Priority effects on the life‐history traits of two carrion blow fly (Diptera,Calliphoridae) species

1. Third instars of the invasive blow fly Chrysomya rufifacies are facultative predators on larvae of the native blow fly Cochliomyia macellaria. 2. The effects of priority arrival time on the survivorship and fitness of C. rufifacies and C. macellaria were investigated in laboratory experiments. 3. Cochliomyia macellaria colonising a resource within 1–2 days after C. rufifacies resulted in a 20–70% reduction in survivorship, pupal weight and fecundity compared with those colonising a resource more than 2 days before or after C. rufifacies. Inversely, C. rufifacies exhibited a 50% increase in survivorship and fecundity when closely (～2 days) associated temporally on the resource with C. macellaria and was negatively affected by disparate arrival. 4. These results demonstrate that arrival sequence significantly affects the fitness of both C. rufifacies and C. macellaria. Early colonisation may allow C. macellaria to persist in a community, while there are fitness benefits for C. rufifacies colonising after C. macellaria. 5. The 60% reduction in C. macellaria survivorship when in close temporal association with C. rufifacies may act as an agent of selection for C. macellaria to colonise a resource early and develop quickly to avoid predation on resources colonised by C. rufifacies. 6. Selection for such traits may explain how C. macellaria is able to persist despite intraguild predation by this invasive species. In contrast, the 50% increase in survivorship and fecundity exhibited by C. rufifacies when arriving after C. macellaria may select for C. rufifacies to delay colonisation.     

Reward partitioning in Capparis spp. along ecological gradient

Summary The genus Capparis is represented in Israel by three taxons of the section spinosa. The pollinators of the three taxa are hawkmoths, crepuscular bees of the genus Proxylocopa and various daily bees. However, the efficiency of the different pollinators is very varied with respect to the individual taxons. Hawkmoths were frequently observed as pollinators of C. spinosa var. aravensis and C. ovata, but rarely on C. spinosa var. aegyptia. All the other bees, on the other hand, were found abundantly on all three taxons, all over the country. The three taxa all provide different rewards for their particular pollinators. Bees visiting C. spinosa var. aegyptia are provided with a lot of pollen but a relatively small amount of nectar, with a low sugar content. C. spinosa var. aravensis and C. ovata (the flowers visited more by hawkmoths), have less pollen but a higher amount of nectar which has a higher concentration of sugar. In drier habitats the emphasis of the reward provided by the flowers is nectar, whilst in the Mediterranean habitats it is the pollen which is the reward, without any connection to the systematic origin of the plant.     

Chromosomal diversification of reef fishes from genus <Emphasis Type="Italic">Centropyge</Emphasis>(Perciformes,Pomacanthidae)

The genus Centropyge is remarkable for species richness, composing a highly specialized fish group amongst members from family Pomacanthidae. However, cytogenetical reports are nearly absent in these animals. New data are provided from karyotypical studies carried out on Centropyge aurantonotus from the Brazilian coast of the Atlantic Ocean and C. ferrugatus from the Philippines Sea of the Indo-Pacific Ocean. Both species present 2n=48 but karyotypes are differentiated by fundamental number. C. aurantonotus has a great number of biarmed chromosomes (4 m + 14 sm+16 st+4 a), while C. ferrugatus presents only acrocentric chromosomes. Single nucleolar organizer regions (NORs) are located at interstitial position of an acrocentric pair in C. ferrugatus and on short arms of a subtelocentric pair in C. aurantonotus, as confirmed by fluorescent in situ hybridization (FISH) with 18S rDNA probes. Heterochromatin is distributed over NOR and centromeric regions in both species, but additional GC-rich heterochromatic blocks on short arms of up to eight chromosomal pairs can be detected in C. aurantonotus. 5S rDNA segments were located interstitially on two chromosomal pairs in C. ferrugatus and on nine pairs in C. aurantonotus, mostly equivalent to heterochromatic blocks on short arms of biarmed chromosomes. C. ferrugatus can be considered a species in which basal chromosomal features proposed for modern Teleosteans were conserved. The derived karyotype pattern of C. aurantonotus seems to be determined by pericentric inversions and heterochromatin addition which probably determined the notorious dispersion of 5S rRNA (pseudo)genes. It is demonstrated that, even within a group generally characterized by cytogenetical homogeneity as the family Pomacanthidae, diversified karyotypes can be found.     

