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Two to 3 ml of Neemos, when applied to the exposed body parts of human volunteers, provided protection for 8 h from the bites of all anopheline species in 2 villages of the Sucre municipality, Bolivar State, Venezuela. Neemos is safe and can be used for protection from malaria in endemic countries.
The ability of antibodies in bloodmeals of mice and hamsters immunized with Leishmania major subcellular fractions and sandfly (Phlebotomus duboscqi) gut antigens to inhibit development of L. major in its vector P. duboscqi was examined. Antibodies from animals immunized with either L. major subcellular fractions alone or sandfly gut antigen alone were not very effective in inhibiting development of L. major in the sandfly. When P. duboscqi were fed on blood from animals immunized with both parasite flagella and sandfly gut antigen, development of L. major was significantly inhibited (P<0,05). Control sandflies fed on naive animals displayed a normal pattern of parasite development to the metacyclic stage. Electron microscopy studies showed that one of the mechanisms through which antisandfly gut antibody can cause inhibition of parasite development is by lysing sandfly gut epithelium. This study has demonstrated that it is possible to reduce transmission of leishmaniosis through immunization against both the parasite and its sandfly vector.
The entomological approach has dominated in the past the geographical--epidemiological study of malaria. Nowadays, new approaches are considering aspects such as representations, attitudes to adopt, change in the transmission process according to the ecosystems. The geographical approach here highlighted implies firstly the knowledge of the geo-epidemiology at the small areas love. This approach should also consider the entomological parameters, the environmental factors and the therapeutic behaviors in order to evaluate the efficiency of the action programmes.
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A tsetse and bovine trypanosomosis survey was conducted during 1998 and 1999 in the Matutuine District of Maputo Province (Mozambique). A total of 59 Glossina brevipalpis and 17 Glossina austeni were captured throughout the district. Survey results suggest that Glossina brevipalpis is mainly concentrated in dense vegetation along the Maputo River and in the wetlands east of the river. G. austeni, on the other hand, was captured mainly in dense thickets in drier areas. Both tsetse species are suspected to be vectors of bovine trypanosomosis. Bovine trypanosomosis (75,5% Trypanosoma congolense) was diagnosed in 53 animals (13,9%) from seven sampling sites distributed throughout the district. The prevalence of cattle with anti-trypanosomal antibodies was high (29,9%). The incidence of trypanosomal infections in sentinel cattle was also high. The widespread distribution of bovine trypanosomosis and the high prevalence of infection are likely to have a significant impact on cattle production and, hence, the cattle restocking exercise in the district.
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Ever since the beginnings of economic entomology in Canada, research in biological control has drawn substantial support from the Federal Department of Agriculture. Enjoying a stable institutional environment with the establishment of the Dominion Parasite Laboratory in Belleville, Ontario, in 1929, biological control has also occupied an important position on the research agenda of the Department until the late sixties. Support from the scientific authorities was nevertheless fraught with important paradoxes. For example, research laboratories in biological control were built at a time when North American economic entomologists relied almost exclusively on synthetic chemical compounds like DDT. For some historians of science, the autonomy of Canadian entomologists explains the growth of this research program in the aftermath of World War II. However, the autonomy of the scientific community is a notion that is taken for granted in these historical explanations. In this article, I will demonstrate the institutional dynamic underlying the autonomy of Canadian entomologists in pursuing a research agenda suited to their interests. I will pay close attention to the role of certain actors -- foreign entomological services and the forest and pulp and paper industries - in the rise of a Canadian expertise in biological control. As well, I will show how their interventions forced a reorganization of research on the biological control of insect pests in agriculture and in forestry, and how this reorganization eventually entailed the dismantling of the Belleville laboratory in 1972.
The effects of the action of extracts from 82 plant species included in 39 families of indigenous flora against the larvae and adults of house fly (Musca domestica), the mosquitoes (Aedes aegypti and Anopheles atroparvus) and the German cockroach (Blattella germanica) are presented. Some of the extracts were prepared from air-dried and ground plant material which was exhaustively extracted with successive solvents of different polarity: ethyl ether, ethyl alcohol and water. Other extracts were prepared either by distillation of the whole water extracts of 24 hours macerated plants or by water extraction from residues of plants remained after distillation. These plant extracts act as toxicants, growth and development and reproduction inhibitors and repellents. The differential responses induced by these plant extracts on assessed insects were influenced by several factors such as the plant species, the solvents used for extractions, the species and the stages of insect life and also the methods employed for evaluation. Some of the tested plants appear to have a great potential for providing safer insect control agents.
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Rabbit antibodies to hemolymph antigens (102.5, 101, 100, 96, 88, 80, 64, 55, 43, 29, and 23 kDa) of Anopheles stephensi reduced fecundity as well as viability in An. stephensi. However, ingestion of these antibodies was not associated with a marked effect on the engorgement of mosquitoes but egg laying was significantly delayed. Antisera raised against hemolymph proteins were also used to identify cross reactive antigens/epitopes present in other tissues by Western blotting, as well as by in vivo ELISA. In addition, a significant reduction in oocyst development was also observed in An. stephensi mosquitoes that ingested anti-hemolymph antibodies along with Plasmodium vivax. The results confirmed the feasibility of targeting mosquito antigens as a novel anti-mosquito strategy, as well as confirmed the usefulness of such antigens for the development of a transmission-blocking vaccine.
