The Importance of Oligosulfides in the Attraction of Fly Pollinators to the Brood-Site Deceptive Species Jaborosa rotacea (Solanaceae)

Premise of research. Brood-site deceptive flowers use dishonest signals—especially floral odors that mimic oviposition substrates—to attract and deceive saprophilous insects to pollinate them. In this work, we recorded the pollinators of the sapromyiophilous species Jaborosa rotacea (Solanaceae) endemic to southern South America. Then, we characterized the floral volatiles of this species, and finally, we carried out field experiments to decouple the effects of scent and color as attractants for saprophilous flies. We made direct observations of pollinators in a natural population of J. rotacea. We characterized floral volatiles by means of gas chromatography–mass spectrometry. Subsequently, we used a mixture of 2 oligosulfides (dimethyl disulfide and dimethyl trisulfide), which our analyses revealed were the main constituents of the floral scent of J. rotacea, as baits to determine the attractiveness of this olfactory signal to flies in a geographical region where J. rotacea is not present. Finally, we used the same foul-scented baits in arrays of artificial flowers resembling those of J. rotacea to assess the dual importance of olfactory and visual cues in fly attraction. Pivotal results. Pollination of J. rotacea occurs when saprophilous flies belonging to the families Calliphoridae, Muscidae, and Sarcophagidae—with similar body dimensions to the anther-stigma distance in these flowers—acquire and deposit pollen in the flowers in a nototribic mode. Our chemical analyses revealed that J. rotacea floral scent is chemically simple and features 2 oligosulfide compounds (dimethyl disulfide and dimethyl trisulfide) commonly found in carrion-mimicking flowers. We found that saprophilous flies belonging to the same families that we recorded as pollinators of J. rotacea in its native South American habitat were attracted to foul-scented baits in temperate North America. The flies’ visitation frequencies (recorded as approaches and landings on the artificial flowers) depended significantly on the presence of the foul-scented baits. These results support the hypothesis that oligosulfides are universally effective signals by which deceptive flowers may effect pollen dispersal by attracting flies that use carrion or carnivore feces as brood sites.

Related papers:

title: Mimicry and Deception in Pollination
abstract: Many flowers produce rewards, usually nectar or pollen or both. C. K. Sprengel (165), the founder of modern floral biology, was the first to report that flowers do not always reward pollinators; his observations were on the genus Orchis. Subsequent authors (7; 51; 66; 97; 99; 105; 186, p. 21; 195) have discussed various aspects of deceitful flowers that attract pollinators by resembling rewarding flowers or other objects.

title: Deceptive Behavior in Plants. I. Pollination by Sexual Deception in Orchids: A Host-Parasite Perspective
abstract: Sexually deceptive orchids attract male insects as pollinators by mimicking the reproductive signals emitted by the targeted females. Since this mimicry system involves the imitation of female mating signals of certain insects, and since mating signals, especially sex pheromones, generally act on a species-specific basis, theory holds that each sexually deceptive orchid is usually pollinated by only one or a few male insect species. While these orchids rely exclusively on their specialized pollinators for their own reproduction, the male insects derive no benefit from this interaction. In this chapter, I will argue that incorporating questions relevant to the field of animal-centered host–parasite interactions into investigations on the evolutionary ecology of orchid pollination by deception will provide important insights at both the proximate (or mechanistic) and at the ultimate (or evolutionary) levels.

title: Carrion mimicry in a South African orchid: flowers attract a narrow subset of the fly assemblage on animal carcasses.
abstract: Although pollination of plants that attract flies by resembling their carrion brood and food sites has been reported in several angiosperm families, there has been very little work done on the level of specificity in carrion mimicry systems and the importance of plant cues in mediating such specialization. Specificity may be expected, as carrion-frequenting flies often exploit different niches, which has been interpreted as avoidance of interspecific competition. Interactions between the orchid Satyrium pumilum and a local assemblage of carrion flies were investigated, and the functional significance of floral traits, especially scent, tested. Pollination success and the incidence of pollinator-mediated self-pollination were measured and these were compared with values for orchids with sexual- and food-deceptive pollination systems.



Observations of insect visitation to animal carcasses and to flowers showed that the local assemblage of carrion flies was dominated by blow flies (Calliphoridae), house flies (Muscidae) and flesh flies (Sarcophagidae), but flowers of the orchid were pollinated exclusively by flesh flies, with a strong bias towards females that sometimes deposited live larvae on flowers. A trend towards similar partitioning of fly taxa was found in an experiment that tested the effect of large versus small carrion quantities on fly attraction. GC-MS analysis showed that floral scent is dominated by oligosulfides, 2-heptanone, p-cresol and indole, compounds that also dominate carrion scent. Flesh flies did not distinguish between floral and carrion scent in a choice experiment using olfactory cues only, which also showed that scent alone is responsible for fly attraction. Pollination success was relatively high (31·5 % of flowers), but tracking of stained pollinia also revealed that a relatively high percentage (46 %) of pollen deposited on stigmas originates from the same plant.



