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Entomological and epidemiological investigations of malaria transmission in relation to population movements in forest areas of north-west Thailand.

Transmission of forest-related malaria was observed entomologically and epidemiologically for 2 transmission seasons in 1990 and 1991 in 5 villages of Mae Sariang district, Mae Hong Son Province, north-west Thailand. The entomological study included collections of mosquitos and determination of infection rate by using enzyme-linked immunosorbent assay in the residential villages and the farm huts. The epidemiological study included fortnightly visits to 30% of the households to interview and record movement activities and illness of villagers. Circumsporozoite proteins, in most cases of Plasmodium falciparum, were detected in Anopheles minimus species A, An. dirus s.l., An. maculatus s.s. and An. sawadwongporni in residential villages and/or farm huts, suggesting transmission could occur there. Movement of people away from their residences occurred throughout the year for several reasons with a sharp peak in July for agricultural activity, mainly ploughing and planting for rice cultivation. The relative risk of infection for people engaged in agricultural activity was 3 times that of people living in the residential villages. Although a higher biting density of vectors was generally evident at the farm huts, the estimated inoculation rates in the 2 settings were similar. Movement for forest activity increased after harvesting rice in the cool dry season and carried the highest malaria risk, suggesting different epidemiological and probably entomological conditions which need further investigation. The significance is discussed of discrepancies between the case classification system used by this study and that used by malaria sector staff.

Animals↗

[Malaria in the southern sanitary district of Dakar (Senegal). 2. Entomologic data].

To complete a parasitological survey, entomological prospections were carried out in the southern sanitary District of Dakar, the most urbanized of the city and which includes the city centre and the oldest administrative districts. The prospections took place between June 1994 and May 1995 in sites 1.5 km apart, and distributed in such a manner that they covered the entire area. On a monthly basis, female Culicidae were collected in each site at night on human volunteers, followed the next day by the collection of early morning residual fauna in 10 bedrooms located in district concessions. For a total of 308 collections at night on human volunteers and from 1,510 rooms for the residual fauna, 22,901 female Culicidae were caught of which 167 anopheles, corresponding to 0.7%, the remaining 98.5% being Culex quinquefasciatus. This was the species that thus explained the mosquito-nuisance of which the inhabitants of the southern District complained during the period of survey. The female anopheles collected belonged to 2 species, An. arabiensis for 97.6% of those caught and An. pharoensis for 2.4%. An. arabiensis were very slightly represented in the southern District with a density of aggressive females of 0.26 bite/man/night (B/M/N) and a density per room of 0.05 female. The aggressive populations appeared to be relatively important only at the end of the rainy season (September-October) with an average of 0.65 B/M/N in sites located at the periphery of the district with a maximum of 1.33 B/M/N. The highest density of endophilic females registered at the end of the rainy season was 0.1 and its highest value in a given site was 0.36 female/room. The parturity rate of aggressive females was 43.5% and those collected in houses of 84% with an anthropophilic index of 0.98. None of the dissected An. arabiensis females (77.3% of those collected) was a carrier of Plasmodium sporozoites and the circum-sporozoite antigen was not found. A very weak density of An. arabiensis and absence of plasmodial infection among dissected females favoured the absence of malarial transmission in the southern District for the period considered. However malaria transmission could not be absolutely ruled out given the presence of hematozoa carriers, as was revealed by the longitudinal follow-up of a cohort carried out concurrently with the entomological prospections of whom some were residents having declared permanent residence in the city for over two years. This entomological data explain the results of the afore mentioned parasitological survey which, with a registered plasmodic index of 0.3%, means that the southern District can be considered as non endemic. The area is however exposed to the risk of epidemic malaria following an important proliferation of anopheles, which is always possible after heavy rains and flooding and/or an important immigration of persons coming from regions of high malarial endemicity.

Animals↗

Fly pupae and puparia as potential contaminants of forensic entomology samples from sites of body discovery.

Fly pupae and puparia may contaminate forensic entomology samples at death scenes if they have originated not from human remains but from animal carcasses or other decomposing organic material. These contaminants may erroneously lengthen post-mortem interval estimates if no pupae or puparia are genuinely associated with the body. Three forensic entomology case studies are presented, in which contamination either occurred or was suspected. In the first case, blow fly puparia collected near the body were detected as contaminants because the species was inactive both when the body was found and when the deceased was last sighted reliably. The second case illustrates that contamination may be suspected at particularly squalid death scenes because of the likely presence of carcasses or organic material. The third case involves the presence at the body discovery site of numerous potentially contaminating animal carcasses. Soil samples were taken along transects to show that pupae and puparia were clustered around their probable sources.

Animals↗

The detection of toxic substances in entomological specimens.

