[Possibility of using trolen in medical insect control].
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Feeding tests showed that the powdered dried leaves and leaf extracts of L. bidwilli are toxic to the larvae of the housefly (Musca domestica), and the codling moth (Laspeyresia pomonella). The powdered material was not toxic to the light-brown apple moth (Epiphyas postvittana). The most active toxin is the lignan beta-peltatin-A methyl ether (II) and at a concentration of 100 ppm in a chemically defined diet it gave 98% mortality of housefly larvae.
During recent years many advances have been made in the development of insect control by genetic manipulation. These methods include the sterile-male technique, now well known, which depends on ionizing radiation or chemosterilization. The recent field experiment carried out by WHO in Rangoon, Burma, on Culex fatigans has demonstrated that naturally occurring cytogenetic mechanisms such as cytoplasmic incompatibility can be used successfully without the use of radiations or chemosterilants. The paper not only describes the experiment on Culex fatigans but also discusses basic concepts and theoretical considerations involved in genetic control of insects of public health importance. The possibility of using genetic mechanisms for the control of other vector species is also discussed. There are a number of problems which require study before genetic control can be used on an operational scale. These problems and suggestions for future research in this field are also outlined.
A genetic method for insect control was evaluated using the test organism, Drosophila melanogaster. The technique involved the displacement under a system of continuous reproduction, of standard strains by those carrying compound autosomes. The eradication of the replacements could subsequently be achieved through the use of temperature-sensitive lethal mutations.-While certain compound autosome strains failed to displace standards in population cages, even at the initial release ratio of 25:1, others were highly successful. Indeed, for some strains when the ratio of compounds to standards was as low as 9:1, the population rapidly went to fixation in favor of the compound line.-Hatchability was found to be an insufficient index of fitness to estimate the initial ratios of compounds to standards that would guarantee fixation of the former. Differences in other fitness components, such as development time, were detected that could seriously modify displacement, especially with continuous overlapping generations. The importance of examining the fitness of various compound lines and selecting the most competitive in cages, prior to field tests, cannot be overemphasized.
Isozyme techniques have proven particularly useful in the past in the field of biological insect control. In this brief review I have tried to give a small selection of the varied approaches that have been used. In the future, isozyme analysis will undoubtedly play a major role. But genetic analyses, as exemplified by the use of isozymes, form but a small part of the knowledge we must have if biological control programs are to be successful. In a pest management program where one is using both chemical and biological methods it is necessary to know a great deal about the biology of the pests, their parasites, predators, and host plants or animals, together with a knowledge of the general ecology of the area where the problem exists. Too often, major control programs have been started with pitifully inadequate basic knowledge of the insect pest concerned, dooming such projects to a series of frantic and generally makeshift attempts to redeem these inadequacies. We are starting to see a much greater emphasis on interrelationships between scientific disciplines, more basic research being conducted, and a resurgence of interaction between those people who are in the applied field and those in the basic sciences. This dialog must be continued. In closing, I want to emphasize again that in pest control we are involved in the management of a coexistence with insects and I think it appropriate to end with the thoughts of W.J. Holland [1949]: when all cities shall have been long dead and crumbled into dust, and all life shall be on the very last verge of extinction on this globe; then on a bit of lichen, growing on the bald rocks beside the eternal snows of Panama, shall be seated a tiny insect, preening its antenna in the glow of the worn-out sun, representing the sole survival of animal life on this our earth--a melancholy 'bug'.
Insect neuropeptides regulate virtually all aspects of insect life and are excellent candidates for development of new methods for pest control. However, they do not penetrate insect cuticle and are degraded by enzymes both in the digestive system and hemolymph. We have designed mimics of model neuropeptides by attachment of various lipidic moieties to the amino terminus of the bioactive core of the neuropeptides. These mimics have amphiphylic characteristics that allowed them to penetrate the hydrophobic insect cuticle. The mimics also induced prolonged physiological responses (up to 20 hours) and were resistant to peptidase attack. This knowledge has been used to develop a novel, species-specific approach to insect control.
Insect growth regulators (IGRs) represent a relatively new category of insect control agents aimed mainly at covering the need for safer compounds and overcoming the development o f resistance to 'classical' insecticides. The various types of IGR are reviewed here by Jean-Francois Graf and their mechanism of action, their practical application and their respective advantages and limitations are discussed. A comprehensive assessment is made of current and future prospects for IGRs in insect and ectoparasite control.
