The Roles of Colour and Shape in Pollinator Deception in the Orchid Mantis Hymenopus coronatus

The orchid mantis Hymenopus coronatus (Insecta: Mantodea) is a deceptive predator that attracts pollinators as prey. Their resemblance to a flower has given rise to the hypothesis that they are flower mimics. However, floral mimicry as a predatory strategy, and in particular, how predatory floral mimicry functions at a mechanistic level is poorly understood. Two main morphological characteristics are thought to make orchid mantises appear similar to flowers and thus attractive to pollinators: (1) their ‘flower‐like’ white colouration and (2) their ‘petal‐shaped’ expansions of exoskeleton on their mid‐femur and hind femur (femoral lobes). I investigated the contribution of these colour and shape characteristics to pollinator attraction using artificial orchid mantis models. Models with the ‘flower‐like’ white colouration of the orchid mantis had higher rates of pollinator inspection than brown models. Manipulating overall body shape by removing or changing the orientation of the ‘petal‐shaped’ femoral lobes did not affect the attractiveness of models. As certain flower‐like characteristics (symmetry and petals) did not affect the attractiveness of models, pollinators may not necessarily cognitively misclassify orchid mantises as flowers. Rather, mantises may be exploiting sensory biases of their pollinator prey, and their UV‐absorbing white colouration may be sufficient to lure pollinators. The effectiveness of using artificial models established here provides a basis for future research into orchid mantis morphology and the fine‐scale interactions between orchid mantises and pollinators.     

A torch in the rain forest: thermogenesis of the Titan arum (Amorphophallus titanum)

An outstanding flagship species in the plant kingdom is the Titan arum ( Amorphophallus titanum ), which produces a fountain-like bloom up to 3 m high. The unique appearance of three simultaneous inflorescences in May 2006 was a chance to analyse the flowering behaviour and thermogenesis of this giant. For the first time, the heating of the central column (spadix) could be documented using a high-performance thermographic camera. Time series analyses of the infrared image sequences revealed that the 3-m high spadix surface heats up in pulses emanating from the base of the inflorescence. The surface temperature reaches over 36 °C, compared to the ambient temperature of 27 °C. Waves of the carrion-like odour are synchronised with these heat pulses. The combination of heat pulses, the fountain-like shape plus the enormous size lead to a unique type of 'convection flower'. On the basis of our observations, we assume that Amorphophallus titanum is able to overcome thermodynamic decoupling by a self-produced convective process.     

Brood parasites lay eggs matching the appearance of host clutches

Interspecific brood parasitism represents a prime example of the coevolutionary arms race where each party has evolved strategies in response to the other. Here, we investigated whether common cuckoos (Cuculus canorus) actively select nests within a host population to match the egg appearance of a particular host clutch. To achieve this goal, we quantified the degree of egg matching using the avian vision modelling approach. Randomization tests revealed that cuckoo eggs in naturally parasitized nests showed lower chromatic contrast to host eggs than those assigned randomly to other nests with egg-laying date similar to naturally parasitized clutches. Moreover, egg matching in terms of chromaticity was better in naturally parasitized nests than it would be in the nests of the nearest active non-parasitized neighbour. However, there was no indication of matching in achromatic spectral characteristics whatsoever. Thus, our results clearly indicate that cuckoos select certain host nests to increase matching of their own eggs with host clutches, but only in chromatic characteristics. Our results suggest that the ability of cuckoos to actively choose host nests based on the eggshell appearance imposes a strong selection pressure on host egg recognition.     

EVOLUTION OF MIMICRY PATTERNS IN METRIORRHYNCHUS (COLEOPTERA: LYCIDAE): THE HISTORY OF DISPERSAL AND SPECIATION IN SOUTHEAST ASIA

The concept of Müllerian mimicry suggests convergent evolution to an intermediate pattern and does not predict polymorphism in mimicry rings. We examined the evolution of mimicry patterns and the order of divergence of various factors, including the role of aposematic patterns in speciation, in a clade of net-winged beetles with a robust phylogeny that suggests that they dispersed from the Australian to Asian plate. We found strong evidence for the evolution of mimicry via advergence in Metriorrhynchus because older patterns are represented in the Oriental region within more than 100 species of lycids from several lineages. Advergence was likely the cause of the observed intraspecific polymorphism in contrast to the predicted universal monomorphism. Polymorphism was found in populations of two species in Sumatra and Borneo and in populations fine-tuned to subtle variants in various habitats. The advergence is likely to be based on the small population sizes of immigrants. The differences in population sizes result in much higher benefits for dispersing species than native populations. Speciation was trigged by the divergence in aposematic coloration, and the genetic differences accumulated slowly during incomplete isolation. We assumed that the differentiation in genitalia through sexual selection ultimately reinforced speciation initiated by the shift between mimicry patterns.     

