Food-plant effects on larval performance do not translate into differences in fitness between populations of Panolis flammea (Lepidoptera: Noctuidae)

In the UK, Panolis flammea (Denis & Schiffermüller) is a pest of monocultures of non-native lodgepole pine Pinus contorta Douglas, but not of the indigenous host Scots pine P. sylvestrisL. This difference in population dynamics may be due to the adaptation of P. flammea populations to the phenology, chemical composition and natural enemy complement of lodgepole pine. To ascertain if there was local adaptation of P. flammea populations to lodgepole pine, this study tested for improved performance of both larvae and adults on the host plant species from which they were sourced, compared with their performance on the alternative host plant species. No difference was found in the relative mean performance of populations sourced from Scots pine or lodgepole pine plantations, when fed on Scots or lodgepole pine foliage. Larvae grew faster on Scots pine but this difference did not translate into differences in pupal weight, female body weight or fecundity. Indeed, those insects that had fed on lodgepole pine had a longer lifespan than those that had fed on Scots pine, which, if translated into greater probability of mating or higher fecundity, could contribute to the observed outbreak dynamics in the field. The prediction that the observed outbreak dynamics of P. flammea can be explained by the existence of populations locally adapted to lodgepole pine was not supported. These results cast doubt on the use of larval growth parameters as surrogates of fitness in Lepidoptera.     

One MADS-box gene does not a flower make

Tandre, K., Svenson, M., Svensson, M.E. and Engström, P. (1998) Conservation of gene structure and activity in the regulation of reproductive organ development of conifers and angiosperms, Plant J. 15, 615–623Rutledge, R., Regan, S., Nicolas, O., Fobert, P., Côté, C., Bosnich, W., Kauffeldt, C., Sunohara, G., Séguin, A. and Stewart, D. (1998) Characterization of an AGAMOUS homologue from the conifer black spruce (Picea mariana) that produces floral homeotic conversions when expressed in Arabidopsis, Plant J. 15, 625–634     

Ovipositional preference ofSiphoninus phillyreae and its fitness on seven host plant species

The relationship between ovipositional preference ofSiphoninus phillyreae (Haliday) (Homoptera: Aleyrodidae) and host plant suitability on seven host plant species (Citrus sinensis (L.) cv. ‘Washington’ [navel orange],Fraxinus uhdei (Wenz.) [shamel ash],Heteromeles arbutifolia Roemer [toyon],Malus domestica Mill. cv. ‘Granny Smith’, [apple],Pistacia vera L. cv. ‘Kerman’ [pistachio],Prunus persica (L.) cv. ‘O’Henry’ [peach], andPyrus communis L. cv. ‘Bartlett’ [pear]) was evaluated. Ovipositional preference ofS. phillyreae was determined by measuring egg density after adult female whitefies were given a simultaneous choice of all host plants for oviposition. Immature survival, developmental time, and adult size were examined to determine host plant suitability forS. phillyreae. All studies were performed under greenhouse conditions.S. phillyreae showed distinct ovipositional preference among host plant species. Host plant species had a significant effect on immature survival, but little or no effect on developmental time or forewing length. For four of the seven host plant species tested, there was an association between ovipositional preference and survival.     

Butterflies show flower colour preferences but not constancy in foraging at four plant species

1. The extent to which flower colour and other visual cues influence butterfly flower choice in the field is poorly understood, especially in comparison with choices by Hymenoptera. 2. Using a novel approach to studies of visitation behaviour by butterflies, flower colour of four Asteraceae species was phenotypically manipulated to decouple the influence of that trait from others (including morphology and nectar rewards) on visitation by Lycaena heteronea, Speyeria mormonia, Cercyonis oetus, and Phyciodes campestris. 3. Flower visits were recorded to experimental flower arrays in subalpine meadows to measure (i) spontaneous preference by butterflies for particular colours and other traits and (ii) flower constancy (longer than expected strings of visits made to flowers of the same species), a behaviour that can reduce interspecific gene flow in plants. 4. Over three field seasons, 3558 individual flower visits in 1386 foraging bouts were observed for free‐flying butterflies. All four butterfly species responded to the phenotypic manipulations of flower colour, although in different ways. Speyeria mormonia and L. heteronea also exhibited preferences based on other flower traits. Lycaena heteronea responded to combinations of traits such that the other traits it preferred depended upon the context of flower colour. 5. None of the butterfly species exhibited flower constancy in any of the arrays employed. 6. The observed preferences show that butterflies, like some other pollinators, are potentially capable of exerting selection on colour and other floral traits. Moreover, these flower preferences can depend on the context of other flower traits. The absence of constancy contrasts with reports of high constancy in many bees.     

