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At least 739 records · Page 41Linked to original sources
PubMed1992

Host immunity to mosquitoes: effect of antimosquito antibodies on Anopheles tessellatus and Culex quinquefasciatus (Diptera: Culicidae).

Rabbit antibodies to antigens derived from the tissues of sugar-fed Anopheles tessellatus Theobald were fed to An. tessellatus and Culex quinquefasciatus Say in blood meals. These antibodies tended to reduce the number of eggs produced by An. tessellatus, but had no effect on the fecundity of Cx. quinquefasciatus. Ingestion of the rabbit antibodies did not detectably affect the mortality of An. tessellatus but increased the mortality of Cx. quinquefasciatus. The results provide preliminary evidence for the potential of antimosquito antibodies to disrupt the physiology of mosquito vectors and indicate the need for further studies with high-titer, monospecific antibodies against the relevant target antigens.

Animals↗
PubMed1995

Field evaluation of four repellents against Leptoconops americanus (Diptera: Ceratopogonidae) biting midges.

Four repellents, deet, AI3-37220, AI3-35765, and CIC-4, prepared as 12.5% ethanol solutions, were evaluated against biting midges on Stansbury Islands, UT. Leptoconops americanus Carter was the only species that was biting human volunteers during the study. This species bit primarily on the ears at rates up to 840 bites per hour. All four repellents significantly reduced the number of bites on treated volunteers. AI3-37220 consistently provided the longest period of protection, giving 97 and 74% protection at 4 and 8 h, respectively. In a direct statistical comparison, AI3-37220 significantly outperformed deet. CIC-4 and AI3-35765 were the least effective repellents, providing 45-47% protection 8 h after application.

Animals↗
PubMed1998

Laboratory studies of susceptibility and resistance to insecticides in Pediculus capitis (Anoplura; Pediculidae).

The susceptibility of local head lice to permethrin, sumithrin, deltamethrin, and carbaryl was determined by laboratory bioassays in field-collected colonies. Head lice collected from the infested heads of children 6-12 yr old were tested within 3 h of collection. The longest survival of control insects in the laboratory was obtained by keeping them in the dark at 18 degrees C and 70-80% RH. The base line susceptibility data obtained for insects collected from children not treated for lice, the reference colony, showed that deltamethrin caused the highest mortality of the insecticides tested (LC50, 0.06%). Permethrin, sumithrin, and carbaryl showed no significant difference in mortality (superposition of confidence intervals), being 10 times lower than that caused by deltamethrin. All field-collected lice required a higher LC50 of permethrin than the reference colony. Resistance levels varied from 3 to > 100 for colonies that were taken from children treated with anti-lice products. Lice colonies with permethrin resistance showed resistance to sumithrin and deltamethrin, but resistance was not observed to the carbamate carbaryl.

Animals↗
PubMed2005

Spatiotemporal patterns of reinfestation by Triatoma guasayana (Hemiptera: Reduviidae) in a rural community of northwestern Argentina.

Triatoma guasayana (Wygodzinsky & Abalos) is a secondary vector of Trypanosoma cruzi (Chagas), the etiologic agent of Chagas disease, in the Chaco region of Argentina, Bolivia, and Paraguay. The spatial distribution of T. guasayana in a rural community in northwestern Argentina is described and analyzed using very high spatial resolution satellite imagery, geographic information systems, and spatial statistics. Since a 1992 residual spraying with insecticides of all houses, site-specific domestic and peridomestic reinfestations by triatomine bugs were monitored using various methods semiannually from 1993 to 2002. The reinfestation by T. guasayana started with finding of only adult bugs in a few sites. Bug abundance was significantly clustered and predominantly peridomestic in the southern and northern extremes of the community. The identified source of reinfestation in the northern cluster was a colonized wood pile, whereas no potential peridomestic source was found for the southern cluster. The spatial distribution of T. guasayana was positively associated with the abundance and spatial distribution of goats. Active dispersal from the hypothesized source and the surrounding sylvatic environment, and passive transport of bugs in wood piles seems to be the most likely mechanisms underlying the observed spatial pattern of T. guasayana. The absence of domestic colonization indicates that, to date, there is no trend toward increased local domiciliation of T. guasayana. The clustering zones can be considered "hot spots" where bug invasion from other sources is expected to be higher and where eventually, introduction of sylvatic T. cruzi to suitable hosts may occur.

