[Community participation in the National Program for Transmission Control of Chagas Disease].
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Chagas' disease: control and surveillance through use of insecticides and community participation in Mambaí, Goiás, Brazil.
This article describes the nature and effectiveness of methods developed for longitudinal surveillance and control of Chagas' disease vectors in Mambaí, Brazil. The surveillance effort made use of an education program in the schools, community leader and resident participation, specific surveillance equipment (Gómez-Núñez boxes, instructive posters, and instructive calendars with special detection papers), periodic manual collection of triatomines, and a network of collection posts. Spraying of infested houses was accomplished partly by community leaders who received special training for this purpose. The methods used offer an affordable approach to triatomine surveillance and control well-suited to use in large-scale national programs.
Animals↗
Insecticidal paint and fumigant canisters for Chagas' disease control: community acceptance in Honduras.
This study assessed public acceptance for two new vectorial control techniques for Chagas' disease: insecticidal paint and fumigant canisters. The study compared the two with traditional fenitrothion insecticide spraying. An experimental field study was performed in an endemic area of central Honduras from August to November 1992, a year after the initial application of the treatments. The objectives of the study were to determine the acceptability of the tools on the part of the population whose homes were treated, and on the part of the personnel applying the treatments. The sample size was drawn up according to a uniform protocol applied in six Latin American countries. For this study a total of 651 persons were surveyed in 15 rural communities. Along with the surveys, focus groups were used to collect information to learn the reasons for accepting or rejecting particular treatments. The survey was done with heads of households. Focus groups were done with heads of households and also with the field operators who applied the treatments. The research showed that insecticidal paint had a low level of community acceptance (28.8%). Field operators strongly disliked the paint because of problems with its transport, application, unpleasant smell, and very low effectiveness against triatomines and pest insects. The traditional insecticide was more acceptable to the community (93.9%) and to the field operators, especially for its strong effect against the triatomines and pest insects. The results showed that in order to increase the public acceptance for insecticidal paint, it would be necessary to make the paint easier to transport and apply and to increase its effectiveness. Because of their very low effectiveness, fumigant canisters did not represent an acceptable alternative for triatomine vector control. A public educational effort should be a component of any new control method developed.
Chagas Disease↗
Stably transformed insect cell lines: tools for expression of secreted and membrane-anchored proteins and high-throughput screening platforms for drug and insecticide discovery.
Insect cell-based expression systems are prominent amongst current expression platforms for their ability to express virtually all types of heterologous recombinant proteins. Stably transformed insect cell lines represent an attractive alternative to the baculovirus expression system, particularly for the production of secreted and membrane-anchored proteins. For this reason, transformed insect cell systems are receiving increased attention from the research community and the biotechnology industry. In this article, we review recent developments in the field of insect cell-based expression from two main perspectives, the production of secreted and membrane-anchored proteins and the establishment of novel methodological tools for the identification of bioactive compounds that can be used as research reagents and leads for new pharmaceuticals and insecticides.
Animals↗
Polychlorinated biphenyl- and mercury-associated alterations on benthic invertebrate community structure in a contaminated salt marsh in southeast Georgia.
The community structure of a benthic macroinvertebrate assemblage in a contaminated salt marsh was evaluated as part of an ecological characterization of a former chloralkali production facility in Georgia. Sample locations were chosen based on a gradient of the primary contaminants of concern, total mercury and polychlorinated biphenyls (PCBs), primarily Aroclor 1268. Sediment concentrations of Aroclor 1268 ranged from 2.3 to 150 mg/kg dry weight, while mercury concentrations ranged from 15 to 170 mg/kg dry weight in the study area. Mercury and PCBs were determined to be co-located in the sediments. Total organic carbon composition of the sediments was negatively associated with PCB and mercury concentrations. A total of 29 benthic taxa was identified in 49 samples; replicate samples were taken at each of five sampling locations. Mean infaunal density across all sampling locations was estimated at approximately 61,000 to 234,000 organisms m(-2). Overall, polychaetes comprised 57% of the infaunal community with Manayunkia aestuarina as the dominant species. Oligochaetes, nematodes, crustacea, insects, and gastropods comprised 23.0, 18.0, 1.0, 0.7, and 0.2% of the overall benthic community, respectively. Density estimates of individual species between sampling locations showed no consistent patterns in response to pollutants. However, an analysis of higher taxonomic levels revealed some general trends. In uncontaminated areas, the benthic community was dominated by nematodes and oligochaetes, whereas moderate to highly contaminated areas were dominated by polychaetes and a smaller percentage of oligochaetes and nematodes. A trophic analysis of the same data set revealed that the community shifted from an evenly distributed percentage of surface and subsurface feeders in the uncontaminated areas to a community dominated by surface feeders in the more contaminated locations. Carnivores comprised from 0.13 to 0.90% of the trophic structure, with the percentage of carnivores generally decreasing with increasing contamination. Mercury and PCBs were bioaccumulating in representative marsh benthic invertebrates, presenting a potential source of contaminants to marsh consumers. Tissue PCB and tissue mercury concentrations were positively related to sediment PCB and mercury concentrations, respectively. A standard 14-day toxicity test using the amphipod Leptocheirus plumulosus showed no acute toxicity across the sampling locations.
