349 research outputs found
Predicting the potential geographical distribution of the harlequin ladybird, Harmonia axyridis, using the CLIMEX model - BioControl
Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) is a ladybird beetle native to temperate and subtropical parts of Asia. Since 1916 populations of this species have been introduced throughout the world, either deliberately, or by accident through international transport. Harmonia axyridis was originally released as a classical biological control agent of aphid and coccid pests in orchards and forests, but since 1994 it is also available as a commercial product for augmentative control in field and greenhouse crops. It is a very voracious and effective natural enemy of aphids, psyllids and coccids in various agricultural and horticultural habitats and forests. During the past 20 years, however, it has successfully invaded non-target habitats in North America (since 1988), Europe (1999) and South America (2001) respectively in a short period of time, attacking a wide range of non-pest species in different insect orders. Becoming part of the agricultural commercial pathway, it is prone to being introduced into large areas across the world by accident. We use the CLIMEX programme (v2) to predict the potential geographical distribution of H. axyridis by means of matching the climate of its region of origin with other regions in the world and taking in account biological characteristics of the species. Establishment and spread seem likely in many regions across the world, including those areas which H. axyridis has already invaded (temperate Europe, North America). Based on the CLIMEX prediction a large part of Mediterranean Europe, South America, Africa, Australia and New Zealand seem highly suitable for long-term survival of H. axyridis as well. In addition we evaluate CLIMEX as a strategic tool for estimating establishment potential as part of an environmental risk assessment procedure for biological control agents we discuss biological and ecological aspects necessary to fine-tune its establishment and spread in areas after it has been introduce
Flying for life : wing dimorphism in closely related species of the genus Calathus (Coleoptera: Carabidae)
Factors governing wing dimorphism in ground beetles (Coleoptera: Carabidae) of the Calathus melanocephalus complex have been studied in relation to dispersal by flight. In Western Europe this complex consists of three well-defined species, as was shown by cross-breeding experiments and morphological studies: Calathus cinctus Motschulsky (= C. erythroderus Gemminger & Harold), Calathus melanocephalus (Linnaeus) and Calathus mollis (Marsham). The synonymy of Calathus erythroderus with C.cinctus was established. To stabilize the nomenclature of the species involved lectotypes were designated for Carabus melanocephalus Linnaeus and Carabus mollis Marsham. Action undertaken to conserve the specific name of Carabus mollis Marsham was approved by the International Commission on Zoological Nomenclature. Data on morphology, life history and distribution of the three species involved were listed and an identification key is included.Calathus cinctus and C. melanocephalus are wing-dimorphic with either strongly reduced wings (short winged or brachypterous) or fully developed wings (long winged or macropterous), whereas C . mollis is always macropterous. Long winged beetles are considered potential flyers, representing the dispersal morph of these species. Populations of C. cinctus and C. melanocephalus showed different proportions of long winged beetles.Wing dimorphism in Calathus cinctus and C . melanocephalus was found to be genetically determined and to be inherited in a simple Mendelian fashion with brachyptery dominant to macroptery. In C.cinctus the long winged genotype is always expressed, whereas in C . melanocephalus the expression of the long winged genotype is under environmental control. It was shown that at least temperature and food-supply affected the expression of the long winged genotype in C.melanocephalus: more favourable temperatures (i.e. relatively high temperatures) and a higher food-supply resulted in a higher number of long winged beetles compared with less favourable temperatures (i.e. both low and extremely high temperatures) and a lower food-supply.Wing-morph frequencies in populations of wing-dimorphic species may also be affected by differences in fitness between short and long winged beetles. Fecundity (egg production and oviposition period), development time, and growth were studied in this respect.In both Calathus cinctus and C.melanocephalus long winged females showed a significantly higher egg production than short winged females, and they also tended to produce eggs during a longer period. Considerable differences in fecundity were observed between the species: the highest egg production was found in Calathus cinctus, a species with a late start and a long oviposition period, and the lowest egg production was found in C . mollis, a species with an early start and a comparably long oviposition period. Calathus melanocephalus showed an egg production intermediate between those of C . cinctus and C.mollis, with an early start and a relatively short oviposition period.In all three species development times were generally shorter at higher temperatures and longer at lower temperatures, but in both Calathus cinctus and C . melanocephalus a general relationship between temperature and development time was found neither for wing-morph nor for sex. Development time and growth of long winged genotypes of Calathus melanocephalus were strongly influenced by food- supply: with a higher food-supply shorter development times and higher hatching weights were found. Long winged beetles of both sexes developed faster and were heavier than short winged ones reared under similar conditions, and females weighed more than males.Under laboratory conditions both long winged males and females of the three species studied built up functional flight muscles and were capable of flight. Flight activity in the field, however, was only observed in Calathus cinctus. Building up flight muscles, flight, and subsequent resorption of flight muscles only occurred in the pre- oviposition period, but mating and even ovarian development may occur during the flight period too.The dispersal abilities of the three species studied are supposed to be different because there are large differences in flight potential between the species. In Calathus cinctus and C.melanocephalus only part of the individuals is long winged and has flight potential, whereas in Calathus