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PubMed2000

Burrowing abilities and swash behavior of three crabs, Emerita analoga Stimpson, Blepharipoda occidentalis Randall, and Lepidopa californica Efford (Anomura, Hippoidea), of exposed sandy beaches.

To investigate factors related to the distribution of intertidal species, and specific predictions of the swash exclusion hypothesis for exposed sandy beaches, we compared the burrowing abilities and swash behavior of three species of anomuran crabs in the superfamily Hippoidea (Emerita analoga, Blepharipoda occidentalis and Lepidopa californica) which commonly inhabit the intertidal and shallow subtidal zones of beaches along the California coast. Burrowing times in the laboratory increased significantly with crab size for all species in five sediment grain sizes ranging from fine sand to gravel (0.15 to 3.24 mm). For each species, burrowing times differed significantly among sand grain sizes, ranging from 0.3 to 21.5 s. Burrowing times for the hippid crab, E. analoga, were relatively constant across sediment types, while those of the albuneid crabs, B. occidentalis and L. californica, were rapid in fine to medium sands, and much slower in coarser sediments. Our results indicate that E. analoga is a substrate generalist while L. californica and B. occidentalis are substrate sensitive. Pre-burrowing times and behavior, distance moved, and burrowing times differed among the species in the swash zone. Combined times of preburrowing and burrowing were shorter than the swash period (6 s) for most E. analoga individuals. Fifty percent of the individuals of L. californica reached the substrate and burrowed in the swash period, while no individuals of B. occidentalis burrowed in that time. Pre-burrowing behavior and time may be valuable in explaining spatial and temporal patterns in the distribution of hippoid crabs on California beaches. Our results support predictions of the swash exclusion hypothesis concerning the burrowing and locomotory abilities of sandy beach macrofauna. The substrate generalist characteristics, and unique orientation and swimming abilities of the hippid crab, E. analoga, in intertidal swash may help explain the success of this species and its congeners, and have important implications for understanding patterns of macrofauna community structure on exposed sandy beaches in California and other regions.

Journal Article↗
PubMed2001

The role of leaf nitrogen content in determining turtlegrass (Thalassia testudinum) grazing by a generalized herbivore in the northeastern Gulf of Mexico.

In shallow marine environments the variability in grazing on seagrasses has been hypothesized to be controlled, in part, by the nutritive quality (i.e., nitrogen content) of their leaves. The few existing studies of the relationship between leaf nitrogen content and seagrass grazing have all found a positive relationship between leaf nitrogen content and preference by selective vertebrate grazers (i.e., the bucktooth parrotfish, green sea turtles, and dugongs). However, most marine herbivores (both vertebrate and invertebrate) are thought to be extreme generalists with broad diets of variable nutritive quality (e.g., detritus, living plants, and animals), suggesting the currently held view on the role leaf nutrient content in explaining the variability of seagrass grazing is an oversimplification.In this study, we evaluated how leaf nitrogen content influenced grazing on turtlegrass by a generalist invertebrate herbivore (the pink sea urchin Lytechinus variegatus) in the northeastern Gulf of Mexico. Using a short-term laboratory test and a longer-term field experiment, we tested the hypothesis that leaf nitrogen content controls sea-urchin grazing on seagrass leaves. We hypothesized that if poor nutritive value of seagrasses is responsible for reduced rates of feeding, then increasing leaf nitrogen concentrations should lead to increased rates of seagrass consumption by sea urchins.In the field experiment, we significantly enriched seagrass leaf nitrogen concentrations (some 10-20% depending on month) in experimental plots with a commercial fertilizer and we manipulated grazing intensity by enclosing adult sea urchins at densities that bracketed the range of average densities observed in the region (i.e., 0, 10 and 20 individuals/m(2)). Comparisons of changes in aboveground seagrass production and biomass showed no evidence that sea urchins grazed significantly more in treatments where leaf nitrogen was enriched. Because the statistical power of our test to detect such differences was low and aboveground seagrass production varied significantly among treatments, we also used a mass balance equation to estimate sea urchin consumption of nitrogen-enriched and unenriched leaves. This showed that sea urchins compensated for low nitrogen levels in our unenriched treatments by eating more leaves than in treatments where leaf nitrogen was elevated. Using a laboratory test, we also found that sea urchins ate less nitrogen-enriched seagrass than unenriched seagrass. In combination, these results show that, in contrast to findings reported for vertebrate herbivores, sea urchins feed at higher rates when offered seagrass leaves of lower leaf nitrogen content, and that low levels of leaf nitrogen are not always an effective defense against herbivores.