Satyrium pumilum selectively attracts flesh flies, probably because its relatively weak scent resembles that of the small carrion on which these flies predominate. In this way, the plants exploit a specific subset of the insect assemblage associated with carrion. Pollination rates and levels of self-pollination were high compared with those in other deceptive orchids and it is therefore unlikely that this mimicry system evolved to promote outcrossing.

title: Mimicry in Plants
abstract: Mimetic phenomena have played a central role in many evolutionary questions and today provide some of the best examples of natural selection. Since its discovery by Bates (1862) in Amazonian Heliconiid butterflies many hundreds of papers have been written on the subject and today it is recognized as a major feature of animal evolution, especially in insects.

title: The olfactory component of floral display in Asimina and Deeringothamnus (Annonaceae).
abstract: Floral scent is a key component of floral display, and probably one of the first floral attractants linking insect pollinators to the radiation of Angiosperms. In this article, we investigate floral scent in two extra-tropical genera of Annonaceae. We discuss floral scent in the context of differing pollination strategies in these genera, and compare their scent to that of a close tropical relative. Floral volatiles were collected for Annona glabra, Asimina and Deeringothamnus whole flowers and dissected floral organs, using a standardized static-headspace solid phase microextraction method. Scents were analyzed using gas chromatography-mass spectrometry, and identified using known standards. The floral scents of these species are highly dynamic, varying between floral organs, sexual stages and species. Maroon-flowered species of Asimina produce 'yeasty' odors, dominated by fermentation volatiles and occasionally containing sulfurous or nitrogenous compounds. White-flowered species of Asimina and Deeringothamnus produce pleasant odors characterized by lilac compounds, benzenoids and hydrocarbons. Annona glabra produces a strong, fruity-acetonic scent dominated by 3-pentanyl acetate and 1,8-cineole. The fermented/decaying scents of maroon-flowered species of Asimina suggest mimicry-based pollination strategies similar to aroids and stapeliads, whereas the pleasant scents of white-flowered species of Asimina suggest honest, reward-based pollination strategies. The scent of Annona glabra is typical of specialized beetle pollination systems common to tropical Annonaceae.

title: The evolution of floral gigantism.
abstract: Flowers exhibit tremendous variation in size (>1000-fold), ranging from less than a millimeter to nearly a meter in diameter. Numerous studies have established the importance of increased floral size in species that exhibit relatively normal-sized flowers, but few studies have examined the evolution of floral size increase in species with extremely large flowers or flower-like inflorescences (collectively termed blossoms). Our review of these record-breakers indicates that blossom gigantism has evolved multiple times, and suggests that the evolutionary forces operating in these species may differ from their ordinary-sized counterparts. Surprisingly, rather than being associated with large-bodied pollinators, gigantism appears to be most common in species with small-bodied beetle or carrion-fly pollinators. Such large blossoms may be adapted to these pollinators because they help to temporarily trap animals, better facilitate thermal regulation, and allow for the mimicry of large animal carcasses. Future phylogenetic tests of these hypotheses should be conducted to determine if the transition to such pollination systems correlates with significant changes in the mode and tempo of blossom size evolution.

title: Flowers as sensory billboards: progress towards an integrated understanding of floral advertisement.
abstract: This paper explores the landscape of integrated sensory signals that are produced by flowers, and the contextual information that modulates pollinator responses to such signals. Chiloglottis orchids are pollinated by mimicking the pheromone and posture of female thynnine wasps, but floral height provides the context within which male wasps respond to these signals. The odor and appearance of carrion attract blowflies to Helicodiceros inflorescences, but flies are more likely to enter the floral chamber when heat is present as a contextual cue. Finally, fragrance, UV-visual cues and echo fingerprints are redundant signals that Glossophaga bats can use to find flowers, depending on prior experience and the photic environment.

title: The chemical nature of fetid floral odours in stapeliads (Apocynaceae-Asclepiadoideae-Ceropegieae).
abstract: By emitting strong fetid scents, sapromyiophilous flowers mimic brood and food sites of flies to attract them as pollinators. To date, intensive comparative scent analyses have been restricted to sapromyiophilous Araceae. Here, we analysed flower volatiles of fetid stapeliads to improve our understanding of the floral biology of fly pollinated species, and to learn whether mimicry types comparable to those found in Araceae exist. Floral volatiles of 15 species out of 11 genera within the Asclepiadoideae-Ceropegieae-Stapeliinae were collected via headspace adsorption and thermal desorption and analysed by gas chromatography-mass spectometry (GC-MS). Data were analysed using CNESS-NMDS statistics. Sapromyiophilous stapeliads are highly diverse in their scent composition, in which sulphur compounds, benzenoids, fatty acid derivatives or nitrogen-containing compounds dominate. Four groups are evident: species with high p-cresol content but low amounts of polysulphides (herbivore faeces mimicry); species with mainly polysulphides and low amounts of p-cresol (carnivore/omnivore faeces or carcass mimicry); species with high amounts of heptanal and octanal (carnivore/omnivore faeces or carcass mimicry); and species with hexanoic acid (urine mimicry). Considering the findings in the unrelated Araceae, our results support the universality of different mimicry types that are obviously subsumed under the sapromyiophilous syndrome.

title: Inflorescence odours of Amorphophallus and Pseudodracontium (Araceae)
abstract: The inflorescence odours of 18 species of Amorphophallus and two species of Pseudodracontium were analysed by headspace techniques and compared to the limited data on potential pollinators. The odours of species with ‘gaseous’ or carrion smells had a simple chemical composition, consisting mainly of dimethyl oligosulphides. The odours of other Amorphophallus species having different smells were also generally dominated by one or two compounds: e.g. trimethylamine in A. brachyphyllus, isocaproic acid in A. elatus, 4-methoxyphenethyl alcohol in A. albispathus, and isoamyl acetate with ethyl acetate in A. haematospadix. The production of odours containing dimethyl oligosulphides appears to be a common feature of sapromyophilous flowers that attract carrion insects.

