Small Host Research Articles

Temporal variation of metacommunity structure in arthropod ectoparasites harboured by small mammals: the effects of scale and climatic fluctuations.

We applied the elements of metacommunity structure (EMS) approach and studied the temporal dynamics of metacommunity structure in arthropod ectoparasites (fleas, gamasid mites and ixodid ticks) harboured by six small mammalian hosts sampled for three decades in the same locality in Western Siberia at three hierarchical scales (inframetacommunities, component metacommunities and a compound metacommunity). All metacommunities were positively coherent. Inframetacommunity structures varied across sampling periods in all host species. The main structural pattern in an inframetacommunity of the same host varied across sampling times but was mostly characterized by clumped species distributions (Clementsian, Gleasonian and their quasi-versions). Component metacommunities in five of the six host species were characterized by either a Clementsian or a quasi-Clementsian distribution. In four of the six host species, this pattern was driven by mite distribution. The temporal structure of compound metacommunity was characterized by a Clementsian pattern. In contrast to the majority of component metacommunities, this pattern was driven by fleas, whereas the temporal structure of gamasid mite compound metacommunities demonstrated a Gleasonian distribution. The temporal gradient in infracommunity composition was not associated with temporal changes in either air temperature or precipitation, whereas the precipitation gradient was positively correlated with the structure of component (in five host species) and compound metacommunities. In conclusion, the best-fit metacommunity structure of ectoparasites varies temporally due to temporal changes in distribution patterns that can be associated with year-to-year climatic variation, affecting both hosts and parasites.

INTERLEUKIN-17 RECEPTOR SIGNALING TO PANETH CELLS HELPS MAINTAIN INTESTINAL INTEGRITY AFTER GAMMA RADIATION INDUCED INJURY

Abstract BACKGROUND IL-17A/F signaling through the IL-17RA/RC receptor complex plays a vital role in immunity and inflammation. The expression of IL-17RA/RC by diverse intestinal epithelial cell types including Paneth cells and the observation that therapies neutralizing IL-17A or IL-17RA in Crohn’s disease (CD) patients induce adverse events suggest essential homeostatic functions of this cytokine. Paneth cells and their antimicrobial products (a-defensins, lysozyme etc.) play a critical role in mediating small intestinal host defense under homeostatic conditions as well as after injury or infection, and their dysregulation constitutes a pathogenic factor for CD. The specific role of intestinal IL-17A signaling in Paneth cells to regulate host defense at steady state or after intestinal inflammation remains poorly understood. Thus, we hypothesize that intestinal IL-17A signaling, specifically in Paneth cells, plays an important role in regulating microbiota colonization as well as maintaining intestinal integrity after gamma radiation induced injury. METHODS To examine the importance of IL-17RA signaling to Paneth cells, we utilized total, entire gut epithelium (Il17rafl/fl;villin-cre) and Paneth cell-specific IL-17RA knockout mice (Il17rafl/fl;Defa6-cre+). We subjected these mice with gamma irradiation (1200 cGy) to study intestinal injury and regenerative responses. Mice were sacrificed 3/5 days post irradiation. Terminal ilium was collected from naïve or irradiated mice for immunofluorescence imaging, RT-PCR, RNA sequencing, and enteroid cultures. RESULTS Our preliminary data from irradiated Il17ra-/- and Il17rafl/fl;villin-cre mice suggest that IL-17A signaling is important in maintaining intestinal barrier integrity. Specifically, these mice revealed increased microbial dissemination to liver and spleen compared to their respective control mice. Reduced expression of Lyz1 3 days post radiation in the terminal ileum of Il17ra-/- mice suggest impaired Paneth cell function. Cessation of Paneth cell specific IL-17RA signaling, also resulted in systemic bacterial dissemination 5 days post radiation. We also observed increased level of fecal Lcn2 in irradiated Il17rafl/fl;Defa6-cre+ mice. To understand Paneth cell-specific IL-17RA functions, we performed 16S microbial and RNA sequencing from ileum luminal contents and terminal ilea of naïve Il17rafl/fl;Defa6-cre+/- mice, respectively. While microbial 16s sequencing revealed no change to the overall microbial community, specific changes were observed at a select family level. Specifically, the level of Streptococcaceae was increased. RNA sequencing data showed no difference in Paneth cell antimicrobial peptides but did show reduced Caspase 4 expression in Il17rafl/fl;Defa6-cre+ mice. Collectively, our data revealed an important role of IL-17RA signaling in Paneth cell function at steady state and after injury.

