Resources exploitation by ants facilitates lizard egg survival

Abstract.  1.  This study investigated the interaction between eggs of the lizard Mabuya longicaudata Hallowell and two species of ant: a lizard egg commensalist ( Paratrechina longicornis Latreille), and an egg predator ( Pheidole taivanensis Forel). The ecological interaction between P. longicornis and lizard eggs was tested, and it was predicted that when the interaction was removed, lizard eggs would be attacked by P. taivanensis .
2. Field observations showed that both ant species actively searched for lizard eggs, and that P. taivanensis typically found new lizard nests earlier than P. longicornis did. Left undisturbed, P. taivanensis predation dramatically reduced lizard egg survival. While P. longicornis usually found nests later, they were able to displace P. taivanensis . As a result, proportional egg survival was higher in nests with P. longicornis (0.95 ± 0.04 eggs) compared to nests without either ant species (0.65 ± 0.09 eggs), or nests occupied by P. taivanensis (0.07 ± 0.02 eggs).
3. When P. longicornis ants were experimentally excluded from lizard nests, the proportion of eggs surviving significantly decreased because of increased P. taivanensis predation. Paratrechina longicornis benefits from water that condenses on the eggs. When this resource disappears P. longicornis abandons the nest, leading to predation of the eggs by P. taivanensis .     

长角血蜱卵黄蛋白的纯化及其性质

用凝胶过滤与离子交换层析、蛋白质电泳和糖脂蛋白染色等方法提取纯化长角血蜱Haemaphysalis longicornis卵黄蛋白,并对其性质进行了研究。PAGE和SDS-PAGE分析表明,长角血蜱的卵黄蛋白只有一种,由8个亚基组成,亚基的相对分子质量分别为112 kD, 103 kD, 80 kD, 78 kD, 71 kD, 68 kD, 62 kD和52 kD,卵黄蛋白经苏丹黑B和希夫试剂染色呈阳性,表明是一种含血红素的糖脂蛋白。     

Effect of temperature on life table parameters of predatory thrips Scolothrips longicornis (Thysanoptera: Thripidae) fed on twospotted spider mites (Acari: Tetranychidae)

Environmental variables such as temperature are important factors that affect the efficiency of biological control agents. This study examined the effect of temperature on the sex ratio, longevity, oviposition periods, fecundity and life table parameters of the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), at six constant temperatures: 15, 20, 26, 30, 35, and 37 degrees C. Approximately 75% of the progeny were female, except at 37 degrees C, at which temperature the proportion of males increased. Adult longevity as well as the preoviposition, oviposition, and postoviposition periods decreased significantly with temperature. Thus, adults lived for approximately 5 wk at 15 degrees C and < 1 wk at 37 degrees C with preoviposition, oviposition, and postoviposition periods ranging from 6.4 to 0.4, 24.4-3.1, and 7-0.8 d between the two temperature extremes, respectively. The maximum (56.48 eggs) and minimum (11.69 eggs) value of total fecundity was recorded at 26 and 37 degrees C, respectively. The intrinsic rate of natural increase (r(m)) of S. longicornis increased linearly with increasing temperature from 0.056 d(-1) at 15 degrees C to 0.310 d(-1) at 35 degrees C. The lower temperature threshold for the population increase of S. longicornis was estimated to be around 5 degrees C. The data suggest that the upper temperature threshold for the predatory thrips is approximately 37 degrees C. The results showed that populations of S. longicornis are able to develop at a broad range of temperatures and that this predator is well adapted to the high temperatures that occur in the Mediterranean region.     

QUANTITATIVE VARIATION OF ECDYSTEROIDS OF IXODID TICKS

Abstract  In order to explore the role of ecdysteroids in development and reproduction of ixodid ticks, we studied the quantitative variation of ecdysteroids in the hemolymph, synganglion, ovary and whole body of the female ixodid ticks, Dermacentor niveus and Haemaphysalis longicornis , before and after engorgement and oviposition by HPLC and RIA. The ecdysteroid content in eggs of these ticks was determined by HPLC. The results indicated that before engorgement the quantitative variation of ecdysteroids in the whole female body was not significant, but their levels increased rapidly after engorgement. The ecdysteroid titer in hemolymph was peaked on the 5th day after engorgement, which was one day prior to oviposition. It may be regarded as a singnal of oviposition. In the synganglion the peak of ecdysteroid level occurred also on the 5th day after engorgement. This is coincident with the secretory activity of neurosecretory cells of synganglion. From the 3rd day after engorgement until oviposition the ecdysteroid level in the ovary increased rapidly. Ecdysteroids were detected in eggs of H. longicornis too. They stem from ovary and accumulated with the process of embryonic development.     