title: Convergent evolution of carrion and faecal scent mimicry in fly-pollinated angiosperm flowers and a stinkhorn fungus.
abstract: Flowers of many angiosperms attract fly pollinators through mimicry of animal carrion and faeces. This phenomenon of “sapromyiophily” is also evident in the sporophytes of some mosses and fruiting bodies of “stinkhorn” fungi, both of which use flies as agents of spore dispersal. We studied the scent chemistry of a stinkhorn fungus ( Clathrus archeri ) and seven fly-pollinated plant species with foetid odours to determine the degree to which these organisms mimic the scent of carrion and faeces (reference scent samples were collected from rotting meat, a rat carcass and horse and dog faeces), as well as the degree of convergent evolution between the fungus and angiosperm flowers. We found that scents of both the fungus and angiosperms tended to contain compounds typical of carrion, such as oligosulphides, and of faeces, such as phenol, indole and p-cresol. This study provides compelling new evidence for mimicry of carrion and faeces, as well as a striking pattern of convergence in the putrid scents of the fungus and the angiosperms, relative to those of confamilial species. The syndrome of sapromyiophily thus encompasses at least two kingdoms (Plantae and Fungi) and provides an effective means of exploiting flies as agents of pollen and spore dispersal.

title: A comparison of Lucitraps® and sticky targets for sampling the blowfly Lucilia sericata
abstract: The Lucitrap® (Miazma Pty Ltd, Queensland, Australia) combined with a synthetic odour bait, Lucilure® (Miazma Pty Ltd, Queensland, Australia), is a commercially available trap for sampling and control of Lucilia cuprina (Wiedemann) in Australia. It was tested in Hungary against Lucilia sericata (Meigen) (Diptera: Calliphoridae), a cause of sheep strike throughout temperate Europe. The standard Lucitrap was tested against black or yellow sticky target traps. Both trap types were baited with either Lucilure or liver and 10% w/v sodium sulphide solution. With Lucilure as bait, L. sericata were caught on sticky traps but not in Lucitraps. With liver and sodium sulphide as bait, sticky traps caught 500–1500 times more L. sericata than Lucitraps. An adhesive sheet fitted to the top of a Lucitrap captured 30–300 times more L. sericata then were captured inside an unaltered Lucitrap. Direct observation of metallic green calliphorids (92.1%L. sericata) alighting on Lucitraps indicated that most flies stayed for a short while (modal class 2–4 s) and only a few stayed longer, to an observed maximum of 28 s. Flies explored a mean of 1.5 entry holes (range 0–7) during a visit but only 6% entered the trap. Size of L. sericata was not a physical barrier to Lucitrap entry, because many larger species were captured. However, L. sericata captured inside Lucitraps were significantly smaller than those captured on sticky traps, demonstrating that size was of behavioural importance. The data demonstrate that the Lucitrap is not effective as a trap for L. sericata in Hungary, due mainly to a failure of flies to enter the trap in large numbers. In Australia and South Africa, L. sericata is commonly caught in Lucitraps baited with Lucilure, although L. cuprina is more numerous. Our study highlights the potential for diversity of fly behaviour between different geographical populations of the same species. Such diversity can have a significant effect on the functioning of systems for fly sampling and control, when these systems depend for their success on certain behavioural responses of the target species.

title: Wind tunnel behavioural response and field trapping of the blowfly Calliphora vicina
abstract: The attraction of the blowfly Calliphora vicina Robineau‐Desvoidy, 1830 (Diptera: Calliphoridae) to single synthetic compounds, blends and authentic odours was investigated in a wind tunnel. A total of 1850 C. vicina (1750 females and 100 males) were tested. A comparison of male and female responses showed significant differences in attraction between the sexes. Females were more attracted than males to liver odour. The attraction of females lay in the ranges of 0–22% for single compounds, 26–64% for synthetic blends and 58–88% for authentic odours. Dimethyl trisulphide was the most attractive single compound. Significant improvement in attraction was achieved with blends and a three‐component lure, consisting of dimethyl trisulphide, mercaptoethanol and o‐cresol, was found to be the best solution for field trapping of C. vicina. Authentic odours from dead fish and mice were significantly more attractive than liver and the three‐component blend, and the blend and liver were similarly effective as attractants. Field tests support the results of the wind tunnel study and a high number of C. vicina were caught in funnel traps. Overall, 99.1% of the specimens caught were females.

title: The missing stink: sulphur compounds can mediate a shift between fly and wasp pollination systems
abstract: The radiation of the angiosperms is often attributed to repeated evolutionary shifts between different pollinators, as this process drives diversification of floral forms and can lead to reproductive isolation. Floral scent is an important functional trait in many pollination systems but has seldom been implicated as a key mechanism in pollinator transitions. In this study, we suggest a role for sulphur compounds in mediating a shift between specialized carrion-fly and pompilid-wasp pollination systems in Eucomis (Hyacinthaceae). Flowers of closely related Eucomis species pollinated by carrion flies or pompilid wasps have very similar greenish-white flowers, but differ markedly in floral scent chemistry (determined by GC–MS analysis of headspace extracts). Comparison of the floral colours of the four Eucomis species in the visual systems of flies and wasps suggests that colour plays little role in pollinator discrimination. Nectar properties and morphology also do not differ strongly between fly- and wasp-pollinated flowers. By comparing floral scent bouquets and experimentally manipulating the scent of plants in the field, we demonstrate that shifts between wasp and fly pollination in these four congeners can depend on the production or suppression of sulphur compounds (dimethyl disulphide and dimethyl trisulphide) in the fragrance bouquet. This suggests that mutations affecting the production of particular scent compounds could precipitate shifts between pollinators, independently of floral morphology, colour or nectar properties.

