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At least 1,351 records · Page 75Linked to original sources
PubMed2006

Insect eggs exert rapid control over an oxygen-water tradeoff.

In terrestrial environments, the exchange of respiratory gases exacts a water cost: obtaining oxygen or carbon dioxide requires losing water. Insect eggs should be especially sensitive to this tradeoff-because they are unable to forage for water, have high surface area-to-volume ratios, and experience large temperature-driven changes in oxygen demand. Previous work from our laboratory, on eggs of a common hawk-moth, Manduca sexta, has shown that, during development, metabolic rate and water loss rates rise in parallel. These correlative data suggest that eggshell conductance increases to accommodate increasing metabolic demand. Here, we test this idea experimentally by subjecting eggs of M. sexta to 15, 21 (normoxia) and 35% oxygen for 24h, while measuring rates of metabolism (as carbon dioxide emission) and water loss. Hypoxia depressed egg metabolic rates, but led to pronounced, rapid increases in water loss. By contrast, hyperoxia had no significant effect on metabolism or water loss. These data demonstrate that insect eggs actively participate in balancing oxygen gain and water loss, and that they use tissue oxygen status, or some correlate of it, as a cue for increasing eggshell conductance. Rapid control over conductance may allow eggs to conserve water during an initial period of low metabolic demand, thereby deferring water costs of respiratory gas exchange until late in development.

Acclimatization↗
PubMed2001

Malaria past and present: the case of North Sulawesi, Indonesia.

The incidence and impact of malaria in North Sulawesi have declined both in the short term during the 1990s, and over a much longer timespan (though perhaps less continuously) since the end of the colonial period. The improvement already seems to have been well underway before deliberate vector control activities became extensive in the second half of the 1970s, and environmental changes affecting the Anopheles mosquito fauna, in particular the replacement of primary and secondary forest by permanent farmland, are probably the principal reasons for the long-term trend; other possible factors include the increasing use of antimalarial drugs. The well-documented decline in malaria incidence over the years 1991-1997, nevertheless, probably reflects the unprecedented scale of residual insecticide spraying in the province during that period, while the slight resurgence of the disease in the last three years corresponds to the subsequent cessation of house spraying as a result of the current economic crisis. Despite the evident importance of environmental change as a factor ameliorating the malaria situation in the long term, experience from the colonial era suggests that the prospects for deliberate environmental management (species sanitation) as an alternative malaria control strategy are poor.

Animals↗
PubMed1995

Vector control without chemicals: a public health perspective.

A public health perspective of vector control without pesticides discusses 2 scenarios, one where vector-borne disease is present and one where vector-borne disease is absent. The conclusion is that in situations where disease is present, particularly in epidemics, pesticides are necessary and there will be a requirement for pesticides into the future. Where disease is not present, nonchemical means of vector control may be a viable option.

Animals↗
PubMed1959

Tests with organo-phosphorus dry sugar baits against houseflies in Israel.

Tests were carried out in rural areas in Israel with various organo-phosphorus dry sugar baits. Malathion 2.5%, diazinon 1% and Dipterex 1% gave equally effective results. Chlorthion 1% and malathion 1% and 2% were used in smaller quantities and were less effective.Dry poisoned baits are considered an important supplementary measure to a rural fly control programme, especially when used as an adjunct to basic sanitation.

Animals↗
PubMed1982

Genetic control of hexokinase variation in insects.

Hexokinase variation in insects appears to be under the control of a single locus in some species and under multiple-locus control in others. It is often difficult to distinguish the number of loci controlling hexokinase expression. Analysis of hexokinase electrophoretic patterns in six species of mosquitoes and five species of crickets, as well as a review of hexokinase variation in other insect species, is used to emphasize the importance of interspecific comparisons when making genetic inferences. Evidence is provided which adds support for multiple hexokinase loci in dipterans. Hexokinase control by multiple loci may be difficult to determine in some species because of tight linkage, disequilibrium, and/or posttranslational modification.

Animals↗
PubMed1963

Trypanosomiasis control in relation to other public health services.

The authors describe the aims and principles of trypanosomiasis control and discuss the individual techniques of control and the ways in which these can be channelled through a general rural health service. They argue that, given the circumstances at present prevailing in rural Africa, a broad-based general public health service should be established before specific campaigns for control or eradication of sleeping-sickness, or indeed any other specific diseases, are instituted. They emphasize the necessity of international co-operation for effective trypanomiasis control.

Africa↗
PubMed1963

INDUCED REGRESSION OF DIELDRIN-RESISTANCE IN THE HOUSEFLY (MUSCA DOMESTICA L.).

A high degree of resistance to cyclodiene insecticides, which appeared in a previously susceptible housefly strain maintained without exposure to insecticides but propagated from early-emerging adults to increase susceptibility to DDT, was found to be due to a single autosomal factor. Subsequent selection of a substrain for late adult emergence over 50 generations was unsuccessful in materially reversing the dieldrin-resistance or in demonstrating that selection of early-emerging flies was responsible for its appearance. However, selection and propagation of the knockdown-susceptible fraction of the population with lindane over 30 generations eliminated cyclodiene-resistance entirely. This method can be of value in maintaining laboratory strains at a normal level of susceptibility to cyclodiene insecticides. It is apparent, nevertheless, that various manipulations of a standard strain may affect its toxicological as well as other characteristics. The authors stress that when a standard reference strain is required for an extended period of time, it should be rigorously controlled and continuously evaluated.

Animals↗
PubMed1990

Onchocerciasis.

Onchocerciasis is a devastating blinding disease caused by the parasite Onchocerca volvulus that infects about 80 million people, causing blindness and visual impairment in 1-2 million people. In hyperendemic areas, more than half of the population will become blind from onchocerciasis before they die. Blindness is the most important effect of the disease and results, in part, from direct invasion of the eye by microfilariae. The recent development of ivermectin has revolutionized our ability to treat this disease. An annual oral dose of only 150 mg/kg completely suppresses the disease manifestations. Programs for the community-based mass distribution of ivermectin are now being conducted and promise to control this major blinding scourge.

Africa↗
PubMed1996

Neuropeptides implicated in the control of diuresis in insects.

Primary urine production in insect Malpighian tubules is stimulated by two classes of neuropeptides, CRF-related diuretic peptides and insect kinins. The CRF-related peptide of the locust, Locusta migratoria, has a hormonal role in the control of postfeeding diuresis, but the functional role of the kinins has yet to be defined. The two classes of peptide act synergistically to stimulate tubule secretion, and the kinins may therefore have a modulatory action in the control of diuresis. The peptides differ in their effects on Malpighian tubule ion transport, and this could be important for the regulation of hemolymph volume and composition.

Amino Acid Sequence↗