Absence of status signalling by structurally based ultraviolet plumage in wintering blue tits (<Emphasis Type="Italic">Cyanistes caeruleus</Emphasis>)

Structurally based ultraviolet (UV)-reflective plumage parts can be important cues in mate choice. However, it remains largely unknown if UV plumage variation can also function as a signal of social status during competitive interactions. In blue tits (Cyanistes caeruleus), the UV-reflective crown plumage functions as a female mate choice cue that probably indicates male quality, as males with higher UV reflectance have been shown to have better chances of over-winter survival. Possibly, the UV crown plumage acts as a status signal in the competition over scarce food sources during winter. To test this idea, we related dominance of individuals at an artificial food source during adverse winter conditions to spectrophotometric measurements of their crown plumage. However, while controlling for the confounding effects of sex, age, and distance from territory, we found no significant effect of crown UV reflectance on dominance. Consistent with this result, we also found no relation between crown UV reflectance and over-winter survival. We conclude that the structurally based UV reflectance of the blue tit crown feathers plays little role in competition between individuals during winter despite its importance as a cue in mate choice.     

Sexual selection in a socially monogamous bird: male color predicts paternity success in the mountain bluebird, <Emphasis Type="Italic">Sialia currucoides</Emphasis>

Ornamental traits are thought to evolve because they give individuals an advantage in securing multiple mates. Thus, the presence of ornamentation among males in many monogamous bird species presents something of a conundrum. Under certain conditions, extra-pair paternity can increase the variance in reproductive success among males, thus increasing the potential for sexual selection to act. We addressed this possibility in the mountain bluebird (Sialia currucoides), a socially monogamous songbird in which males possess brilliant ultraviolet (UV)-blue plumage. Specifically, we asked whether a male’s success at siring offspring within his own nest and within the nests of other males was related to his coloration. In pairwise comparisons, males that sired extra-pair offspring were not more colorful than the males that they cuckolded. However, males that sired at least one extra-pair offspring were, on average, brighter and more UV-blue than males that did not sire extra-pair offspring. Brighter, more UV-blue males sired more offspring both with their own mate and tended to sire more offspring with extra-pair mates and thus sired more offspring overall. Our results support the hypothesis that the brilliant UV-blue ornamental plumage of male mountain bluebirds evolved at least in part because it provides males with an advantage in fertilizing the eggs of multiple females.     

Rank-dependent hoarding effort in willow tits (<Emphasis Type="Italic">Parus montanus</Emphasis>): a test of theoretical predictions

Many birds and mammals store energy as hoarded food supplies. A supply of stored food is beneficial during periods when food is scarce, but building up and managing such a supply also entails costs. The optimal number of caches will be reached when the net benefit is at its maximum. If dominants can steal more stored food from subordinates than the other way around, the optimum will differ between these categories. A previous theoretical model of hoarding in groups with dominant and subordinate members produced three testable predictions: (1) hoarders should store more food as anticipated future conditions get worse; (2) subordinate flock members should store more food than dominants; and (3) dominants should increase hoarding relatively more than subordinates as conditions get worse. Here we present a field experiment on willow tits (Parus montanus) designed to test these predictions. We found support for all three. Hoarding increased as conditions got worse, subordinates stored at a higher rate than dominants, and dominants increased their hoarding effort relatively more than subordinates as conditions worsened. These results support the incorporation of information on dominance and food availability into models predicting food storage behaviour.Communciated by J. Dickinson     

Multiple feeding stimulants in <Emphasis Type="Italic">Sinapis alba</Emphasis> for the oligophagous leaf beetle <Emphasis Type="Italic">Phaedon cochleariae</Emphasis>