Animals↗
Induced defensive response of myrtle oak to foliar insect herbivory in ambient and elevated CO2.
The rising level of atmospheric CO2 has stimulated several recent studies attempting to predict the effects of increased CO2 on ecological communities. However, most of these studies have been conducted in the benign conditions of the laboratory and in the absence of herbivores. In the current study, we utilized large octagonal chambers, which enclosed portions of an intact scrub-oak community to investigate the interactive effects of CO2 and insect herbivory on myrtle oak, Quercus myrtifolia. Specifically, we assessed the effects of ambient and elevated CO2 (2x current concentrations) on percent foliar nitrogen, C:N ratio, total relative foliar tannin content, and the presence of leaf damage caused by leaf mining and leaf chewing insects that feed on myrtle oak. Total foliar N declined and C:N ratios increased significantly in oaks in elevated CO2 chambers. The percentages of leaves damaged by either leafminers or leaf chewers tended to be lower in elevated compared to ambient chambers, but they co-occurred on leaves less than expected, regardless of CO2 treatment. Leaves that had been either mined or chewed exhibited a similar wounding or defensive response; they had an average of 25 and 21% higher protein binding ability, which is correlated with tannin concentration, compared to nondamaged control leaves, respectively. While the protein-binding ability (expressed as total percent tannin) of leaves from elevated CO2 was slightly higher than from leaves grown in ambient chambers, this difference was not significant.
Animals↗
Biodiversity and agro-ecology in field margins.
This multidisciplinary study investigates agro-ecological functions (nature conservation, agriculture, environment) and implications of newly created, mown sown and unsown field margin strips installed on ex-arable land to increase biodiversity. From conservational concern, the development of species rich field margin strips was not strongly affected by the installed type of margin strip since species diversity converged over time, whether strips were sown or not. Convergence between unsown and sown margin strips occurred also in terms of species composition: unsown and sown strips became similar over time. Mowing without removal of cuttings significantly reduced species richness, yielded more grassy margin strips and delayed similarity in species composition between sown and unsown margin strips. Species richness on the longer term was not significantly affected by light regime nor by disturbance despite significant temporary effects shortly after the disturbance event. On the contrary vegetation composition in terms of importance of functional groups changed after disturbance: the share of spontaneous species within functional groups increased resulting in higher similarity between the sown and unsown vegetation. Furthermore risk of invasion was highest in the disturbed unsown community on the unshaded side of a tree lane. A positive effect of botanical diversity on insect number and diversity was found. However the effects of botanical diversity on insect number was mediated by light regime. At high light availability differences between plant communities were more pronounced compared to low light availablilty. The abundance of some insect families was dependent on the vegetation composition. Furthermore light availability significantly influenced insect diversity as well as the spatial distribution of families. From agricultural concern, installing margin strips by sowing a species mixture and a mowing regime with removal of cuttings are good practices to diminish the risk of species ingrowth into adjacent crops by creeping roots and rhizomes. Seed dispersal was only problematic one year after the installation of the field margin strips particularly nearby the unsown margin strip and wind-borne seeds were dispersed over limited distances, mainly within 4 m of field margins. Annual herbage yield was not affected by mowing management. DM yield of sown/unsown communities converged over time. Compared to herbage from an intensively managed fertilized grassland, field margin herbage revealed a low feeding value, owing to a low crude protein content, a low digestibility and a high crude fibre content. The unsown community had a higher forage quality than communities sown to bred commercially available grass varieties. Both digestibility and crude protein content decreased over time irrespective of plant community or location. Mid June cuts were more productive than mid September cuts but digestibility and crude protein content was lower. The use of herbage from field margins as hay for horses or as a component in farmland compost are good alternatives. A strong relation was found between the distribution of pest insects and their antagonist families along field margin strips indicating a status of biological equilibrium. From environmental concern, field margin strips buffered boundary vegetation and watercourses against cropped areas loaded with high levels of mineral nitrogen. Margin strips reduced the mineral nitrogen content of the soil in the margin and mineral nitrogen loss during wintermonths. Mineral nitrogen loss was not affected by field margin type but by distance from the field crop. A minimal width of 5 m is necessary to reach an optimal reduction in mineral soil N and N losses.