Animals↗
PubMed2005

Evaluation of environmental data for identification of Anopheles (Diptera: Culicidae) aquatic larval habitats in Kisumu and Malindi, Kenya.

This research evaluates the extent to which use of environmental data acquired from field and satellite surveys enhances predictions of urban mosquito counts. Mosquito larval habitats were sampled, and multispectral thermal imager (MTI) satellite data in the visible spectrum at 5-m resolution were acquired for Kisumu and Malindi, Kenya, during February and March 2001. All entomological parameters were collected from January to May 2001, June to August 2002, and June to August 2003. In a Poisson model specification, for Anopheles funestus Giles, shade was the best predictor, whereas substrate was the best predictor for Anopheles gambiae, and vegetation for Anopheles arabensis Patton. The top predictors found with a logistic regression model specification were habitat size for An. gambiae Giles, pollution for An. arabensis, and shade for An. funestus. All other coefficients for canopy, debris, habitat nature, permanency, emergent plants, algae, pollution, turbidity, organic materials, all MTI waveband frequencies, distance to the nearest house, distance to the nearest domestic animal, and all land use land cover changes were nonsignificant. MTI data at 5-m spatial resolution do not have an additional predictive value for mosquito counts when adjusted for field-based ecological data.

Animals↗
PubMedDate not supplied

Insecticide resistance genes in mosquitoes: their mutations, migration, and selection in field populations.

Insecticides have been used intensively to control insect populations over the last 50 years and many species of insects have developed resistance to several families of insecticides. These resistances are mainly due to two mechanisms: mutation of the insecticide target protein (leading to a decrease in its affinity for the concerned insecticide family), and increased detoxification. Recent molecular studies suggest that the mutations conferring resistance are rare and sometimes unique events in any given species. The wide geographic distribution of some of these genes can then only be explained by the balance between migration and selection at the population level.

Acetylcholinesterase↗
PubMed2006

The effects of anticholinergic insecticides on human mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are located primarily in the bone marrow and are characterized by their capacity to differentiate into mesenchymal lineages such as bone, fat, and cartilage in response to appropriate signals. Several signaling mechanisms act to control MSC survival, proliferation, and differentiation, and failure or disruption of these signaling pathways can lead to degenerative disease or neoplasia. Organophosphate (OP) and carbamate pesticides, which are used in large amounts in agriculture to control insects, are designed to disrupt acetylcholine signaling by inhibiting the enzyme acetylcholinesterase (AChE). Effects of OP and carbamate pesticides on the human central nervous system have been well documented. However, AChE is broadly distributed, and the effects of anticholinergic insecticides on nonnervous tissue have received little attention. In the present study we found that human MSCs express AChE, which makes these cells potential targets for AChE inhibiting agents. We therefore examined the effects of an OP pesticide, chlorpyrifos, and a carbamate, carbofuran, on MSC characteristics. It was found that micromolar concentrations of these anticholinergic insecticides had no effect on MSC survival or proliferation but limited MSC differentiation capacity by inhibiting osteogenic differentiation. These results demonstrate that exposure to micromolar concentrations of OP and carbamate pesticides may affect tissue turnover and pathophysiology by interfering with MSC regulation.

Acetylcholinesterase↗
PubMed1995

Inhibition of Diabrotica Larval Growth by Patatin, the Lipid Acyl Hydrolase from Potato Tubers.

Patatin, the nonspecific lipid acyl hydrolase from potato (Solanum tuberosum L.) tubers, dose-dependently inhibits the growth of southern corn rootworm (SCR) and western corn rootworm when fed to them on artificial diet. The 50% growth reduction levels are somewhat cultivar dependent, ranging from 60 to 150 [mu]g/g diet for neonate SCR larvae. A single patatin isoform also inhibits larval growth. Neonate SCR continuously exposed to patatin are halted in larval development. Treatment with di-isopropylfluorophosphate essentially eliminates patatin's phospholipase, galactolipase, and acyl hydrolase activities. SCR growth inhibition is eliminated also, indicating that patatin's serine hydrolase activity is responsible for the observed activities. Patatin-mediated phospholipolysis is highly pH and cultivar dependent, with specific activities up to 300-fold less at pH 5.5 than at pH 8.5. Esterase or phospholipase activities do not correlate with insect growth inhibition. Galactolipase activity, being cultivar and pH independent, correlates significantly with SCR growth inhibition. Insect-growth inhibition of patatin is significantly reduced with increased dietary cholesterol levels. In conclusion, patatin represents a new class of insect-control proteins with a novel mode of action possibly involving lipid metabolism.

