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At least 775 records · Page 43Linked to original sources
PubMed2005

Codling moth cytogenetics: karyotype, chromosomal location of rDNA, and molecular differentiation of sex chromosomes.

We performed a detailed karyotype analysis in the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), the key pest of pome fruit in the temperate regions of the world. The codling moth karyotype consisted of 2n = 56 chromosomes of a holokinetic type. The chromosomes were classified into 5 groups according to their sizes: extra large (3 pairs), large (3 pairs), medium (15 pairs), small (5 pairs), and dot-like (2 pairs). In pachytene nuclei of both sexes, a curious NOR (nucleolar organizer region) bivalent was observed. It carried 2 nucleoli, each associated with one end of the bivalent. FISH with an 18S ribosomal DNA probe confirmed the presence of 2 clusters of rRNA genes at the opposite ends of the bivalent. In accordance with this finding, 2 homologous NOR chromosomes were identified in mitotic metaphase, each showing hybridization signals at both ends. In highly polyploid somatic nuclei, females showed a large heterochromatin body, the so-called sex chromatin or W chromatin. The heterochromatin body was absent in male nuclei, indicating a WZ/ZZ (female/male) sex chromosome system. In keeping with the sex chromatin status, pachytene oocytes showed a sex chromosome bivalent (WZ) that was easily discernible by its heterochromatic W thread. To study molecular differentiation of the sex chromosomes, we employed genomic in situ hybridization (GISH) and comparative genomic hybridization (CGH). GISH detected the W chromosome by strong binding of the Cy3-labelled, female-derived DNA probe. With CGH, both the Cy3-labelled female-derived probe and Fluor-X labelled male-derived probe evenly bound to the W chromosome. This suggested that the W chromosome is predominantly composed of repetitive DNA sequences occurring scattered in other chromosomes but accumulated in the W chromosome. The demonstrated ways of W chromosome identification will facilitate the development of genetic sexing strains desirable for pest control using the sterile insect technique.

Animals↗
PubMed1993

Evolution of Drosophila insecticide resistance.

The impact of insecticide resistance is well documented. It includes the toxic effects of pesticides on the environment and the cost of the increased amounts of insecticides required to effectively control resistant insects. Resistance evolves by the selection of genes that confer tolerance to insecticides. Several resistance genes have been identified and cloned in Drosophila, including genes for mutant target molecules and genes that increase insecticide degradation. Drosophila is a useful system to understand the evolution of quantitative traits in general as well as the population genetics of insecticide resistance. Through it, we may hope to understand the relationship between discrete genetic change and continuously varying characters. In addition, molecular genetic techniques developed using Drosophila can eventually be transferred to other insects in order to help control pest populations.

Acetylcholinesterase↗
PubMed1995

Resistance to avermectins: extent, mechanisms, and management implications.

The avermectins represent a group of natural compounds with potent pesticidal activities. Because of their novel mode of action, they represent an important resource for pest control and resistance management. In the Colorado potato beetle, the house fly, and the two-spotted spider mite, resistance to abamectin is usually autosomal, recessive, and polygenic. Although these aspects are beneficial in resistance management, the fact that resistance could be readily selected for suggests that abamectin needs to be used in moderation. Furthermore, several major resistance mechanisms (e.g. excretion, oxidative metabolism, penetration) and minor factors (e.g. altered target site, conjugation, hydrolysis/sequestration) have been implicated in abamectin resistance. Thus, the question is not whether resistance to abamectin will occur but is simply when and how it will occur. To address this problem, we have gathered information on the genetics, biochemical mechanisms, effectiveness of synergists, and cross-resistances to other insecticides from three abamectin-resistant insects. Judicious implementation of this information may prove useful in the resistance management of this natural pesticide.

Animals↗
PubMed1995

Malaria: current and future prospects for control.