硬蜱中蜕皮激素含量的变化(英语)

为阐明蜕皮激素在硬蜱发育和生殖中的作用,用高效液相色谱法(HPLC)和放射免疫测定法测定了银盾革蜱和长角血蜱中饱血和产卵前后雌虫整体、血淋巴、合神经节及卵巢中蜕皮激素含量的变化.此外,还用HPLC测定了长角血蜱的卵和幼虫中蜕皮激素的含量.结果表明:在饱血前雌虫整体中蜕皮激素含量的变化不大,饱血后迅速增加.血淋巴中的蜕皮激素在饱血后第5天(即产卵前1天)达到高峰,可做为产卵的信号.合神经节中蜕皮激素含量的高峰在饱血后第5天,与血淋巴中高峰出现的时间一致,这与神经分泌细胞的分泌活性变化相吻合.从饱血后第3天起,卵巢中蜕皮激素含量增加很快,直到产卵时止,在长角血蜱的卵中也测到α-蜕皮素,来源于卵巢,随胚胎发育进程其含量逐渐增加.卵产出后第4天到第12天,蜕皮激素的含量增加十几倍.     

Host genotype determines cytoplasmic incompatibility type in the haplodiploid genus Nasonia

In haplodiploid species, Wolbachia-induced cytoplasmic incompatibility (CI) can be expressed in one of two ways: as a "conversion" of diploid fertilized eggs into haploid males or as embryonic mortality. Here we describe CI-type variation within the parasitic wasp genus Nasonia and genetically analyze the basis of this variation. We reach four main conclusions: (i) CI is expressed primarily as conversion in N. vitripennis, but as embryonic mortality in the sibling species N. giraulti and N. longicornis; (ii) the difference in CI type between N. giraulti (mortality) and N. vitripennis (conversion) is determined by host nuclear genotype rather than by Wolbachia differences; (iii) N. vitripennis "conversion genes" are recessive in hybrid females; and (iv) a difference in CI level between the sibling species N. giraulti and N. longicornis is due to the different Wolbachia infections in the species rather than to the host genotype. These results show that host nuclear genes can influence the type of CI present in a species. On the basis of these findings, we propose a model for how different CI types evolve in haplodiploids due to selection on nuclear genes modifying CI.     

Assessing the In Situ Fertilization Status of Two Marine Copepod Species,Temora longicornis and Eurytemora herdmani; How Common Are Unfertilized Eggs in Nature?

We utilized an egg staining technique to measure the in situ fertilization success of two marine copepod species, Temora longicornis and Eurytemora herdmani from May to October 2008 in coastal Maine and correlated fertilization success with environmental conditions in their habitat. T. longicornis is a free spawning species that releases eggs into the ambient seawater after mating. In contrast, E. herdmani carries eggs in an egg sac until they hatch. The proportion of fertilized eggs within E. herdmani egg sacs was significantly higher than the freely spawned clutches of T. longicornis. This may be a result of the asymmetrical costs associated with carrying vs. spawning unfertilized eggs. T. longicornis frequently laid both fertilized and unfertilized eggs within their clutch. T. longicornis fertilization was negatively associated with chlorophyll concentration and positively associated with population density in their local habitat. The fertilization status of E. herdmani egg sacs was high throughout the season, but the proportion of ovigerous females was negatively associated with an interaction between predators and the proportion of females in the population. This study emphasizes that, in addition to population level processes, community and ecosystem level processes strongly influence the fertilization success and subsequent productivity of copepods.     

Identification and molecular characterization of a chitinase from the hard tick Haemaphysalis longicornis