Journal Article↗
PubMed2000

A new model for 20-hydroxyecdysone and dibenzoylhydrazine binding: a homology modeling and docking approach.

The ecdysone receptor (ECR), a nuclear transcription factor controlling insect development, is a novel target for insecticides such as dibenzoylhydrazines with low environmental and toxicological impacts. To understand the high selectivity of such synthetic molecules toward ECR, two homology models of the Chironomus tentans ECR ligand-binding domain (LDB) have been constructed by taking as templates the known LBD crystal structures of the retinoic acid and vitamin D receptors. Docking of 20-hydroxyecdysone (20E) and dibenzoylhydrazines to the receptor suggests a novel superposition of the natural and synthetic molecules; the N-tert-butyl substituent of the dibenzoylhydrazines extends significantly beyond the 20E volume. Our ECR-LBD protein models rationalize how 20E and dibenzoylhydrazines interact with the ligand-binding pocket. The homology model complexes provide new insights that can be exploited in the rational design of new environmentally safe insecticides.

Amino Acid Sequence↗
PubMed1991

Recovery of Triatoma infestans populations after insecticide application: an experimental field study.

The capacity of populations of Triatoma infestans (Klug) (Hemiptera: Reduviidae) to survive and recover was assessed after application of insecticide (gamma-HCH at a rate of 0.5 g a.i./m2) at different seasons. T. infestans populations were maintained in experimental chicken houses under natural climatic conditions in a region of Argentina endemic for Chagas disease transmitted by these bugs. Based on previous studies of T. infestans populations in these habitats, each experimental group was set up with a total of 626 T. infestans, comprising 390 eggs, 204 nymphs of particular stages, fourteen male and eighteen female adults. The chicken houses were dismantled and rebuilt at monthly intervals to study the vector population changes over a period of 33 months. When the insecticide was applied during winter, spring or summer, populations of T. infestans recovered to untreated or precontrol levels during the next reproductive season (i.e. during the hot season, October-March). In contrast, populations treated during autumn (March) remained at very low densities for 2 years and then increased rapidly to surpass the untreated populations. All populations of the bugs fell to very low numbers (sometimes less than twenty individuals) after gamma-HCH applications, but none was driven to extinction. In all cases, the density of surviving populations was independent of their density before treatment. The fact that all treated populations recovered within 1-3 years, to at least the density of untreated populations, shows the high reproductive potential of T. infestans to recover from very low population densities. Moreover, the additive effect of climatic-induced mortality and insecticide-induced mortality is only apparent when insecticides are applied just before the onset of the cold winter months during which reproductive rates are at their lowest.

Animals↗
PubMed1993

Impact of permethrin-impregnated mosquito nets compared with DDT house-spraying against malaria transmission by Anopheles farauti and An.punctulatus in the Solomon Islands.

In villages of northern Guadalcanal in the Solomon Islands, where the predominant malaria vector is An.farauti No. 1 and An.puctulatus is also involved, malaria transmission rates were compared for three zones: (1) non-intervention: 438 people in seventeen villages; (2) residual DDT house-spraying two cycles per year: 644 people in thirty villages; (3) bednets impregnated with permethrin 0.5 g/m2 twice per year, used by 580 people in sixteen villages. Regular DDT spraying in zones 1 and 3 had been withdrawn 18 months previously. Malariological blood smear surveys of children aged 1-9 years in August 1986 to January 1987 showed a mean baseline malaria parasite rate of 38% (32/84). By February 1988, 18 months after introduction of impregnated bednets, the Plasmodium falciparum infection rate in children was lowest in the zone using impregnated bednets (21% of 29), intermediate in the untreated zone (29% of 34) and highest in the DDT zone (46% of 53), but these differences were not statistically significant. P. vivax infection rates were 9-14%. Using ELISA tests for malaria circumsporozoite antigen in the vectors, overall positivity rates were 0.7% of 49,902 An.farauti and 2.54% of 118 An.punctulatus, comprising 228 P.falciparum and 124 P.vivax infections. In the study zones, vector positivity rates were 0.93% of 31,615 An.farauti in the untreated zone; 0.32% of 16,883 An.farauti in the DDT zone; 0.07% of 1404 An.farauti and 2.54% of 118 An.puctulatus in the impregnated bednet zone. here was no significant correlation between malaria parasite rates in the vectors and the children.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