Removal of a specialization-associated symbiont does not affect aphid fitness

Symbioses are ubiquitous in nature. However, these interactions, in particular those which are facultative from the perspective of the host, are still poorly understood. One major question is whether facultative symbionts affect host fitness, and in particular whether they can benefit the host. In pea aphid, host plant specialization was found to be associated with the presence of Pea Aphid U‐type Symbiont [Proc. R. Soc. Lond. B 270 (2003) S209]. Host and symbiont genomes are normally co‐transmitted, making it difficult to determine which is responsible for causing this variation in fitness. Here antibiotic treatment is used to selectively remove the symbiont, thus partitioning symbiont and host genomes. I find that PAUS is not responsible for causing host plant specialization. Examination of aphids in which PAUS presence has been naturally manipulated also supports this conclusion. Additional work will be necessary to determine the forces maintaining this symbiont in host populations, and whether it benefits the host insect under different conditions.     

Spiny east Mediterranean plant species flower later and in a drier season than non-spiny species

We compared the flowering phenology of spiny and non-spiny native species belonging to three families (Asteraceae, Fabaceae and Lamiaceae), which include the highest number of spiny species in the flora of Israel. We found that the peak of flowering (when the highest number of species flowered) was 4–8 weeks later for spiny species than for non-spiny species. The flowering peak of non-spiny species was in late March, while that of spiny species was at the beginning of May. The seasonal shift in flowering time from the main season, when most Mediterranean plants bloom, to the end of the flowering season, when fewer species bloom, might be the evolutionary result of a change in phenology reducing the competition for pollinators. Our results clearly indicate that spinescence of plants in the semi-arid east Mediterranean region is associated with a delayed flowering season at the beginning of the dry summer when most of the herbaceous vegetation is already dry. During this season, mammalian grazers consume any edible herbaceous vegetation, selecting for late flowering species that allocate more resources for anti-herbivore defenses than early flowering species. There is a well-known global geographical trend where the occurrence of spiny plants is higher in arid regions than in humid ones. In parallel to the global trend, we show a seasonal one, that non-spiny plants grow and flower in the spring, which is the main flowering season in the Mediterranean basin, while spiny plants flower later, in the hot and dry summer. Under the current trend of global warming, there are prospects of future increase in the dominance of spiny species in the Mediterranean region.     

Pollen consumption by flower mites in three hummingbird-pollinated plant species

Laboratory studies suggest that pollen consumption by flower mites may decrease the male fitness of the plant by reducing the available pollen for dispersal. Here we assessed pollen consumption by flower mites under natural conditions in three plant species with long-lived, protandrous flowers, Moussonia deppeana (Gesneriaceae), Lobelia laxiflora and L. cardinalis (Lobeliaceae). Total pollen mass was measured after 24 and 48 h in flowers exposed to flower mites and excluded from hummingbirds, flowers exposed to mites and hummingbird visitation, and in flowers recently opened with dehisced anthers. Compared with recently opened flowers, pollen availability was reduced about half in the presence of flower mites and the same effect was observed in the three plant species. Our results suggest that flower mites are removing a great deal of pollen and the reduction of pollen implies the possibility of direct impact on pollen transfer.     

Early activation does not translate into effector differentiation of peripheral CD8T cells during the acute phase of Kawasaki disease

Early diagnosis of acute Kawasaki disease (KD), lying in the spectrum between infectious and autoimmune diseases, can be difficult. To clarify the role of peripheral CD8T cells in KD, we examined their activation, proliferation, maturation, and effector function by four-color flow cytometry. Compared to healthy/febrile controls, acute KD patients showed striking increase in early activation marker CD69⁺CD8T cells and maturation subsets, but HLA-DR⁺CD8T cells representing late activation did not increase. Although Ki67⁺CD8T cells reflecting ongoing cell division increased in acute KD and febrile controls, absolute numbers of CD8T cells and maturation subsets decreased in acute KD versus healthy controls. Effector cells were lower in acute than in convalescent KD. Perforin⁺CD8T cells, denoting cytolytic activity, were lower in KD patients versus febrile controls. CD69⁺CD8T cells increase in acute KD but effector differentiation is absent. CD69⁺CD8T cells could be a marker to determine disease progression, treatment response, and convalescence in acute KD.     