Malaria is the most important insect-transmitted human disease, but progress in its control has been slow, especially in Africa where approximately 90% of the infections occur. Several factors have contributed to the problem. Parasites and vectors have developed resistance to antimalarial drugs and insecticides; differences in the biology of major malaria vectors preclude the development of simple, universally applicable strategies for malaria control; and the cost of available malaria-control tools often exceeds the public health resources in the most malarious parts of the world. New tools are desperately needed. Current efforts include the testing of tools such as insecticide-impregnated bed nets that could become available in the near term, as well as long-term projects such as the development of malaria vaccines and mosquito-targeted genetic control strategies. The success or failure of any of these approaches will depend ultimately on understanding the natural patterns of malaria transmission in the field.

Animals↗
PubMed1996

Ecology of insect communities in nontidal wetlands.

Published research about wetland insects has proliferated, and a conceptual foundation about how wetland insect populations and communities are regulated is being built. Here we review and synthesize this new body of work. Our review begins with a summary of insect communities found in diverse wetland types, marshes, forested floodplains, and peatlands. Next, we critically discuss research on the population and community ecology of wetland insects, including the importance of colonization strategies and insect interactions with the physical environment, plants, predators, and competitors. Results from many of the experimental studies that we review indicate that some commonly held beliefs about wetland insect ecology require significant reevaluation. We then discuss the importance of wetland insect ecology for some applied concerns such as efforts to manage wetland insect resources as waterfowl food and development of ecologically sound strategies to control pest mosquitoes. We conclude with a discussion of wetland conservation, emphasizing insect aspects.

Journal Article↗
PubMed1998

Fire and insects in northern and boreal forest ecosystems of North America.

Fire and insects are natural disturbance agents in many forest ecosystems, often interacting to affect succession, nutrient cycling, and forest species composition. We review literature pertaining to effects of fire-insect interactions on ecological succession, use of prescribed fire for insect pest control, and effects of fire on insect diversity from northern and boreal forests in North America. Fire suppression policies implemented in the early 1900s have resulted in profound changes in forest species composition and structure. Associated with these changes was an increased vulnerability of forest stands to damage during outbreaks of defoliating insects. Information about the roles that both fire and insects play in many northern forests is needed to increase our understanding of the ecology of these systems and to develop sound management policies.

Journal Article↗
PubMed2005

Thysanoptera: diversity and interactions.

Published literature on thrips has been dominated by descriptive taxonomy, pest control work, and generalized synecology. The lack of studies examining the detailed biology or autecology of any species limits our understanding of how thrips live and the processes underlying their diversification. Similarly, the phylogenetic inadequacy of thrips classification limits our ability to examine the evolution of biological traits. The extent to which our knowledge of the biology of thrips has increased in recent years is reviewed, such as the behavior of particular species and their interactions with other organisms, including host plant associations, pollination, predation, and natural enemies--factors involved in driving diversification within this order of opportunistic insects.

Animals↗
PubMed2004

The gut bacteria of insects: nonpathogenic interactions.

The diversity of the Insecta is reflected in the large and varied microbial communities inhabiting the gut. Studies, particularly with termites and cockroaches, have focused on the nutritional contributions of gut bacteria in insects living on suboptimal diets. The indigenous gut bacteria, however, also play a role in withstanding the colonization of the gut by non-indigenous species including pathogens. Gut bacterial consortia adapt by the transfer of plasmids and transconjugation between bacterial strains, and some insect species provide ideal conditions for bacterial conjugation, which suggests that the gut is a "hot spot" for gene transfer. Genomic analysis provides new avenues for the study of the gut microbial community and will reveal the molecular foundations of the relationships between the insect and its microbiome. In this review the intestinal bacteria is discussed in the context of developing our understanding of symbiotic relationships, of multitrophic interactions between insects and plant or animal host, and in developing new strategies for controlling insect pests.

Animals↗
PubMed2007

Biology of the bed bugs (Cimicidae).