Entomotoxicology (the study of drugs in insects), a new field of forensic investigations, has still to be precisely defined especially with respect to the toxic substances that can be assessed in entomological specimens. The aim of the present work was to review the relevant entomological publications in order to analyse and describe the various toxic substances that have been detected in biological specimens. Experimental studies have been reviewed separately from case reports. Toxic substances have been classified according to forensic toxicology methodology and on the basis of the chemical and analytical features. This classification will help investigators to identify the compounds that can be found in such biological samples and may stimulate new analytical research investigations. Given the heterogeneity of specimens, the use of non-specific tests (such as immunoenzyme assays) is not recommended and specific and sensitive techniques are suggested. Methods such as GC-MS and HPLC-MS allow the exact identification of the toxic substances and their metabolites.

Animals↗

Social isolation and delayed discovery of bodies in houses: the value of forensic pathology, anthropology, odontology and entomology in the medico-legal investigation.

The bodies of socially isolated people may remain undiscovered in their own houses for prolonged periods. Occasionally the body is in situ for sufficient time to become skeletonised, or partially so. Medico-legal investigation of these cases is complicated by degradation and contamination of evidence. Thus, a multidisciplinary forensic investigation is recommended. The potential contributions of forensic pathology, anthropology, odontology and entomology are outlined here with reference to two cases that occurred in Victoria, Australia, in 2003. Forensic pathologists are often unable to determine the cause of death in skeletonised bodies, however, they may find evidence to support either a natural or unnatural mode of death, and they may describe skeletal pathology or trauma, and identify skeletal features to support radiological identification of the deceased. Anthropologists can provide supplementary evidence of skeletal trauma. Additionally, they can assess age, sex, stature and racial affiliation from skeletal remains. Odontologists can identify individuals through comparison with ante-mortem dental records; however, potential difficulties exist in identifying the treating dentist of a socially isolated person. Odontologists may also examine the teeth and oro-facial skeleton for trauma. Entomologists may estimate minimum death time and/or season of death. Entomological examination of insect remains may also confirm that a body has lain in situ for a considerable period.

Adipose Tissue↗

Activity of the forensic entomology department of the French Gendarmerie.

The criminal research Institute of the French Gendarmerie deals with several disciplines which are part of forensic science. Forensic entomology is one of the last laboratories created in Rosny-Sous-Bois. As with all other departments of the Institute, its main mission is carrying out its expertise on behalf of justice. Another important mission is to educate on one hand the "scene of crime" officers in order to increase the quality of the specimens collected and on the other hand to magistrates to make forensic entomology better known. At last, a research program is available to follow scientific development and to improve services to justice.

Animals↗

History from the ground up: bugs, political economy, and God in Kirby and Spence's Introduction to Entomology (1815-1856).

William Kirby and William Spence's Introduction to Entomology is generally recognized as one of the founding texts of entomological science in English. This essay examines the ideological allegiances of the coauthors of the Introduction. In particular, it analyzes the ideological implications of their divergent opinions on animal instinct. Different vocational pursuits shaped each man's natural history. Spence, a political economist, pursued fact-based science that was shorn of references to religion. Kirby, a Tory High Churchman, placed revelation at the very heart of his natural history. His strong commitment to partisan sectarianism cautions against reference to a homogeneous "natural theology" that was an agent of mediation. Fissures in the "common intellectual context" reached beyond the clash between natural theologians and radical anatomists to render the intellectual edifice of natural theology structurally less sound for the future.

Agriculture↗

Impact of the Internet on entomology teaching and research.

The Internet is affecting entomology teaching and research. Internet tools help students communicate and easily find and access information. Entomology instructors who adopt these tools may discover they are surprisingly time consuming to implement. Requiring students to use the Internet teaches them to glean from the glut of available information and to communicate electronically, both vital skills in today's workplace. The Internet helps meet the growing need for distance education by providing a medium that allows students to conveniently access course materials and to communicate with the instructor and other students. Researchers benefit from using the Internet for one-to-one and one-to-many communication and from access to large cooperative databases, for example, in molecular biology and systematics. Perhaps the greatest impact on research will be the migration to the Web of journals and other specialized research literature. This may permit free access and will change the content and format of journal articles. In the online version of this chapter, the hyperlinks in the Literature Cited section are active.

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Species traits and environmental constraints: entomological research and the history of ecological theory.