title: House Flies and Pig Manure Volatiles: Wind Tunnel Behavioral Studies and Electrophysiological Evaluations'
abstract: Nine compounds from the headspace of fresh pig manure were identified as elcctrophysiologically active on virgin female house Oy (Mu.sca domeslico L.) antennae, and mixtures of these compounds attracted female house nics in wind-tunnel behavioral assays. Identification was accomplished by using coupled gas chromatographic-electroantennographic (GC·EACl recordings, coupled gas chromatographic-mass spectrometric (Ge­ MS) analysis, elec:iroantennographic (EAG) assays of standards, and wind tunnel behavioral studies. The pig manure volatiles eliciting responses from female antennae were butanoic acid, 3-methylbutanoic acid, dimcthyldisulfide, dimethyltrisulfide. dimethyltetrasullide, phenol, benzencethnnol. indole, and 3·methylindole. )n EAG dose-response tests butanoic acid, 3-methylbutnnoic acid, indole, and 3-methylindole elicited the highest responses on female house fly antennae, and dimethylLrisulfide, phenol, and benzeneethanol elicited more moderate responses. )n wind-Lunnel behavioral studies, female house nies new upwind in the plume and landed on the source in response to pig manure volatiles. The ability of individual EAG-active compounds to attract female house flies was not significantly gteater than that of the control. However, two mixtures, one comprised of seven EAG-adivc compounds and a second made up of only three compounds, were capable of attracting female nics in a similar manner as found with pig manur·c. The behavioral significance of these compounds as potential attractants is discussed.

title: Decomposition and dipteran succession in pig carrion in central Argentina: ecological aspects and their importance in forensic science
abstract: Data on the insect species associated with corpse decomposition are particularly important for estimation of the post‐mortem interval (PMI) in forensic science because the PMI is based on the lifecycle and behaviour of necrophagous insects, among other measures. To determine the dipteran succession on pig carrion, four experiments, one in each season, were carried out during 2004 in a rural area of Córdoba, central Argentina. Two pigs (Sus scrofa L.) were used in each of the four experiments. At each time‐point one pig was placed in the shade and the other under direct sunlight. Insects were collected daily during the first 4 weeks and thereafter every 2 or 3 days. Five stages of decomposition were observed and a total of 24 710 adult specimens were collected, belonging to the following eight families of Diptera: Calliphoridae; Muscidae; Sarcophagidae; Phoridae; Piophilidae; Fanniidae; Sphaeroceridae, and Anthomyiidae. All Calliphoridae collected in this study were considered to be of potential forensic importance because of their necrophagous behaviour and because their immature stages use carrion as a food source. Other species, such as Musca domestica L. and Ophyra aenescens (Wiedemann), were also considered to represent potential forensic indicators.

title: The reproductive biology ofJaborosa integrifolia (Solanaceae): Why its fruits are so rare?
abstract: Jaborosa integrifolia exhibits stigma-height polymorphism. There are individuals with flowers where anthers and stigma are at the same height but the rule is variable herkogamy, the most common type (75%) being that with an exerted stigma. Self- and cross-tubes did not differ in their capability to reach the ovary (t = −0.67,P < 0.53); they had a high growth rate (6.95 ± 2.28 mm h−1). There is not autogamy but mostly self-incompatibility. Fruits from controlled cross-pollination showed the highest seed set and seed viability. The nectar sugar is characterized by a similar amount of glucose and fructose, and by the absence of sucrose. Although nectar secretion was continuous throughout the life of the flower, most nectar was secreted during the first 24 h after flower opening. Nectar production costs appear to be lower than in other species since nectar secretion is neither inhibited after a removal (i.e. a pollinator visit) nor reabsorbed as the flower ages. Sphingids visit the flowers mainly after midnight. They insert their proboscis down to the base of the corolla tube to reach the nectar. The upper limit to fruit production is set by pollinator visits. Fruits produced from open-pollinated flowers are often predated by numerous larvae (mainly lepidopteran ones). Considering that this species is mostly self-incompatible and pollination is limited, that each plant displays only a low number of flowers throughout the flowering season, and that there is a high rate of fruit predation, it is not surprising that fruits ofJ. integrifolia are so rare.

title: Pollination systems in the Asclepiadaceae: a survey and preliminary analysis☆
abstract: Using published and unpublished records of pollination in the dicot family Asclepiadaceae (the ‘milkweeds’) we offer a preliminary analysis of present-day pollination systems in the family. Variation in principal pollinators is apparent at and below the tribal level. The tribes Marsdenieae and Stapelieae and Asclepiadeae subtribe Gonolobineae are primarily Diptera-pollinated, a tentative conclusion also for the tribe Periploceae, and we emphasize the ubiquity and importance of fly pollination in the family. The rest of the tribe Asclepiadeae is pollinated in the main by Hymenoptera and Lepidoptera. Lack of data makes it impossible to draw even initial conclusions for the remaining tribes, Secamoneae and Fockeeae. Within the Asclepiadeae, there has been a trend towards more diverse pollination systems (incorporating butterflies and wasps) in the New World compared to the Old World. In terms of the taxonomic breadth of pollinators of individual species, Stapelieae is the most specialized tribe. We emphasize that this is only a preliminary account of pollination in the Asclepiadaceae, and detail areas where further work is urgently required.