The cimicids, or bed bugs, belong to a highly specialized hematophagous taxon that parasitizes primarily humans, birds, and bats. Their best-known member is the bed bug, Cimex lectularius. This group demonstrates some bizarre but evolutionarily important biology. All members of the family Cimicidae show traumatic insemination and a suite of female adaptations to this male trait. Cimicids therefore constitute an ideal model system for examining the extreme causes and consequences of sexual selection. Our dual goal in re-examining the extensive literature on this group is to identify issues relevant to pest control, such as dispersal ecology and the recent global spread, and to understand the selective forces that have shaped the unique aspects of this insect's biology.

Animals↗
PubMed1999

Wolbachia pipientis: microbial manipulator of arthropod reproduction.

The alpha-proteobacterium Wolbachia pipientis is a very common cytoplasmic symbiont of insects, crustaceans, mites, and filarial nematodes. To enhance its transmission, W. pipientis has evolved a large scale of host manipulations: parthenogenesis induction, feminization, and male killing. W. pipientis's most common effect is a crossing incompatibility between infected males and uninfected females. Little is known about the genetics and biochemistry of these symbionts because of their fastidious requirements. The affinity of W. pipientis for the microtubules associated with the early divisions in eggs may explain some of their effects. Such inherited microorganisms are thought to have been major factors in the evolution of sex determination, eusociality, and speciation. W. pipientis isolates are also of interest as vectors for the modification of wild insect populations, in the improvement of parasitoid wasps in biological pest control, and as a new method for interfering with diseases caused by filarial nematodes.

Animals↗
PubMed2004

Oestradiol potentiates the effects of certain pyrethroid compounds in the MCF7 human breast carcinoma cell line.

Pyrethroids are the most widely used insecticides for indoor pest control, so human exposure to them is common. The main target of pyrethroids is the nervous system, but their endocrine disrupting capabilities may also be of toxicological concern. In the present study, the proliferation of the breast cancer cell line, MCF7, was studied after a 7-day exposure to various concentrations of pyrethrin, permethrin and cypermethrin. The effects of oestradiol and the combined effects of oestradiol (0.10 nM) and pyrethroids (0.1-100 microM) on MCF7 cell proliferation were also evaluated. Proliferation and cell toxicity were studied by measuring the ATP content with a luminescence method, and mitochondrial metabolic enzyme activity with the WST-1 test. In the ATP test, low concentrations (0.1-1 microM) of pyrethroids in co-exposure with oestradiol caused a clear statistically significant increase in the proliferation of MCF7 cells. This was evident when compared to the proliferative effect caused by 0.1 nM oestradiol alone. High concentrations were cytotoxic, and the greatest cell toxicity was that of cypermethrin, which has a cyano group in its molecular structure.

Adenosine Triphosphate↗
PubMed1988

Regulation of pesticides in Canada.

Pesticides are registered in Canada under the authority of the Pest Control Products Act (PCP), administered by the Department of Agriculture. The Department of Agriculture calls upon various federal departments, including Health & Welfare Canada, to provide expert advice on hazards which may be associated with the use of the product. The Department of Health and Welfare requires and reviews a range of toxicological studies to assess potential health hazards which may be associated with exposure to the chemical. Studies required include acute, sub-acute, chronic, reproduction, teratology and metabolism. In addition, exposure studies are also required to provide estimates of anticipated human exposure during typical field use of the chemical. In summary, the various steps involved in the registration of pesticides will be discussed and the relationship between the predictive toxicology as determined through animal testing and exposure estimates for estimating hazard will be shown.

Animals↗
PubMed1994

Persistence of sodium monofluoroacetate in livestock animals and risk to humans.

1. Sodium monofluoroacetate (1080), a vertebrate pesticide widely used in New Zealand, was administered orally to sheep and goats at a dose level of 0.1 mg kg-1 body weight to assess risk to humans of secondary poisoning from meat. Blood, muscle, liver, and kidney were analysed for 1080 residues. 2. The plasma elimination half-life was 10.8 h in sheep and 5.4 h in goats. Concentrations of 1080 in muscle (0.042 microgram g-1), kidney (0.057 microgram g-1), and liver (0.021 microgram g-1) were substantially lower than those in plasma (0.098 microgram ml-1) at 2.5 h after dosing. 3. Only traces of 1080 (< 0.002 to 0.008 microgram g-1) were found in sheep tissues after 96 hours. 4. Livestock are normally excluded from areas where 1080 is being used for pest control, reducing the risk of secondary poisoning. Even with accidental exposure to a sublethal dose 1080 would not persist in tissues for more than a few days because it is cleared rapidly from the body. Therefore the occurrence of 1080 in meat intended for human consumption is highly unlikely.

