Identification of a microspordium isolated from Megacopta cribraria (Hemiptera: Plataspidae) and characterization of its pathogenicity in silkworms

A new microsporidium isolated from Megacopta cribraria was characterized by both biological characteristics and phylogenetic analysis. Moreover, its pathogenicity to silkworms was also studied. The spores are oval in shape and measured 3.64 ± 0.2 × 2.20 ± 0.2 μm in size. Its ultrastructure is characteristic of the genus Nosema: a diplokaryon, 13–14 polar filament coils and posterior vacuole. Its life cycle includes meronts, sporonts, sporoblasts and mature spores, with a typical diplokaryon in each stage and propagation in a binary fission. A phylogenetic tree based on SSU rRNA and rRNA ITS gene sequence analysis further indicated that the parasite is closely related to Nosema bombycis and should be placed in the genus Nosema and sub-group ‘true’ Nosema. Furthermore, the microsporidium heavily infects lepidopteran silkworm insect and can be transmitted per os (horizontally) and transovarially (vertically). Our findings showed that the microsporidium belongs to the ‘true’ Nosema group within the genus Nosema and heavily infects silkworms. Based on the information obtained during this study, we named this new microsporidium isolated from M. cribraria as Nosema sp. MC.     

Effect of Selenium Yeast Supplementation on Naturally Acquired Parasitic Infection in Ewes

Gastrointestinal parasites cause substantial economic losses in pasture-based sheep production systems. Supranutritional organic selenium (Se) supplementation may be beneficial because it improves immune responses to pathogens. To evaluate the effect of Se-yeast supplementation on gastrointestinal parasite load, 30 ewes per treatment group were drenched weekly with no Se, 4.9 mg Se/week as Se yeast (maximum FDA-allowed concentration), or supranutritional concentrations of Se yeast (14.7 and 24.5 mg Se/week) starting early fall for 85 weeks. Fecal samples were collected at weeks 63, 66, 78, and 84 and counted for total trichostrongyle-type eggs and Haemonchus contortus eggs (in samples with ≥200 trichostrongyle eggs/g feces). During breeding season (fall), ewes were kept on pasture; ewes receiving 24.5 mg Se/week had lower fecal trichostrongyle egg counts (93?±?40 eggs/g feces) compared with ewes receiving no Se (537?±?257 eggs/g feces; P?=?0.007) or ewes receiving 4.9 mg Se/week as Se yeast (398?±?208 eggs/g feces; P?=?0.03). In winter, fecal trichostrongyle egg counts decreased, and group differences were not apparent. During lambing season (spring), ewes were kept in the barn and fecal trichostrongyle egg counts increased, although no group differences were observed. However, none of the ewes receiving supranutritional Se yeast, and with trichostrongyle egg counts ≥200 eggs/g of feces, but four of the ewes receiving lower Se dosages had H. contortus egg counts ≥1,000 eggs/g feces (P?=?0.04). Our results suggest that supranutritional Se-yeast supplementation may enhance resistance to naturally occurring H. contortus gastrointestinal parasitism in sheep.     

基于EB1基因的环介导等温扩增（LAMP）法检测感染家蚕微粒子病的蚕卵

【目的】家蚕 Bombyx mori 微粒子病一直影响着蚕种业的健康发展,快速而准确地检测出寄生于蚕卵中的家蚕微孢子虫 Nosema bombycis 对于有效控制家蚕微粒子病危害意义重大。【方法】环介导等温扩增（loop-mediated isothermal amplification, LAMP）法是一种快速、灵敏、特异的DNA体外恒温扩增方法,本文基于LAMP检测法的原理,依据家蚕微孢子虫孢子繁殖复制相关的 EB1 基因（GenBank登录号：KF421134.1）设计LAMP引物,对LAMP反应体系的最佳反应温度、内外引物浓度比、检测反应的特异性、灵敏度等进行研究,建立了一种检测蚕卵感染家蚕微粒子病的LAMP检测方法。【结果】结果表明,基于EB1 基因建立的LAMP检测方法在63℃恒温下在1.5 h内就可完成对样品的有效检测,本LAMP法对家蚕微孢子虫孢子DNA的检测灵敏度为5.0×10^-3 ng/μL,对EB1-pMD^TM19-T质粒标准品的检测灵敏度为1.0×10² copies/μL,同时对人工感染家蚕微粒子病单个母蛾产下蚕卵的1/8卵圈量或1粒蚕卵均能检出阳性结果。上述结果都分别应用凝胶电泳法、恒温荧光检测仪以及SYBR GreenⅠ显色肉眼观察法得到同步判定。【结论】本研究建立的基于EB1基因LAMP法可用于蚕卵微粒子病的检测,LAMP法为蚕种质量检验及成品卵微粒子病现场检疫提供了新技术。     