Preimaginal conditioning does not affect oviposition preference in the diamondback moth

Abstract.  1. In holometabolous insects, learning has been demonstrated in both larval and adult stages. Whether learning can be retained through metamorphosis from larva via pupa to adult has long been a subject of debate. The present study is designed to distinguish between preimaginal and imaginal conditioning in the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) using oviposition preference tests on females exposed to various types of learning experiences during immature and adult stages.
2. Cohorts of test insects were reared from egg to pupa on an artificial diet, or on one of two host plants, Chinese cabbage, Brassica campestris L. ssp. pekinensis , and common cabbage, Brassica oleracea L. var. capitata . The ensuing females reared on the three kinds of food showed similar oviposition preference between the two plants. A brief experience of the less preferred host, common cabbage, by adults slightly increased their preference for this plant.
3. Cohorts of test insects were reared from egg to pupa on an artificial diet with or without the addition of a neem-based oviposition deterrent (Neemix^® 4.5). Larval feeding experience did not alter oviposition response to the deterrent. However, emergence conditioning and early adult learning, achieved through experience of a residue of the deterrent carried over from the larval food on pupal cuticle and cocoons, altered oviposition preference significantly.
4. The combined results revealed no evidence of preimaginal conditioning in this insect but a strong effect of emergence conditioning and early adult learning on oviposition preference.     

Morph-dependent resource acquisition and fitness in a polymorphic bird

Understanding genetic colour polymorphism has proved a major challenge, both in terms of the underlying genetic mechanisms and the evolutionarily forces maintaining such genetic variation. In this context, genetic differences in aggression or competitive-related traits may covary with the expression of alternative phenotypes, and affect the evolutionary stability and maintenance of colour polymorphisms. Genetic red and black head-colour morphs of the Gouldian finch (Erythrura gouldiae) co-occur in temporally and geographically stable frequencies in sympatric populations. Gouldian finches are obligate cavity-nesters with highly specific preferences for nest-site morphometry that directly affect reproductive success. Because intra- and interspecific competition for high quality nest-sites is prevalent, and fitness is directly related to nest-site quality, we investigated the relative access (and consequences for reproductive success) of alternative morphs to this critical limiting resource in the wild. Red males defended higher quality nest-sites, and overcame greater levels of nest-site competition against conspecifics and superior heterospecific competitors than black males. Red-headed males also produced more fledglings (especially with red-headed females) than black-headed males, independent of nest-site quality. Finally, the independent (positive) effect of nest-site quality on reproductive success was confirmed. Such competitive asymmetries are important to relative selection among coexisting morphs, and are likely to contribute to the maintenance of alternative sympatric colour-morphs in wild populations.     

Glycosylation of procathepsin L does not account for species molecular-mass differences and is not required for proteolytic activity.

Cathepsin L is a major lysosomal cysteine proteinase in mouse and human cells. Despite similar predicted molecular masses, procathepsin L in these two species migrates on SDS/polyacrylamide gels with apparent molecular masses of 39 kDa and 42 kDa respectively. To determine if glycosylation differences account for this discrepancy, and to ascertain whether glycosylation is essential for enzymic activity, mouse and human procathepsins L were expressed at high concentrations in mouse NIH 3T3 cells or in human A431 cells after DNA-mediated transfection of cloned DNAs for these enzymes. In pulse-chase studies, human procathepsin L transfectants synthesized and secreted large amounts of enzymically active 42 kDa proenzyme and processed it into 34 kDa and 26 kDa intracellular peptides, a pattern of secretion and processing similar to that seen with endogenous or transfected mouse procathepsin L. Both translation of cloned procathepsin L cDNAs in vitro and Endoglycosidase H treatment of 39 kDa mouse and 42 kDa human procathepsin L resulted in non-glycosylated proteins 2 kDa lower in molecular mass than the untreated proteins for both species. This suggests that glycosylation differences are not responsible for the molecular-mass disparity between the two species. Moreover, Endoglycosidase H-treated mouse enzyme retained full proteolytic activity, indicating that glycosylation of cathepsin L is not essential for enzymic function.     

