Evidence Of Negative Interaction Research Articles

Adding a Natural Enemy to Respond to Pest Immigration and Delayed Natural Enemy Releases in Augmentative Biological Control.

Whether increased natural enemy density or adding a second natural enemy species will provide superior pest suppression in greenhouse augmentative biological control is unknown for many commercially available natural enemy species. In this study, we use sweetpotato whiteflies, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), on poinsettias, Euphorbia pulcherrima Willd. ex Klotzsch (Malpighiales: Euphorbiaceae), to determine whether adding Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) to Eretmocerus eremicus Rose and Zolnerowich (Hymenoptera: Aphelinidae) is better for B. tabaci suppression compared with either natural enemy alone, both with and without challenges with whitefly immigration or delayed natural enemy releases. The number of whiteflies on caged poinsettias treated with different natural enemy release rates (single or double rate), natural enemy species (one or two species), natural enemy delayed release (weeks 4 and 8), and whitefly immigration treatments (introduced at week 4 or week 8) was censused biweekly for 16 wk. Both species used in combination provided similar or better suppression of whiteflies compared with either natural enemy alone. Both species combined also provided superior suppression of whiteflies when challenged with whitefly immigration or delays in natural enemy releases compared with E. eremicus alone. Whitefly immigration or delays in E. eremicus releases did not increase whitefly populations, suggesting that suppression of whiteflies by E. eremicus alone is relatively robust. This study found no evidence for negative interactions between E. eremicus and A. swirskii for suppressing B. tabaci.

Pack hunting by a common soil amoeba on nematodes.

Soils host the most complex communities on Earth, including the most diverse and abundant eukaryotes, i.e. heterotrophic protists. Protists are generally considered as bacterivores, but evidence for negative interactions with nematodes both from laboratory and field studies exist. However, direct impacts of protists on nematodes remain unknown. We isolated the soil-borne testate amoeba Cryptodifflugia operculata and found a highly specialized and effective pack-hunting strategy to prey on bacterivorous nematodes. Enhanced reproduction in presence of prey nematodes suggests a beneficial predatory life history of these omnivorous soil amoebae. Cryptodifflugia operculata appears to selectively impact the nematode community composition as reductions of nematode numbers were species specific. Furthermore, we investigated 12 soil metatranscriptomes from five distinct locations throughout Europe for 18S ribosomal RNA transcripts of C. operculata. The presence of C. operculata transcripts in all samples, representing up to 4% of the active protist community, indicates a potential ecological importance of nematophagy performed by C. operculata in soil food webs. The unique pack-hunting strategy on nematodes that was previously unknown from protists, together with molecular evidence that these pack hunters are likely to be abundant and widespread in soils, imply a considerable importance of the hitherto neglected trophic link 'nematophagous protists' in soil food webs.

Shared resources between giant panda and sympatric wild and domestic mammals

Interactions between sympatric species may negatively affect a species’ fitness, and complicate management of species assemblages in protected areas. An example of the need to quantify the strength and direction of the species interactions is giant panda conservation in newly established reserves. Although the habitat requirements of giant panda have been broadly studied, the degree of its interactions with sympatric large mammals remains unclear. In this paper, we systematically surveyed for species occurrence in the southwestern China during 2008–2013, to better understand the interactions between giant panda and four sympatric large mammal species. We constructed species-specific occupancy models based on camera-trapping data using both environmental and detection variables. We then used the important predictor variables for each species to construct pairwise species co-occurrence models following a Bayesian framework. Our analysis detected significant habitat overlap between giant panda and its sympatric species. However, there was no evidence of native species limiting the distribution of giant pandas despite their extensive use of the same forests. The only evidence for negative interactions was between the distributions of giant panda and domestic cattle within bamboo forest, the primary habitat of giant pandas. The co-occurrence model has value for any conservation planning that benefits from knowledge of inter-species interactions. Our study suggests that, in southwestern China, strict grazing control of domestic cattle in protected areas is warranted until the nature of its interactions with native large mammals can be determined.