Journal Article↗
PubMed1998

Modeling the future workforce of obstetrics and gynecology.

OBJECTIVE: To examine the current supply and distribution of obstetrician-gynecologists and project future supply under various scenarios. METHODS: A discrete actuarial supply model was developed, and practice patterns were analyzed. Supply projections under different scenarios, distributions, and practice profiles were examined. RESULTS: Women are expected to become the majority of practitioners by 2014. Continuation of current residency output will result in slow to no growth in obstetrician-gynecologist-to-female population ratios over the next 20 years. A minor (10%) reduction in specialty training would slow specialty growth over the next decade, followed by a slight reduction in supply. Services provided chiefly involve ambulatory reproductive health care, pregnancy, and surgical correction of conditions specific to the female genitourinary system. Even though the proportion of deliveries performed by midwives has increased and family practitioners have maintained their share, obstetrician-gynecologists provide the vast majority of obstetric care and virtually all services for perinatal complications. Generalist services represent relatively minor aspects of their practices. Care of the aged female population is highly fragmented among specialties; more than 50% of all aged Medicare beneficiaries who saw an obstetrician-gynecologist at least once failed to receive a majority of services from any one physician specialty. CONCLUSION: On the basis of trends in patient demographics and care patterns, obstetrician-gynecologists must resolve whether to provide more generalist office-based care, especially to the rapidly growing older female population, or to invest more intensively in surgical specialty care. The specialty's unique contributions to women's health should influence this decision.

Forecasting↗
PubMedDate not supplied

Neuron types, receptors, behavior, and taste quality.

Neurophysiological studies on chorda tympani (CT) single fibers and behavioral studies on generalization of learned aversions in hamsters (Mesocricetus auratus) are reviewed. The work on hamsters is compared to work on other species, including the laboratory rat and several primate species, including humans. This body of data demonstrates associations between response profiles of physiologically defined specialist CT neurons and behavioral stimulus generalizations on one hand, and characteristics of putative taste receptors, on the other. Response profiles of generalist CT neurons are similarly associated with receptor characteristics, but are not associated with specific behavioral discriminations. The associations of peripheral nerve data with both receptor and behavior strongly suggest specific codes for "sucrose-like" and "NaCl-like" taste qualities. Definitive conclusions regarding "patterns" or "labeled lines" requires an understanding of mechanisms of central neural processing of the several specialist and generalist taste-afferent inputs.

Animals↗
PubMed2003

HIV disease in primary care.

During the past decade, a large number of new drugs for treating HIV and its complications have been developed. The increasingly sophisticated use of these drugs in combination has led to a marked reduction in HIV-related morbidity and mortality in countries where they are available. HIV/AIDS patients receiving treatment are now expected to live into old age. The beneficial effect of HIV treatment has resulted in an expanding population of persons living with HIV/AIDS who will need the care of an HIV specialist because of the complexity of the treatment regimens and the rapidly changing HIV/AIDS knowledge base. However, this growing and aging population will also benefit from the care of a primary care physician. The primary care generalist is in the best position to recognize and diagnose HIV infection, evaluate HIV risk in his or her patient population, and help prevent HIV infection in persons at risk. In patients known to be infected, the primary care generalist will be best able to manage hyperlipidemia, diabetes, cardiovascular disease, and other disorders of an aging population with an increased risk of these and other conditions. Patients with HIV infection frequently accumulate a large number of specialist physicians, and the unique ability of the primary care physician to monitor their care and act as a knowledgeable patient advocate is a great benefit to the patient.