Consequences of nectar robbing for the fitness of a threatened plant species

The effect of nectar robbing on plant fitness is poorly understood and restricted to a few plant species. Furthermore, the available studies generally evaluate the effects of nectar robbing on female fitness, disregarding the male component. Here we measured the effects of the nectar-robbing bumblebees on male (measured as pollen analogue flow distance) and female (measured as seed production) reproductive success in the insect-dependent Polygala vayredae, a narrow endemic species from the pre-Pyrenees (Spain). Intense nectar robbing by bumblebees significantly reduced the nectar available to legitimate pollinators in the studied population, and this reduction affected both male and female fitness. Significant differences were observed in fluorescent dye dispersion between robbed and non-robbed flowers within the population. Fluorescent dyes from non-robbed flowers were dispersed to larger distances and over a larger number of flowers when compared with robbed ones. Moreover, significant differences were observed in both fruit set and seed ovule ratios between the two groups, with non-robbed flowers presenting higher reproductive outcomes. However, no effect on seed weight was detected among treatments. The data obtained suggest that in this species, nectar robbing has important indirect and negative effects on plant fecundity, through both male and female functions, due to a modification in the foraging behaviour of legitimate visitors.     

Flowering phenology and female fitness: impact of a pre-dispersal seed predator on a sexually polymorphic species

In order to produce seeds, animal-pollinated plants must flower synchronously with and be attractive to their pollinators while avoiding antagonists. Here, we explore temporal and inter-individual patterns in pollination and pre-dispersal seed predation of Dianthus sylvestris by Hadena moths, within and among three sex morphs. We scored plants that started flowering at different periods in 2001 and 2003 and found that fruit set decreased and predation rates increased over one season, and most of the other season, granting a female reproductive advantage to early flowering plants, though, we found no morph-specific temporal patterns. Female plants set more fruits, and more of their fruits escaped predation in one year, but this did not grant them a reproductive advantage since they produce fewer flowers per plant than the other morphs. Instead, mixed plants showed a clear female reproductive advantage. We also examined predation types by Hadena and seed production in attacked and intact fruits of individually marked flowers. Though female Hadena moths laid eggs preferentially into perfect flowers, flower sexes suffered similar predation by itinerant caterpillars. Attacked fruits contained fewer and lighter seeds than un-attacked ones. We conclude that pre-dispersal seed predation by Hadena may select on flowering onset of this sexually polymorphic species.     

Inter-species variation in unpalatability does not explain polymorphism in a mimetic species

Conspicuous colouration in unpalatable organisms acts as a warning signal of their unprofitability, a phenomenon known as aposematism. The protection conferred by such colouration can lead to evolutionary convergence in warning signals between aposematic species, because sharing warning signals reduces the per capita cost of predator learning. Consequently, most aposematic species display a single colour pattern and participate in a single mimetic community (i.e. mimicry ring) at any given locality. However, some, like the Amazonian butterfly Heliconius numata, are polymorphic and participate in several mimicry rings within the same locality. We tested whether the unexpected polymorphism of H. numata could be due to a weak defence against predators. Poorly defended species participating in a mimicry ring are subject to negative frequency dependent selection, because their presence weakens the protection provided by the shared signal. This could promote polymorphism and participation in multiple mimicry rings. Using wild caught great tits (Parus major), we compared the palatability of H. numata to one of its locally monomorphic co-mimics (Mechanitis polymnia) and to two other locally monomorphic Heliconius species (H. melpomene and H. erato). The tested birds strongly rejected the polymorphic species H. numata, as well as the two other Heliconius species. Unexpectedly, a significantly weaker rejection was found towards M. polymnia, which relies on different toxic compounds to Heliconius. Our study demonstrates that the origin of polymorphic mimicry in H. numata is unlikely to stem from low unpalatability and raises new questions on defence variation within mimetic communities.     