INTERLEUKIN-17 RECEPTOR SIGNALING TO PANETH CELLS HELPS MAINTAIN INTESTINAL INTEGRITY AFTER GAMMA RADIATION INDUCED INJURY

IL-17A/F signaling through the IL-17RA/RC receptor complex plays a vital role in immunity and inflammation. The expression of IL-17RA/RC by diverse intestinal epithelial cell types including Paneth cells and the observation that therapies neutralizing IL-17A or IL-17RA in Crohn’s disease (CD) patients induce adverse events suggest essential homeostatic functions of this cytokine. Paneth cells and their antimicrobial products (a-defensins, lysozyme etc.) play a critical role in mediating small intestinal host defense under homeostatic conditions as well as after injury or infection, and their dysregulation constitutes a pathogenic factor for CD.

LncRNA SNHG12 Inhibition Based on Microsystem Cell Imaging Technology Protects the Endothelium from LPS-Induced Inflammation by Inhibiting the Expression of miR-140-3p Target Gene fndc5.

Acute lung injury (ALI) is a serious disease with a high incidence rate, characterized by uncontrolled inflammation and apoptosis. At present, long-chain noncoding RNA (lncRNA) is a noncoding RNA with a length of more than 200 nucleotides. It plays an important role in ALI, cell cycle regulation, cell differentiation regulation, and many other life activities. Therefore, the current focus is to identify and evaluate the possible functions and potential molecular mechanisms of lncRNA small nuclear host gene 12 (SNHG12). Lipopolysaccharide (LPS)-induced mice model and in vitro cell model were established. Gene knockout is to use the principle of DNA homologous recombination to replace the target gene fragment with the designed homologous fragment, so as to achieve the purpose of gene knockout. The relationship between lncRNA SNHG12 expression and ALI was studied through knockdown and overexpression experiments. The qRT-PCR, ROS, immunohistochemistry, histopathology, TUNEL, and cell permeability tests were performed to further verify the possible targets and mechanisms of action. The expression of lncRNA SNHG12 in lung tissue was lower than that in normal tissue. The results showed that lncRNA SNHG12 could reduce lung cell injury and inflammatory cytokines induced by ALI. Bioinformatics analysis showed that lncRNA SNHG12 interacted with miR-140-3p. Subsequent experiments confirmed the link between lncRNA SNHG12, miR-140-3p, and fndc5. Furthermore, this study indicates that lncRNA SNHG12 has a key function in ALI. The results of this study demonstrated the role of lncRNA SNHG12 in the pathological process of ALI and provided a reference for developing novel anti-ALI treatments so that patients can get timely treatment, avoid causing multiple organ failure, and will not endanger their life safety.

SNHG6 203 RNA May be Involved in the Cell Cycle Progression in HER2-Negative Breast Cancer Cells.

Background & Objective:Long noncoding RNAs (lncRNAs) as challenging molecules are more known than those in the last decade. These transcripts have been validated for carcinogenesis in many types of tissue. Functions of lncRNAs in cancer induction include cell cycle, epithelial to mesenchymal transition progression, apoptosis inhibition, cell migration, and invasion stimulation. LncRNA small nucleolar host gene 6 (SNHG6) have been proven as an oncogenic transcript in many types of cancer. Methods:RNA extraction was performed for 47 breast specimens in patients with cancer and cDNAs were synthesized. Relative expression of target variants was determined by qPCR and calculated based on the ΔΔCt method. SNHG6 203 was cloned into pcDNA 3.1+ vector for overexpression in MCF7 (HER2-) and SK-BR3 (HER2+) cells. The cell cycle progression of transfected cells was assessed by flow cytometry. Cell migration ability of transfected cells was evaluated by the scratch method and Image J software. Finally, cell viability was assessed by the MTT method.Results:Among four splice variants of SNHG6 (202, 203, 204, and 207), SNHG6 203 was proved as an overexpressed splice variant in breast tumors. This transcript was expressed in HER2-negative breast tumors more frequently than in the positive ones. Overexpression of this variant in target cells resulted in cell cycle progression of MCF7 as HER2-negative cells. Moreover, the overexpression of SNHG6 203 led to lower migration ability of MCF7 cells and a non-significant reduction of their viability as HER2-negative breast cancer cells. Conclusion:Our results revealed that SNHG6 203 may be involved in the carcinogenesis of HER2-negative breast cancers via cell cycle progression.