Schistosoma mansoni and Biomphalaria glabrata share epitopes: antibodies to sporocysts bind host snail hemocytes

Using an independent protocol, we have confirmed that sporocysts of the human blood fluke, Schistosoma mansoni, synthesize antigens which stimulate rabbit antibody activity to epitopes on infermediate snail host hemocytes. This molecular mimicry may aid S. mansoni to escape the innate immune system of this host, Biomphalaria glabrata.     

Delayed plumage maturation in green‐backed flycatchers (Ficedula elisae): An evidence of female mimicry

Delayed plumage maturation (DPM) is the delayed acquisition of an adult color and pattern of plumage until after the first potential breeding period. Among the hypotheses proposed to explain DPM, the female mimicry hypothesis (FMH) has received considerable attention. FMH predicts that after‐second‐calendar‐year (ASY) males should attack ASY males more than second‐calendar‐year (SY) males and females, while no difference between the two latter. Few studies have been thought as support for FMH, while in fact most of them give no conclusive evidence to the assumption of FMH that ASY males are unable to distinguish SY males from females. Thus, other support besides behavioral experiments, such as it is physiologically impossible to discriminate SY males and females from avian perspective, is important in testing FMH. We studied color differences in six plumage patches between ASY male, SY male and female by analyzing reflectance spectra in the avian visual system, and tested the prediction of FMH by conducting intrusion experiments on territorial males with three kinds of conspecifics (i.e., ASY males, SY males and females) as territory “intruders” in the green‐backed flycatcher (Ficedula elisae). It is physiologically impossible for ASY males to distinguish SY males and females through the plumage color of crown, mantle, rump, and throat patches, moreover difficult to distinguish through breast and belly patches even under reasonable viewing conditions. ASY males were more aggressive toward ASY males than SY males and females with no differences between the two latter. SY males showed a slightly but not significantly higher attack intensity on ASY males than SY males and females. Our results suggest that female mimicry is more likely to be the explanation for DPM in the green‐backed flycatcher. To our knowledge, this is the first study combining avian visual system and behavioral experiments in testing hypotheses of DPM.     

Deceptive orchids with Meliponini as pollinators

Visitation of orchids by Meliponini (stingless bees) is confirmed only in 13Melipona, Partamona andTrigona, forXylobium andMaxillaria, with the addition ofTrigona fulviventris visitingIonopsis. Some bees evinced multiple floral visitation by carrying several stipes and viscidia from pollinaria, thus may cause seed set. None foraged pseudopollen, nor is collection of this substance by bees verified. Meliponine-visited orchids had pollinia in quartets with emplacement on the bee's scutellum, possibly devices for pollinia survival on a social bee passing through its nest. Further, orchids produced no nectar, but bees repeatedly came to flowers. A testable basis for the orchid-meliponine relationship is mimicry of rewarding resources, or bee pheromone mimicry, recently documented for some honey bees. Meliponine pheromone analogs (nerol and 2-heptanol) are here noted forMaxillaria, but lack of foraging with pheromones byMelipona suggests multiple avenues of mimicry by orchids, including alarm pheromone and carrion mimicry.     

The ecology and social behaviour of the Neotropical butterfly Heliconius xanthocles Bates in Colombia

The mimicry, population ecology¹, adult behaviour and life cycle of Heliconius xanthocles were studied at two sites in Colombian tropical forest. The results were compared with the known biology of other Heliconius species. H. xanthocles is probably unpalatable and is a Mullerian comimic of some other species. In the Amazon basin H. xanthocles belongs to the 'dennis ray' mimicry ring of the Heliconiini, which includes Eueides tales, H. bumeyi, H. elevatus, H. melpomene and H. erato. In the Rio Negro valley, where the latter species either do not exist or have different mimetic allegiances, the 'clennis-ray' pattern of H. xanthocles breaks down. The adults are pollen-feeders, like other Heliconius. but they also visit other food sources such as bird droppings. During a mark-recapture programme in the Rio Negro, adults were found to be almost entirely restricted to small areas near their foodplant Passiflorapraeacuta. Females were rarer than males, but this was probably due to a behavioural difference between the sexes. The males had a Fisher-Ford survival rate of 0.95 per day and a life expectancy of 19 days. Population size estimates of males were between 11 and 17 individuals. These estimates are lower than, but comparable to those for other Heliconius. Males as well as females visit the larval toodplant, and an adult male was observed hovering over a small group of larvae. The females lav batches of 12–41 eggs. The largest batch (41 eggs) was laid cooperatively by two females. The larvae are gregarious feeders on shoot-tips of Passiflora praeacuta. and all lile stages are described for the first time. Predation on the larvae by a bug is described. The pupa has a distinctive morphology unlike that of other Heliconius. The adult population ecology, mimicry and larval behaviour are discussed.