A semi-artificial rearing system for the specialist predatory ladybird Cryptolaemus montrouzieri

In the present study a semi-artificial rearing system for the Australian ladybird Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae), a specialist predator of mealybugs, was developed. In a first step, a rearing system using eggs of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) as a food and synthetic polyester wadding as an oviposition substrate was compared with a natural rearing system using the citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), as to its effects on the predator’s developmental and reproductive parameters. In a second series of experiments the performance of C. montrouzieri on bee pollen or on a mixture of E. kuehniella eggs and bee pollen was assessed. E. kuehniella eggs proved to be a suitable food to support larval development of the predator. Ladybird larvae reared on flour moth eggs developed two days faster and weighed approximately 10 % more than their counterparts reared on mealybugs. Despite a prolongation of the preoviposition period with ca. eight days and a decrease in egg hatch by about 10 %, C. montrouzieri females fed moth eggs accepted the synthetic wadding as an oviposition substrate and deposited the same number of eggs their counterparts maintained on mealybugs. A mixture of E. kuehniella eggs with pollen yielded similar developmental and reproductive rates as E. kuehniella eggs alone, but a diet of bee pollen alone was not adequate for the predator. Our findings indicate the potential of a rearing system using E. kuehniella eggs as a factitious food and synthetic wadding as an artificial oviposition substrate for the mass production of C. montrouzieri.     

An enzyme-linked immunosorbent assay to detect alkali-soluble spore surface antigens of strains of Nosema bombycis (Microspora: Nosematidae)

Spore surface antigens of strains of Nosema bombycis were extracted with alkaline solutions and used in an indirect enzyme-linked immunosorbent assay. Treatment of N. bombycis spores with 0.1 n potassium carbonate or potassium hydroxide solution at 27°C for 30 min was sufficient for the extraction of the antigens. Usually, 10⁸ spores of N. bombycis liberated ca. 30 μg spore surface proteins. The indirect enzyme-linked immunosorbent assay detected as little as 60 ng of spore surface proteins (ca. 2000 spore-equivalent antigen). The alkali-soluble spore surface antigens of N. bombycis contained a specific antigen and were stable under storage at −20°C for more than 1 year. The serological assay separated the Nosema isolates pathogenic to the silkworm into three groups.     

Genome-Wide Transcriptional Response of Silkworm (Bombyx mori) to Infection by the Microsporidian Nosema bombycis

Microsporidia have attracted much attention because they infect a variety of species ranging from protists to mammals, including immunocompromised patients with AIDS or cancer. Aside from the study on Nosema ceranae, few works have focused on elucidating the mechanism in host response to microsporidia infection. Nosema bombycis is a pathogen of silkworm pébrine that causes great economic losses to the silkworm industry. Detailed understanding of the host (Bombyx mori) response to infection by N. bombycis is helpful for prevention of this disease. A genome-wide survey of the gene expression profile at 2, 4, 6 and 8 days post-infection by N. bombycis was performed and results showed that 64, 244, 1,328, 1,887 genes were induced, respectively. Up to 124 genes, which are involved in basal metabolism pathways, were modulated. Notably, B. mori genes that play a role in juvenile hormone synthesis and metabolism pathways were induced, suggesting that the host may accumulate JH as a response to infection. Interestingly, N. bombycis can inhibit the silkworm serine protease cascade melanization pathway in hemolymph, which may be due to the secretion of serpins in the microsporidia. N. bombycis also induced up-regulation of several cellular immune factors, in which CTL11 has been suggested to be involved in both spore recognition and immune signal transduction. Microarray and real-time PCR analysis indicated the activation of silkworm Toll and JAK/STAT pathways. The notable up-regulation of antimicrobial peptides, including gloverins, lebocins and moricins, strongly indicated that antimicrobial peptide defense mechanisms were triggered to resist the invasive microsporidia. An analysis of N. bombycis-specific response factors suggested their important roles in anti-microsporidia defense. Overall, this study primarily provides insight into the potential molecular mechanisms for the host-parasite interaction between B. mori and N. bombycis and may provide a foundation for further work on host-parasite interaction between insects and microsporidia.     