mollis all individuals have this ability. Moreover, in Calathus cinctus the long winged genotype, and so the potential for flight, is always expressed, whereas in C . melanocephalus the expression of the long winged genotype depends on environmental conditions, such as temperature and food- supply, and therefore the flight potential for flight is partly expressed only.Differences in flight potential were clearly associated with differences in life histories and habitat selection. Calathus cinctus occupies temporary habitats, showing a high potential for flight and a high turnover of populations, whereas C . melanocephalus occurs in less temporary habitats, showing a much lower potential for flight and a relatively low turnover of populations. Calathus mollis inhabits coastal dunes and blowing sands, showing a maximum potential for flight, obviously to keep pace with changes in this extreme environment.The higher fecundity of long winged females, closely linked with larger body size and higher weight, is considered to benefit the colonization abilities of the species.The wing-morph determination found in Calathus cinctus and C . melanocephalus fitted the current model, but a trade-off between flightlessness and fecundity was not found. Both flight capability and high fecundity are considered to represent closely linked characters of species adapted to unstable, temporary habitats.Wing dimorphism is supposed to be maintained by a 'balance' between the loss of long winged genotypes by flight activities and the frequency of successful (re)colonizations. In Calathus cinctus both the loss of long winged genotypes and the colonization success is supposed to be high (a short term, opportunistic 'strategy'), whereas in C . melanocephalus both the loss of long winged genotypes and the colonization success is supposed to be low. However, in the latter species the maintenance of wing dimorphism is favoured by the environmental control of the expression of long winged genotypes (a long term, more ensuring 'strategy')
Influence of Conversion and Anastomotic Leakage on Survival in Rectal Cancer Surgery; Retrospective Cross-sectional Study
Background Conversion and anastomotic leakage in colorectal cancer surgery have been suggested to have a negative impact on long-term oncologic outcomes. The aim of this study in a large Dutch national cohort was to analyze the influence of conversion and anastomotic leakage on long-term oncologic outcome in rectal cancer surgery. Methods Patients were selected from a retrospective cross-sectional snapshot study. Patients with a benign lesion, distant metastasis, or unknown tumor or metastasis status were excluded. Overall (OS) and disease-free survival (DFS) were compared between laparoscopic, converted, and open surgery as well as between patients with and without anastomotic leakage. Results Out of a database of 2095 patients, 638 patients were eligible for inclusion in the laparoscopic, 752 in the open, and 107 in the conversion group. A total of 746 patients met the inclusion criteria and underwent low anterior resection with primary anastomosis, including 106 (14.2%) with anastomotic leakage. OS and DFS were significantly shorter in the conversion compared to the laparoscopic group (p = 0.025 and p = 0.001, respectively) as well as in anastomotic leakage compared to patients without anastomotic leakage (p = 0.002 and p = 0.024, respectively). In multivariable analysis, anastomotic leakage was an independent predictor of OS (hazard ratio 2.167, 95% confidence interval 1.322-3.551) and DFS (1.592, 1077-2.353). Conversion was an independent predictor of DFS (1.525, 1.071-2.172), but not of OS. Conclusion Technical difficulties during laparoscopic rectal cancer surgery, as reflected by conversion, as well as anastomotic leakage have a negative prognostic impact, underlining the need to improve both aspects in rectal cancer surgery
Adjustment disorder in cancer patients after treatment:Prevalence and acceptance of psychological treatment
PURPOSE: To investigate the prevalence of adjustment disorder (AD) among cancer patients and the acceptance of psychological treatment, in relation to sociodemographic, clinical, and psychological factors. METHODS: Breast, prostate, and head and neck cancer patients of all stages and treatment modalities (Nâ=â200) participated in this observational study. Patients completed the Hospital Anxiety and Depression Scale, Checklist Individual Strength, Distress Thermometer and problem list. Patients with increased risk on AD based on these questionnaires were scheduled for a diagnostic interview. Patients diagnosed with AD were invited to participate in a randomized controlled trial on the cost-effectiveness of psychological treatment. Participation in this trial was used as a proxy of acceptance of psychological treatment. Logistic regression analyses were used to investigate associated factors. RESULTS: The overall prevalence of AD was estimated at 13.1%. Sensitivity analyses showed prevalence rates of AD of 11.5%, 15.0%, and 23.5%. Acceptance of psychological treatment was estimated at 65%. AD was associated both with being employed (ORâ=â3.3, CIâ=â1.3â8.4) and having a shorter time since diagnosis (ORâ=â0.3, CIâ=â0.1â0.8). CONCLUSION: Taking sensitivity analysis into account, the prevalence of AD among cancer patients is estimated at 13 to 15%, and is related to being employed and having a shorter time since diagnosis. The majority of cancer patients with AD accept psychological treatment
Trees WantedâDead or Alive! Host Selection and Population Dynamics in Tree-Killing Bark Beetles
Bark beetles (Coleoptera: Curculionidae,
Scolytinae) feed and breed in dead or severely weakened
host trees. When their population densities are high, some species aggregate on
healthy host trees so that their defences may be exhausted and the inner bark
successfully colonized, killing the tree in the process. Here we investigate
under what conditions participating with unrelated conspecifics in risky mass
attacks on living trees is an adaptive strategy, and what this can tell us about
bark beetle outbreak dynamics. We find that the outcome of individual host
selection may deviate from the ideal free distribution in a way that facilitates
the emergence of tree-killing (aggressive) behavior, and that any heritability
on traits governing aggressiveness seems likely to exist in a state of flux or
cycles consistent with variability observed in natural populations. This may
have implications for how economically and ecologically important species
respond to environmental changes in climate and landscape (forest) structure.