LncRNA SNHG6 Silencing Could Arrest Progression of High Grade Colorectal Cancers.

Background & Objective:Colorectal cancer (CRC), like other cancers, needs faster and more accurate identifications. A well-timed prognosis of CRC could be an important turning point in the survival of patients. Supplementary signs, such as long non-coding RNAs (lncRNAs), could be helpful for this purpose. A new possible biomarker for CRC identification is introduced by this study. Methods: RNA extraction was performed by the RNX-Plus solution for 64 tumor and non-tumor tissues. Complementary DNAs (cDNAs) were synthesized, and quantitative real-time PCR was performed for relative expression level measurement and the data was analyzed statistically using the Prism 6 software. For Small nucleolar host gene 6 knockdown, siRNA was designed based on Reynolds rules. The cells were cultured in their appropriate media, and the siRNA-lipofectamine complex was formed. The transfection complex was presented for sw48, sw480, and sw1116 as CRC cells with different grades. After transfection, the SNHG6/β actin ratio was determined. Then, the distribution of siRNA-treated cells was determined by the Partec flow cytometer instrument and analyzed by the FloMax software.Results:SNHG6 was more expressed in CRC tumors than non-tumor tissues. In tumor tissues, SNHG6 upregulation and tumors’ grade progression were concurrent. SNHG6 was upregulated in cases with lymphovascular invasion than in cases with perineural invasion. The knockdown of SNHG6 conduced to G1 arrest in CRC cells, more noticeably in high-grade ones. Conclusion:SNHG6 could be applied as a consideration to differentiate tumor and non-tumor tissues and grade definition in colorectal malignancies, and it could participate in colorectal tumor formation as a cell cycle progressive factor.

Emergence of Ixodes scapularis (Acari: Ixodidae) in a Small Mammal Population in a Coastal Oak-Pine Forest, Maine, USA.

In the United States, surveillance has been key to tracking spatiotemporal emergence of blacklegged ticks [Ixodes scapularis Say (Ixodida:Ixodidae)] and their pathogens such as Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner (Spirochaetales: Spirochaetaceae), the agent of Lyme disease. On the Holt Research Forest in midcoastal Maine, collection of feeding ticks from live-trapped small mammal hosts allowed us to track the emergence and establishment of I. scapularis, 1989-2019. From 1989-1995, we collected only I. angustus Neumann (Ixodida: Ixodidae)(vole tick), Dermacentor variabilis Say (Ixodida: Ixodidae) (American dog tick), and I. marxi Banks (Ixodida: Ixodidae) (squirrel tick) from seven species of small mammals. The most abundant tick host was the white-footed mouse [Peromyscus leucopus Rafinesque (Rodentia:Cricetidae)] followed by the red-backed vole (Myodes gapperi Vigors (Rodentia: Cricetidae)). Emergence of I. scapularis was signaled via the appearance of subadult I. scapularis in 1996. Emergence of B. burgdorferi was signaled through its appearance in I. scapularis feeding on mice in 2005. There was a substantial increase in I. scapularis prevalence (proportion of hosts parasitized) and burdens (ticks/host) on white-footed mice and red-backed voles in 2007. The ~11-yr time-to-establishment for I. scapularis was consistent with that seen in other studies. White-footed mice comprised 65.9% of all captures and hosted 94.1% of the total I. scapularis burden. The white-footed mouse population fluctuated interannually, but did not trend up as did I. scapularis prevalence and burdens. There were concurrent declines in I. angustus and D. variabilis. We discuss these results in the broader context of regional I. scapularis range expansion.