Summary. In earlier investigations on host plant discrimination of leaf beetles glucosinolates were described as feeding stimulants for the Brassicaceae specialist Phaedon cochleariae F. (Coleoptera: Chrysomelidae). However, since these findings could not be confirmed in later studies offering 2-propenylglucosinolate in concentrations corresponding to those detected in host plant leaf material, the identification of feeding stimulants of this leaf beetle species remained unclear. In order to investigate which compounds of the host plant Sinapis alba (Brassicaceae) are involved in feeding stimulation, leaf extracts of different polarities were tested in bioassays with adults of P. cochleariae. Number of feeding beetles and net consumption rates were highest on pea leaves painted with methanol extracts of S. alba, whereas weak feeding responses were also detectable for hexane extracts. In subsequent bioassay-guided fractionations of methanol extracts with semi-preparative high performance liquid chromatography, two distinct fractions, one containing glucosinolates and another containing flavonoids, were found to stimulate beetles to feed to variable degrees. Other collected fractions had zero activity. The combination of both active fractions evoked significantly higher consumption rates and stimulated more beetles to feed than fractions tested individually. At least one compound of each fraction, among these the main glucosinolate of S. alba, 4-hydroxybenzylglucosinolate, act additively. Effects of two different naturally-occurring ratios of glucosinolates and flavonoids on the strength of feeding responses were investigated by use of extracts of two sets of host plants differently exposed to radiation. One set was outdoors-exposed, whereas the second set was kept in the greenhouse. However, the feeding behaviour of P. cochleariae was not affected by the significantly different relative compositions of both compound classes in the host material. In conclusion, mustard leaf beetles need a combination of distinct plant metabolites acting in concert for feeding stimulation, whereby the mere presence of these stimulants, but probably not the ratio of involved compounds, determines their feeding response.     

Varying levels of female promiscuity in four <Emphasis Type="Italic">Apodemus</Emphasis> mice species

Sexual selection in most vertebrates is based on the evolution of fitness optimization strategies such as multiple-male mating (MMM). Several ecological correlates of MMM have been identified in bird and fish populations; however, only few studies have documented the effects of environmental change on promiscuity in mammals. In this study, the 127 pregnant females from four central European and ecologically diverse species of field mice (genus Apodemus) were studied to assess the role of ecological factors that may have shaped the evolution of particular mating systems. MMM was found in all analyzed species: in Apodemus uralensis and Apodemus flavicollis, up to two males could be identified as the fathers of a particular litter, while three males sired 9.1% of analyzed litters of Apodemus sylvaticus and 20.6% of Apodemus agrarius. Furthermore, there were obvious differences between species in relative testes size and the proportion of multiple sired litters during those seasons when the opportunity for multiple mating was high. The species with the smallest testes and the least promiscuous was A. uralensis (only 43.5% of multiple sired litters), while the species with the biggest testes and the most promiscuous was A. agrarius (69.2%). MMM was significantly associated with higher litter size in A. flavicollis, and the probability of MMM strongly increased with season in A. agrarius and with abundance in A. uralensis. These results indicate that ecological factors are associated with MMM rates in Apodemus field mice and more research is needed to fully understand the evolution of mating strategies at different levels of biological resolution.     

Paternity and performance of golden-winged warblers (<Emphasis Type="Italic">Vermivora chrysoptera</Emphasis>) and golden-winged X blue-winged warbler (<Emphasis Type="Italic">V. pinus</Emphasis>) hybrids at the leading edge of a hybrid zone

We examined two components of reproduction in a population of golden-winged warblers in the initial stages of hybridization with blue-winged warblers. First, we used genetic analyses of mate choice to determine whether copulations outside the social pairbond (extra-pair copulations; EPCs) occur in these species and their hybrids. Second, we compared several aspects of reproduction (pairing success, clutch size, hatching success, fledging success, and loss of paternity) in nests raised by phenotypic golden-winged warblers to those raised by hybrid individuals. Together, these data provide us with the first quantitative analysis of reproduction within this hybrid system. Our data suggest several reasons why the level of hybridization between these species is likely being underestimated. First, many birds in our population showed only subtle phenotypic signs of introgression indicating that hybrid status can only be determined by close examination. Second, high rates of extra-pair paternity indicate that we cannot base our estimates of hybridization on pairbond data alone. More than 30% of nestlings were the result of EPCs, occurring in 55% of all nests. Third, there was no difference in the number of hybrid or “pure” golden-winged warbler males chosen as social mates, relative to their abundance. Indeed, based on several components of nesting success, it appears as though hybrids are having as great realized reproductive success as are phenotypic golden-winged warblers in our population. Accordingly, we argue that hybrid reproductive success and extra-pair fertilizations are likely playing a major role in the ongoing hybridization between blue-winged and golden-winged warblers. Studies such as this one are important to our understanding of the process and implications of hybridization, and findings may be applicable to other hybrid zones.     