<Emphasis Type="Italic">Puccinia calystegiae-soldanellae</Emphasis>, a new rust species on <Emphasis Type="Italic">Calystegia soldanella</Emphasis> from Japan

A rust species on Calystegia soldanella in Japan has been treated as Puccinia convolvuli to date. However, morphological characteristics of specimens on C. soldanella collected from Japan are significantly different from those of specimens on other Calystegia and Convolvulus species from different areas of the world. It is proved by inoculation experiment that the rust on C. soldanella is specific to C. soldanella. Based on these results, Puccinia rust on C. soldanella from Japan is described as a new species, Puccinia calystegiae-soldanellae.     

Gene rearrangements in Chlamydomonas chloroplast DNAs are accounted for by inversions and by the expansion/contraction of the inverted repeat

To gain insight into the mutational events responsible for the extensive variation of chloroplast DNA (cpDNA) within the green algal genus Chlamydomonas, we have investigated the chloroplast gene organization of Chlamydomonas pitschmannii, a close relative of the interfertile species C. eugametos and C. moewusii whose cpDNAs have been well characterized. At 187 kb, the circular cpDNA of C. pitschmannii is the smallest Chlamydomonas cpDNA yet reported; it is 56 and 105 kb smaller than those of its C. eugametos and C. moewusii counterparts, respectively. Despite this substantial size difference, the arrangement of 77 genes on the C. pitschmannii cpDNA displays only three noticeable differences from the organization of the corresponding genes on the collinear C. eugametos and C. moewusii cpDNAs. These changes in gene order are accounted for by the expansion/contraction of the inverted repeat and one or two inversions in a single-copy region. In land plant cpDNAs, these kinds of events are also responsible for gene rearrangements. The large size difference between the C. pitschmannii and C. eugametos/C. moewusii cpDNAs is mainly attributed to multiple events of deletions/additions as opposed to the usually observed expansion/contraction of the inverted repeat in land plant cpDNAs. We also found that the mitochondrial genome of C. pitschmannii is a circular DNA molecule of 16.5 kb which is 5.5 and 7.5 kb smaller than its C. moewusii and C. eugametos counterparts, respectively.     

Field and laboratory studies to determine the suitability of Cissoanthonomus tuberculipennis (Coleoptera: Curculionidae) for release against Cardiospermum grandiflorum (Sapindaceae) in South Africa

Cardiospermum grandiflorum is an invasive creeper that was targeted for biological control in South Africa in 2003. To determine ecological host range of its natural enemies, surveys were conducted on C. grandiflorum and 11 other Sapindaceae at 40 sites in the weed's native range (Argentina). These surveys indicated that the seed-feeding weevil Cissoanthonomus tuberculipennis was restricted to C. grandiflorum, and that it was among the common natural enemies, occurring at most sites where C. grandiflorum was recorded. Open-field tests were conducted under natural conditions in Argentina to determine the host preference of C. tuberculipennis and other natural enemies of C. grandiflorum among three Cardiospermum species. These tests revealed that C. tuberculipennis and the bug Gargaphia sp. were restricted to C. grandiflorum though the latter subsequently developed on non-target Cardiospermum species in the laboratory. C. tuberculipennis was found to be highly damaging, destroying up to 44% of the seeds per plant in Argentina. In all the host-specificity tests, including no-choice, paired-choice and multi-choice tests, C. tuberculipennis only fed and developed on C. grandiflorum. Failure of C. tuberculipennis to feed and develop on all congeners of C. grandiflorum shows that the weevil is highly host-specific to the target weed. Results of host-specificity tests, open field tests and long-term monitoring of C. tuberculipennis populations demonstrate that the weevil poses no threat to non-target plant species, and therefore safe for release against C. grandiflorum in South Africa. Permission to release C. tuberculipennis in South Africa has been granted by the relevant regulatory authorities.     