Population size impacts host-pathogen coevolution.

Ongoing host–pathogen interactions are characterized by rapid coevolutionary changes forcing species to continuously adapt to each other. The interacting species are often defined by finite population sizes. In theory, finite population size limits genetic diversity and compromises the efficiency of selection owing to genetic drift, in turn constraining any rapid coevolutionary responses. To date, however, experimental evidence for such constraints is scarce. The aim of our study was to assess to what extent population size influences the dynamics of host–pathogen coevolution. We used Caenorhabditus elegans and its pathogen Bacillus thuringiensis as a model for experimental coevolution in small and large host populations, as well as in host populations which were periodically forced through a bottleneck. By carefully controlling host population size for 23 host generations, we found that host adaptation was constrained in small populations and to a lesser extent in the bottlenecked populations. As a result, coevolution in large and small populations gave rise to different selection dynamics and produced different patterns of host–pathogen genotype-by-genotype interactions. Our results demonstrate a major influence of host population size on the ability of the antagonists to co-adapt to each other, thereby shaping the dynamics of antagonistic coevolution.

Genetic diversity of Pasteurella multocida isolates of Indian origin

In the current study, correlation among specific capsular types, sequence types and specific hosts were observed. Study proves high diversity with respect to small ruminant isolates belonging to capsular type A. Higher sharing of sequence types among small ruminant, porcine and avian hosts indicate the close association of these isolates getting adapted for diverse host species. The study also shows that CC229, mostly from small ruminant hosts, was genetically related to HS-specific ST122 indicating recent diversification and possibly, similar genotype and pathogenesis.

Phenothiazine dioxide end-capped spiro[fluorene-9,9′- xanthene] as host for efficient blue TADF OLEDs

A spiroconfigured phenothiazine dioxide compound 10-(2- spiro [fluorenyl-9,9′-xanthen])-phenothiazine 5,5-dioxide (SFX-PzO2) was successfully synthesized via C–N cross-coupling with Pd(PPh3)4 as a catalyst, to set up the state-of-the-art models of spiroconfigured phenothiazine dioxide-based small molecular host, which was systemically researched to understand the structure-property relationships deeply to accumulate the increase of device performance rationally and accelerate the commercialization of OLEDs. The high thermal (Td, 394 °C) and morphological stabilities of SFX-PzO2 were obtained due to its rigid spiroconfigured structure and 3D steric hindrance effect. The twisted non-conjugation connection between spiro [fluoren-9,9′-xanthen] and phenothiazine dioxide ensures the compound possesses high triplet energy level (2.87 eV), which is vital to achieve high performance devices. A SFX-PzO2 hosted blue TADF device was achieved as a host with the maximum external quantum efficiency (EQE) and lowest driving voltage of 13.9% and 6.5 V at a luminance of 1000 cd m−2, respectively, for phenothiazine dioxide derivative hosted device.

Automatic barcode gap discovery reveals diverse clades of Rhipicephalus spp. and Haemaphysalis spp. ticks from small mammals in 'Asir, Saudi Arabia

BackgroundThe ixodid tick genera Rhipicephalus and Haemaphysalis contain several species of medical and/or veterinary importance, but their diversity in some regions of the world remains under-explored. For instance, very few modern studies have been performed on the taxonomy of these genera on the Arabian Peninsula.MethodsIn this study, we trapped small mammals in the 'Asir Mountains of south-western Saudi Arabia and collected tick specimens for morphological examination and molecular barcoding, targeting three mitochondrial loci: cox1, 16S rRNA and 12S rRNA.ResultsWe obtained a total of 733 ticks (608 Haemaphysalis spp. and 125 Rhipicephalus spp.) from 75 small mammal hosts belonging to six species. All tick specimens were immature except for nine adults recovered from a hedgehog (Paraechinus aethiopicus). Morphologically, the Rhipicephalus ticks resembled R. camicasi, but the Haemaphysalis ticks showed differences in palp morphology compared with species previously described from Saudi Arabia. Phylogenetic analysis and automatic barcode gap discovery identified a novel clade of Rhipicephalus sp. representing most of the nymphs. This was most closely related to R. leporis, R. guilhoni and R. linnaei. The adult ticks and a small proportion of nymphs clustered with R. camicasi sequences from a previous study. Finally, the Haemaphysalis nymphs formed two distinct clades that were clearly separated from all reference sequences but closest to some African species.ConclusionsThis apparent high level of tick diversity observed in a single study site of only ~ 170 km2, on a relatively small number of hosts, highlights the potential for the discovery of new tick species on the Arabian Peninsula.Graphical