Leaf surface compounds of the potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis>) and their influence on Colorado potato beetle (<Emphasis Type="Italic">Leptinotarsa decemlineata</Emphasis>) feeding

Summary.  The sampling behavior of the Colorado potato beetle Leptinotarsa decemlineata Say (CPB) involves examination of the surface of potato leaves. It has been suggested that leaf surface compounds (volatiles and cuticular waxes) may be involved in host-plant recognition, acceptance or discrimination. Here we report on the effect of leaf surface extracts of six Polish commercial potato varieties on CPB feeding. We tested the influence of potato leaf surface extracts on CPB adult and larval feeding, then separated the extracts with HPLC, and finally tested the effect of the HPLC-separated fractions on CPB feeding. The bioassays were performed using potato leaf discs deprived of their original surface compounds. Applied to test discs at concentrations ten times higher than natural (10 leaf area equivalent), the extracts deterred CPB adults and larvae from feeding. HPLC-separated fractions composed of alkanes, sesquiterpene hydrocarbons, wax esters, benzoic acid esters, fatty acid methyl, ethyl, isopropyl and phenylethyl esters, aldehydes, ketones, methyl ketones, fatty acids, primary alcohols, β-amyrin and sterols did not affect adult CPB feeding. Similarly, alkanes, sesquiterpene hydrocarbons, wax esters, methyl ketones, sesquiterpene alcohols and secondary alcohols had no effect on larval CPB feeding. The sterol fraction (cholesterol, β-sitosterol and stigmasterol) acted as a phagostimulant to CPB larvae. We isolated a fraction demonstrating a phagodeterrent effect on CPB adults and larvae. The qualitative composition of the deterrent fraction was quite similar in all potato extracts, but there were quantitative differences between the varieties. Much further work is needed to identify the compounds that can produce the deterrent effect.     

Selected polyandry: female choice and inter-sexual conflict in a small nocturnal solitary primate (<Emphasis Type="Italic">Microcebus murinus</Emphasis>)

Sex-specific interests over the maximization of reproductive success lead to an inter-sexual conflict over the optimal mating system in a species. Traditionally, the outcome of this inter-sexual conflict has been studied from the male perspective but it also depends on female mating strategies, such as manipulating the temporal distribution of sexual activity, advertisement, and mate choice. We used a small nocturnal primate, the gray mouse lemur (Microcebus murinus) to determine the relative importance of female mating strategies on the outcome of this conflict in a species where females are solitary during their activity period. We studied their mating behavior over three consecutive annual mating seasons and determined the genetic relationships among more than 300 study animals to quantify individual reproductive success. We found that most females were receptive asynchronously. Females did not exhibit any obvious direct mate choice, probably due to a highly male-biased operational sex ratio and the corresponding costs of choosiness. However, females exercised indirect choice for multiple matings. They mated with 1–7 males up to 11 times during their single night of receptivity. As a result, mixed paternity was common but heavier males sired more offspring, meaning that indirect female choice for superior males cannot be excluded. Females exhibited a mixed mating strategy, avoiding costly direct mate choice but still counteracting male efforts to monopolize mating, successfully increasing genetic variability among offspring. Thus, females had a major influence on the outcome of the inter-sexual conflict despite male monopolization attempts.Communicated by J. Setchell     

Factors affecting vigilance within wild mixed-species troops of saddleback (<Emphasis Type="Italic">Saguinus fuscicollis</Emphasis>) and moustached tamarins (<Emphasis Type="Italic">S. mystax</Emphasis>)