The role that entomology has played in the historical (1800s-1970s) development of ecological theories that match species traits with environmental constraints is reviewed along three lineages originating from the ideas of a minister (Malthus TR. 1798. An Essay on the Principle of Population. London: Johnson) and a chemist (Liebig J. 1840. Die Organische Chemie in ihrer Anwendung auf Agricultur und Physiologie. Braunschweig: Vieweg). Major developments in lineage 1 focus on habitat as a filter for species traits, succession, nonequilibrium and equilibrium conditions, and generalizations about the correlation of traits to environmental constraints. In lineage 2, we trace the evolution of the niche concept and focus on ecophysiological traits, biotic interactions, and environmental conditions. Finally, we describe the conceptual route from early demographic studies of human and animal populations to the r-K concept in lineage 3. In the 1970s, the entomologist Southwood merged these three lineages into the "habitat templet concept" (Southwood TRE. 1977. J. Anim. Ecol. 46:337-65), which has stimulated much subsequent research in entomology and general ecology. We conclude that insects have been a far more important resource for the development of ecological theory than previously acknowledged.

Animals↗

[Malaria acquired during entomological research in the Serra do Mar, southeastern region of Brazil].

A focus of malaria was discovered at the beginning of 1993, in the Coastal Range State Park, in the Atlantic Forest area of the State of S. Paulo, Brazil. The entomological research carried out there caused malaria infection by Plasmodium vivax in three workers of the Endemic Research Control Superintendancy (Superintendência de Controle de Endemias - SUCEN), of the State Health Secretariat. It is worth emphasizing that transmission occurred in an area which had been presenting low levels of incidence of the disease; also, the capturers who were undertaking their entomological activities in the area were exposed for an extremely short period of time in one case for only three hours.

Brazil↗

Sampling techniques for adult Afrotropical malaria vectors and their reliability in the estimation of entomological inoculation rate.

Various entomological indicators and sampling techniques are used to monitor and evaluate the impact of many vector control interventions. A number of methods have been used in sampling mosquitoes for the purpose of estimating the entomological inoculation rate (EIR) and each is subject to some bias or shortcomings. It was the aim of this paper to critically evaluate the most common mosquito sampling techniques in relation to their reliability in the estimation of EIR. The techniques include man-landing, light trap, light trap/bednet combination and odour-baited traps. Although man-landing technique is the most reliable, it however, expose the catcher to mosquito-borne infections. On the other hand, light traps have been found to capture mosquitoes with higher sporozoite rates as compared to those from human bait catch thus leading to an overestimation of EIR. From an epidemiological point of view, the use of light-trap-bed net combination is an approach that is more meaningful than using light trap alone because, a light trap functions more efficiently when placed near the normal flight paths of mosquitoes such as inside huts or under the eaves. Unfortunately, it has been shown that estimates of EIR are influenced by trap position, hence affecting the number caught and the sporozoite rates. A variety of bednets have been used to sample mosquitoes attracted to man. Studies have shown that bednet traps normally catch fewer mosquitoes than do human baits outside them. Although the collections by indoor resting technique give a good estimate of the mean house density in a given area, they may not necessarily give a good estimate of EIR. Thus the development of improved sampling systems based on an improved understanding of host-oriented behaviour is needed. Moreover, there is need to standardise all the sampling techniques in use to enable us make valid comparisons between various studies done by different people and in different areas. In this article, the inherent limitations of conventional mosquito sampling techniques when used in estimating the EIR are discussed.

Africa↗

"Spray, Spray, Spray!": insecticides and the making of applied entomology in Canada, 1871-1914.

As insecticides were adopted by Canadian farmers and fruit-growers after 1871, the resources conferred on economic entomology by the Dominion and Ontario governments grew. In 1886, with the establishment of the Experimental Farms system, James Fletcher, the Dominion entomologist and botanist, and his colleagues inherited the task of promoting insecticides to orchardists and others. In 1898-1900, in response to the arrival in Ontario of the San Jose scale, Canada and Ontario adopted laws mandating the use of insecticides, as sprays and fumigants, in orchards and at plant quarantine stations. To meet the resulting demand for trained technicians and scientifically-minded farmers, the institutions of applied entomology federally and at the Ontario Agricultural College were further developed. In 1910, after a decade of rapid diffusion of insecticides, Parliament adopted the Destructive Insects and Pest Act, thus creating a national system of horticultural hygiene.

Agriculture↗

Wildlife forensic entomology: determining time of death in two illegally killed black bear cubs.

Forensic entomology is now commonly used to determine time of death in human death investigations. However, it can be equally applicable to wildlife crimes. This paper describes the use of entomology to determine time of death in the illegal killing of two young bear cubs in Manitoba, Canada. Two cubs were found shot, disemboweled, with their gall bladders removed. Natural Resource officers (Conservation Officers) and a Royal Canadian Mounted Police (R.C.M.P.) officer examined the remains, and the R.C.M.P. officer collected insect evidence. The only insects on the remains were adult blow flies coming to lay eggs and the blow fly eggs themselves (Diptera: Calliphoridae). The time of hatch was recorded and the insects were reared to adulthood. Time of hatch, together with species identification, macro and micro climate and lab developmental data were used to determine the time of death. The time was consistent with the time that the defendants were seen at the scene and was used in their conviction. This case illustrates that insect evidence can be equally as valuable in poaching cases as in homicide cases. However, in most cases Conservation Officers are unaware of this science. It is therefore, extremely important for more Conservation Officers to be educated about this field.