Are birds reliable indicators of most valuable natural areas? Evaluation of special protection areas in the context of habitat protection

Territorial protection of nature in any country is limited by various factors and therefore it is necessary to carefully select protected areas. Currently, they are often selected according to particular indicator taxa because of the simplicity and applicability of this approach. For example, Natura 2000 Special Protection Areas (SPAs) in EU are established to protect selected species of birds. We asked how well do SPAs cover valuable natural habitats, i.e., whether the areas selected for the protection of birds are also important for the conservation of natural habitats. We focused on the Czech Republic because detailed data on habitat composition are available for the whole country. Although SPAs covered only 9% of the whole country they contained disproportionately high part of the whole area of preserved natural habitats (36%). This was because 64% of SPAs area was covered by natural habitats compared to only 11% in the rest of the country. However, the importance of SPAs for different habitats and their formation groups varied significantly. Further, we found a positive relationship between habitat rareness and the proportion of rare habitats within SPAs. Despite their relatively small overall area SPAs host disproportionally large areas of natural habitats in the Czech Republic. This pattern suggests that birds are reliable indicators for territorial protection. SPAs thus show large importance for habitat conservation.

Dark diversity of flea assemblages of small mammalian hosts: effects of environment, host traits and host phylogeny

An assemblage of species in a locality comprises two components, namely (i) species that are present (realised diversity) and (ii) species from the regional pool that may potentially inhabit this locality due to suitable ecological conditions, but that are absent (dark diversity). We investigated factors affecting the dark diversity of component communities of fleas parasitic on small mammals in the northern Palearctic at two scales. First, we considered the dark diversity of flea assemblages of the same host (for 13 host species) across regions and tested for the effects of environmental factors and the number of available host species on the dark diversity of within-region flea assemblages. Second, we considered the dark diversity of fleas across host species within a region (for 20 regions) and asked whether within-host dark diversity is associated with host phylogeny and/or traits. We found that the dark diversity of flea assemblages harboured by small mammals varied substantially (i) within the same host species across space (in 12 of 13 host species) and (ii) between host species within a region (in eight of 20 regions). The size of the dark diversity of flea assemblages of the same host across regions was generally affected by environmental factors (mainly by the amount of green vegetation), whereas the size of the dark diversity of flea assemblages of a host species within a region was affected by host traits (mainly by the degree of host sociality and the structure of its shelter and, to a lesser degree, by its geographic range size) but was not associated with host phylogenetic affinities. We conclude that application of the dark diversity concept to parasite communities across space or hosts allows a better understanding of the factors affecting the species richness and composition of these communities.

Long Noncoding RNA SNHG1 Promotes Lipopolysaccharide-Induced Activation and Inflammation in Microglia via Targeting miR-181b