Agriculture↗
Why are there so many species of herbivorous insects in tropical rainforests?
Despite recent progress in understanding mechanisms of tree species coexistence in tropical forests, a simple explanation for the even more extensive diversity of insects feeding on these plants has been missing. We compared folivorous insects from temperate and tropical trees to test the hypothesis that herbivore species coexistence in more diverse communities could reflect narrow host specificity relative to less diverse communities. Temperate and tropical tree species of comparable phylogenetic distribution supported similar numbers of folivorous insect species, 29.0 +/- 2.2 and 23.5 +/- 1.8 per 100 square meters of foliage, respectively. Host specificity did not differ significantly between community samples, indicating that food resources are not more finely partitioned among folivorous insects in tropical than in temperate forests. These findings suggest that the latitudinal gradient in insect species richness could be a direct function of plant diversity, which increased sevenfold from our temperate to tropical study sites.
Animals↗
Life history and production of stream insects.
Studies of the production of stream insects are now numerous, and general factors controlling the secondary production of stream communities are becoming evident. In this review we focus on how life-history attributes influence the production dynamics of stream insects and other macroinvertebrates. Annual production of macroinvertebrate communities in streams world-wide ranges from approximately 10(0) to 10(3) g dry mass m-2. High levels are reported for communities dominated by filter feeders in temperate streams. Filter feeding enables the accrual and support of high biomass, which drives the very highest production. Frequently disturbed communities in warm-temperate streams are also highly productive. Biomass accrual by macroinvertebrates is limited in these streams, and production is driven by rapid growth rates rather than high biomass. The lowest production, reported for macroinvertebrate communities of cool-temperate and arctic streams, is due to the constraints of low seasonal temperatures and nutrient or food limitation. Geographical bias, paucity of community-wide studies, and limited knowledge of the effects of biotic interactions limit current understanding of mechanisms controlling stream productivity.
Animals↗
Support for the allotonic frequency hypothesis in an insectivorous bat community.
The allotonic frequency hypothesis proposes that certain insectivorous bat species can prey upon moths that can hear bat echolocation calls by using echolocation frequencies outside the sensitivity range of moth ears. The hypothesis predicts that the peak frequencies of bat echolocation calls are correlated with the incidence of moths in the diets of these bats. The aim of this study was to test this prediction on a bat community dominated by bats using low duty cycle echolocation calls, i.e. aerial foraging, insectivorous species using frequency modulated calls. The community consisted of nine species, two molossids, Sauromys petrophillus and Tadarida aegyptiaca, five vespertilionids, Eptesicus capensis, Eptesicus hottentotus, Miniopteris schreibersii, Myotis tricolor, and Myotis lesueuri, one rhinolophid, Rhinolophus clivosus, and one nycterid, Nycteris thebaica. The insect fauna in the habitat used by the bat community was suited to the testing of the allotonic frequency hypothesis because more than 90% of the moths comprising the insect fauna were tympanate. These included Pyralidae (3.8%), Geometridae (44.9%), Notodontidae (3.8%), Arctiidae (4.6%), Lymantriidae (0.8%) and Noctuidae (32.4%). As predicted, peak echolocation frequency was correlated with the incidence of moths in the diets of these nine species (r=0.98, df=7, P<0.01). Furthermore, multivariate analysis revealed that echolocation frequency (t=9.91, n=129, P<0.001) was a better predictor of diet than forearm length (t=5.51, n=129, P<0.001) or wing area (t=-3.41, n=129, P<0.001). This suggests that the selection pressure exerted by moth hearing might have acted directly on call frequency and secondarily on body size and wing morphology, as part of the same adaptive complex. It is unlikely that dietary differences were due to temporal and spatial differences in the availability of prey because the pattern of differences in skull morphology of the nine species supported our dietary analyses. The skull morphology of a bat represents a historical record of the kind of diet it has become adapted to over its evolutionary history. These results suggest that prey defences may mediate other factors structuring bat communities, e.g. competition. Competition may be reduced for those species of bats that can circumvent prey defences.