Differences in evolutionary history translate into differences in invasion success of alien mammals in South Africa

Attempts to investigate the drivers of invasion success are generally limited to the biological and evolutionary traits distinguishing native from introduced species. Although alien species introduced to the same recipient environment differ in their invasion intensity – for example, some are “strong invaders”; others are “weak invaders” – the factors underlying the variation in invasion success within alien communities are little explored. In this study, we ask what drives the variation in invasion success of alien mammals in South Africa. First, we tested for taxonomic and phylogenetic signal in invasion intensity. Second, we reconstructed predictive models of the variation in invasion intensity among alien mammals using the generalized linear mixed‐effects models. We found that the family Bovidae and the order Artiodactyla contained more “strong invaders” than expected by chance, and that such taxonomic signal did not translate into phylogenetic selectivity. In addition, our study indicates that latitude, gestation length, social group size, and human population density are only marginal determinant of the variation in invasion success. However, we found that evolutionary distinctiveness – a parameter characterising the uniqueness of each alien species – is the most important predictive variable. Our results indicate that the invasive behavior of alien mammals may have been “fingerprinted” in their evolutionary past, and that evolutionary history might capture beyond ecological, biological and life‐history traits usually prioritized in predictive modeling of invasion success. These findings have applicability to the management of alien mammals in South Africa.     

Experimental mood manipulation does not induce change in preference for natural landscapes

According to evolutionary theory, emotions are psychological mechanisms that have evolved to enhance fitness in specific situations by motivating appropriate (adaptive) behavior. Taking this perspective, a previous study examined the relationship between mood and preference for natural environments. It reported that participants’ anxiety level was associated with a preference for landscapes offering what Appleton called "refuge," while participants’ anger and cheerfulness were both associated with a preference for landscapes offering what Appleton called "prospect." We attempted to replicate these results and to improve on the study by experimentally manipulating mood. Using a between-subjects design, 80 participants were instructed to self-induce one of four moods: anger, sadness, anxiety, or joy. After the mood induction, they viewed fourteen landscape photographs and recorded the seven most preferred. It was hypothesized that subjects experiencing anger or joy would prefer landscapes rich in "prospect" features, whereas participants experiencing sadness or anxiety would prefer landscapes rich in "refuge" features. In contrast to the previous study, the predictions were not supported: artificially induced moods may not provide ecological validity as a test of the "mood as motivator" model; alternatively, the first study may have reported an alpha error. To see whether the model has practical value, we recommend a study of landscape preference using participants with clinically significant levels of mood dysphoria. Bernadette Klopp received her B.A. (Honours) in Psychology from the University of Queensland. Her areas of research interest focus on environment and aesthetics, environmental psychology, and the evolution of art as a form of social communication. Bernadette is currently employed by the Commonwealth Rehabilitation Service of Queensland, but she hopes to pursue further graduate study. Linda Mealey, Ph.D., is just finishing a three-year stint as Senior Lecturer at the School of Psychology, University of Queensland, before returning to her Associate Professor position at the College of St. Benedict in central Minnesota. She is Vice-President/President-Elect of the International Society for Human Ethology, a Councilor of the Human Behavior and Evolution Society, and a member of the editorial board of Politics and the Life Sciences.     

Background matching behaviour and pathogen acquisition: plant site preference does not predict the bacterial acquisition efficiency of vectors

Many insect-borne pathogens are heterogeneously distributed within their hosts: therefore, a vector’s within-plant distribution may be a predictor of its exposure to pathogens. In this study, we set out to quantify plant site preference, in the context of background matching, and investigated its effect on acquisition of a bacterial pathogen by its leafhopper vectors. The two green-coloured species, Graphocephala atropunctata and Draeculacephala minerva, preferred green plant tissue and artificial backgrounds whereas the brown-coloured Homalodisca vitripennis preferred brown stem tissue and backgrounds. Within-plant feeding site did not predict either the acquisition success or the number of plant-pathogenic Xylella fastidiosa cells acquired by the vectors; an 86% mortality for G. atropunctata was reported on the lignified stem tissue. Overall, H. vitripennis acquired significantly more cells than G. atropunctata. A novel artificial diet-based transmission system was used to further illustrate that the observed between-species difference in the number of cells acquired was independent of vector-host plant interactions. H. vitripennis, a less efficient vector of the bacterium X. fastidiosa on grapevines, acquired more bacterial cells than G. atropunctata, possibly due to its larger size. Contrary to previous assumptions, pathogen acquisition efficiency by the vectors did not explain their reported differences in inoculation. Vector interactions with the host during the inoculation stage should be evaluated as another determinant of X. fastidiosa transmission efficiency.