Introduction: Long noncoding RNA small nuclear host gene 1 (SNHG1) was involved in neuroinflammation in microglial BV-2 cells; however, its interaction with microRNA (miR)-181b in lipopolysaccharide (LPS)-induced BV-2 cells remained poor. Methods: BV-2 cells were treated with LPS and then were subjected to observation on morphology and immunofluorescence staining. After transfection, levels of inflammatory cytokines interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) were determined with enzyme-linked immunosorbent assay (ELISA). The potential binding sites between SNHG1 and miR-181b were confirmed using dual-luciferase reporter assay. Quantitative real-time polymerase chain reaction and Western blot were applied for detecting the mRNA and protein expressions of proinflammatory cytokines, ionized calcium-binding adapter molecule 1 (Iba1), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). Results: LPS led to the morphological changes and activation of BV-2 cells. The transfection of SNHG1 overexpression vector further promoted LPS-induced SNHG1 upregulation, inflammatory cytokines (IL-1β, IL-6, and TNF-α) generation and Iba-1, COX-2, and iNOS expressions, whereas silencing SNHG1 did the opposite. miR-181b functions as a downstream miRNA of SNHG1. In LPS-treated cells, the inhibition of miR-181b induced by SNHG1 promoted inflammation response and the expressions of Iba-1, COX-2, and iNOS. Conclusion: SNHG1 was involved in LPS-induced microglial activation and inflammation response via targeting miR-181b, providing another evidence of the roles of SNHG1 implicated in neuroinflammation of microglia.

Dispersal-based versus niche-based processes as drivers of flea species composition on small mammalian hosts: inferences from species occurrences at large and small scales.

Biological communities may be assembled by both niche-based and dispersal-based (= historic) processes with the relative importance of these processes in community assembly being scale- and context-dependent. To infer whether (a) niche-based or dispersal-based processes play the main role in the assembly of flea communities parasitic on small mammals and whether (b) the main processes of flea community assembly are scale-dependent, we applied a novel permutation-based algorithm (PER-SIMPER) and the dispersal-niche continuum index (DNCI), to data on the species incidence of fleas and their hosts at two spatial scales. At the larger (continental) scale, we analysed flea communities in four biogeographic realms across adjacent continental sections. At the smaller (local) scale, we considered flea communities across two main regions (lowlands and mountains) and seven habitat types within Slovakia. Our analyses demonstrated that species composition of fleas and their small mammalian hosts depended predominantly on historical processes (dispersal) at both scale. This was true for the majority of biogeographic realms at continental scale (except the Nearctic) and both regions at local scale. Nevertheless, strong niche-based assembly mechanism was found in the Nearctic assemblages. At local scale, the intensity of dispersal processes was weaker and niche-driven processes were stronger between habitats within a region than between mountain and lowland regions. We provide historical and ecological explanations for these patterns. We conclude that the assembly of compound flea communities is governed, to a great extent, by the dispersal processes acting on their hosts and, to a lesser extent, by the niche-based processes.

Collaborations, Networks, Failures, Weak Ties

“What are some collaborations if not the marriage of minds,” is one introductory provocation with which Jill Ehnenn confronts the reader of her Women’s Literary Collaboration, Queerness, and Late-Victorian Culture.[1] In 2008, when Ehnenn’s book was published, collaboration had already been the topic of a small host of books, articles, and collections; and scholarship has

Remora optimization algorithm

In this paper, Remora Optimization Algorithm (ROA) is proposed, which is a new bionics-based, natural-inspired, and meta-heuristic algorithm. The inspiration for ROA is mainly due to the parasitic behavior of remora. Different locations are updated in different hosts: In some large hosts, remora feeds on the host's ectoparasites or wreckage and evades natural enemies, for example in the case of giant whales. In some small hosts, remora follows the host to move to the bait-rich area to prey, taking the fast-moving swordfish as an example. In the case of these two update methods, remora also makes some judges based on experience. If it takes the initiative to prey, it updates the host, makes a global update. If it eat around the host, remora does not change the host, and continues to local update. This algorithm is more inclined to provide a new idea for memetic algorithm, because the host in ROA can be reasonably replaced, such as ships, turtles, etc. The above dynamic mode and behavior are simulated mathematically and the validity of the ROA is tested with 29 benchmark questions and 5 actual engineering questions. Parallel comparisons are made with 10 other natural heuristics. The statistical results and comparisons show that ROA provides a very promising prospect and a strong competitive ability compared to other state-of-the-art heuristic techniques.