Acoustics↗
Arthropod community structure in pastures of an island archipelago (Azores): looking for local-regional species richness patterns at fine-scales.
The arthropod species richness of pastures in three Azorean islands was used to examine the relationship between local and regional species richness over two years. Two groups of arthropods, spiders and sucking insects, representing two functionally different but common groups of pasture invertebrates were investigated. The local-regional species richness relationship was assessed over relatively fine scales: quadrats (= local scale) and within pastures (= regional scale). Mean plot species richness was used as a measure of local species richness (= alpha diversity) and regional species richness was estimated at the pasture level (= gamma diversity) with the 'first-order-Jackknife' estimator. Three related issues were addressed: (i). the role of estimated regional species richness and variables operating at the local scale (vegetation structure and diversity) in determining local species richness; (ii). quantification of the relative contributions of alpha and beta diversity to regional diversity using additive partitioning; and (iii). the occurrence of consistent patterns in different years by analysing independently between-year data. Species assemblages of spiders were saturated at the local scale (similar local species richness and increasing beta-diversity in richer regions) and were more dependent on vegetational structure than regional species richness. Sucking insect herbivores, by contrast, exhibited a linear relationship between local and regional species richness, consistent with the proportional sampling model. The patterns were consistent between years. These results imply that for spiders local processes are important, with assemblages in a particular patch being constrained by habitat structure. In contrast, for sucking insects, local processes may be insignificant in structuring communities.
Animals↗
Ethical, legal and social issues of genetically modifying insect vectors for public health.
The use of genetically modified (GM) insects for control of human disease can be consistent with common ethical norms of international society to reduce human suffering. This paper considers a range of ethical issues including animal rights, informed consent, community consensus and environmental viewpoints. Each community needs to decide its own priorities for methodology of disease policy guidance for ethical genetic engineering, and to negotiate with neighbouring countries. The approach to genetically modify insects raises few intrinsic ethical issues; however, important environmental and human health concerns need to be assessed before release of any GM insects. The policy that each community adopts should be the product of open dialogue involving all sectors of society. It can be expected that this process will take years and not all communities will endorse genetic control approaches to insect vectors.
Animal Rights↗
Scaling in stream communities.
Scaling relationships between population density (N) and body size (W), and of their underlying size distributions, can contribute to an understanding of how species use resources as a function of size. In an attempt to resolve the controversy over the form of scaling relationships, an extensive dataset, comprising 602 invertebrate species, was obtained from two geographically separate stream communities (Seebach in Austria and Mynach in Wales). We analysed the temporal consistency of the N-W relationship, which was subjected to ordinary least squares (OLS), bisector (OLS(BIS)) and quantile regressions, and species-size spectra with seasonally collated data. Slopes of seasonal OLS(BIS) regressions did not depart from -1 in either community, indicating a seasonally convergent scaling relationship, which is not energetically constrained. Species-size spectra may scale with habitat complexity, providing an alternative explanation for the observed body-size scaling. In contrast to the right-skewed species-size frequency distributions of single-species assemblages, the size spectra of these benthic communities exhibited 'central tendencies', reflecting their phyletic constitution. The shape of species body-mass spectra differed between the two communities, with a bimodal and seasonally convergent pattern in the Seebach community and a seasonally shifting unimodality in the Mynach community. The body-size spectra of large, mostly insect, species (greater than or equal to 1 mm) scaled to seasonal variations in habitat complexity (i.e. fractal D), suggesting that habitat structure constrains the community organization of stream benthos.
Animals↗
Evaluation of lambdacyhalothrin-impregnated bednets in a malaria endemic area of India. Part 1. Implementation and acceptability of the trial.
In malaria endemic forested villages in Orissa State, India, a 3-year comparison of nylon nets treated with lambdacyhalothrin at 25 mg/m2, untreated nets, and no nets was carried out. Treated nets retained high insecticidal efficacy for more than 7 months. Nets washed after 3 months of use gave 98% kill in a bioassay with a 3-min exposure. Based on these bioassays during the first year, nets were later reimpregnated at 6-monthly intervals with participation of the users. Compliance with the use of nets was good. Eighty-eight percent of nets were usable even after 3 years. The main benefits perceived by treated net users were reductions in malaria, mosquito bites, head louse infestations, and other nuisance insects. The trial was well accepted by the community. Issues related to social marketing and promotion of nets are discussed.