AIDS-Related Opportunistic Infections↗
PubMed2002

The Danish health system through an American lens.

The organization and financing of the Danish health care system was evaluated within the framework of a SWOT analysis (analysis of strengths, weaknesses, opportunities and threats) by a panel of five members with a background in health economics. The evaluation was based on reading an extensive amount of selected documents and literature on the Danish health care system and a 1-week visit to health care authorities, providers and key persons. The present paper includes the main findings by one of the panel members. Primary care is much more accessible in Denmark than the USA. A mixed capitation-fee-for-service method of paying generalist physicians in Denmark ensures that everyone has a primary care physician and generalist physicians are responsive to providing services quickly, typically same-day appointments. An organized off-hours service ensures accessible care 24 h a day, 7 days a week. Denmark has the highest public satisfaction with health care, reflecting the value placed on accessibility of primary care. Inpatient hospital care consumes a disproportionate share of Danish health expenditures. Global hospital budgets provide little incentive for hospital or surgical productivity. Long waits for hospitalization, especially surgical procedures and cancellation of scheduled surgery, are a source of patient dissatisfaction. Women's health, patient health risk counseling and coordination of preventive and primary care are major weaknesses of the Danish health system. Patients have a choice of primary care physician within a given geographic area and may go to a hospital of their choice. However, patient surveys and feedback are underdeveloped and very little effort has been made to make services responsive to patients' preferences. While innovations in electronic prescribing are noteworthy, further development of health information technology is needed.

Delivery of Health Care↗
PubMed1998

Dermatologists meet the primary care standard for first contact management of skin disease.

BACKGROUND: It has been suggested that first contact for skin disease should be the domain of primary care providers because they provide comprehensive services beyond those offered by dermatologists. OBJECTIVE: The purpose of this study was to test the hypothesis that dermatologists do not meet the standards for providing primary care to which generalists are held. METHODS: National Ambulatory Medical Care Survey data from the year 1995 were used to determine the frequency at which counseling and preventive examinations were performed at visits to primary care providers and dermatologists. RESULTS: Counseling and preventive examinations were performed at a minority of visits for skin disease. No counseling was reported at 91% of the visits to primary care providers and at 94% of visits to dermatologists. Preventive examinations other than blood pressure were done at 4.7% of the visits to primary care providers and at 1.5% of visits to dermatologists. CONCLUSION: The standard of primary care for skin disease, as set by the generalist, is attention to the skin disease and not comprehensive medical care. Dermatologists are best able to meet this standard.

Adolescent↗
PubMed2002

Dynamics of change in local physician supply: an ecological perspective.

The purpose of this study is to employ an ecological framework to identify factors that have an impact on change in local physician supply within the USA. A particular specialty type of patient care physicians in a local market is defined as a physician population. Four physician populations are identified: generalists, medical specialists, surgical specialists, and hospital-based specialists. Based on population ecology theory, the proposed framework explains the growth of a particular physician population by four mechanisms: the intrinsic properties of this physician population; the local market's carrying capacity, which is determined by three environmental dimensions (munificence, concentration, diversity); competition within the same physician population; and interdependence between different physician populations. Data at the level of Metropolitan Statistical Areas (MSAs) were compiled from the US Area Resources File, the American Hospital Association Annual Surveys of Hospitals, the American Medical Association Census of Medical Groups, the InterStudy National HMO Census, and the US County Business Patterns. Changes in the number and percentage of physicians in a particular specialty population from 1985 to 1994 were regressed, respectively, on 1985-94 changes in the explanatory variables as well as their levels in 1985. The results indicate that the population ecology framework is useful in explaining dynamics of change in the local physician workforce. Variables measuring the three environmental dimensions were found to have significant, and in some cases, differential effects on change in the size of different specialty populations. For example, both hospital consolidation and managed care penetration showed significant positive eflects on growth of the generalist population but suppressing effects on growth of the specialist population. The percentage of physicians in a particular specialty population in 1985 was negatively related to change in the size of that specialty population between 1985 and 1994, suggesting the existence of competition. Overall, the findings of this study facilitate a better understanding of the complexity of physician workforce supply.