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Wild-caught Phlebotomus ariasi Tonnoir permitted to feed on dogs infected with Leishmania infantum Nicolle were marked with fluorescent powder and released into their natural habitat in an uninhabited area of the Cévennes in southern France. Over a period of 29 days after release, 253 females were recaptured with CDC miniature light traps or by active search at night with portable UV lamps. The ovaries and infections in the alimentary tract were then examined. The females oviposited 6 nights after in infecting blood meal. Second blood meals were never taken during the maturation of eggs. During the first ovarian cycle, midgut infections with promastigotes were only moderately heavy. The intensity of infection increased markedly during the second ovarian cycle and, in the third ovarian cycle, the first pharynx infected with paramastigotes was seen (on day 19). From day 19 to day 29, 76% of the flies had pharyngeal infections. Three out of 19 sand flies with pharyngeal infections recaptured during this period had metacyclic promastigotes in their mouthparts. The long time required for parasites to reach the proboscis in completely natural conditions suggests that their presence in the mouthparts is not a prerequisite for transmission by bite. It is more likely that transmission is most commonly by the regurgitation of metacyclic promastigotes from the thoracic midgut following damage to the stomodaeal valve by chitinase produced by the parasite during its development in the gut of the fly. Nevertheless, it is reasonable to assume that the bite of a fly with metacyclic promastigotes in the proboscis (or salivary glands) would also be infective.
California (USA) agriculture employs pyrethroid and organophosphate insecticides to control insects in orchards and other crops. Diazinon and esfenvalerate were selected for this study because of their application overlaps. Toxicological and biochemical responses of larval fathead minnows (Pimephales promelas) exposed singly and in combinations to esfenvalerate and diazinon were determined. Exposures were 96-h static renewal tests that used standard U.S. Environmental Protection Agency acute toxicity test methods. After pesticide exposures, larvae were evaluated for carboxylesterase and acetylcholinesterase activity, and histopathological effects. Carboxylesterase activity was examined because of its potential influence on the toxicity of both organophosphates and pyrethroids. In vivo studies demonstrated that diazinon significantly inhibited carboxylesterase activity at nominal water concentrations as low as 50 microg/L. However, esfenvalerate did not affect carboxylesterase activity at any concentration tested. Liver glycogen depletion was the only histopathological effect observed; this effect was demonstrated with the individual pesticides and pesticide combinations (i.e., mixtures). The combinations of diazinon and esfenvalerate causing acute toxicity to fathead minnow larvae appeared to be greater than additive (i.e., synergistic) in all three tests.
Acute lethal toxicity of Cyanobacteria (blue-green algae) was investigated against 3rd larval stages of Musca domestica, and Culex pipiens, and 4th larval stages of Spodoptera littoralis and Agrotis ipsilon. The LD50s were 1.94, 2.33, 7.59 and 9.10 microg for M. domestica, C. pipiens, S. littoralis and A. ipsilon respectively. The slope functions were 4,045 +/- 0.332 (M. domestica), 4.122 +/- 0.336 (C. pipiens), 4.15 +/- 0.35 (S. littoralis) and 3.72 +/- 0.34 (A. ipsilon). These LD50s markedly affected the larval, pupal and adult time of durations as well as suppressed the oviposition of the survivor adults. The LD50 didn't show any marked effect as serum acetyl cholinesterase and gave nearly the same level of AchE activity. No doubt, Cyanobacteria are safe and promising agent for insect control.
The research of air-adjustment storing ginseng shows that when the concentration of CO2 is above 50% and the concentration of O2 is under 5%, all adults will die in four days; all eggs and larvas will die in fifteen days. During the year of using this method air-adjustment, no vermins and mould have been found.
Urban and suburban watersheds have the potential to be highly impacted by chemicals, especially insecticides to control insect pests on lawns, ornamental plants, and home gardens. Three of the most common lawn-care insecticides detected in urban watersheds, carbaryl, chlorpyrifos, and malathion, have been evaluated using an acute orbital shaker toxicity test to determine their respective concentrations that produce 50% mortality (LC50) in Simulium vittatum Zetterstedt cytospecies IS-7 larvae. Results of the 48-h LC50 tests show chlorpyrifos to be the most toxic to black fly larvae (LC50 = 0.28 microg/L) followed by carbaryl (LC50 = 23.72 microg/L) and malathion (LC50 = 54.20 microg/L). These insecticides were also tested as binary and ternary mixtures using the toxic unit (TU) approach. Toxicity was shown to be greater than additive for the ternary mixture of chlorpyrifos-carbaryl-malathion (LC50 = 0.56 TU) and the binary mixtures of chlorpyrifos-malathion (LC50 = 0.72 TU) and carbaryl-malathion (LC50 = 0.78 TU). The binary combination of chlorpyrifos and carbaryl was shown to be additive (LC50 = 0.98 TU). These results indicate that aquatic invertebrate populations in urban and suburban streams may experience a higher-than-expected increase in toxicity-related effects when all three chemicals are present in the waterway.