title: When Flowers Smell Fermented: The Chemistry and Ontogeny of Yeasty Floral Scent in Pawpaw (Asimina triloba: Annonaceae)
abstract: Floral scent plays important roles in basal angiosperms such as the pantropical woody family Annonaceae. The North American genus Asimina (Adans.) (Annonaceae) includes eight species of shrubs and small trees, of which Asimina triloba has the broadest and northernmost distribution. We characterized the yeastlike fragrance of these flowers using gas chromatography–mass spectrometry in natural populations in South Carolina. The odors of A. triloba and baker’s yeast Saccharomyces cerevisiae shared ethanol, ethyl acetate, acetic acid, and other compounds but differed in relative amounts of 3‐methyl‐1‐butanol, 3‐OH‐2‐butanone, and butane‐2,3‐diol. Immature green flowers of A. triloba produced sesquiterpenes common to the foliage of many plants. In contrast, sexually mature flowers emitted fermentation volatiles, with additional nitrogenous compounds (androgynoecium) and butanediols (outer corolla) emitted by male flowers. Some compounds were detected only when scent was sampled from at least 10 flowers. Chemical composition was more complex during day than night for immature and female flowers but not for males. Emission rates were fourfold greater in male than female flowers during the day but were comparable at night, perhaps because of overlapping gender expression. The yeasty odor of A. triloba is unusual in angiosperms and may serve to attract novel fly and beetle pollinators.

title: Spectral Categories in the Learning Behaviour of Blowflies
abstract: Wavelength discrimination in the flower visiting blowfly Lucilia spec, was investigated in an attempt to elucidate the mechanisms underlying colour vision in this insect. The flies were subjected to a classical conditioning procedure in which they had to discriminate between a rewarded and an unrewarded monochromatic light stimulus. The results reveal large wavelength ranges within which no discrimination occurs, between which, however, a very distinct discrimination is found. The first range consists of the UV region up to 400 nm (UV). The second range comprises wavelengths between 400 nm and 515 nm (BLUE) and the third range all wavelengths longer than 515 nm (YELLOW). A simple model consisting of two colour opponent subsystems (R7p /R8p and R7y/R8y) can explain these results. Each of the two subsystems is assumed to evaluate only whether the sign of the difference between the excitations of R7 and R8 is positive or negative. For the whole system there are thus four possible conditions: p+y+, p+y-, p-y+, p-y-. Three of them correspond to the experimentally obtained wavelength ranges. The fourth condition (p+y-) might represent a still hypothetical PURPLE category in which the stimulus is made up of both short and long wavelengths.

title: Flower colours along an alpine altitude gradient, seen through the eyes of fly and bee pollinators
abstract: Alpine flowers face multiple challenges in terms of abiotic and biotic factors, some of which may result in selection for certain colours at increasing altitude, in particular the changing pollinator species composition, which tends to move from bee-dominated at lower elevations to fly-dominated in high-alpine regions. To evaluate whether growing at altitude—and the associated change in the dominant pollinator groups present—has an effect on the colour of flowers, we analysed data collected from the Dovrefjell National Park in Norway. Unlike previous studies, however, we considered the flower colours according to ecologically relevant models of bee and fly colour vision and also their physical spectral properties independently of any colour vision system, rather than merely looking at human colour categories. The shift from bee to fly pollination with elevation might, according to the pollination syndrome hypothesis, lead to the prediction that flower colours should shift from more bee-blue and UV-blue flowers (blue/violet to humans, i.e. colours traditionally associated with large bee pollinators) at low elevations to more bee-blue-green and green (yellow and white to humans—colours often linked to fly pollination) flowers at higher altitude. However, although there was a slight increase in bee-blue-green flowers and a decrease in bee-blue flowers with increasing elevation, there were no statistically significant effects of altitude on flower colour as seen either by bees or by flies. Although flower colour is known to be constrained by evolutionary history, in this sample we also did not find evidence that phylogeny and elevation interact to determine flower colours in alpine areas.

title: An introduction to categorical data analysis
abstract: Two--Way Contingency Tables. Three--Way Contingency Tables. Generalized Linear Models. Logistic Regression. Loglinear Models for Contingency Tables. Building and Applying Logit and Loglinear Models. Multicategory Logit Models. Models for Matched Pairs. A Twentieth--Century Tour of Categorical Data Analysis.

title: The ecology and evolution of fly dispersed dung mosses (Family Splachnaceae): Manipulating insect behaviour through odour and visual cues
abstract: The use of sensory attractants is central to most animal-mediated pollination and seed dispersal interactions. Approximately half the 73 species of mosses’ in the family Splachnaceae are entomophilous (have their spores dispersed by flies) and are coprophilous (grow on feces and carrion). When mature, entomophilous species often produce brightly coloured, scented sporophytes which, for several species, have been shown to attract flies. In a number of cases, sporophyte colours and odours, as well as the flies that visit them, have been shown to be species-specific, suggesting that the mosses co-exist by signal diversification, just as flowering plants are thought to reduce competition for pollinators. Analyses of scent chemistry identified an odour contrast between generations; gametophytes were either unscented or weakly scented in most species, whereas sporophyte odours were universally stronger per unit mass and much more chemically complex. Sporophyte odours of North and South American species sampled were both complex and diverse, with an apparent inverse relationship between the size and showiness of the apophysis and its odour complexity. Furthermore, phylogenetic evidence suggests that fly dispersal of spores through visual and olfactory signals has evolved multiple times in the Splachnaceae and that modifications of sporophyte morphology may have followed, rather than triggered, the transitions to coprophily and entomophily. We review the ecological and evolutionary aspects ofentomophily, with particular emphasis on the chemistry of sporophyte odours and the means by which they mimic decaying organic matter.