Notes onPatasson lameerei [Hym.: Mymaridae], an egg parasitoid ofSitona spp. [Col.: Curculionidae] in the mediterranean region

Patasson lameerei Debauche is the most important of three egg parasitoids found onSitona spp. attacking lucerne and annual medics in the North-Western Mediterranean. The mymarids were lacking in eggs extracted from the soil in Morocco, Algeria and Tunisia. The biology and the behaviour of the egg parasitoid are described. In Central Europe, adults ofP. lameerei are recorded from May to September, but in the Montpellier region (Southern France), this species aestivates in the larval stage within the eggs of its hosts during the same period.     

Eight SNPs of the Myf5 gene and diplotypes associated with growth and reproductive traits in Jinghai yellow chicken

The objective of this study was to analyze possible associations between single nucleotide polymorphisms (SNPs) in the Myf5 gene with chicken growth and reproductive traits. SNPs in Myf5 of the Jinghai yellow chicken were detected by the polymerase chain reaction single-strand conformation polymorphism method and the haplotypes were analyzed. Eight SNPs were identified in the exons of Myf5. Nine haplotypes were established in a group of 379 Jinghai yellow chickens. In terms of growth traits, least square analysis showed that haplotype H1H5 had significant effects on weight at weeks 8 and 12 (P < 0.05). Haplotype H2H6 had significant effects on weight at weeks 12 and 14 (P < 0.05). For reproductive traits, H1H5 had higher body weight for the first egg than H1H4 and H2H4 (P < 0.05), and H1H3 (P < 0.01). H1H3 had a poor performance in average egg weight at 300 days. On the other hand, H1H3 had an advantage in egg number at 300 days. The results showed that SNPs of Myf5 have certain effects on growth and reproductive traits in Jinghai yellow chickens, which can be used in marker-assisted selection to accelerate chicken genetic progress.     

Morphological Features and Hatching Patterns of Eggs in Acartia Steueri (Crustacea, Copepoda) from Sagami Bay, Japan

Morphology, production rate and hatching success of the eggs spawned by Acartia steueri from Sagami Bay, Japan were examined from November 2000 to December 2001. A. steueri produced two morphological types of egg. One with a smooth surface (smooth egg) and the other with branched spines on the envelope (spiny egg). Abundance of adult A. steueri increased from April to June 2001, and then decreased from July 2001. Adult A. steueri were low in abundance between August and October 2001, then increased in November 2001. Smooth eggs were produced through out the study period, while spiny eggs were produced during restricted periods from March to July 2001. Six of thirteen females produced both smooth and spiny eggs within 24 h. All the smooth eggs hatched within 48 h, like the so-called subitaneous eggs. Spiny eggs that did not hatch within the time determined by the Bělehrádek's temperature function of egg development time plus 24 h were categorized as diapausing eggs. In the present study, A. steueri seems to survive by utilizing egg dormancy during the period of environmental adversity, and produced two physiologically different types of eggs. This may be why A. steueri dominants in temperate coastal waters where environmental conditions vary drastically.     

Construction of transformed,cultured silkworm cells and transgenic silkworm using the site-specific integrase system from phage φC31

The Streptomyces bacteriophage, φC31, uses a site-specific integrase enzyme to perform efficient recombination. The recombination system uses specific sequences to integrate exogenous DNA from the phage into a host. The sequences are known as the attP site in the phage and the attB site in the host. The system can be used as a genetic manipulation tool. In this study it has been applied to the transformation of cultured BmN cells and the construction of transgenic Bombyx mori individuals. A plasmid, pSK-attB/Pie1-EGFP/Zeo-PASV40, containing a cassette designed to express a egfp-zeocin fusion gene, was co-transfected into cultured BmN cells with a helper plasmid, pSK-Pie1/NLS-Int/NSL. Expression of the egfp-zeocin fusion gene was driven by an ie-1 promoter, downstream of a φC31 attB site. The helper plasmid encoded the φC31 integrase enzyme, which was flanked by two nuclear localization signals. Expression of the egfp-zeocin fusion gene could be observed in transformed cells. The two plasmids were also transferred into silkworm eggs to obtain transgenic silkworms. Successful integration of the fusion gene was indicated by the detection of green fluorescence, which was emitted by the silkworms. Nucleotide sequence analysis demonstrated that the attB site had been cut, to allow recombination between the attB and endogenous pseudo attP sites in the cultured silkworm cells and silkworm individuals.     