Catchment Area, Health↗
PubMed1998

Managed care: future good news or bad news for vascular surgeons.

Recently, William W. McGuire, Chief Executive Officer of United Health-Care, emphasized that the key from the patient's viewpoint is access. He stated, "We use the term gateway rather than gatekeeper." He emphasizes the importance of direct access of the patient to the right physician, whether it be a specialist or a generalist. Although some health care strategists believe that patients should initially see a generalist before receiving specialty care, this approach may not save dollars in the long run. Managed care is likely to have a major impact on vascular surgeons. Currently, business purchasing cooperatives are one model for containing costs of expensive invasive procedures among the working population. Such cooperatives are likely to achieve a stronger penetration in the health care market and to negotiate aggressively for packaged fee contracts for specialized cardiovascular care and procedures. Because the vast majority of vascular patients are more than 65 years of age, the movement of Medicare toward managed care may also affect vascular surgery in a major way. If vascular surgeons are to survive financially in the managed care environment, they must continue to provide evidence-based solutions to clinical problems at a reasonable cost and with good outcomes. They must also understand that involvement in the administrative and political leadership of health care is essential to maintaining some influence on the future reimbursement for our services.

Contract Services↗
PubMed1995

The initial worcester experience with laparoscopic hysterectomy.

STUDY OBJECTIVE: To examine three community hospital's experience with the first 108 attempted laparoscopic hysterectomies. DESIGN: Retrospective analysis of hospital and office charts using a standardized data-collection sheet. SETTING: All procedures were performed at the Medical Center of Central Massachusetts, St. Vincent's Hospital, or the University of Massachusetts Medical School, Worcester, Massachusetts. PATIENTS: The first 108 patients to have a laparoscopic hysterectomy attempted. Ninety procedures were completed successfully. MEASUREMENTS AND MAIN RESULTS: Areas that were analyzed were indications for surgery, type of laparoscopic hysterectomy, surgeons' instrument preference, failure to complete the operation, complications, and relative cost. Surgical indications, patient demographics, and complication rates were comparable with those unpublished papers. However, our data showed no improvement in estimated blood loss or operating room time with increased operator experience. Review of pathology reports indicated no cases in which an unsuspected malignancy was encountered. CONCLUSIONS: Laparoscopic hysterectomy can be performed safely and successfully by generalists in obstetrics and gynecology. Additional study is required to know whether variables such as operating room time and expense will improve as this procedure is increasingly performed by generalists rather than specialists.

Adult↗
PubMed1996

Trends in asthma therapy in the United States: 1965-1992.

BACKGROUND: Many recent studies indicate an increasing morbidity and mortality of asthma in the past two decades. This study uses data from the National Disease and Therapeutic Index (NDTI) to document and analyze trends in drug therapy for asthma in the United States from 1965 through 1992. METHODS: The NDTI maintains a continuous rotating national sampling of approximately 1% of US physicians in office-based practice proportionately representative of practicing generalists and specialists who report issuance of drugs in treatment by diagnosis for all patient encounters for a period of two days every 3 months. Annual summaries of five demographic categories and 14 drug categories, characterizing the asthma patient-physician encounters as percent of visits for the 28-year period of 1965 through 1992 are analyzed and characterized. RESULTS: Physician visits for asthma treatment have shifted somewhat from generalists to specialists in internal medicine and pediatrics. Allergists treat a significant proportion of the asthmatic population. Most patients are seen in the office. There has been no significant change in rates of inpatient visits. Age distribution of the population of patient visits for asthma has been stable, but there is a steady drop in ratio of males to females. Since the mid-1970s, inhaled adrenergic bronchodilator prescriptions have been issued at a markedly increasing rate. Concurrently, issuance of xanthines and oral adrenergic drugs also rose dramatically but then decreased beginning in the mid-1980s. Corticosteroids are used in 15% to 20% of visits, but only recently has the inhaled route of administration shown prominence. Allergen immunotherapy for asthma has decreased more than 10-fold. Cromolyn is prescribed infrequently. CONCLUSIONS: Major changes have occurred in drug treatment by physicians for asthma in the US since 1965. Bronchodilating drugs predominate, and they are being prescribed in more effective forms at a generally increasing rate. Corticosteroid use has increased at a slower rate and in smaller proportion of patient-visits, while allergen immunotherapy has dramatically declined. The male-to-female ratio of asthmatic patients who visit doctors for treatment appears to be decreasing.

