82 research outputs found
Continental comparisons of the interaction between climate and the herbivorous mite, Floracarus perrepae (Acari : Eriophyidae)
The Old World climbing fern, Lygodium microphyllum, is an invasive weed in the Florida Everglades and the leaf roll galling mite, Floracarus perrepae, is a proposed biological control agent. Field studies were conducted for one to two years at sites in its native range in Australia, New Caledonia, and India to evaluate the effect of climate on F perrepae. Monthly counts of the proportion of L. microphyllum subpinnae (leaflets) with leaf roll galls were used to measure the incidence of damage caused by F perrepae. Between sites the most significant weather variable was rainfall 14 to 28 days prior to sampling, with higher levels having a depressive effect on the incidence of leaf rolls. Within sites the mean maximum temperature was the only significant weather variable, showing a decrease in the incidence of leaf rolls above 27 degrees C, and it was predicted that no leaf rolls would form above 35 degrees C. The weather parameters in Homestead, Florida for 2002 were within the range of those evaluated in the eight native range field sites. Thus, we do not predict that climate will prevent the establishment of this biological control agent for L. microphyllum in southern Florida
Automated quantitative MRI volumetry reports support diagnostic interpretation in dementia: a multi-rater, clinical accuracy study
Objectives: We examined whether providing a quantitative report (QReport) of regional brain volumes improves radiologists’ accuracy and confidence in detecting volume loss, and in differentiating Alzheimer’s disease (AD) and frontotemporal dementia (FTD), compared with visual assessment alone. Methods: Our forced-choice multi-rater clinical accuracy study used MRI from 16 AD patients, 14 FTD patients, and 15 healthy controls; age range 52–81. Our QReport was presented to raters with regional grey matter volumes plotted as percentiles against data from a normative population (n = 461). Nine raters with varying radiological experience (3 each: consultants, registrars, ‘non-clinical image analysts’) assessed each case twice (with and without the QReport). Raters were blinded to clinical and demographic information; they classified scans as ‘normal’ or ‘abnormal’ and if ‘abnormal’ as ‘AD’ or ‘FTD’. Results: The QReport improved sensitivity for detecting volume loss and AD across all raters combined (p = 0.015* and p = 0.002*, respectively). Only the consultant group’s accuracy increased significantly when using the QReport (p = 0.02*). Overall, raters’ agreement (Cohen’s κ) with the ‘gold standard’ was not significantly affected by the QReport; only the consultant group improved significantly (κs 0.41➔0.55, p = 0.04*). Cronbach’s alpha for interrater agreement improved from 0.886 to 0.925, corresponding to an improvement from ‘good’ to ‘excellent’. Conclusion: Our QReport referencing single-subject results to normative data alongside visual assessment improved sensitivity, accuracy, and interrater agreement for detecting volume loss. The QReport was most effective in the consultants, suggesting that experience is needed to fully benefit from the additional information provided by quantitative analyses. Key Points: • The use of quantitative report alongside routine visual MRI assessment improves sensitivity and accuracy for detecting volume loss and AD vs visual assessment alone. • Consultant neuroradiologists’ assessment accuracy and agreement (kappa scores) significantly improved with the use of quantitative atrophy reports. • First multi-rater radiological clinical evaluation of visual quantitative MRI atrophy report for use as a diagnostic aid in dementia
How predatory mites cope with the web of their tetranychid prey: a functional view on dorsal chaetotaxy in the Phytoseiidae
Food Webs, Risks of Alien Enemies and Reform of Biological Control
As ilwasions of alien species mount, biological control will become an increasingly important tool of conservation and agriculture. In an effort to understand indirect interactions in biological control, we review food web ecology in terms of resource competition, trophic cascades, intraguild predation, apparent competition, omnivory and a diverse set of tritrophic interactions. The most inclusive study suggests that food webs in biological control are simpler than in natural communities. Risks to non-target species created by biological control have been studied seriously for only about 20 years, and knowledge of these risks is incomplete. The greatest risks are known to be posed by the organisms with the broadest diets, such as vertebrates and the snail Euglandina rosea, which has probably caused the extinction of an entire genus of native snails in Polynesia. Some parasitoid species have been introduced that are sufficiently polyphagous to attack native insects, and cases of serious harm to non-target populations are now coming to light. However, polyphagous organisms continue to be imported for biological control. One case in point is the campaign against the Russian wheat aphid, in which over 8.5 million individual invertebrates, including more than 1 million individuals of 12 species of ladybird beetles new to North America, were released over the past 15 years, with little study of potential non-target effects, direct or indirect. Another case is the new use of the polyphagous black carp for suppression of pest snails in industrial catfish ponds. This fish poses great risks to the high native diversity of molluscs in the Mississippi drainage. We argue that risk to native flora in biological control of weeds can be judged before introduction. For the New World, the lowest non-target risk comes from stenophagous insects released against weeds with no native congeners. When weeds have native congeners, introductions of even relatively stenophagous insects have led to the use of non-target, native plants