A cDNA encoding tick chitinase was cloned from a cDNA library of mRNA from Haemaphysalis longicornis eggs and designated as CHT1 cDNA. The CHT1 cDNA contains an open reading frame of 2790 bp that codes for 930 amino acid residues with a coding capacity of 104 kDa. The deduced amino acid sequence shows a 31% amino acid homology to Aedes aegypti chitinase and a multidomain structure containing one chitin binding peritrophin A domain and two glycosyl hydrolase family 18 chitin binding domains. The endogenous chitinase of H. longicornis was identified by a two-dimensional immunoblot analysis with mouse anti-rCHT1 serum and shown to have a molecular mass of 108 kDa with a pI of 5.0. A recombinant baculovirus AcMNPV.CHT1-expressed rCHT1 is glycosylated and able to degrade chitin. Chitin degradation was ablated by allosamidin in a dose-dependent manner. The optimal temperature and pH for activity of the purified chitinase were 45 degrees C and pH 5-7. The CHT1 cDNA has an ELR motif for chemokine-mediated angiogenesis and appears to be a chitinase of the chemokine family. Localization analysis using mouse anti-rCHT1 serum revealed that native chitinase is highly expressed in the epidermis and midgut of the tick. AcMNPV.CHT1 topically applied to H. longicornis ticks exhibited replication. This is the first report of insect baculovirus infection of ticks. The importance of AcMNPV.CHT1 as a novel bio-acaricide for tick control is discussed.     

Immunization effect of recombinant P27/30 protein expressed in Escherichia coli against the hard tick Haemaphysalis longicornis (Acari: Ixodidae) in rabbits

We investigated the induction of resistance to Haemaphysalis longicornis infestation in rabbits that had been immunized with recombinant H. longicornis P27/30 protein. The success of immunological control methods is dependent upon the use of potential key antigens as tick vaccine candidates. Previously, we cloned a gene encoding 27 kDa and 30 kDa proteins (P27/30) of H. longicornis, and identified P27/30 as a troponin I-like protein. In this study, rabbits that were immunized with recombinant P27/30 expressed in Escherichia coli showed the statistically significant longer feeding duration for larval and adult ticks (P<0.05), low engorgement rates in larval ticks (64.4%), and an apparent reduction in egg weights, which suggest that H. longicornis P27/30 protein is a potential candidate antigen for a tick vaccine. These results demonstrated that the recombinant P27/30 protein might be a useful vaccine candidate antigen for biological control of H. longicornis.     

Development, survival, fecundity and behaviour of Haemaphysalis (Kaiseriana) longicornis (Ixodidae) at two locations in southeast Queensland.

The free-living stages of the tick Haemaphysalis (Kaiseriana) longicornis were studied at Mt Tamborine (526 m altitude) and Amberley (25 m altitude) in southeast Queensland between 1971 and 1980. Data are presented on the number of eggs and larvae produced, the moulting success of engorged larvae and nymphs and the survival and behaviour of unfed larvae, nymphs and adult females. Temperature, moisture, daylength, grass length and age of unfed ticks were investigated as sources of variation in development rates, fecundity or survival. At Mt Tamborine the life cycle was well synchronized with the seasons to produce one generation per year. At Amberley higher temperatures accelerated development rates and would have delayed diapause, so disrupting the life cycle.     

Nutritive Value and Selection of Food Particles by Copepods During a Spring Bloom of Phaeocystis sp. in the English Channel, as Determined by Pigment and Fatty Acid Analyses

In this study phytoplankton pigments and fatty acids were usedas biomarkers to study trophic relationships between phytoplanktonand zooplankton. These markers permit the characterization ofboth suspended matter and copepods, allowing examination ofthe transfers from food to zooplankton. A drogue study was carriedout to follow a water mass in the coastal waters off the easternEnglish Channel over a 3-day period, with samples collectedevery 3 h. The study focused on the dominant calanoid copepodspecies: Temora longicornis, Acartia clausi and Pseudocalanuselongatus. Our study was performed during the spring phytoplanktonbloom when solitary cells of Phaeocystis sp. formed 90% of thetotal phytoplankton. Fatty acid analyses provided an indicationof the low nutritive value of these algal cells; in contrastto other algal species which had higher nutritional value (e.g.colony-forming diatoms, Cryptophytes and dinoflagellates). Ourresults suggest that all species selectively grazed on Phaeocystissp. and non-selectively on diatoms. Dinoflagellates were avoidedby all species. Temora longicornis selectively grazed on Cryptophytes,which may be related to the nutritional value of this algae.The fatty acid composition of the three copepod species indicatedan ‘herbivorous’ diet for P.elongatus and an omnivorousone for A. clausi and T. longicornis, which is less opportunist.     

The ecology, genetic diversity, and phylogeny of Huaiyangshan virus in China

Surveys were carried out to better understand the tick vector ecology and genetic diversity of Huaiyangshan virus (HYSV) in both regions of endemicity and regions of nonendemicity. Haemaphysalis longicornis ticks were dominant in regions of endemicity, while Rhipicephalus microplus is more abundant in regions of nonendemicity. HYSV RNA was found in human and both tick species, with greater prevalence in H. longicornis and lesser prevalence in R. microplus. Phylogenetic analyses indicate that HYSV is a novel species of the genus Phlebovirus.     

