Orientation of agents of wound myiasis to hosts and artificial stimuli in Hungary

Abstract. The orientation of adults of the myiasis species Wohlfahrtia magnified and Lucilia sericata to artificial visual stimuli (cloth targets) and olfactory stimuli ('swormlure-4', a potent screwworm attractant), was studied in sheep pastures near to Sarbogard in Hungary. Experiments with odour-baited cloth targets, enclosed in electrocuting grids, demonstrated that colour was an important factor influencing catches on targets: a black target caught most flies of both species, with other colours in the following order of effectiveness, blue > white > yellow. Wohlfahrtia magnified did not respond to swormlure-4 in the strong manner that L. sericata did. The sex ratios of W. magnifica caught on targets (67.2% males) and hand-netted from fence posts (68.8% males) were similar and biased towards males, whereas that of L. sericata on targets was strongly biased towards females (15.6% males), indicating a fundamental difference in the response of these two myiasis species towards the swormlure-baited targets. The orientation of these two species towards hosts was also recorded together with that of a third species, Phormia regina . Electric nets placed beside infested sheep caught significantly more flies of all three species than those placed beside uninfested sheep or in the absence of sheep. The sex ratio of W. magnified caught around infested sheep was the reverse of that on targets, with 68.5% females. Wohlfahrtia magnifica responded more strongly to healthy, uninfested sheep than did L. sericata and P. regina . The potential for use of targets both for population monitoring and control is discussed.     

The relationship between sea surface temperature and population change of Great Cormorants Phalacrocorax carbo breeding near Disko Bay,Greenland

Arctic seas have warmed and sea ice has retreated. This has resulted in range contraction and population declines in some species, but it could potentially be a boon for others. Great Cormorants Phalacrocorax carbo have a partially wettable plumage and seem poorly suited to foraging in Arctic waters. We show that rates of population change of Cormorant colonies around Disko Bay, Greenland, are positively correlated with sea surface temperature, suggesting that they may benefit from a warming Arctic. However, although Cormorant populations may increase in response to Arctic warming, the extent of expansion of their winter range may ultimately be limited by other factors, such as sensory constraints on foraging behaviour during long Arctic nights.     

Symbiotic streptomycetes in antennal glands of the South American digger wasp genus Trachypus (Hymenoptera,Crabronidae)

Several insect taxa have evolved symbioses with actinobacteria that protect the host or its nutritional resources against pathogens. Digger wasps of the genus Philanthus (‘beewolves’; Hymenoptera, Crabronidae) cultivate ‘Candidatus Streptomyces philanthi’ (Ca. S. philanthi) in specialized antennal glands and transfer them to subterranean brood cells, where the symbionts provide protection for the beewolf larva against pathogens by producing a cocktail of antibiotic substances. The present study investigates the occurrence of antennal symbionts in two species of the genus Trachypus, which is the closest relative to Philanthus. Cross sections of the antennae from females of both Trachypus denticollis and Trachypus boharti reveal bacteria‐containing gland reservoirs that are morphologically very similar to those found in Philanthus spp. Polymerase chain reaction‐based screens with specific primers, sequencing of the partial 16S rRNA gene, and fluorescence in situ hybridization confirm the presence of close relatives of ‘Ca. S. philanthi’ in T. denticollis and T. boharti. However, 16S rRNA sequence divergence between Trachypus spp. and Philanthus spp. symbionts is much higher for T. boharti than for T. denticollis, suggesting that horizontal transmission and/or de novo uptake of symbionts from the environment occurs occasionally. The results obtained indicate that the protective symbiosis with antennal actinobacteria is older and more widespread than previously recognized and occurs in at least two genera of digger wasps that comprise approximately 170 species.     

Foraging activity and dietary spectrum of wood ants (Formica rufa group) and their role in nutrient fluxes in boreal forests

Abstract 1. We monitored three different‐sized wood ant (Formica aquilonia Yarrow) mounds over a 3‐year period in Finnish boreal forests dominated by Norway spruce (Picea abies Karst.), to assess the seasonal temperature dependency of ant activity. Additionally, we also monitored Norway spruce trees around the mounds for descending honeydew foragers. 2. The amount of collected honeydew and prey and its composition, as well as the carbon (C), nitrogen (N), and phosphorus (P) in honeydew and invertebrate prey was also investigated. 3. The number of warm days (average temperature above 20 °C) and the amount of precipitation differed among the years. Ant activity at the mounds (but not on the trees) was highly correlated with air temperature throughout the ant‐active season (May–September), but ant activity in spring and autumn was lower than in summer at similar temperatures. During all 3 years, honeydew played a major role in wood ant nutrition (78–92% of dry mass). Invertebrate prey was mainly Diptera (on average 26.2%), Coleoptera (12.5%), Aphidina (9.3%), and Arachnoida (8.5%). 4. The total amounts of C, N, and P input brought into the ant mounds in the form of food (both honeydew and prey) on the stand level were 12.6–39.0, 1.6–4.6 and 0.1–0.4 kg ha^?1 year^?1, respectively, which is equivalent to 2–6%, 12–33% and 27–58% of the fluxes in annual needle litterfall in typical boreal Norway spruce forests. Thus, wood ants can play a significant role in short term and local N and P cycling of boreal forest ecosystems.     