Animals↗
[Community structure and its dynamics of predatory arthropod in different tobacco varieties fields].
With principal component analysis and using community structural characteristic indices, this paper studied the community structure and its dynamics of predatory arthropod in fields planted with tobacco varieties Nc89, Nc82 and K326. The results showed that in all test fields, spiders and predatory insects were the predominant components of the predatory arthropod community, and their relative abundances were 83.25%-86.87% and 13.13%-16.38%, respectively. There was a significant difference in the mean density (individuals per 8 plants) of the most common predatory arthropod groups between different tobacco varieties fields, which was the highest in K326 field, followed by Nc82, and Nc89 field. The individuals of both Linyphiidae and Coccinellidae played the dominant role in the community. There was a significant difference in the richness of predatory arthropod community between Nc89 and Nc82 fields, but the differences of other structural characteristic indices were not significant. The temporal dynamics of the richness and dominancy in all test fields had a trend of low-high-low, and those of the diversity and evenness index were high-low-high.
Animals↗
Bacterial succession in necrotic tissue of agria cactus (Stenocereus gummosus).
The bacterial communities associated with the development of necroses in injured agria cactus tissue were examined in the field by using both human-induced injuries and cactus tissue inoculated with cactophilic bacteria. Whole-cell bacterial fatty acids were used to determine when and where each of 23 detected species occurred. This information was then used to describe successional patterns of bacterial colonization. Although the number of bacterial species in human-induced injuries reached a maximum on day 16, the Shannon-Weaver diversity index increased to a plateau, which reflects a stable bacterial community. The potential of the bacterial community to macerate the injured cactus tissue was also examined, and the results indicate that the bacteria initially colonizing the newly injured cactus tissue were more likely to contain pectinolytic, proteolytic, and lipolytic enzymes than were the bacteria entering the injuries once tissue maceration had already begun. The cactophilic fruit fly Drosophila mojavensis has been previously shown to carry bacteria to newly injured cactus tissue. In these studies, exclusion of these insects did not significantly affect bacterial succession or community structure. This supports our contention that bacteria colonize injured tissue primarily by passive transport, e.g., on wind-blown particles.
Animals↗
Axial differences in community structure of Crenarchaeota and Euryarchaeota in the highly compartmentalized gut of the soil-feeding termite Cubitermes orthognathus.
Methanogenesis represents an important electron sink reaction in the hindgut of soil-feeding termites. This is the first comprehensive analysis of the archaeal community structure within the highly compartmentalized intestinal tract of a humivorous insect, combining clonal analysis and terminal restriction fragment (T-RF) length polymorphism (T-RFLP) fingerprinting of the archaeal communities in the different gut compartments of Cubitermes orthognathus. We found that the morphological and physicochemical heterogeneity of the gut is reflected in a large phylogenetic diversity and pronounced axial differences in the composition of the archaeal gut microbiota, notably among those clones or ribotypes that could be assigned to methanogenic taxa. Comparative analysis of the relative frequencies of different archaeal lineages among the small-subunit rRNA gene (SSU rDNA) clones and their corresponding T-RF indicated that the archaeal community in the anterior, extremely alkaline hindgut compartment (P1) consists mainly of members of the Methanosarcinaceae, whereas Methanobacteriaceae and Methanomicrobiales predominate in the subsequent, more posterior compartments (P3/4a and P4b). The relative abundance of Thermoplasmales increased towards the rectum (P5). SSU rDNA sequences representing Crenarchaeota, which have not yet been reported to occur in the intestinal tracts of arthropods, were detected in all gut sections. We discuss how the spatial distribution of methanogenic populations may be linked to axial heterogeneity in the physicochemical gut conditions and to functional adaptations to their respective ecological niches.
Animals↗
Domestic triatomines (Reduviidae) and insect trypanosome infections in El Salvador, C.A.
Twenty-five Salvadoran communities have been surveyed to learn more about the distribution of Chagas' disease vectors and trypanosome parasites in that country. The results indicate that each of several factors--local variations in housing construction, insecticide applications, geographic elevation, and the vector species involved--can have a critical effect on transmission of the disease agent.
Altitude↗