Importance of Pollen and Senescent Petals in the Suppression of Alfalfa Blossom Blight (Sclerotinia sclerotiorum) by Coniothyrium minitans

The effect of pollen and senescent petals on the suppression of alfalfa (Medicago sativa L.) blossom blight (Sclerotinia sclerotiorum) by the mycoparasite Coniothyrium minitans was investigated. When incubated at 20°C for 39 h, germination of conidia of C. minitans and ascospores of S. sclerotiorum was 99.9 and 98.6%, respectively, in the presence of alfalfa pollen (9×10⁴ pollen grains mL^?1), whereas spore germination of both organisms was &lt;0.5% in the absence of pollen (in water). In the presence of a commercial pollen product, Swiss? pollen granules (mainly bee pollen), germination was 99.6% for C. minitans and 98.3% for S. sclerotiorum when the pollen concentration was 1.0% (w/v). When the pollen concentration was reduced to 0.1% (w/v), germination was reduced to 13.0% for C. minitans and 10.8% for S. sclerotiorum. Tests on detached alfalfa florets showed that the colonization of alfalfa florets by S. sclerotiorum was significantly suppressed by C. minitans in the presence of pollen (1.0% Swiss? pollen granules), especially when C. minitans was inoculated 1-day before S. sclerotiorum. In vivo inoculation tests revealed that the efficacy of C. minitans in the protection of alfalfa pods from the infection by S. sclerotiorum was affected by the time at which C. minitans was applied. When C. minitans was applied on young blossoms of alfalfa at the anthesis stage, pod infection was 96.6% for the treatment of C. minitans+S. sclerotiorum and 99.6% for the treatment of S. sclerotiorum alone. However, when C. minitans was applied on senescent petals of alfalfa at the pod development stage, pod infection was 8.0% for the treatment of C. minitans+S. sclerotiorum compared to 90.8% for the treatment of S. sclerotiorum alone. These results suggest that timing of the application of C. minitans is critical for the mycoparasite to compete with S. sclerotiorum for the source of nutrients from pollen and senescent petals, and for its control of alfalfa blossom blight caused by S. sclerotiorum.     

PREDICTING HOST RANGE EVOLUTION: COLONIZATION OF CORONILLA VARIA BY COLIAS PHILODICE (LEPIDOPTERA: PIERIDAE)

Extensive sympatry is currently arising between the common sulfur butterfly, Colias philodice Latreille (Lepidoptera: Pieridae) and a potential leguminous host plant, Coronilla varia (L.). In laboratory trials, larval surviviorship and growth were higher on the primary host, Medicago sativa (L.), than on the nonhost C. varia. However, because females reared from C. varia were on average more fecund than females reared from M. sativa, fitness on C. varia (approximately as survivorship times fecundity) was commensurate with fitness on M. sativa. Thus, it is predicted that selection would favor oviposition on C. varia, if such behavior were to arise. In addition, significant among-family variation exists for several measures of larval performance on both C. varia and M. sativa, indicating that C. philodice can potentially respond to selection for increased performance on each species. Moreover, larval performance was significantly positively correlated across these species, suggesting that selection for increased performance on each species will facilitate, not constrain, evolution of increased performance on the other. It is concluded that behavioral rather than physiological barriers currently account for the absence of C. philodice from C. varia and that, if such barriers are overcome, C. philodice will expand its host plant range to include C. varia.     

Approaching risk assessment of complex disease development in horse chestnut trees: a chemical ecologist's perspective