Animals↗

Molecular entomology and prospects for malaria control.

During the past decade, the techniques of molecular and cell biology have been embraced by many scientists doing research on anopheline vectors of malaria parasites. Some of the most important research advances in molecular entomology have concerned the development of sophisticated molecular tools for procedures such as genetic and physical mapping and germ line transformation. Major advances have also been made in the study of specific biological processes such as insect defence against pathogens and the manner in which malaria parasites and their anopheline hosts interact during sporogony. One of the most important highlights of this research trend has been the emergence during the past year of a formal international Anopheles gambiae genome project, which at present includes investigators in several laboratories in Europe and the USA. Although much of this molecular research is directed towards the development of malaria control strategies that are probably many years from implementation, there are some important areas of molecular entomology that may have a more near-term impact on malaria control. We highlight developments over the past decade in three such areas that we believe can make important contributions to the development of near-term malaria control strategies. These areas are anopheline species identification, the detection and monitoring of insecticide susceptibility/resistance in wild anopheline populations and the determination of the genetic structure of anopheline populations.

Animals↗

A statistical analysis of successional patterns in carrion-arthropod assemblages: implications for forensic entomology and determination of the postmortem interval.

A set of statistical protocols is proposed for analyzing carrion-arthropod succession in forensic entomology investigations. A total of 23 carrion-arthropod data sets from temperate, tropical, desert, and coastal environments were assembled in a standard format and analyzed using randomization tests and methods derived from quantitative community ecology. The data were analyzed in three ways. First, patterns of arthropod visitation on nonhuman carcasses were analyzed in each of the 23 cases. Analysis revealed two groups of taxa: those that persist on the carcass over a single time interval (= nonreoccurring taxa, 80% of the taxa) and those that appear, leave, and reappear over time on the carcass (= reoccurring taxa, 20%). Reoccurring taxa, which can confound estimation of the postmortem interval (PMI), were found in 6 classes, 12 orders, and 29 taxonomic families of arthropods, including some forensically important taxa (for example, calliphorids, sarcophagids, histerids). The recognition that reoccurring taxa exist and that they are found in forensically important groups is an early step toward factoring in their potential importance in future entomological investigations. Second, temporal changes in the taxonomic composition of the carrion-arthropod community were studied by quantifying the degree of taxonomic similarity between pairwise combinations of time-specific samples of the succession. In 13 of the 18 illustrated cases, the midsuccessional samples, owing to their higher species richness, were taxonomically more similar to all other pairwise samples, on the average, than early and late successional samples which were poorer in species. Variability in taxonomic composition is the norm for most periods of the succession; however, in 17 of the 23 cases, some successional periods (particularly endpoint samples) revealed no changes in arthropod species composition (= matching sample-pairs). When applied to medicolegal cases, it is suggested that data sets with large fractions of matching sample-pairs should produce wider-ranging PMI estimates, on the average, than data sets with smaller fractions of matching sample-pairs. Third, Monte Carlo simulation was applied to each of the 23 assemblages to test specific hypotheses about community-wide patterns of arthropod visitation times on nonhuman carcasses. Simulation results revealed that arthropod residence times in the majority of cases (13 or 56%) followed a "clumped" succession model, whereas, the remaining 10 cases (44%) showed a more "uniform" spacing pattern of residence times on carcasses. Comparison of species accumulation curves for observed and simulated data further revealed that among the 13 "clumped" cases, most (9 or 69%) followed a "clumped, early" model (rather than "clumped, midterm" or "clumped, late" models).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

An alternative for the extraction and storage of DNA from insects in forensic entomology.

An important area of recent research in forensic entomology has been the use of insect DNA to provide identification of insects for fast and accurate estimation of time since death. This requires DNA to be extracted efficiently and in a state suitable for use in molecular procedures, and then stored on a long-term basis. In this study, Whatman FTA cards were tested for use with the Calliphoridae (Diptera). In particular, testing examined their ability to effectively extract DNA from specimens, and store and provide DNA template in a suitable condition for amplification using the polymerase chain reaction (PCR). The cards provided DNA that was able to be amplified from a variety of life stages, and thus appears to be of sufficient quality and quantity for use in subsequent procedures. FTA cards therefore appear suitable for use with calliphorids, and provide a new method of extraction that is simple and efficient and allows for storage and transportation without refrigeration, consequently simplifying the handling of DNA in forensic entomological cases.

Animals↗