Development of megagametophyte, embryo, and seed in Senna corymbosa (Lam.) H.S. Irwin & Barneby (Leguminosae – Caesalpinioideae)

The main aspects of seed ontogeny in Senna corymbosa were studied by standard anatomical microtechniques for light microscope observations. The results revealed an ana-campylotropous, bitegmic, and crassinucelate mature ovule. A single archesporocyte developed by an archesporial cell enlargement from the subhypodermal multicellular archesporium. Meiosis originated linear or T-shaped megasporic tetrads. The functional megaspore was the chalazal one. Megagametophytic development conformed to the Polygonum type. Fertilization was porogamic. Endosperm development was free nuclear and conformed to a chalazal haustorium. Cellular endosperm was initiated from the micropylar end during the globular embryo stage. Embryogeny derived from a linear proembryonal tetrad. The mature embryo showed an oblique axis. The testa derived from the outer ovular integument. Nucellar and endosperm remnants, and the micropylar region of the inner ovular integument, persisted at embryo maturity. The absence of a pleurogram would be adaptative to wetland habitats. The taxonomic use of the mature embryo axis in the Cassieae and the phylogenetic employment of megasporic arrangements in Leguminosae needs some reinterpretation.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 169–179.     

Importance of drought on the distribution of the birds nest fern,Asplenium nidus,in the canopy of a lowland tropical rainforest in north‐eastern Australia

Abstract The birds nest fern, Asplenium nidus, contributes greatly to the epiphytic biomass in the canopies of both south‐east Asia and tropical north Queensland rainforests. It is generally believed that their abundance and their capacity to store water is an important feature for habitat fragmentation in the canopy. We investigated the microclimate of A. nidus and the effects of severe drought periods on the A. nidus population over a 20‐year period, hypothesizing that water availability is the most important factor controlling the population under drought conditions. One of two neighbouring A. nidus plants of the same size and age was irrigated artificially before, during and after a significant dry period in 2000. By monitoring the microclimate within and around both ferns we were able to estimate that four continuous weeks of rainless weather completely dried out the accumulated humus of the non‐irrigated A. nidus fern. Prolonged dry periods were shown to kill the roots of A. nidus, which attach the fern to the bark and eventually the affected A. nidus on verticals stems fell to the ground. Periods longer than 8 weeks may even kill adult plants sitting in more protected branch forks. Analysis of the whole A. nidus population within the 1‐ha Canopy Crane plot and the determination of the morphological age of all plants enabled an evaluation of the historical development of the population. The oldest plant originated in 1985, just 1 year after the longest recorded drought for the site. We suspect that the 1984 drought killed every A. nidus plant within the study plot. Years with low recruitment coincide with years with long drought periods.     

Niche segregation and genetic structure of Campylobacter jejuni populations from wild and agricultural host species

Bacterial populations can display high levels of genetic structuring but the forces that influence this are incompletely understood. Here, by combining modelling approaches with multilocus sequence data for the zoonotic pathogen Campylobacter, we investigated how ecological factors such as niche (host) separation relate to population structure. We analysed seven housekeeping genes from published C. jejuni and C. coli isolate collections from a range of food and wild animal sources as well as abiotic environments. By reconstructing genetic structure and the patterns of ancestry, we quantified C. jejuni host association, inferred ancestral populations, investigated genetic admixture in different hosts and determined the host origin of recombinant C. jejuni alleles found in hybrid C. coli lineages. Phylogenetically distinct C. jejuni lineages were associated with phylogenetically distinct wild birds. However, in the farm environment, phylogenetically distant host animals shared several C. jejuni lineages that could not be segregated according to host origin using these analyses. Furthermore, of the introgressed C. jejuni alleles found in C. coli lineages, 73% were attributed to genotypes associated with food animals. Our results are consistent with an evolutionary scenario where distinct Campylobacter lineages are associated with different host species but the ecological factors that maintain this are different in domestic animals such that phylogenetically distant animals can harbour closely related strains.