We examine vigilance within a mixed-species troop of saddleback (Saguinus fuscicollis) and moustached (S. mystax) tamarins over a complete year. Saddleback tamarins were consistently more vigilant than moustached tamarins. This may be linked to their preference for lower strata. In accordance with previous studies of other primates, vigilant tamarins of both species were significantly further away from their nearest neighbours, and were also at lower heights in the forest than non-vigilant individuals. There was no observed sex difference in the amount of time spent vigilant. In terms of modes of scanning, the saddleback tamarins looked up significantly more frequently than the moustached tamarins, whereas there was no difference between the species in the frequency of side sweeps. There were no differences between the sexes in the frequencies of either type of vigilant behaviour. The proportion of time spent vigilant was higher than average immediately prior to entering a sleeping site for saddleback tamarins, but not for moustached tamarins. Both species were more vigilant immediately after exiting a sleeping site than at other times of the day. There was significant variation in the amount of time devoted to vigilance over the course of the year. These findings are discussed with respect to the social structure, ecology and main predator threats facing these species.Communicated by D. Watts     

Sex pheromone communication of tentiform leaf-miners <Emphasis Type="Italic">Phyllonorycter insignitella</Emphasis> and <Emphasis Type="Italic">Ph. nigrescentella</Emphasis> from two related species groups

Summary.  Females of both species start their pheromone-releasing activity on the second day after emergence at the beginning of the photophase. During the present work, a peak of calling activity with close to 100% of active Ph. nigrescentella females was registered 1.5 hour after the light had been put on. The high pheromone release behaviour with 50% active females lasted for 3 hours. The calling activity of the group of females was about 6 h/day. The beginning of a photophase under laboratory conditions or an early morning in nature is a common period for sex pheromone release in the genus Phyllonorycter. (8Z,10E)-tetradecadien-1-yl acetate (8Z,10E-14:Ac), (8Z,10E)-tetradecadien-1-ol (8Z,10E-14:OH) and (8E,10Z)-tetradecadien-1-yl acetate (8E,10Z-14:Ac) in the ratio 96:4:traces as well as 8Z,10E-14:Ac and 8Z,10E-14:OH in the ratio 88:12 collected by Solid Phase Micro Extraction (SPME) were found to be specific for the calling periods of virgin Phyllonorycter insignitella and Ph. nigrescentella females respectively. Field trapping experiments demonstrated that all three compounds are important for the attraction of Ph. insignitella males while only 8Z,10E-14:Ac is the essential sex pheromone component for Ph. nigrescentella. The pheromone activity of all three compounds is reported for the first time. Addition of either 8Z,10E-14:OH or 8E,10Z-14:Ac to 8Z,10E-14:Ac did not have a significant effect on the attraction of Ph. nigrescentella males, while the efficiency of the three component blend was 5 times lower as compared to that of 8Z,10E-14:Ac. Our data demonstrate that 8Z,10E-14:OH and 8E,10Z-14:Ac play a dual function, they are minor sex pheromone components of Ph. insignitella essential for attraction of conspecific males and show an allelochemical, antagonistic effect on Ph. nigrescentella males and, thus, ensuring specificity of the mate location signal in two related Phyllonorycter species.     

Antioxidant enzyme activities of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> in response to nonylphenols and degradation of nonylphenols by <Emphasis Type="Italic">M. aeruginosa</Emphasis>

The aim of this study was to examine the effects of chemical nonylphenols (NPs) on the antioxidant system of Microcystis aeruginosa strains. The degradation and sorption of NPs by M. aeruginosa were also evaluated. High concentrations of NPs (1 and 2 mg/l) were found to cause increases in superoxidase dismutase (SOD) and glutathione-S-transferase (GST) activities and in glutathione (GSH) levels. These results suggest that toxic stress manifested by elevated SOD and GST levels and GSH contents may be responsible for the toxicity of NPs to M. aeruginosa and that the algal cells could improve their antioxidant and detoxification ability through the enhancement of enzymatic and nonenzymatic prevention substances. The observed elevations in GSH levels and GST activities were relatively higher than those in SOD activities, indicating that GSH and GST contributed more in eliminating toxic effects than SOD. Low concentrations of NPs (0.05–0.2 mg/l) enhanced cell growth and decreased GST activity in algal cells of M. aeruginosa, suggesting that NPs may have acted as a protecting factor, such as an antioxidant. The larger portion of the NPs (>60%) disappeared after 12 days of incubation, indicating the strong ability of M. aeruginosa to degrade the moderate persistent NP compounds. The sorption ratio of M. aeruginosa after a 12-day exposure to low nominal concentrations of NPs (0.02–0.5 mg/l) was relatively high (>30%). The fact that M. aeruginosa effectively resisted the toxic effects of NPs and strongly degraded these pollutants indicate that M. aeruginosa cells have a strong ability to adapt to variations in environmental conditions and that low and moderate concentrations of organic compounds may favor its survival. Further studies are needed to provide detailed information on the fate of persistent organic pollutants and the survival of algae and to determine the possible role of organic pollutants in the occurrence of water blooms in eutrophic lakes.     