Habitat variation and invasive species as factors influencing the distribution of native fishes in the lower Fraser River Valley, British Columbia, with an emphasis on brassy minnow (Hybognathus hankinsoni)

Brassy minnow (Hybognathus hankinsoni Hubbs, 1929) have disjunct distributions in western Canada, making them a species of conservation concern. We assessed changes in the distribution of invasive species as factors influencing the distribution of brassy minnow and other native species by comparing historical and current distributions in the lower Fraser River in British Columbia. We tested effects of physical habitat parameters on local distributions of brassy minnow and for evidence of negative interactions between brassy minnow and invasive brown bullhead (Ameiurus nebulosus (Lesueur, 1819)). Comparison of contemporary and historical (1956 and 1959) fish distributions indicated significant declines in native cypriniform (minnows and suckers) species, including brassy minnow, but no change in the number of invasive species, although there was some faunal turnover. Logistic regression suggested that conductivity, turbidity, and water temperature were important predictors of brassy minnow presence. Appearances of adult-sized brown bullhead at one site corresponded with reduced abundance of native fishes. In growth experiments with brassy minnow, brown bullhead, and redside shiner (Richardsonius balteatus (Richardson, 1836)), brassy minnow exhibited mass loss and mortalities, suggesting that they were poor competitors. Our results contribute to a better understanding of abiotic and biotic factors affecting distribution and persistence of brassy minnow.

The role of South African traditional health practitioners in the treatment of HIV/AIDS; A study of their practices and use of herbal medicines

Background
 A large proportion of HIV positive South Africans regularly consult Traditional Health Practitioners (THPs) for their healthcare needs, despite some evidence of negative interactions with antiretrovirals (ARVs) and no published peer-reviewed clinical evidence for the efficacy of traditional medicines in the treatment of HIV. In this study, we investigated the dominant practices of THPs towards HIV positive patients and whether these practices have changed following widespread public awareness campaigns covering HIV and its treatment.
 
 Method
 The study used a semi-structured interviewer-administered questionnaire in the home language of the interviewee. A total of 52 THPs from four provinces (Gauteng, Limpopo, Kwazulu Natal and Eastern Cape) were interviewed. 38% of the respondents were based in the rural areas, and 69% classified themselves as inyangas, with the remainder being sangomas. 
 
 Findings
 All of the THPs in the survey offered treatment for HIV, although only 20% claimed to be able to cure the disease. 88% prepared their own medication, mostly from plant material, and sold their products as aqueous extracts in labelled bottles. None of these products had been systematically evaluated, and there was mostly no record keeping, either of the patient, or of the medicine itself. Quality control practices such as expiry dates, controlled storage conditions and batch records were totally unknown in our sample. Only 38% of the THPs had received training on HIV/AIDS although 75% believed that they were well informed about the disease. Our own assessment was that only 50% had a working knowledge of HIV; more disturbingly 37% believe that only traditional medicines should be used for the treatment of HIV and a further 50% believe that both traditional medicines and ARVs can be taken simultaneously.
 
 Interpretation
 Despite ongoing public educational campaigns on HIV, some of which have specifically targeted THPs, the care of HIV positive patients continues to be compromised by the traditional sector. Although some progress is evident, THP approaches to HIV treatment fails to conform to minimum standards proposed by the World Health Organisation and other organisations, and represents a considerable challenge to the integration of THPs with the biomedical sector, and with the antiretroviral treatment programme in South Africa.

Supplementing iron and zinc: double blind, randomized evaluation of separate or combined delivery

Many children have diets deficient in both iron and zinc, but there has been some evidence of negative interactions when they are supplemented together. The optimal delivery approach would maximize clinical benefits of both nutrients. We studied the effectiveness of different iron and zinc supplement delivery approaches to improve diarrhea and anemia in a rural Bangladesh population. Randomized, double blind, placebo-controlled factorial community trial. Iron supplementation alone increased diarrhea, but adding zinc, separately or together, attenuated these harmful effects. Combined zinc and iron was as effective as iron alone for iron outcomes. All supplements were vomited <1% of the time, but combined iron and zinc were vomited significantly more than any of the other supplements. Children receiving zinc and iron (together or separately) had fewer hospitalizations. Separating delivery of iron and zinc may have some additional benefit in stunted children. Separate and combined administration of iron and zinc are equally effective for reducing diarrhea, hospitalizations and improving iron outcomes. There may be some benefit in separate administration in stunted children.