Adolescent↗
PubMed2002

The effects of noise on the auditory sensitivity of the bluegill sunfish, Lepomis macrochirus.

As concerns about the effects of underwater anthropogenic noises on the auditory function of organisms increases, it is imperative to assess if all organisms are equally affected by the same noise source. Consequently, auditory capabilities of an organism need to be evaluated and compared interspecifically. Teleost fishes provide excellent models to examine these issues due to their diversity of hearing capabilities. Broadly, fishes can be categorized as hearing specialists (broad hearing frequency range with low auditory thresholds) or hearing generalists (narrower frequency range with higher auditory thresholds). The goal of this study was to examine the immediate effects of white noise exposure (0.3-2.0 kHz, 142 dB re: 1 microPa) and recovery after exposure (1-6 days) on a hearing generalist fish, bluegill sunfish (Lepomis macrochirus). Noise exposure resulted in only a slight, but not statistically significant, elevation in auditory threshold compared to fish not exposed to noise. In combination with results from our previous studies examining effects of noise on a hearing specialist fish, the fathead minnow (Pimephales promelas), this study provides evidence supporting the hypothesis that fish's auditory thresholds can be differentially affected by noise exposure.

Animals↗
PubMed2000

Plant invasions--the role of mutualisms.

Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive. Mutualisms involving animal-mediated pollination and seed dispersal, and symbioses between plant roots and microbiota often facilitate invasions. The spread of many alien plants, particularly woody ones, depends on pollinator mutualisms. Most alien plants are well served by generalist pollinators (insects and birds), and pollinator limitation does not appear to be a major barrier for the spread of introduced plants (special conditions relating to Ficus and orchids are described). Seeds of many of the most notorious plant invaders are dispersed by animals, mainly birds and mammals. Our review supports the view that tightly coevolved, plant-vertebrate seed dispersal systems are extremely rare. Vertebrate-dispersed plants are generally not limited reproductively by the lack of dispersers. Most mycorrhizal plants form associations with arbuscular mycorrhizal fungi which, because of their low specificity, do not seem to play a major role in facilitating or hindering plant invasions (except possibly on remote islands such as the Galapagos which are poor in arbuscular mycorrhizal fungi). The lack of symbionts has, however, been a major barrier for many ectomycorrhizal plants, notably for Pinus spp. in parts of the southern hemisphere. The roles of nitrogen-fixing associations between legumes and rhizobia and between actinorhizal plants and Frankia spp. in promoting or hindering invasions have been virtually ignored in the invasions literature. Symbionts required to induce nitrogen fixation in many plants are extremely widespread, but intentional introductions of symbionts have altered the invasibility of many, if not most, systems. Some of the world's worst invasive alien species only invaded after the introduction of symbionts. Mutualisms in the new environment sometimes re-unite the same species that form partnerships in the native range of the plant. Very often, however, different species are involved, emphasizing the diffuse nature of many (most) mutualisms. Mutualisms in new habitats usually duplicate functions or strategies that exist in the natural range of the plant. Occasionally, mutualisms forge totally novel combinations, with profound implications for the behaviour of the introduced plant in the new environment (examples are seed dispersal mutualisms involving wind-dispersed pines and cockatoos in Australia; and mycorrhizal associations involving plant roots and fungi). Many ecosystems are becoming more susceptible to invasion by introduced plants because: (a) they contain an increasing array of potential mutualistic partners (e.g. generalist frugivores and pollinators, mycorrhizal fungi with wide host ranges, rhizobia strains with infectivity across genera); and (b) conditions conductive for the establishment of various alien/alien synergisms are becoming more abundant. Incorporating perspectives on mutualisms in screening protocols will improve (but not perfect) our ability to predict whether a given plant species could invade a particular habitat.