Population dynamics of calanoid copepods and the implications of their predation by clupeid fish in the Central Baltic Sea

Population dynamics of major Baltic calanoid copepod speciesin the Gotland Basin during the last two decades were characterizedby a decline of Pseudocalanus elongatus associated with decliningsalinities, and an increase of Temora longicornis and Acartiaspp. potentially due to warmer conditions. Additionally thisstudy investigated the effect of predation by the major planktivorousfish species herring (Clupea harengus) and sprat (Sprattus sprattus)for the period 1977–1996 in the Gotland Basin (CentralBaltic Sea). Examination of consumption by these fish speciesin relation to copepod production estimates showed a switchby herring from consuming mainly CV/VI of P. elongatus and T.longicornis, to preying on CII of the latter copepod. This switchwas potentially due to increased competition with the drasticallyincreased sprat stock since the late 1980s. Further, an increasedpredation pressure by sprat on CV/CVI of both copepod speciesin spring resulted in higher copepod mortality rates. In consequence,based on these results we suggest that the increase in the spratstock since the late 1980s contributed to a decline of P. elongatus,and additionally prevented an even more pronounced temperature-drivenincrease in the T. longicornis stock, as was observed for Acartiaspp., which was not significantly consumed.     

Multiscale patchiness of the calanoid copepod Temora longicornis in a turbulent coastal sea

We present evidence that intermittent variability in zooplanktonabundance can be characterized in terms of multifractals. A3-min-resolution time series of abundance in the calanoid copepodTemora longicornis, taken from a fixed mooring in the coastalwaters of the Eastern English Channel for 66 h, provided thedata for our analysis. The multifractal nature of the distributionof T. longicornis abundance appears to be very different fromthose of purely passive scalars (i.e. temperature and salinity),and also from phytoplankton biomass over a similar range ofscales in similar environments. Finally, we show that the multifractaldistribution of T. longicornis can be wholly described by threebasic parameters in the framework of universal multifractals,opening up very large perspectives for future modeling of pelagicecosystem structures and functions.     

Molecular characterization of a troponin I-like protein from the hard tick Haemaphysalis longicornis.

A cDNA expression library prepared from mRNA of Haemaphysalis longicornis (H. longicornis) was screened with a H. longicornis-infested rabbit serum. A cDNA encoding 27/30kDa proteins was cloned and designated P27/30 gene. The predicted amino acid sequence of the P27/30 gene shows a rather high homology (58% amino acid identities and 11% amino acid similarity) with Drosophila melanogaster troponin I clone E2. H. longicornis P27/30 possesses amino acid sequence of actin-binding domains of troponin I at the amino acid residues 128-148, suggesting that H. longicornis P27/30 is a troponin I-like protein. By immunoblot analysis, mouse anti-recombinant P27/30 serum reacted with major constituent protein bands in extracts of adult ticks, and also immunoreacted with muscle, cuticle, gut, and salivary gland in H. longicornis ticks. Moreover, immunohistochemistry using the anti-P27/30 serum showed a strong reactivity in muscle, suggesting that native P27/30 is expressed abundantly in that tissue.     

Dietary shifts in the copepod Temora longicornis during spring: evidence from stable isotope signatures, fatty acid biomarkers and feeding experiments

The calanoid copepod Temora longicornis occurs year-round inthe southern North Sea. Owing to its limited ability to storeenergy, this species relies on a constant food supply. Thus,when the phytoplankton stock as the primary food source is lowin winter and early spring, T. longicornis needs to utilizeother food items. In this study, the feeding strategy of T.longicornis females is elucidated using a broad methodologicalapproach. From March to May 2005 we conducted weekly grazingexperiments using natural plankton (<70 µm) as foodsource. In addition, gut contents, stable isotopes (¹⁵N, ¹³C)and fatty acid composition of the females were analysed, aswas the natural plankton composition. Our data suggest thatfemales were omnivorous during late winter and early spring,switching to a more herbivorous feeding mode with increasingphytoplankton stock in spring. The ¹⁵N values in March/Aprilare the highest reported so far for this species, and we suggestthat they mirror the copepods' trophic level throughout ontogenesisrather than reflecting the feeding history of only the females.T. longicornis adjusted its feeding mode to ambient food conditions,utilizing a broad range of food sources. Experiments, however,revealed strong selection for cells >12.5 µm. Feedingon dinoflagellates was generally intense; diatoms were ingestedmainly in March. Thus, the grazing impact of T. longicorniscan be substantial on those taxa, which are selected for.     