How Does Nutrient Availability Affect the Population Dynamics of the Invasive New Zealand Mud Snail (Potamopyrgus Antipodarum)?

A primary goal of invasion biology is to predict which introduced species become invasive and which systems are susceptible to invasion. Therefore it is vital to understand how invasive species sustain positive population growth rates in their introduced range and what environmental factors control population growth. The New Zealand mud snail (Potamopyrgus antipodarum) (Figure 1.) has spread throughout Europe, Australia, and North America, and has reached pest densities in many streams in the Greater Yellowstone Area (GYA) since their introduction in the 1980‘s. High rates of growth and secondary production have been documented for mud snails in its introduced range in the GYA, as have evidence of negative interactions between mud snails and native macroinvertebrates and higher trophic levels. However, little is known about how the availability of nutrients affects the invasion success of mud snails.

Interactions among predators and phytophagous mites on apple; possible impact on biocontrol of Panonychus ulmi by Typhlodromus pyri in orchards

Laboratory experiments were conducted to determine the potential impact of the phytoseiid Euseius finlandicus, the mirid Blepharidopterus angulatus and the anthocorid Orius majusculus on the Typhlodromus pyri/Panonychus ulmi predator/prey relationship on apple. Euseius finlandicus consumed more immature spider mites than did T. pyri. When both phytoseiids were present and spider mite prey was abundant, there was no evidence of a negative interaction between the predators. In experiments where each predatory mite was confined with large numbers of the other predator, interspecific predation was exhibited by adults of each species on immatures of the other, but more so by E. finlandicus. In the predatory insect/phytoseiid experiments, when confined with spider mites and large numbers of T. pyri, both B. angulatus and O. majusculus consumed some T. pyri, but spider mites were the preferred prey. In experiments with B. angulatus, O. majusculus and T. pyri feeding on P. ulmi, there was no evidence of negative interactions between the predatory insects and T. pyri.

SPATIAL PATTERNS AND DYNAMIC INTERACTIONS AMONG RACCOONS IN EASTERN KANSAS

Abstract We report on intrasexual spatial patterns and dynamic interactions of northern raccoons in eastern Kansas. In general, extensive spatial overlap occurred among female and male dyads in each season and among age classes. The dynamic interaction test revealed positive interaction among 5 of 9 male dyads, and no evidence of negative interaction. Some male dyads denned and traveled together for intervals of varying lengths (2 to 16 days) in each season of the year. There was no evidence of dynamic interaction among female dyads. We provide additional evidence that social behavior of male raccoons exhibits geographic variation, and some level of sociality might be more common than currently described for this species.

Resource utilization and interspecific relations of sympatric bobcats and coyotes

We used scat analysis and radiotelemetry to characterize use of foods and habitats by sympatric bobcats and coyotes, and evaluated these in the context of spatial and temporal relationships to assess the potential for, and evidence of, interspecific competition. Bobcats and coyotes exhibited broad and overlapping diets. However, diets of the two predators differed in the relative contributions of small and large prey, with bobcats consuming relatively more rodent and lagomorph biomass and coyotes consuming relatively more ungulate biomass. Consumption among rodent prey species was highly correlated between bobcats and coyotes, indicating no evidence of prey partitioning within this group. Habitat selection by the two predators differed slightly at the landscape scale but not within home ranges. Bobcats and coyotes occupied small, overlapping home ranges, such that the likelihood of interspecific encounters (direct or indirect) was high. Bobcats displayed slight avoidance of overlapping coyote core areas during coyote reproductive seasons (winter and spring), when coyotes are typically most territorial (toward conspecifics), but displayed slight attraction during times of year when coyotes were not engaged in reproductive activities. Relative to coyotes, which were strongly nocturnal, diel activity patterns of bobcats were more diurnal and variable. However, activity patterns were not inversely correlated. Overall, these predators appeared to use resources independently and we found little evidence of negative interactions. Differences in resource use by bobcats and coyotes appeared to relate to fundamental niche differences as opposed to competition‐related resource partitioning.