Determination of glassy state by cryo-SEM and DSC in cryopreservation of mint shoot tips by encapsulation–dehydration

Cryopreservation of mint shoot tips grown in vitro (Mentha × piperita) was performed after encapsulation in alginate beads. Encapsulated shoot tips were first precultured in sucrose enriched medium (0.75 M) and then dried under a sterile air flow (0–6 h). After cooling in liquid nitrogen and warming in a warm water bath, alginate beads were transferred to solid culture medium for 4 weeks. The effect of dehydration time of the encapsulated shoots was evaluated for water content, cooling and warming rates, ice crystal formation and cellular vitrification, by using low temperature scanning electron microscopy and differential scanning calorimetry. Viability of the recovered material showed a close relation between the dehydration time, cooling and warming rates, ice formation avoidance and tissue vitrification. At short drying periods (up to 3 h), ice crystals were formed and the viability was low or absent. After longer drying periods (5 and 6 h), both beads and specimens became vitrified.     

Effects of colony size and polyp position on polyp fecundity in the scleractinian coral genus Acropora

This study examined the effects of colony size and polyp position on six variables of polyp fecundity [egg number, egg size, total egg volume, total testis volume, total gonad volume, and gonad ratio (egg volume/testis volume)] in three tabular Acropora corals (Scleractinia), A. hyacinthus, A. japonica, and A. solitaryensis. Samples were collected from various colony sizes (n = 21–30 colonies species^?1), just before the predicted spawning at Kochi, Japan, in 2009. Five replicate polyps were sampled at three positions (center, middle, and outer) from the center to the marginal area in each tabular colony. Results indicated effects of colony size and polyp position on both male and female gonads polyp^?1. A positive effect of colony size was observed on variables of female gonads polyp^?1 (egg number, total egg volume) in A. hyacinthus only, while the positive effect on the variable of male gonads polyp^?1 (total testis volume) was common in all Acropora species, with total testis volume polyp^?1 increasing 2–4-fold from the small (200–400 cm²) to the large size class (5,000–9,000 cm²). Among the polyp positions, lower values were observed mostly in center polyps in A. hyacinthus, while lower values were observed only in outer polyps in the other Acropora species. The distinct patterns between A. hyacinthus and the other two Acropora species suggest different reproductive strategies at the species level. Further studies are needed to confirm the prevalence of these effects in scleractinian corals, which will broaden our understanding of reproductive life history strategies and improve the estimation of reproductive performance.     

Effect of <Emphasis Type="Italic">BBX-B8</Emphasis> overexpression on development,body weight,silk protein synthesis and egg diapause of <Emphasis Type="Italic">Bombyx mori</Emphasis>

Bombyxin (BBX) is an insulin-like peptide exists in the silkworm Bombyx mori. Our previous studies on the effects of inhibiting BBX-B8 expression found that BBX-B8 is important for the development of organ, reproduction and trehalose metabolism in the silkworms. In this paper, we investigated the expression profile of the BBX-B8 gene and effect of BBX-B8 overexpression on the development, body weight, silk protein synthesis and egg diapause of B. mori to further understand BBX-B8 functions. BBX-B8 gene expression could be detected in the brains, midguts, anterior silkglands, ovaries, testes, fat bodies, hemolymph, malpighian tubules and embryos by RT-PCR, however it was mainly expressed in the brain. Western blots showed that the change in BBX-B8 expression was not obvious in the brain of 1- to 4-day-old larvae of fifth instar silkworms, but expression increased substantially at 5- to 6-day-old larvae of fifth instar silkworms. Transgenic silkworms overexpressing BBX-B8 were obtained by introducing non-transposon transgenic vector pIZT-B8 containing a BBX-B8 gene driven by Orgyia pseudotsugata nucleopolyhedrovirus IE2 promoter into the genome. Development duration of the transgenic silkworms was delayed by 2.5–3.5 days. Cocoon shell weight of transgenic silkworms was reduced by 4.79 % in females and 7.44 % in males, pupal weight of transgenic silkworms was reduced 6.75 % in females and 13.83 % in males compared to non-transgenic silkworms, and 5.56–14.29 % of transgenic moths laid nondiapausing eggs. All results indicated that BBX-B8 plays an important role in the development, silk protein synthesis and egg diapause of silkworm.     