Animals↗
PubMedDate not supplied

Pesticide-related illness among migrant farm workers in the United States.

Surveillance data show that pesticide-related illness is an important cause of acute morbidity among migrant farm workers in California. A few categories (organophosphates and carbamates, inorganic compounds, and pyrethroids) account for over half of the cases of acute illness. Skin effects dominate the illnesses, although ocular and systemic effects are also common. Exposures occur in various ways (e.g., residues, drift), suggesting that the use of pesticides creates a hazardous work environment for all farm workers. The health care system provided through the Migrant Health Program appears to be underutilized, partially due to barriers to health care access. Pesticide hazards should be ranked based on acute toxicity, chronic toxicity (including reproductive risks), carcinogenic potency, volume applied, and magnitude of worker poisonings. Current surveillance effort should be supported. Risk prevention should focus on substitution of safer compounds, establishing effective protections, and ensuring that these measures are enforced. Improved education for health care providers should be a priority. Growers should be educated about alternative forms of pest control and incentives should be provided to encourage their use.

Agricultural Workers' Diseases↗
PubMedDate not supplied

Time trends of occupational pesticide-related injuries in Costa Rica, 1982-1992.

To evaluate time trends of occupational pesticide-related injuries in Costa Rica, a survey was carried out three times over a ten-year period at a national reporting system for occupational accidents and diseases among wage-earning workers. The sample comprised the accidents reported during the months of June of the years 1982, 1987, and 1992. The overall incidence rates were 1.8, 2.7, and 2.5 per 1,000 agricultural workers, respectively. Rates among female workers increased (3.1, 3.7, 5.4) and were elevated as compared with male workers (1.7, 2.6, 2.3). The trend for topical lesions was upgoing (1.2, 1.4, 2.1), consistent with an increased use of fungicides and lack of safety measures for pesticides with low acute toxicity. Systemic poisonings peaked in 1987 (0.6, 1.2, 0.5), declining in 1992 with increased use of biologic pest control and pyrethroid insecticides less toxic than cholinesterase inhibitors, and improved safety during nematocide applications on banana plantations. In 1992, despite the largest decline of systemic poisonings in the banana-producing Atlantic Region, poisonings as well as topical injuries were still four times more frequent in this region than in the rest of the country. Restriction of highly toxic pesticides together with implementation of occupational safety measures can reduce systemic poisonings in developing countries. Such policies need to be extended to other pesticides to prevent less life threatening but often disabling skin and eye injuries.

Accidents, Occupational↗
PubMed2001

Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus.

BACKGROUND: Scorpion venom contains insect and mammal selective toxins. We investigated the venom of the South Indian red scorpion, Mesobuthus tamulus for the purpose of identifying potent insecticidal peptide toxins. RESULTS: A lepidopteran-selective toxin (Buthus tamulus insect toxin; ButaIT) has been isolated from this venom. The primary structure analysis reveals that it is a single polypeptide composed of 37 amino acids cross-linked by four disulfide bridges with high sequence homology to other short toxins such as Peptide I, neurotoxin P2, Lqh-8/6, chlorotoxin, insectotoxin I5A, insect toxin 15 and insectotoxin I1. Three dimensional modeling using Swiss automated protein modeling server reveals that this toxin contains a short alpha-helix and three antiparallel beta-strands, similar to other short scorpion toxins. This toxin is selectively active on Heliothis virescens causing flaccid paralysis but was non-toxic to blowfly larvae and mice. CONCLUSION: This is the first report of a Heliothine selective peptide toxin. Identification of diverse insect selective toxins offer advantages in employing these peptides selectively for pest control.

Amino Acid Sequence↗