Abstract The chemo‐ecological predispositions were investigated for the development of a complex disease on the basis of an insect–fungus mutualism using the system of horse chestnuts (Aesculus hippocastanum and Aesculus x carnea), the horse chestnut leaf miner (Cameraria ohridella) and the biotrophic powdery mildew (Erysiphe flexuosa). Both C. ohridella and E. flexuosa can appear on the same horse chestnut leaf tissue simultaneously. The olfactory detection of fungal infection by the insect, its ability to discriminate the potentially mutualistic fungus from other fungi and the impact of fungal infection on insect oviposition were examined. Gas chromatography coupled with mass spectroscopic and electroantennographic detection by C. ohridella (GC‐MS/EAD) was used to assess the olfactory detection of fungal‐infected A. hippocastanum and A. x carnea leaves by C. ohridella. Infection‐related compounds, such as benzyl alcohol, dodecane, tridecane and methyl salicylate as well as fungus‐related C8 compounds, are perceived by C. ohridella. The discrimination of E. flexuosa from another phytopathogenic fungus, such as Guignardia aesculi, is based primarily on the differing pattern of C8 compounds of these fungi. Oviposition on fungal‐infected leaves of A. hippocastanum and leaves treated with fungal‐related compounds showed that C. ohridella is able to respond to the modifications in the leaf volatile profiles of horse chestnuts caused by the different fungal infections. Thus, from the perception point of view, the necessary predispositions for the development of a close insect–fungus relation between the biotrophic fungus E. flexuosa and the leaf‐mining insect C. ohridella are fulfilled. However, decreased oviposition on infected leaves does not enhance the selective contact between the species. As a consequence, an important predisposition for forming an insect–fungus mutualism is not fulfilled by these two species and, according to this approach, the risk of forming a complex disease can be assessed as low.     

Breeding system and pollination of selected orchids of the genus Chloraea (Orchidaceae) from central Chile

The breeding system determines different ways whereby seeds will be produced, and the degree of dependency of plants on pollinators for seed set. The genus Chloraea (Orchidaceae) has its main center of diversity in southern South America. There is only poor knowledge concerning its breeding system and pollination. We determined the breeding system of C. crispa, C. chrysantha, C. galeata, and two color forms of C. bletioides (yellow- and white-flowered forms). None of the species in this study produced fruits through apomixis or autogamy, thereby indicating a complete dependency on pollen and pollinators. Geitogamy did not differ significantly with respect to xenogamy excepting in the yellow-flowered form of C. bletioides. Thus, the indexes of self-incompatibility for the white- and yellow-flowered forms of C. bletioides, C. galeata, C. crispa, and C. chrysantha, were 1.00, 0.56, 0.82, 1.09, and 0.81, respectively; indicating that, excluding the yellow-flowered form of C. bletioides which must be regarded as partially self-incompatible, all orchids assessed are totally self-compatible plants. Natural fruiting in the yellow-flowered C. bletioides, C. chrysantha and C. galeata was high, in spite of being nectarless orchids, since the availability of pollinators under natural conditions seemingly resulted unlimited. However, no pollinator was observed visiting C. chrysantha and C. galeata, whereas the yellow-flowered form of C. bletioides was visited by hymenopterans and coleopterans. At contrast, reproductive success of the white-flowered form of C. bletioides and C. crispa was pollen limited, the former being visited by hymenopterans, dipterans, and colepterans; and the latter by two hymenopterans.     

Ammonites of the genus <Emphasis Type="Italic">Cadoceras</Emphasis> (Cardioceratidae) from the uppermost Bathonian-Lowermost Callovian of the northern Caucasus (Ingushetia)

Based on the study of the ammonite collection assembled by A.S. Sakharov from the Middle Jurassic Armkhi Formation of the Gerchyoch Mountain Pass (northern Ingushetia) and on literature sources, the species composition and stratigraphic position of northern Caucasian Cadoceras are discussed. Early Callovian C. tchegemicum Lominadze, C. tschernyschewi Sokolov, and C. suevicum Callomon et Dietl are identified; the name C. loginovae Lominadze, 2004 is synonymized under C. stupachenkoi Mitta, 1998. The Late Bathonian species are identified as C. sakharovi sp. nov. and C. aff. perrarum Voronetz. The presence of Upper Bathonian sediments is substantiated for the northern Caucasus; the theory of the inversion of the Kepplerites beds is shows to be erroneous.     

Description of Eucalyptodiplosis chionochloae sp. nov., a cecidomyiid feeding on inflorescences of Chionochloa (Poaceae) in New Zealand

Abstract

A cecidomyiid that feeds on developing seeds in the inflorescences of the New Zealand tussock grasses Chionochloa australis, C. conspicua, C. crassiuscula, C.flavescens, C. macra, C. oreophila, C. pallens, C. rigida, C. rubra, C. spiralis and C. teretifolia is formally described from C. pallens. The new species, named Eucalyptodiplosis chionochloae Kolesik, is the most ubiquitous of flower feeders of Chionochloa. Its larvae do not form galls but feed on the developing seeds in autumn, overwinter as diapausing larvae inside the floret, and pupate then rapidly eclose in summer, sometimes after extended diapause. Methods for rearing adults are described. Based on its morphological characters this species is most closely related to two described congeners that form galls on buds of Eucalyptus trees in Australia. Seed predation by Eucalyptodiplosis chionochloae larvae appears to be the primary driver of the extreme mast seeding (variation among years in flower crops) seen in the host Chionochloa species.     