Correlates of boldness in three-spined sticklebacks (<Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>)

Behavioural variation is known to occur between individuals of the same population competing for resources. Individuals also vary with respect to their boldness or shyness. An individuals position along the shy-bold axis may be defined as the extent to which it is willing to trade off potentially increased predation risks for possible gains in resources. Similarly, group living may be interpreted as a trade-off between anti-predatory tactics and foraging efficiency. The responses of three-spined sticklebacks (Gasterosteus aculeatus) were tested across four social contexts to assess relative boldness or shyness and to further examine whether their behaviour would be consistent within and between contexts. Individuals displayed consistent responses within and between the first two contexts: those individuals which resumed foraging rapidly after a simulated aerial predator attack also displayed low shoaling tendencies. Such fish were deemed to be bold, whilst those which displayed the converse behaviour, slow resumption of foraging and a high shoaling tendency, were deemed to be shy. In a third context, bold individuals out-competed shy conspecifics for food. Boldness was also positively correlated with growth over a 6-week period. The position adopted by an individual within a group is usually interpreted as a trade-off between predation risk and foraging efficiency—both are greater at the front of a mobile group. Bold individuals showed significantly stronger tendencies towards front positions than shy conspecifics. The results suggest that, contrary to some previous studies on other animals, bold or shy behaviour in sticklebacks is consistent between contexts.Communicated by T. Czeschlik     

Bearded vultures (<Emphasis Type="Italic">Gypaetus barbatus</Emphasis>) prefer fatty bones

In animal species, prey processing and the provisioning of nutrients are subject to several constraints related with finding, ingesting and processing food. In most bird species, these constraints are obvious as a consequence of food morphology. In the case of the bearded vulture (Gypaetus barbatus), in comparison with other species, its behavioural and physiological adaptations apparently allow this vulture to ingest bone remains irrespective of their morphology. Here, by comparing bones delivered to the nest to be consumed (selected) and remains found at an experimental feeding station and at bone-breaking sites or ossuaries (rejected), I tested whether bearded vultures are capable of choosing from among the various anatomical parts of an animal carcass in relation to their fatty acid content (nutrient concentration hypothesis), their size (width-reduction hypothesis) or both. The results suggest that bearded vultures prefer the fatty anatomical parts (with a high percentage of oleic acid) of an animal carcass regardless of bone length, although bone morphology as a consequence of handling efficiency or the ingestion process may also play a secondary role in food selection. The close association between the bones selected and their high fat value implies an optimisation of foraging time and of the increased energy gained from the food. This is in line with selective foraging to redress specific nutritional imbalances (nutrient concentration hypothesis) and, secondarily, the width-reduction hypothesis.     

Main nutrient compounds in food bodies of Mexican <Emphasis Type="Italic">Acacia</Emphasis> ant-plants

Summary. Myrmecophytic plants use obligate ant mutualists as a constitutive indirect defence mechanism. These plants often produce cellular food bodies (FBs) to nourish their resident ants. Lipids, proteins, and even highly specialised compounds such as glycogen have been reported from FBs, but detailed chemical analyses of FB composition have so far been presented only for Southeast Asian Macaranga and Central American Piper myrmecophytes. Here we report the chemical composition of FBs of five myrmecophytic Acacia (Fabaceae) species from Mexico using HPLC (carbohydrates and proteins) and GC-MS (lipids). Feeding experiments revealed no hints on any use of external food sources by the inhabiting Pseudomyrmex ants. These ants obviously rely completely on FBs and extrafloral nectar provided by their hosts. The total content of nutrients in Acacia FBs was 15-25% of FB dry mass, being much lower than in Macaranga or Piper FBs. Proteins were dominating (8-14 % dm) in Acacia FBs and thus were present in higher amounts than in Macaranga FBs, yet in lower amounts than in Piper. Lipids contributed 1-9 % of dry mass, showing a lower proportion than in FBs of Macaranga or Piper. Carbohydrates made up 3-11 % dm, reaching in most Acacia species the same range as observed in Macaranga and in Piper FBs. Water content was 18-24 % of FB fresh mass, and structural tissue obviously made up a much higher proportion in Acacia FBs than in Macaranga or Piper FBs. Both characters might represent an adaptation to producing FBs unprotected at the leaf tips under dry conditions. Acacia FBs contain all amino acids and all fatty acids that are considered essential for insects, and their contents of lipids and proteins are higher than in the leaves from which they are ontogenetically derived. This indicates a putatively adaptive enrichment of nutritionally valuable compounds in structures functioning as ant-food.     