This paper concentrates on the system that controls the femur-tibia joint in the legs of the stick insect, Carausius morosus. Earlier investigations have shown that this joint is subject to a mixture of proportional and differential control whereby the differential part plays a prominent role. Experiments presented here suggest another interpretation: single legs of a stick insect were systematically perturbed using devices of different compliance and compensatory forces and movements monitored. When the compliance is high (soft spring), forces are generated that return the leg close to its original position. When the compliance is low (stiff spring), larger forces are generated but sustained changes in position occur that are proportional to the force that is applied. Selective ablation of leg sense organs showed that the leg did not maintain its position after elimination of afferents of the femoral chordotonal organ. Ablation of leg campaniform sensilla had no effect. These data support the idea that different control strategies are used, depending upon substrate compliance. In particular, what we and other authors have called a differential controller, is now considered as an integral controller that "intelligently gives up" when the correlation between motor output and movement of the leg is low.
Explore the source record for details and available documents.
Control mechanisms that regulate body size and tissue size have been sought at both the cellular and organismal level. Cell-level studies have revealed much about the control of cell growth and cell division, and how these processes are regulated by nutrition. Insulin signaling is the key mediator between nutrition and the growth of internal organs, such as imaginal disks, and is required for the normal proportional growth of the body and its various parts. The insulin-related peptides of insects do not appear to control growth by themselves, but act in conjunction with other hormones and signaling molecules, such as ecdysone and IDGFs. Size regulation cannot be understood solely on the basis of the mechanisms that control cell size and cell number. Size regulation requires mechanisms that gather information on a scale appropriate to the tissue or organ being regulated. A new model mechanism, using autocrine signaling, is outlined by which tissue and organ size regulation can be achieved. Body size regulation likewise requires a mechanism that integrates information at an appropriate scale. In insects, this mechanism operates by controlling the secretion of ecdysone, which is the signal that terminates the growth phase of development. The mechanisms for size assessment and the pathways by which they trigger ecdysone secretion are diverse and can be complex. The ways in which these higher-level regulatory mechanisms interact with cell- and molecular- level mechanisms are beginning to be elucidated.
Irradiation processing has been researched extensively and is now in use worldwide for many food commodities. Irradiation has been successfully used to reduce pathogenic bacteria, eliminate parasites, decrease postharvest sprouting, and extend the shelf life of fresh perishable foods. Although food irradiation is widely accepted in world food markets, U.S. markets have been slower to accept the idea of irradiated food products. For fruits and vegetables, irradiation is not a cure for shelf life problems; cost and quality problems damage preclude its general use. It appears that the most likely use of irradiation in fruits and vegetables is as an insect control in those commodities for which there is no effective alternative method. For grains such as rice and wheat, irradiation has been used primarily to control insect infestation when insects have been shown to develop resistance to the traditional fumigation methods. Treatment of spices with irradiation doses of 10 kGy has proved to extend shelf life without causing significant changes in sensory or chemical quality. Higher doses that effectively sterilize spices, however, may cause undesirable chemical and sensorial changes. For meat, especially red meat, irradiation is considered a viable alternative in the effort to improve the safety of meat products. With time, the authors believe that economic realities and the technical superiority of irradiation for specific poultry products will lead to public acceptance of the process. Irradiation of seafood products is still being considered for approval by the USFDA, although it is currently used in Asian and European markets, especially for shrimp. It is our belief that scientifically based research in food irradiation and the positive results thereof will also prove economical in the twenty-first century. As we move to a more peaceful world with reduced threat of nuclear holocaust, these valid opinions will prevail and will overshadow the distortions and misinformation generated by the opponents of irradiation.
Insect growth regulators (IGRs) are diverse groups of chemical compounds that are highly active against larvae of mosquitoes and other insects. The IGRs in general have a good margin of safety to most nontarget biota including invertebrates, fish, birds, and other wildlife. They are also relatively safe to man and domestic animals. The IGR compounds do not induce quick mortality in the preimaginal stages treated. Mortality occurs many days later after treatment. This is indeed a desirable feature of a control agent because larvae of mosquitoes and other vectors are an important source of food for fish and wildlife. On account of these advantages of IGRs and the high level of activity against target species, it is likely that IGRs will play an important role in vector control programs in the future.
Explore the source record for details and available documents.
Explore the source record for details and available documents.