Stable Parasite Guilds: Coccidia in Spermophiline Rodents

A guild of six species of intestinal protozoan (Apicomplexa: Eimeriidae) was monitored in 496 live-trapped Wyoming ground squirrels (Spermophilus elegans) in two populations in 1989 and 1990. Three species were present at high levels (>40% of all squirrels infected at any time) and three at low levels (<20% infected) in both populations within and across years. Results of logistic regression indicated that age of individual was a key parameter in predicting infection within each of the species. For the common species, adults had a higher probability of infection than juveniles and the observed number of reinfections in recaptured squirrels was slightly greater than predicted. For the three rare species, juveniles had a higher probability of infection than adults and there was a slight decrease in probability of reinfection. Over the two years, time of sampling had no effect on probability of infection. There was no evidence for negative interactions (competition) between guild members but several positive interactions were noted. This eimerian guild appears stable within these populations and we hypothesize that the three prevalent species are commensals (little or no effect on host fitness) and the three low prevalence species have a greater effect on host fitness (parasite). Further, some species of this assemblage also infect two other species of sciurids sympatric with the Wyoming ground squirrel. The processes important in structuring this assemblage may include the differential immune response of the host animals to the different eimerian species, the non-limiting resource base (the intestinal epithelia), the high reproductive capacities of the eimerian species, the varying ability of infective oocysts for each species to persist under ambient environmental conditions, the high colonization rates of host populations, and the ability of the symbionts to infect sympatric host species.

The Behaviour and Survival of Rehabilitated Hedgehogs (Erinaceus Europaeus)

AbstractFull ‘rehabilitation’ of sick and injured wild animals should include restoration to the wild. Few attempts have been made to discover the fate of released ‘rehabilitated’ animals, a significant omission in terms of animal welfare. They may die, unable to find adequate food or nest sites in unfamiliar places. They may be ostracized or even attacked by wild resident conspecifics.Eight ‘rehabilitated’ hedgehogs (Erinaceus europaeus) were released into farmland and radio-tracked to monitor their movements and nesting; they were also weighed frequently. Three wild hedgehogs caught on site were studied in parallel.Only one animal remained close to the release site throughout the eight week study. The rest scattered, perhaps seeking more familiar terrain. One animal died, possibly not having fully recovered from its original disorder. Of the seven others, three survived at least seven weeks, but two then met with accidental deaths (drowning and road kill). Contact was lost with four animals, but circumstances suggested that they were probably still alive at least five weeks after release. There was no evidence of negative interaction with local wild hedgehogs nor any indication of difficulty with foraging, nesting or finding their nests again. Body-weights were generally maintained or increased. It is concluded that rehabilitated adult hedgehogs can probably cope well with release.

Lime-phosphorus interactions in the growth of temperate pasture species on highly-weathered soils

Lime and phosphorus (P) requirements for the growth of temperate pasture species on acid, well-drained soils in the Natal Midlands were evaluated in factorial field trials. Species studied were white clover (Trifolium repens), tall fescue (Festuca arundinacea) and Italian ryegrass (Lolium multiflorum). All three species exhibited large yield responses to lime and P. In addition, evidence for both positive and negative lime-P interactions was present in dry matter production data. Positive interactions, exhibited during the establishment phase of growth of white clover and Italian ryegrass, appeared to be restricted to conditions of severe P deficiency. Yield data of all species contained evidence of negative interactions, which occurred at more favourable levels of P supply. Negative interactions reflect a decrease in response to P with increasing lime supply (to salt pH values of approximately 5.5). The latter interactions are of major importance from a practical standpoint since they imply a ‘trade-off’...

Recent developments in the psychotherapy of depression

The effectiveness of several types of psychotherapy for ambulatory, nonpsychotic depressed patients has been demonstrated in controlled clinical studies. Psychotherapy combined with antidepressant drug treatment appears to be the most effective form of treatment for most outpatients with major depression, although either treatment alone can be effective for patients who will not accept both. There is no evidence for negative interactions between psychotherapy and drug treatment. Interpersonal psychotherapy, cognitive therapy, and intensive psychodynamic cognitive therapy are types of individual psychotherapy that appear to have particular relevance for depression.