Foraging behaviour by an intraguild predator blowfly, <Emphasis Type="Italic">Chrysomya albiceps</Emphasis> (Diptera: Calliphoridae)

Optimal foraging theory assumes that predators use different prey types to maximize their rate of energetic gain. Studies focusing on prey preference are important sources of information to understand the foraging dynamics of Chrysomya albiceps. The purpose of this investigation is to determine the influence of larval starvation in C. albiceps on the predation rate of different prey blowfly species and instars under laboratory conditions. Our results suggest that C. albiceps prefers Cochliomyia macellaria larvae to Chrysomya megacephala under non-starvation and starvation conditions. Nevertheless, predators gained more weight consuming C. macellaria. This result suggests that C. albiceps profit more in consuming C. macellaria rather than C. megacephala. The foraging behaviour displayed by C. abiceps on their prey and the consequences for the blowfly community are also discussed.     

Kinetics of recA function in conjugational recombinant formation.

Summary Genetic recombination was studied in F^- strains of E. coli carrying a mutation (recA200) that confers a thermosensitive Rec^- phenotype. Recombination during Hfr matings at 35C was monitored by raising the temperature of incubation to 42C at various intervals so that only merozygotes that had completed those functions dependent on the activity of the recA gene product could form recombinant progeny. The results indicated that no more than 1–2% of the merozygotes present while mating was in progress were able to form recombinant colonies at 42C. Separation of mating pairs reduced the yield of recombinants obtained at 35C by 50 to 200-fold if plating on agar medium was delayed for 15–30min by continuing incubation in broth medium. recA200 merozygotes that were also recB21 sbcB15 proved relatively stable when plating was delayed in this manner, which suggested that Hfr DNA is prone to exonuclease inactivation in recA200 merozygotes after mating pairs have separated. Post-mating incubation in high salt medium or on agar plates promoted the recovery of recombinants at 35C. However, the majority of recA200 merozygotes did not acquire the ability to form recombinant colonies at 42C under these more stable conditions until mating pairs had been separated and incubation continued at 35C for 40–60 min. It was concluded that recA200 strains are partially defective for recombination even at low temperature but that terminating mating promotes the recovery of recombinants. A mechanism involving the stimulation of RecA activity by mating pair separation is postulated to account for the efficient recovery of recombinants from HfrxF^- recA200 crosses at 35C.     

Genetic diversity of <Emphasis Type="Italic">Caragana</Emphasis> species of the Ordos Plateau in China

Plants of the genus Caragana (Fabaceae) are dominant shrub species of high ecological and economic importance on the Ordos Plateau in China. Due to natural environmental variability and anthropogenic impacts, Caragana pastures have experienced severe degradation, which has decreased their carrying capacity. In this study, we investigated the genetic diversity of eight Caragana species (C. purdomii, C. opulens, C. stenophylla, C. intermedia, C. korshinskii, C. roborovskyi, C. tibetica and C. brachypoda) on the Ordos Plateau by using ISSR markers. The results reveal high genetic diversity of all the species, with the percentage of polymorphic bands (PPB) reaching 100%. However, interspecific differences in genetic diversity within the genus were significant, as indicated by higher levels of genetic diversity of C. stenophylla, C. tibetica, C. intermedia, C. korshinskii and C. roborovskyi (PPB > 86%) when compared to the C. brachypoda with the lowest genetic diversity (PPB = 42.86%). Caragana brachypoda showed the lowest genetic similarity with and largest genetic distance from other taxa of the genus. Caragana tibetica had higher genetic diversity than C. roborovskyi. A large genetic distance was found between C. roborovskyi and C. tibetica, although the two species belong to Ser. Tragacanthoides and grow in a semidesert area. Such differences in genetic structure may be the reason for large areas occupied by C. tibetica, whereas C. roborovsky has rather limited distribution in the semidesert area. Caragana intermedia had high genetic diversity and a large genetic differentiation between intraspecific populations implying strong adaptability of the species to environmental fluctuations and selection capabilities. There was an obvious gene flow between C. intermedia and C. korshinskii, suggesting possible hybridization between these species is consistent with ecological variability, which may be important characteristics of Caragana plants in terms of molecular variation in the ecotone of Ordos plateau. Our results provide a molecular basis for sustainable management, utilization and conservation of Caragana plants on the Ordos plateau.     