Identification of BmELP as an interaction partner of Bmtutl-519 in the silkworm,Bombyx mori

The Turtle protein could act as a signaling receptor or function as a membrane-bound ligand for an unknown receptor. Alternatively, the Turtle protein could function as a co-receptor in a multi-protein receptor complex. Earlier work on the function of Bmtutl-519 suggested that it may act as a cell surface receptor or as a regulatory factor in the infection process of Nosema bombycis. To further investigate the function of Bmtutl-519 in the process of microsporidian infection and the possible regulatory pathways involved, we performed yeast two-hybrid screening on a silkworm midgut cDNA library and identified a Bombyx mori extensin-like protein/BmELP as a binding partner of Bmtutl-519. The interaction between Bmtutl-519 and BmELP was verified by GST pull-down and co-immunoprecipitation assays. Quantitative RT-PCR analysis showed that BmELP was commonly expressed in all of the examined tissues of the silkworm, and the expression was highest in the head. Moreover, BmELP was expressed throughout the entire development period, and the lowest levels of expression were observed at the egg stage. The results of infection experiments showed that N. bombycis infection caused the up-regulation of BmELP expression, especially in vitro. Taken together, our findings may provide new insights into the roles of BmELP and Bmtutl-519 in microsporidian infection.     

Prey range of the predatory ladybird Cryptolaemus montrouzieri

The prey range of Cryptolaemus montrouzieri was studied in the laboratory to investigate whether the mealybug destroyer can contribute to the suppression of other pest insects besides mealybugs and to assess its potential impact on non-mealybug populations as part of an environmental risk assessment for its use in biological control. Prey tested in these experiments were: tobacco aphid Myzus persicae nicotianae (Sulzer)(Hemiptera: Aphididae), pea aphid Acyrthosiphon pisum (Harris)(Hemiptera: Aphididae), tobacco whitefly Bemisia tabaci (Gennadius)(Hemiptera: Aleyrodidae), southern green stinkbug Nezara viridula (L.)(Hemiptera: Pentatomidae) eggs, western flower thrips Frankliniella occidentalis (Pergande)(Thysanoptera: Thripidae), two-spotted ladybird Adalia bipunctata (L.)(Coleoptera: Coccinellidae) eggs and eggs of the greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae). Larval survival was high to moderate when C. montrouzieri was provided with hemipteran prey and poor to zero when the ladybirds were provided with non-hemipteran prey. Females reared on M. persicae and A. pisum produced similar numbers of eggs as their counterparts fed the citrus mealybug Planococcus citri (Risso)(Hemiptera: Pseudococcidae), but fecundity was significantly lower when the ladybirds were reared on B. tabaci nymphs or on A. bipunctata eggs. Prey species that were found to be less suitable for immature development of C. montrouzieri could still be an adequate food source for reproduction and survival of adult ladybirds. For example, only 8 % of the predator larvae reached the adult stage when provided with A. bipunctata eggs, but females that had developed on eggs of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) and that were supplied with A. bipunctata eggs from adult emergence on, were only 35 % less fecund than females provided with mealybugs in their adult life. The results are discussed in relation to the development of a suitable methodology for prey/host range testing in the framework of an environmental risk assessment for arthropod natural enemies.     

The predatory mirid Dicyphus maroccanus as a new potential biological control agent in tomato crops

The first record of the omnivorous predator Dicyphus maroccanus Wagner (Hemiptera: Miridae) inhabiting tomato crops in the Valencia region (East Coast of Spain) was in 2009. Since then, D. maroccanus has often been found preying on the eggs of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in this area. To evaluate this predator’s potential as a biological control agent, its life-history traits in the presence and absence of prey [(eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)] on tomato plants were studied under laboratory conditions. Immature stages that preyed on eggs of E. kuehniella developed successfully. However, no nymph completed development on the plant without the addition of E. kuehniella eggs. To reach adulthood, male and female D. maroccanus nymphs consumed 267 and 312 E. kuehniella eggs, respectively. The net reproductive rate (R₀) was estimated to be 34.52 female eggs per female, the generation time (T) was 40.48 days, and the estimated intrinsic rate of increase (r_m) was 0.0868 females per female per day at 25 °C. In a second experiment, the capacity to detect plants infested or not infested with T. absoluta was studied using a Y-tube olfactometer. Female D. maroccanus were strongly attracted to the odor of T. absoluta-infested plants. In a third experiment, the capacity of D. maroccanus to control T. absoluta on tomato plants was investigated under extended laboratory conditions. Dicyphus maroccanus significantly reduced the number of T. absoluta-infested leaves in over 90 % of cases relative to control conditions. These results suggest that D. maroccanus could play a significant role in T. absoluta management. The potential of this zoophytophagous predator as a biocontrol agent on tomato crops is discussed.     