title: Review of the Sarcophaginae (Diptera: Sarcophagidae) of Buenos Aires Province (Argentina), with a key and description of a new species.
abstract: Thirty-nine species of Sarcophaginae are recorded from Buenos Aires Province (Argentina). A new species, Microcerella asymmetrica sp. nov., is described. Females of Oxysarcodexia bicolor Lopes, O. marina Hall, and Sarcophaga (Lipoptilocnema) koehleri Blanchard are described for the first time. Four nomenclatorial actions are reported: Sarcohelicobia elegans Blanchard is established as a new junior synonym of Nephochaetopteryx cyaneiventris Lopes, and lectotypes are designated for Oxysarcodexia delpontei Blanchard [a junior synonym of Oxysarcodexia paulistanensis (Mattos)], Sarcophaga argentina Brethes [a junior synonym of Sarcophaga (Liopygia) argyrostoma (Robineau-Desvoidy)], and Neobellieria brethesi Blanchard [a junior synonym of Sarcophaga (Neobellieria) polistensis Hall]. Blaesoxipha (Tephromyia) hospes (Aldrich), Peckia (Euboettcheria) florencioi (Prado & Fonseca), Ravinia advena (Walker), R. aureopyga (Hall) and Sarcodexia lambens (Wiedemann) are newly recorded from Buenos Aires Province, and Udamopyga percita is newly recorded from Argentina. A key is presented to the adult males and females of 36 of the 39 species of Sarcophaginae recorded from Buenos Aires province. Notes on distribution, biology, life history and host records are also given.

title: Floral biology and pollination in stapeliads — new results and a literature review
abstract: The myiophilous pollination syndrome of stapeliads is investigated. Olfactory stimuli, imitating dung or decaying organic (zoogenic or phytogenic) matter, are used as attractants, together with mimetic colouration and, sometimes mimetic sculpturing. In most species nectar is present. The nectar mainly serves as optical attractant causing brilliance effects, and as visitor guide. However, nectar obviously is also a reward in many species. Flies (Calyptratae) constitute the most important pollinating group. In the pollination process they carry pollinaria only at the distal parts of their proboscis, never on their legs. No fundamental differences between the pollinator spectra of flowers in habitat and cultivated ones were observed.

title: Floral scent variation in two Antirrhinum majus subspecies influences the choice of naïve bumblebees
abstract: Two wild subspecies of snapdragon, Antirrhinum majus, subspecies pseudomajus and striatum, differ in floral color and can be visually discriminated by insect visitors. The extent to which olfactory cues derived from floral scents contribute to discrimination between snapdragon subspecies is however unknown. We tested whether these two subspecies differ in floral scent and whether these olfactory differences are used by bumblebees (Bombus terrestris) to discriminate between them. We grew individuals of both subspecies, collected from a total of seven wild populations, under controlled conditions. We quantified the volatile organic compounds (VOCs) emitted by the flowers using gas-chromatography/mass-spectrometry/flame-ionization-detection. We studied antennal detection of VOCs by bumblebees, by means of electroantennogram study (EAG). We also performed behavioral experiments in a Y-maze to determine the innate response of bumblebees to the main floral VOCs emitted by our snapdragon subspecies. The floral scent of Antirrhinum majus pseudomajus contained three volatile benzenoids absent in the floral scent of Antirrhinum majus striatum. One of them, acetophenone, contributed over 69% of the absolute emissions of A. majus pseudomajus. These benzenoids elicited a significantly higher EAG response compared with other VOCs. In the Y-maze, bumblebees were significantly less attracted by acetophenone, suggesting an aversive effect of this VOC. Our findings indicate that bumblebees are able to discriminate between the two Antirrhinum majus subspecies. Differences in flower scent between these subspecies and olfactory bumblebee preferences are discussed in the light of biochemical constraints on VOCs synthesis and of the role of flower scent in the evolutionary ecology of A. majus.

title: Cheaters and liars: Chemical mimicry at its finest
abstract: Chemical mimicry is an essential part of certain interspecific interactions, where the outcome for both species may depend on the degree to which the original signals are mimicked. In this review, we discuss a number of specific cases relating to pollination and obtaining nutrient resources that we believe exemplify recent advances in our understanding of chemical mimicry. Subsequently, we suggest avenues for future ecological and chemical research that should allow us to gain further insight into the evolution of chemical mimicry.

title: The sweet stench of decay.
abstract: The scents of flowers have long inspired writers such as Shakespeare, who had Juliet consider: ‘That which we call a rose by any other word would smell as sweet.’ Beautiful flowers are also frequently the subjects of painters, and, combined, these artistic endeavours conjure up a natural world that is all vibrant colour and heady fragrance, as gorgeous blooms attract butterflies, moths and bees for pollination. So far, so pleasant: but such a view is somewhat restricted, because flowers that attract pollinators such as blowflies and dung beetles with the unlikely lures of putrefaction, decay and fermentation have also evolved in many plant families, including the Araceae, Aristolochiaceae, Orchidaceae and Apocynaceae. The scents of relatively few such species have been chemically characterized, but now a paper in this issue of New Phytologist by Andreas Jürgens, Stefan Dötterl and Ulrich Meve (pp. 452–468) has for the first time analysed the flower scents of stapeliads, the so-called ‘carrion flowers’ of the Apocynaceae (subfamily Asclepiadoideae, tribe Ceropegieae, subtribe Stapeliinae).