New repellent semiochemicals for three species of <Emphasis Type="Italic">Dendroctonus</Emphasis> (Coleoptera: Scolytidae)

Summary. Nine compounds identified from captured volatiles of the Douglas-fir beetle, Dendroctonus pseudotsugae, the mountain pine beetle, D. ponderosae, and the spruce beetle, D. rufipennis, that elicited antennal responses in males and females of one or more of these species were tested in the field to determine behavioural activity. 1-Octen-3-ol, found in the volatiles of females of all three species decreased the response of male and female coastal and male interior D. pseudotsugae and both sexes of D. ponderosae to their aggregation pheromones. Acetophenone, identified in the volatiles of females of all three species, significantly decreased the response of interior female D. pseudotsugae. trans-Verbenol, a potent aggregation pheromone of D. ponderosae, decreased the response of both sexes of D. pseudotsugae, while 3-methyl-2-cyclohexen-1- one (MCH), the antiaggregation pheromone of D. pseudotsugae and D. rufipennis decreased the response of both sexes of D. ponderosae. While it has been demonstrated that semiochemical mediated interspecific communication occurs among bark beetles infesting the same host, this study demonstrates that beetles can perceive signals emitted by heterospecifics attacking nonhosts and can potentially use them to avoid attacking the wrong species of conifer.     

Extra-pair paternity and the evolution of testis size in a behaviorally monogamous tropical mammal,the large treeshrew (<Emphasis Type="Italic">Tupaia tana</Emphasis>)

Monogamy is rare in mammals (<5% spp.) but occurs in greater frequency among primates (15%) and their close relatives, the treeshrews (100%; Order: Scandentia). Two genetic studies of parentage in monogamous primates revealed high rates of extra-pair paternity (EPP), but to date parentage has not been studied in a treeshrew species. I analyzed the genetic parentage of 22 offspring from two populations of large treeshrews in Sabah, Malaysia (NE Borneo), using seven autosomal microsatellite loci and one mitochondrial DNA marker. Half of these offspring were sired by males that were not the presumed partner of the mother (50% EPP), and three litters exhibited evidence of multiple paternity. However, comparative analysis indicated that the high rate of EPP in Tupaia tana is not associated with intense sperm competition. Relative testis size of treeshrews was similar to testis size in 22 primate species with uni-male mating systems but smaller than 44 primates with multi-male mating systems. After factoring out the effects of body size and phylogeny, I also found that the evolution of multi-male mating systems was significantly associated with the evolution of larger testis size. Male–female pairs of T. tana occupy joint territories but forage and sleep alone (“dispersed pair-living”), and I argue that this form of behavioral monogamy renders mate guarding ineffective. The adaptive advantages of behavioral monogamy likely differ from the advantages driving EPP in large treeshrews. However, small testis size suggests that behavioral monogamy is not masking a dispersed multi-male mating system in this species.     