A functional analysis reveals extremely low redundancy in global mangrove invertebrate fauna

Deforestation results in habitat fragmentation, decreasing diversity, and functional degradation. For mangroves, no data are available on the impact of deforestation on the diversity and functionality of the specialized invertebrate fauna, critical for their functioning. We compiled a global dataset of mangrove invertebrate fauna comprising 364 species from 16 locations, classified into 64 functional entities (FEs). For each location, we calculated taxonomic distinctness (Δ+), functional richness (FRi), functional redundancy (FRe), and functional vulnerability (FVu) to assess functional integrity. Δ+ and FRi were significantly related to air temperature but not to geomorphic characteristics, mirroring the global biodiversity anomaly of mangrove trees. Neither of those two indices was linked to forest area, but both sharply decreased in human-impacted mangroves. About 60% of the locations showed an average FRe < 2, indicating that most of the FEs comprised one species only. Notable exceptions were the Eastern Indian Ocean and west Pacific Ocean locations, but also in this region, 57% of the FEs had no redundancy, placing mangroves among the most vulnerable ecosystems on the planet. Our study shows that despite low redundancy, even small mangrove patches host truly multifunctional faunal assemblages, ultimately underpinning their services. However, our analyses also suggest that even a modest local loss of invertebrate diversity could have significant negative consequences for many mangroves and cascading effects for adjacent ecosystems. This pattern of faunal-mediated ecosystem functionality is crucial for assessing the vulnerability of mangrove forests to anthropogenic impact and provides an approach to planning their effective conservation and restoration.

Reproductive success and progeny sex ratio of a laboratory colony of Anagyrus fusciventris (Hymenoptera: Encyrtidae)

ABSTRACT Anagyrus fusciventris (Girault) is a parasitoid of both Pseudococcus calceolariae (Maskell) and P. longispinus (Targioni Tozzetti), two economically important mealybug pests in New Zealand. A male-biased sex ratio was often observed in a laboratory colony of A. fusciventris. We investigated the effect of mating status on female A. fusciventris longevity, fecundity, progeny sex ratio and the rate of parasitism achieved under controlled laboratory conditions. In addition, the impact of host body size on progeny sex ratio was investigated. The progeny sex ratio of unmated (virgin) females (VF) and two types of mated females (24hM: opportunities for mating limited to 24 h or LtM – lifetime opportunities for mating) was tested under similar conditions. Results indicated that females can be reproductively active within 24 h. On average, 24hM females produced 23% female offspring while LtM females produced 45% females, suggesting that multiple mating is required for a balanced sex ratio. VF produced only male offspring through arrhenotokous parthenogenesis. When reared at 23°C and 16 h photoperiod, VF, 24hM and LtM females lived for 25, 44, 51 days, and parasitised 46, 67 and 87 mealybugs respectively. The average lifetime reproductive output (total number of offspring emerged) of VF, 24hM and LtM females was 41, 58 and 75 offspring, respectively. Female-biased progeny emerged from larger hosts while male-biased progeny often emerged from smaller hosts. Implications of these results are discussed in relation to opportunities to improve the quality of a laboratory colony with a balanced progeny sex ratio.

Life-cycle complexity in helminths: What are the benefits?

Parasitic worms (i.e., helminths) commonly infect multiple hosts in succession. With every transmission step, they risk not infecting the next host and thus dying before reproducing. Given this risk, what are the benefits of complex life cycles? Using a dataset for 973 species of trophically transmitted acanthocephalans, cestodes, and nematodes, we tested whether hosts at the start of a life cycle increase transmission and whether hosts at the end of a life cycle enable growth to larger, more fecund sizes. Helminths with longer life cycles, that is, more successive hosts, infected conspicuously smaller first hosts, slightly larger final hosts, and exploited trophic links with lower predator-prey mass ratios. Smaller first hosts likely facilitate transmission because of their higher abundance and because parasite propagules were the size of their normal food. Bigger definitive hosts likely increase fecundity because parasites grew larger in big hosts, particularly endotherms. Helminths with long life cycles attained larger adult sizes through later maturation, not faster growth. Our results indicate that complex helminth life cycles are ubiquitous because growth and reproduction are highest in large, endothermic hosts that are typically only accessible via small intermediate hosts, that is, the best hosts for growth and transmission are not the same.