Characterization of Cryptopygus antarcticus Endo-β-1,4-Glucanase from Bombyx mori Expression Systems

Endo-β-1,4-glucanase (CaCel) from Antarctic springtail, Cryptopygus antarcticus, a cellulase with high activity at low temperature, shows potential industrial use. To obtain sufficient active cellulase for characterization, CaCel gene was expressed in Bombyx mori-baculovirus expression systems. Recombinant CaCel (rCaCel) has been expressed in Escherichia coli (Ec-CaCel) at temperatures below 10 °C, but the expression yield was low. Here, rCaCel with a silkworm secretion signal (Bm-CaCel) was successfully expressed and secreted into pupal hemolymph and purified to near 90 % purity by Ni-affinity chromatography. The yield and specific activity of rCaCel purified from B. mori were estimated at 31 mg/l and 43.2 U/mg, respectively, which is significantly higher than the CaCel yield obtained from E. coli (0.46 mg/l and 35.8 U/mg). The optimal pH and temperature for the rCaCels purified from E. coli and B. mori were 3.5 and 50 °C. Both rCaCels were active at a broad range of pH values and temperatures, and retained more than 30 % of their maximal activity at 0 °C. Oligosaccharide structural analysis revealed that Bm-CaCel contains elaborated N- and O-linked glycans, whereas Ec-CaCel contains putative O-linked glycans. Thermostability of Bm-CaCel from B. mori at 60 °C was higher than that from E. coli, probably due to glycosylation.     

Ontogenetic shift to dependence on salmon-derived nutrients in Dolly Varden char from the Iliamna River,Alaska

The upstream migration, spawning, and death of anadromous, semelparous Pacific salmon brings nutrients to terrestrial and aquatic communities around the Pacific Rim. Many fishes use these resources but the relationship between fish body size and the reliance on salmon-derived nutrients might follow one of several patterns related to the onset of egg consumption with body size as fish grow, and possible shifts to alternative prey such as fishes as they grow larger still. In this study, these size-dependent hypotheses of marine subsidy use by resident Dolly Varden, Salvelinus malma, were tested using diet and stable isotope analyses. S. malma did not shift abruptly to a reliance on salmon eggs after they became large enough to eat eggs (i.e., no gape limitation). Rather, fish large enough to eat eggs but < 150 mm showed diets that blended salmon nutrients with aquatic insects, likely because they were spatially segregated from the highest concentration of spawning sockeye salmon, Oncorhynchus nerka. From intermediate through the largest sizes observed (150 to > 600 mm long) S. malma received ca. 80 % of their nutrients from salmon (eggs, flesh, and maggots that had scavenged dead salmon) based on diet analysis and stable isotope ratios despite being large enough to consume fish, as many similarly-sized salmonids do in other ecosystems. The few fish sampled in June, prior to the availability of salmon subsidies, had stable isotope signatures that also reflected heavy (ca. 90 %) reliance on marine sources, likely because they had eaten little since the end of the salmon run the previous fall. This apparent avoidance of piscivory in favor a rich yet pulsed marine subsidy highlights the importance of healthy salmon runs for the sake of not only the salmon but resident fishes that consume them.     

Estimating the extent of seabird egg depredation by introduced Common Mynas on Ascension Island in the South Atlantic

Common Mynas Acridotheres tristis were introduced to the small, isolated barren island of Ascension in the tropical Atlantic Ocean in the 1880s. The founder population of 52 pairs increased at a rate of 2 % per annum. Mynas cause egg losses in other species by puncturing and consuming eggs, puncturing eggs with no consumption or displacing incubating birds that then desert viable eggs. The principal target seabirds of Mynas on Ascension Island are Sooty Terns Onychoprion fuscatus which number 388,000 birds and constitute 97 % of all seabirds on the island. Five censuses of Mynas and 20 of the Sooty Tern population were carried out between 1994 and 2015, and Myna depredation was monitored on 10 occasions between 2000 and 2008. Of all seabird eggs laid annually, we estimated that 19 % of them were depredated by c. 1000 Mynas. In declining severity of impacts of Mynas on all eggs lost, we estimated that 40 % was attributable to desertion, 39 % to puncturing eggs with no consumption and 21 % to puncturing and consumption. As far as we know, our study is the first to estimate the scale of seabird egg depredation by Mynas. Care is needed when applying our findings to other seabird populations. The scarcity of alternative food sources and the ease of locating high densities of Sooty Tern eggs on Ascension Island may have magnified the frequency of egg depredation by Mynas. That said, it is clear that Mynas are major egg predators and the severity of their impacts on native avian populations can be high.