A dynamic trait affects continuous pair assessment in the blue-footed booby,<Emphasis Type="Italic"> Sula nebouxii</Emphasis>

Bright colours of male birds have often been shown to be the target of sexual selection through female choice, yet few studies have looked at the role of colour expressed after pairing on female motivation and behaviour. Here we analyse the role of an integumentary colour in the spectral range of 400–700 nm, the foot colour in male blue-footed boobies, Sula nebouxii, which is prominently displayed during pair courtship. Measurements early in the breeding season showed that foot colour of courting males is pale (high values of brightness) and has an aqua-blue chroma, and females in better body condition were mated to males with brighter feet. We carried out an experimental manipulation which modified the foot colour of males in courtship, making it closer to the foot colour of males in low nutritional state. We found that females paired to experimental males courted less and were less likely to copulate than females in the control group. Male behaviour was apparently unaffected by the manipulation; thus the change in female behaviour can be attributed exclusively to foot colour manipulation. These results strongly support the hypothesis of female preference for an integumentary colour and suggest that this dynamic trait is used as a male ornament after pairing.Communicated by J. Graves     

(<Emphasis Type="Italic">Z,Z</Emphasis>)-11,13-Hexadecadienyl acetate and (<Emphasis Type="Italic">Z,E</Emphasis>)-11,13,15-hexadecatrienyl acetate: synergistic sex pheromone components of oak processionary moth,Thaumetopoea processionea (Lepidoptera: Thaumetopoeidae)

Summary. Our objective was to identify sex pheromone components of the oak processionary moth, Thaumetopoea processionea (Lepidoptera: Thaumetopoeidae), whose larvae defoliate oak, Quercus spp., forests in Eurasia and impact human health. Coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric (MS) analyses of pheromone gland extract of female T. processionea revealed two consistently EAD-active compounds. They were identified as (Z,Z)-11,13-hexadecadienyl acetate (Z11,Z13-16:OAc) and (Z,E)-11,13,15-hexadecatrienyl acetate (Z11,E13,15-16:OAc) by comparative GC, GC-MS and GC-EAD analyses of insect-produced compounds and authentic standards. In replicated field experiments (2000, 2001) in Nordbaden, Südbaden and Sachsen-Anhalt (Germany), Z11,Z13-16:OAc and Z11,E13,15-16:OAc in combination, but not singly, attracted significant numbers of male moths. It will now be intriguing to investigate whether Z11,E13,15-16:OAc, or its corresponding alcohol or aldehyde, serves as a pheromone component also in other species of the Thaumetopoeidae.     

Brood sex ratio adjustment in collared flycatchers (<Emphasis Type="Italic">Ficedula albicollis</Emphasis>): results differ between populations

Recently, a number of studies have found adaptive brood sex ratio (BSR) manipulation in birds. The reason for such manipulations is thought to be the different reproductive value of male and female nestlings. Several studies have found that parental quality and food supply can affect BSR, however results are sometimes inconsistent between species and populations. We investigated BSR patterns in a Hungarian population of Collared Flycatchers (Ficedula albicollis) and compared the results with those obtained in a previous study of the same species in Sweden. We found two significant differences. First, the male forehead patch size, a heritable, sexually selected trait, affected the brood sex ratio in the Swedish population, but not in our Hungarian study population. This difference might be a consequence of the different information content of the forehead patch size in the two populations. Second, a seasonal shift in BSR (more sons late in the season) was observed in the Hungarian, but not in the Swedish population.Communicated by J. Graves     

Extremely high mating frequency in the Florida harvester ant (<Emphasis Type="Italic">Pogonomyrmex badius</Emphasis>)

High effective multiple queen mating is a rare but taxonomically widespread phenomenon in eusocial Hymenoptera that has arisen convergently in several taxa. In ants, high effective mating frequencies have been confirmed in only two clades: the higher leaf-cutters (Atta, Acromyrmex) and the Pogonomyrmex seed harvesters. We analysed polyandry in Pogonomyrmex badius, which has a life-history unique within the genus, and report the highest numerical mating frequencies thus far recorded in ants. We also show that P. badius is characterized by one of the highest effective mating frequencies hitherto found in ants. It is now clear that all major sub-clades of Pogonomyrmex sensu stricto exhibit high levels of polyandry. Therefore, multiple mating must have arisen early in the evolution of the genus, and may have constituted a mechanism to increase offspring variability for queens that were confronted with increasingly complex levels of organization. Too few congeners have been investigated by the same method to be certain that polyandry in P. badius is really higher than in the rest of the genus. If so, research should concentrate on a possible link between high queen mating frequency and the distinct caste system found in P. badius.Communicated by L. Keller