Trace fossils at the basal Upper Greensand (Albian, Cretaceous) unconformity surface in east Devon (southwest England) and the nature of the unconformity surface
Along the east Devon coast the early Cretaceous Upper Greensand Formation rests unconformably on bioturbated firmground and hardground surfaces on mid-Triassic to early Jurassic rocks (Mercia Mudstone Group to Lias Group). The classification and interpretation of the burrows and borings preserved on and beneath these surfaces are discussed, and compared with those from similar bioturbated surfaces elsewhere in Europe. In east Devon, the nature of the preservation of these trace fossils is dependent not only on the nature of the substrate but also on that of the infilling materials. These range from poorly defined, irregular infillings composed of pebbly mudstone to well-defined casts of cemented fine-grained sandstone that preserve detailed external ornaments. The most prominent trace fossils recorded are regularly spaced, flask-shaped Gastrochaenolites ornatus Kelly & Bromley produced by an as yet unidentified bivalve that rotated during penetration. At Branscombe, where the Upper Greensand rests on Triassic mudstones, many of the crypts are ellipsoidal to subhemispheroidal in cross-section. Their producer(s) are also enigmatic. Some infillings contain fragments of Myopholas or Girardotia, bivalves that rotate during penetration of soft to firm substrates. These burrows were probably initiated above the unconformity surface and extended down into an already perforated and softened mudstone surface. A few burrows may be due to a burrowing coelenterate. Bioturbation at the sub-Albian unconformity is ubiquitous in southern and eastern England, and indicates that the erosion surface was available for colonization for a considerable period of time
Continental comparisons of the interaction between climate and the herbivorous mite, Floracarus perrepae (Acari : Eriophyidae)
The Old World climbing fern, Lygodium microphyllum, is an invasive weed in the Florida Everglades and the leaf roll galling mite, Floracarus perrepae, is a proposed biological control agent. Field studies were conducted for one to two years at sites in its native range in Australia, New Caledonia, and India to evaluate the effect of climate on F perrepae. Monthly counts of the proportion of L. microphyllum subpinnae (leaflets) with leaf roll galls were used to measure the incidence of damage caused by F perrepae. Between sites the most significant weather variable was rainfall 14 to 28 days prior to sampling, with higher levels having a depressive effect on the incidence of leaf rolls. Within sites the mean maximum temperature was the only significant weather variable, showing a decrease in the incidence of leaf rolls above 27 degrees C, and it was predicted that no leaf rolls would form above 35 degrees C. The weather parameters in Homestead, Florida for 2002 were within the range of those evaluated in the eight native range field sites. Thus, we do not predict that climate will prevent the establishment of this biological control agent for L. microphyllum in southern Florida
The genetic diversity, relationships, and potential for biological control of the lobate lac scale, Paratachardina pseudolobata Kondo & Gullan (Hemiptera: Coccoidea: Kerriidae)
The lobate lac scale Paratachardina pseudolobata Kondo & Gullan (Kerriidae) is a polyphagous pest of woody plants in Florida (U.S.A.) the Bahamas, Christmas Island (Australia) and it has been reported from Cuba. Its recent appearance as a pest in these places indicates that this scale is introduced; however, its native range is unknown. Until 2006, this pest species was identified mistakenly as Paratachardina lobata (Chamberlin) [now P. silvestri (Mahdihassan)], which is native to India and Sri Lanka. Quarantine laboratory acceptance trials with Indian P. silvestri parasitoids indicated a strong immune response from P. pseudolobata. Gregarious development of encyrtid wasps was the only observed parasitism, but parasitization levels were below 3%. Identification of the native range of P. pseudolobata would facilitate the search for natural enemies better adapted to the scale. Sequence data from the D2–D3 region of the nuclear large subunit ribosomal RNA gene (LSU rRNA, 28S) and the mitochondrial gene cytochrome oxidase I (COI) distinguished P. pseudolobata from the morphologically similar species P. silvestri and P. mahdihassani Kondo & Gullan, and showed P. pseudolobata to be more closely related to these Indotropical species than to an Australian species of Paratachardina Balachowsky. Paratachardina pseudolobata was genetically uniform throughout its exotic range, consistent with a single geographic origin, although lack of variation in these genes is not unusual for scale insects. Molecular identification of morphologically similar Paratachardina species was possible using the D2–D3 region of 28S, despite its length variation, suggesting that this gene region might be suitable as a non-COI barcoding gene for scale insects
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