Animals↗
PubMed1994

The relationship between pattern and scale in parasite communities: a stranger in a strange land.

Problems of pattern and scale are considered in relation to helminth communities of freshwater fish by examining them at different hierarchical taxonomic and spatial scales, with a view to seeking generalizations of heuristic value, assessing the importance of phylogenetic and ecological determinants of community structure and improving understanding of unpredictable communities. Initially, communities were analysed at the level of salmonid genera, focusing on Oncorhynchus, in its heartland in Canada: then in O. mykiss throughout its global range and finally in individual localities to which it has been introduced in Britain. In the heartland, communities are dominated by salmonid specialist helminths, forming a phylogenetic element: the minority ecological element comprises broad generalists and non-salmonid specialists. Most species except generic specialists are shared between host genera. As the distance to which O. mykiss was translocated from its heartland increases, so generic specialists disappear first and then salmonid specialists decline. The community is thus increasingly composed of generalists and it also becomes increasingly poor. Helminths may be acquired from native salmonids and/or unrelated hosts, depending on availability. This same pattern is paralleled in individual localities in a restricted region: the phylogenetic element reflects the native salmonid species present and the ecological element the presence of other genera of fish; i.e., a supply-side situation. The change of scale in analysis has thus enabled the recognition of generalizations and patterns of heuristic value and improved the understanding of unpredictable communities by interpreting local variation as ecological 'noise' that often obscures fundamental patterns. In this and other taxa of fish, phylogenetic elements dominate helminth communities in the heartlands, but ecological elements dominate as the host increasingly becomes a stranger in a strange land.

Animals↗
PubMedDate not supplied

GFscore: a general nonlinear consensus scoring function for high-throughput docking.

Most of the recent published works in the field of docking and scoring protein/ligand complexes have focused on ranking true positives resulting from a Virtual Library Screening (VLS) through the use of a specified or consensus linear scoring function. In this work, we present a methodology to speed up the High Throughput Screening (HTS) process, by allowing focused screens or for hitlist triaging when a prohibitively large number of hits is identified in the primary screen, where we have extended the principle of consensus scoring in a nonlinear neural network manner. This led us to introduce a nonlinear Generalist scoring Function, GFscore, which was trained to discriminate true positives from false positives in a data set of diverse chemical compounds. This original Generalist scoring Function is a combination of the five scoring functions found in the CScore package from Tripos Inc. GFscore eliminates up to 75% of molecules, with a confidence rate of 90%. The final result is a Hit Enrichment in the list of molecules to investigate during a research campaign for biological active compounds where the remaining 25% of molecules would be sent to in vitro screening experiments. GFscore is therefore a powerful tool for the biologist, saving both time and money.

Molecular Structure↗
PubMed2002

Systemic, genotype-specific induction of two herbivore-deterrent iridoid glycosides in Plantago lanceolata L. in response to fungal infection by Diaporthe adunca (Rob.) Niessel.