title: Pollination Biology of Hydnora africana Thunb. (Hydnoraceae) in Namibia: Brood‐Site Mimicry with Insect Imprisonment
abstract: Hydnora africana is a root holoparasite of southern Africa that emerges only to flower. The trimerous flowers of H. africana have androecial and gynoecial chambers and attract floral visitors with putrid odors emitted from prominent osmophores. We observed floral phenology and insect visitation for H. africana at two sites in southern Namibia and evaluated the insect imprisonment mechanism with beetle addition and pollen viability assays. Flowers are putatively protogynous for 3 d. We observed 18 floral visitors, including 10 coleopteran species imprisoned by the smooth inner surface of the androecial chamber. The hide beetle Dermestes maculatus (Tenebrionidae) accounted for 76.9% of the imprisoned insects, with a density of 
\documentclass{aastex}
\usepackage{amsbsy}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{mathrsfs}
\usepackage{pifont}
\usepackage{stmaryrd}
\usepackage{textcomp}
\usepackage{portland,xspace}
\usepackage{amsmath,amsxtra}
\usepackage[OT2,OT1]{fontenc}
\newcommand\cyr{
\renewcommand\rmdefault{wncyr}
\renewcommand\sfdefault{wncyss}
\renewcommand\encodingdefault{OT2}
\normalfont
\selectfont}
\DeclareTextFontCommand{\textcyr}{\cyr}
\pagestyle{empty}
\DeclareMathSizes{10}{9}{7}{6}
\begin{document}
\landscape
$$2.2\pm 0.6$$
\end{document} per flower. The D. maculatus addition experiment (
\documentclass{aastex}
\usepackage{amsbsy}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{mathrsfs}
\usepackage{pifont}
\usepackage{stmaryrd}
\usepackage{textcomp}
\usepackage{portland,xspace}
\usepackage{amsmath,amsxtra}
\usepackage[OT2,OT1]{fontenc}
\newcommand\cyr{
\renewcommand\rmdefault{wncyr}
\renewcommand\sfdefault{wncyss}
\renewcommand\encodingdefault{OT2}
\normalfont
\selectfont}
\DeclareTextFontCommand{\textcyr}{\cyr}
\pagestyle{empty}
\DeclareMathSizes{10}{9}{7}{6}
\begin{document}
\landscape
$$n=9$$
\end{document} ) clearly demonstrated imprisonment during the carpellate stage. Changes in the inner surfaces of the androecial chamber, stippling, and texturing allowed D. maculatus to escape after pollen release. More than 55.5% of the beetles escaped, dusted with pollen, within 3 d after pollen release. Pollen was still viable 3 d after pollen release. The beetle addition and pollen assays demonstrate the efficiency of the H. africana imprisonment mechanism.

title: Sulphur-containing “perfumes” attract flower-visiting bats
abstract: We tested the attractiveness of individual scent compounds of bat-pollinated flowers to their pollinators, small flower-visiting bats of the genus Glossophaga (Phyllostomidae). Twenty compounds belonging to four different chemical substance classes were tested, both in the laboratory and in the field. In the laboratory, the bats (Glossophaga soricina) approached odour sources spontaneously and without preceding experience. Without ever receiving any reward they preferred the scent of a sulphur-containing compound, dimethyl disulphide, to several other odour components emitted by bat-pollinated flowers, and to scentless controls. In the field, at La Selva station in the tropical lowland rain forest of Costa Rica, G. commissarisi were attracted by two sulphur-containing compounds, dimethyl disulphide and 2,4-dithiapentane, to visit artificial flowers filled with sugar water. Thus, in nectarivorous bats the sense of smell obviously plays an important role in searching for and localising food sources, and even single components of the scent bouquets of bat-pollinated flowers are attractive. The preference for sulphur-containing odours seems to be innate.

title: Aristolochia gorgona (Aristolochiaceae), a new species with giant flowers from Costa Rica and Panama
abstract: Aristolochia gorgona is described from the Atlantic watershed of Costa Rica and central and eastern Panama. It is similar toA. grandiflora Sw., with which it has been confused in the past. The extensive reported synonymy ofA. grandiflora is reviewed and compared with the new entity. Some new terms are proposed for better describing floral structure in this species complex, and suggestions are made for its collection and study.Aristolochia gorgona is one of the largest-flowered plant species (in terms of perianth area) in the Neotropics.ResumenAristolochia gorgona se describe de la vertiente Atlántica de Costa Rica y del centro y este de Panamá. Es similar aA. grandiflora Sw., con la cual se ha confundido en el pasado. La extensa sinonimia reportada paraA. grandiflora es revisada, y comparada con la nueva entidad. Se proponen algunos términos nuevos para describir mejor la estructura floral en éste complejo de especies, y se ofrecen sugerencias para su recolección y estudio.Aristolochia gorgona es una de las especies vegetales con flores más grandes (en cuanto al área del perianto) en el Neotrópico.

title: Foliar Herbivory Affects Floral Characters and Plant Attractiveness to Pollinators: Implications for Male and Female Plant Fitness
abstract: Plants are subject o selection exerted by both herbivores and pollinators simultaneously. Despite this fact, no previous tudy has directly linked foliar herbivory and pollination. A few studies have addressed how floral displays that attract pollinators may subsequently attract seed predators, when flowers mature to fruits (Campbell 1991; Brody 1992), but no one has examined how folivore-caused changes in floral characters, particularly corolla characters, affect pollinators. In the past, it has been assumed that floral characters, and particularly corolla characters, are relatively invariant because of the fitness consequences that reduced attractiveness to pollinators may have for self-incompatible plants (e.g., Harper 1977, p. 195). However, it is well known that natural variation in flower size, flower number, nectar production, and pollen production affects the attractiveness of plants to pollinators (e.g., Schemske 1980; Roubick and Buchmann 1984; Willmer 1986; Stanton and Preston 1988; Galen 1989). Effects of foliar herbivory on floral traits other than flower number are not well known (but see McKone 1989; Frazee and Marquis 1994; Quesada et al. 1995). Herbivore damage directly to corollas reduced the attractiveness of flowers to pollinators (Karban and Strauss 1993). The effects of foliar damage by herbivores on floral traits and, in turn, on the attractiveness of plants to pollinators have been generally ignored (Crawley 1989; Marquis 1992). The significance of floral responses to foliar herbivory is twofold. First, estimates of the effects of herbivory on plant fitness based on female fitness (seed production) may be misleading if plants suffer a reduction in male fitness (number of seeds sired on other plants through pollen). Herbivory affecting attractiveness to pollinators has the potential to strongly influence plant fitness through male function, since visitation rates can often affect male fitness (number of seeds sired by pollen) more strongly than female plant fitness (numbers of seeds set) (Bell 1985). Only a handful of studies have documented male and female plant fitness imultaneously, and at least three have shown that male and female plant fitness are either negatively or only weakly correlated (Bertin 1982; Ennos and Dodson 1987; Schlichting and Devlin 1989; Broyles and Wyatt 1990; Devlin and Ellstrand 1990). Thus, the impact of herbivory on the fitness of hermaphroditic plants requires knowledge of both male and female reproductive success. Second, how plants have evolved to respond to damage from herbivores in allocation patterns to floral resources may be influenced or constrained by floral adaptations