Bidirectional incompatibility among divergent Wolbachia and incompatibility level differences among closely related Wolbachia in Nasonia

Most insect groups harbor obligate bacterial symbionts from the alpha-proteobacterial genus Wolbachia. These bacteria alter insect reproduction in ways that enhance their cytoplasmic transmission. One of the most common alterations is cytoplasmic incompatibility (CI) - a post-fertilization modification of the paternal genome that renders embryos inviable or unable to complete diploid development in crosses between infected males and uninfected females or infected females harboring a different strain. The parasitic wasp species complex Nasonia (N. vitripennis, N. longicornis and N. giraulti) harbor at least six different Wolbachia that cause CI. Each species have double infections with a representative from both the A and B Wolbachia subgroups. CI relationships of the A and B Wolbachia of N. longicornis with those of N. giraulti and N. vitripennis are investigated here. We demonstrate that all pairwise crosses between the divergent A strains are bidirectionally incompatible. We were unable to characterize incompatibility between the B Wolbachia, but we establish that the B strain of N. longicornis induces no or very weak CI in comparison to the closely related B strain in N. giraulti that expresses complete CI. Taken together with previous studies, we show that independent acquisition of divergent A Wolbachia has resulted in three mutually incompatible strains, whereas codivergence of B Wolbachia in N. longicornis and N. giraulti is associated with differences in CI level. Understanding the diversity and evolution of new incompatibility strains will contribute to a fuller understanding of Wolbachia invasion dynamics and Wolbachia-assisted speciation in certain groups of insects.     

Different phylogeographic patterns in two Japanese Silpha species (Coleoptera: Silphidae) affected by climatic gradients and topography

To reveal differences in phylogeographic patterns of flightless insect species occurring in different regions of Japan, we studied the phylogeography and demographic history of Silpha beetles occurring in cool-temperate habitats of two major islands, Honshu and Hokkaido, using sequences of the mitochondrial cytochrome oxidase subunit I (COI) gene. Honshu has a more mountainous topography, and cool-temperate habitats occur discontinuously, whereas Hokkaido, located to the north of Honshu, has more continuous cool-temperate habitats. A species endemic to Honshu, S. longicornis occurs on Honshu, whereas S. perforata occurs on Hokkaido and the East Asian continent. Our results indicate that the ancestors of S. longicornis colonized Honshu via a south-west route c . 0.7 Mya and the species has highly divergent populations in isolated mountainous areas of Honshu, whereas S. perforata colonized Hokkaido via a northern route less than 90 000 years ago and has less divergent geographic populations. During the last glacial period, S. perforata was probably restricted to refugia in southern Hokkaido and later expanded into northern Hokkaido, whereas S. longicornis populations existed in many isolated refugia, probably because of the complex topography of Honshu. Thus, our study demonstrates that, even between closely related species, interactions among biology, latitudinal climatic gradients and topography can produce different phylogeographic patterns.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 452–467.     

Interspecific and intraspecific associations of two species of hard ticks, Haemaphysalis longicornis and Haemaphysalis megaspinosa, in relation to questing site

The effects of intraspecific and interspecific interactions on preferred questing sites of ticks, specifically nymphs and larvae of Haemaphysalis longicornis and Haemaphysalis megaspinosa, were examined in Boso Peninsula of central Japan from October 1996 to September 1999. Haemaphysalis longicornis were primarily segregated from H. megaspinosa by season. All stages of the 2 tick species preferred sedges. Three-way contingency tables and log-linear models were used to test for independence of occurrence and to quantify associations between species and stages with similar host ranges. The shifts of questing site from leaves to stem tips and from 40-49 cm to greater heights were observed in both species, which suggests that these sites are more suitable for ticks and that aggregation may serve as protection from severe conditions. In contrast, a shift to a lower height was observed in H. longicornis nymphs and larvae when other species were present, suggesting that they were driven away by other species, especially H. megaspinosa. Heterospecific clusters composed of at least 2 species were formed on stem tips more frequently. It is concluded that questing site was affected by both aggregation pattern and the presence of other species.