The population dynamics emerging from individual behavior are complex, capable
of switching between âendemicâ and âepidemicâ regimes
spontaneously or following changes in host availability or resistance. Model
predictions are compared to empirical observations, and we identify some factors
determining the occurrence and self-limitation of epidemics
B-cell receptor-driven MALT1 activity regulates MYC signaling in mantle cell lymphoma.
Mantle cell lymphoma (MCL) is a mature B-cell lymphoma characterized by poor clinical outcome. Recent studies revealed the importance of B-cell receptor (BCR) signaling in maintaining MCL survival. However, it remains unclear which role MALT1, an essential component of the CARD11-BCL10-MALT1 complex that links BCR signaling to the NF-ÎșB pathway, plays in the biology of MCL. Here we show that a subset of MCLs is addicted to MALT1, as its inhibition by either RNA or pharmacologic interference induced cytotoxicity both in vitro and in vivo. Gene expression profiling following MALT1 inhibition demonstrated that MALT1 controls an MYC-driven gene expression network predominantly through increasing MYC protein stability. Thus, our analyses identify a previously unappreciated regulatory mechanism of MYC expression. Investigating primary mouse splenocytes, we could demonstrate that MALT1-induced MYC regulation is not restricted to MCL, but represents a common mechanism. MYC itself is pivotal for MCL survival because its downregulation and pharmacologic inhibition induced cytotoxicity in all MCL models. Collectively, these results provide a strong mechanistic rationale to investigate the therapeutic efficacy of targeting the MALT1-MYC axis in MCL patients
Rapid generation of human B-cell lymphomas via combined expression of Myc and Bcl2 and their use as a preclinical model for biological therapies
Although numerous mouse models of B-cell malignancy have been developed via the enforced expression of defined oncogenic lesions, the feasibility of generating lineage-defined human B-cell malignancies using mice reconstituted with modified human hematopoietic stem cells (HSCs) remains unclear. In fact, whether human cells can be transformed as readily as murine cells by simple oncogene combinations is a subject of considerable debate. Here, we describe the development of humanized mouse model of MYC/BCL2-driven âdouble-hitâ lymphoma. By engrafting human HSCs transduced with the oncogene combination into immunodeficient mice, we generate a fatal B malignancy with complete penetrance. This humanized-MYC/BCL2-model (hMB) accurately recapitulates the histopathological and clinical aspects of steroid-, chemotherapy- and rituximab-resistant human âdouble-hitâ lymphomas that involve the MYC and BCL2 loci. Notably, this model can serve as a platform for the evaluation of antibody-based therapeutics. As a proof of principle, we used this model to show that the anti-CD52 antibody alemtuzumab effectively eliminates lymphoma cells from the spleen, liver and peripheral blood, but not from the brain. The hMB humanized mouse model underscores the synergy of MYC and BCL2 in âdouble-hitâ lymphomas in human patients. Additionally, our findings highlight the utility of humanized mouse models in interrogating therapeutic approaches, particularly human-specific monoclonal antibodies.Kathy and Curt Marble Cancer Research FundSingapore-MIT Alliance for Research and TechnologyNational Institutes of Health (U.S.) (Grant R01-CA128803)Virginia and Daniel K. Ludwig Graduate FellowshipNational Institute of General Medical Sciences (U.S.) (Medical Scientist Training Program Grant T32GM007753)MIT School of Science (Cancer Research Fellowship
No increase in fluctuating asymmetry in ground beetles (Carabidae) as urbanisation progresses
New Species in the Old World: Europe as a Frontier in Biodiversity Exploration, a Test Bed for 21st Century Taxonomy
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