Candida sonckii sp. nov.

A new yeast species with basidiomycetous affinities is described as Candida sonckii Hopsu-Havu et al. It differs from C. fujisanensis and C. maris by growing with KNO₃ as nitrogen source, from C. vanderwaltii by its lower mol % G+C, lower maximum temperature for growth and failure to grow on D-arabinose and citrate.     

Transmission of the mycoparasite Coniothyrium minitans by collembolan Folsomia Candida (Collembola: Entomobryidae) and glasshouse sciarid Bradysia sp. (Diptera: Sciaridae)

Folsomia Candida was maintained on potato dextrose agar (PDA) plates precolonised by the mycoparasite Coniothyrium minitans for 3 yr but the sciarid Bradysia sp. survived for a maximum of only three generations. Collembolans and sciarid larvae from these cultures were able to transmit C. minitans to uninoculated PDA plates through the survival of spores in faecal pellets. Adult and larval sciarids also transmitted C. minitans from PDA culture to uninoculated PDA plates by contamination on the cuticle. In soil and sand both sciarids and collembolans were able to transmit C. minitans from C. m/m'tans-inoculated to uninoculated sclerotia of Sclerotinia sclerotiorum. Inoculation of sclerotia with C. minitans enabled greater populations of larger collembolans to develop. In the glasshouse where C. minitans had been applied to the soil, one adult sciarid and four collembolans out of 70 and 101 insects collected respectively yielded C. minitans on placement onto PDA + Aureomycin.     

CYTOGENETIC STUDIES IN CLARKIA,SECTION PRIMIGENIA. IV. A CYTOLOGICAL SURVEY OF CLARKIA GRACILIS

Clarkia gracilis (2n = 28) is an allotetraploid which combines genomes from two subsections of section Primigenia. Natural populations consist of plants homozygous for a single chromosome arrangement, which may differ from the arrangements in other populations by one or more reciprocal translocations. One arrangement, the “standard,” was widespread. Cytological observations on plants derived from crosses between populations of C. gracilis, and on triploid plants derived from crosses with C. amoena subsp. huntiana, one of the parents of the tetraploid, were used to determine the end arrangements present. Ten arrangements were identified, and it was found that the standard amoena subgenome of C. gracilis is identical in end arrangement to the previously defined standard arrangement of the diploid C. amoena. Hence a race of C. amoena with this arrangement was involved in the hybridization which gave rise to C. gracilis. Evidence was found that other arrangements of C. amoena have probably been introduced into C. gracilis by subsequent introgressive hybridization. Cytological differences, coupled with differences in morphology, ecology, and distribution indicate that C. gracilis should be subdivided into four subspecies instead of the three presently recognized.     

Photosynthetic carbon assimilation by Crassula helmsii

Photosynthesis of Crassula helmsii, an amphibious aquatic macrophyte weed species, has been measured with respect to pH and irradiance. C. helmsii shows a marked diel fluctuation in titratable acidity, which can be accounted for by changing levels of malic acid. C. helmsii is unable to use HCO _inf3 ^sup- for photosynthesis and exhibits generally low photosynthetic rates when CO₂ is not limiting. The photon flux density at which the onset of light saturation of photosynthesis is reached (E _K ) is low for aquatic macrophytes. Some advantages conferred on C. helmsii by the possession of crassulacean acid metabolism are an extension of the period of assimilation of dissolved inorganic carbon, resulting in a reduction in the limitation imposed on photosynthesis in aquatic environments by a very high CO₂ diffusion resistance.