Iridoid glycosides are a group of terpenoid secondary plant compounds known to deter generalist insect herbivores. In ribwort plantain (Plantago lanceolata), the iridoid glycosides aucubin and catalpol can be induced following damage by insect herbivores. In this study, we investigated whether the same compounds can be induced following infection by the fungal pathogen Diaporthe adunca, the causal agent of a stalk disease in P. lanceolata. Significant induction of aucubin and catalpol was observed in two of the three plant genotypes used in this study following inoculation with the pathogen. In one of the genotypes, induction occurred within 6 hr after inoculation, and no decay was observed within 8 days. The highest level of induction was observed in reproductive tissues (spikes and stalks) where infection took place. In these tissues, iridoid glycoside levels in infected plants were, on average, 97% and 37% higher than the constitutive levels in the corresponding control plants, respectively. Significant induction was also observed in leaves (24%) and roots (17%). In addition to significant genotypic variation in the level of induction, we found genetic variation for the tissue-specific pattern of induction, further broadening the scope for evolutionary fine-tuning of induced responses. Recent studies have revealed a negative association between iridoid glycoside levels in P. lanceolata genotypes and the amount of growth and reproduction of D. adunca that these genotypes support. However, for the three genotypes used in the present study, differences in resistance were not related to their constitutive or induced levels of iridoid glycosides, suggesting that additional resistance mechanisms are important in this host-pathogen system. We conclude that iridoid glycosides in P. lanceolata can be induced both by arthropods and pathogenic micro-organisms. Pathogen infection could, therefore, potentially enhance resistance to generalist insect herbivores in this species.

Adaptation, Physiological↗
PubMed2004

The relationship between dietary specialism and availability of food and water on cannibalistic interactions among predatory mites in protected crops.

The interplay between dietary specialism, the tolerance of food and water stress and level of cannibalism is likely to be important in determining the outcome of biological control using inundative releases of multiple natural enemies, such as phytoseiid mites in protected crops. The dietary specialist, Phytoseiulus persimilis, with a short immature development time (4-5 days) when plentiful food was available had a low ability to survive without food (5 days), even with access to water. The dietary generalists, Neoseiulus californicus, N. cucumeris and lphiseius degenerans, had longer immature development times (by up to 2 days) than P. persimilis. Survival ability differed amongst the generalist species when they were starved but provided with constant access to water. Both N. californicus and N. cucumeris survived the longest (8-10 days) and I. degenerans survived the shortest period (4 days). No negative intra-specific interaction between immatures was observed with P. persimilis when food was available and in the absence of food this species tended to starve rather than act cannibalistically. Both N. californicus and N. cucumeris showed a low degree of cannibalism between immatures, either when food was available, or when starved but given access to water. Even when food was available survival of I. degenerans fell by 30% in 4 days and remained at 60-70% for 3 further days; survival continued to decline rapidly when they were starved but provided with water. This indicates that immatures of I. degenerans could either feed on dead conspecifics or that they were capable of a degree of cannibalism. Adult females of P. persimilis did not feed on conspecific eggs even when deprived of food but provided with water. Adult female N. californicus and N. cucumeris did feed on conspecific eggs but at a low level (<1 egg per day), which occurred only after 48 h starvation. Although egg cannibalism occurred more consistently with adult female I. degenerans than with other mite species it was at a low level (<1 egg per day). If the tendency to cannibalism, not just of eggs but with more susceptible life stages such as larvae, is reduced when water is available freely this could be important in determining the interactions that occur under natural conditions.

Animals↗
PubMed2004

Classifying life-style types of phytoseiid mites: diagnostic traits.

Several traits are useful for identifying life-style types of predaceous phytoseiid mites when either 2 (diet generalist-specialist) or 4 (specialist I and II-generalist III and IV) type models [McMurtry J.A. and Croft B.A. 1997. Annu. Rev. Entomol. 42: 291-321] are considered. Traits useful for both models are developmental time and oviposition rates when feeding on several food types. Discriminating for the 2-types model are dorsal shield setae lengths, and intra- and inter-specific predation. Another trait useful for both models is feeding preferences of adult female phytoseiids on eggs versus larvae of Tetranychus urticae Koch. In this paper, we review established and other traits that need more study such as mouthpart types, other morphological features, spider mite webbing effects, distributions relative to prey-foods, plant-host relationships including domatia and sap feeding, density-dependent responses to prey and predator-prey ratios required for biological control. Uses of life-style data in biological control decision-making are discussed.

Animals↗