title: A sheep in wolf's clothing: do carrion and dung odours of flowers not only attract pollinators but also deter herbivores?
abstract: Carrion and dung odours of various flowers have traditionally been considered an adaptation for attracting the flies and beetles that pollinate them. While we accept the role of such odours in pollinator attraction, we propose that they may also have another, overlooked, anti‐herbivore defensive function. We suggest that such odours may deter mammalian herbivores, especially during the critical period of flowering. Carrion odour is a good predictor for two potential dangers to mammalian herbivores: (1) pathogenic microbes, (2) proximity of carnivores. Similarly, dung odour predicts faeces‐contaminated habitats that present high risks of parasitism. These are two new types of repulsive olfactory aposematic mimicry by plants: (1) olfactory feigning of carcass (thanatosis), a well‐known behavioural defensive strategy in animals, (2) olfactory mimicry of faeces, which also has a defensive visual parallel in animals.

title: The Sauromatum guttatum appendix as an osmophore: excretory pathways, composition of volatiles and attractiveness to insects.
abstract: This report combines chemical, electron microscopic and ecological studies on the volatiles liberated by the Sauromatum guttatum appendix on D-Day, the day of inflorescence-opening and heat-production. More than 100 compounds from at least nine different chemical classes (monoterpenes, sesquiterpenes, fatty acids, ketones, alcohols, aldehydes, indole, and phenolic and sulphur compounds) are liberated during the thermogenic activity. The volatiles were identified using gas chromatography-mass spectrometry. Electron microscopy provides additional evidence that the endoplasmic reticulum (ER) interacts with the plasma membrane, creating novel routes of excretion of the volatiles to the exterior of the cell. It seems that the fusion event creates channels from the interior to the exterior of the cell. Furthermore, a multitubular body, conceivably originating in the ER, seems to fuse with the plasma membrane and to appear only on D-day. This multitubular body is closely associated with lipid bodies during heat-production and might be involved in the oxidation of lipids to volatile products. The foul odour produced by the appendix attracts at least 30 species of insects.

title: Fly pollination in Ceropegia (Apocynaceae: Asclepiadoideae): biogeographic and phylogenetic perspectives.
abstract: Ceropegia (Apocynaceae subfamily Asclepiadoideae) is a large, Old World genus of >180 species, all of which possess distinctive flask-shaped flowers that temporarily trap pollinators. The taxonomic diversity of pollinators, biogeographic and phylogenetic patterns of pollinator exploitation, and the level of specificity of interactions were assessed in order to begin to understand the role of pollinators in promoting diversification within the genus.



Flower visitor and pollinator data for approx. 60 Ceropegia taxa were analysed with reference to the main centres of diversity of the genus and to a cpDNA-nrDNA molecular phylogeny of the genus.



Ceropegia spp. interact with flower-visiting Diptera from at least 26 genera in 20 families, of which 11 genera and 11 families are pollinators. Size range of flies was 0.5-4.0 mm and approx. 94 % were females. Ceropegia from particular regions do not use specific fly genera or families, though Arabian Peninsula species are pollinated by a wider range of Diptera families than those in other regions. The basal-most clade interacts with the highest diversity of Diptera families and genera, largely due to one hyper-generalist taxon, C. aristolochioides subsp. deflersiana. Species in the more-derived clades interact with a smaller diversity of Diptera. Approximately 60 % of taxa are so far recorded as interacting with only a single genus of pollinators, the remaining 40 % being less conservative in their interactions. Ceropegia spp. can therefore be ecological specialists or generalists.



The genus Ceropegia has largely radiated without evolutionary shifts in pollinator functional specialization, maintaining its interactions with small Diptera. Intriguing biogeographic and phylogenetic patterns may reflect processes of regional dispersal, diversification and subsequent specialization onto a narrower range of pollinators, though some of the findings may be caused by inconsistent sampling. Comparisons are made with other plant genera in the Aristolochiaceae and Araceae that have evolved flask-shaped flowers that trap female flies seeking oviposition sites.

title: Deception in plants: mimicry or perceptual exploitation?
abstract: Mimicry involves adaptive resemblance between a mimic and a model. However, despite much recent research, it remains contentious in plants. Here, we review recent progress on studying deception by flowers, distinguishing between plants relying on mimicry to achieve pollination and those relying on the exploitation of the perceptual biases of animals. We disclose fundamental differences between both mechanisms and explain why the evolution of exploitation is less constrained than that of mimicry. Exploitation of perceptual biases might thus be a precursor for the gradual evolution of mimicry. Increasing knowledge on the sensory and cognitive filters in animals, and on the selective pressures that maintain them, should aid researchers in tracing the evolutionary dynamics of deception in plants.