (autapomorphies). In addition, the co-occurrence of compounds between species (synapomorphies) exhibits a strongly hierarchical chemo-taxonomic pattern which has been demonstrated to be largely consistent with a previous cladistic analysis based on adult morphology. The potential significance of these findings in relation to chemical communication and speciation in these mimetic butterflies is discussed.

Androconial systems in Danainae (Lepidoptera): functional morphology of Amauris, Danaus, Tirumala and Euploea

The morphology of abdominal and alar androconial organs of four species representing four genera of danaine butterflies is described in detail, based mainly on scanning electron microscopy. The findings are discussed with respect to functional significance and phyletic development of the organs.

Terpenoids from bark beetles, solitary bees and danaine butterflies

Abstract