Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INSECT CONTROL”

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.

At least 667 records · Page 37Linked to original sources
PubMed1995

Hymenolepis diminuta-induced fecundity reduction may be caused by changes in hormone binding to Tenebrio molitor ovaries.

Aspects of vitellogenesis, known to be controlled by juvenile hormone, are adversely affected by Hymenolepis diminuta infection of Tenebrio molitor, in spite of circulating titres of the hormone remaining unchanged. It has therefore been proposed that juvenile hormone binding is disrupted at the tissue site level. Juvenile hormone III binding sites were located in the nuclear, microsomal and post-microsomal supernatant fractions of the follicle cells of Tenebrio molitor. When JH-III binding was quantified for both control and Hymenolepis diminuta-infected beetles, binding in the nucleus and cytosol were found to be largely unaffected. However, microsomal binding was severely disrupted; on days 3 and 6 post-infection, binding was greatly diminished, on day 9 post-infection, binding was slightly reduced and, by day 15, binding was 'restored' to that of control insects. Using follicle cell microsomes at day 3 post-infection, previous Scatchard analysis revealed the presence of at least two JH-III binding sites. The first is of higher affinity, Kd = 5.3 x 10(-8) M, Bmax = 1.5 x 10(-11) mol/mg protein and the second of lower affinity Kd = 7.7 x 10(-7) M, Bmax = 9.75 x 10(-11) mol/mg protein. A comparison with microsomal binding parameters of follicle cells from non-infected Tenebrio indicated that although the Bmax values were unchanged, the Kd value of the higher affinity site was increased by approximately 5-fold. These data are indicative of a parasite-induced competitive binding inhibitor.

Animals↗
PubMed1996

Hymenolepis diminuta: metacestode-induced reduction in the synthesis of the yolk protein, vitellogenin, in the fat body of Tenebrio molitor.

Vitellogenin synthesis by the fat body has been monitored using in vitro culture and immunoprecipitation. This system was found to be efficient for measuring vitellogenin production in both non-infected Tenebrio molitor and those infected with Hymenolepis diminuta. In fat bodies from infected beetles, vitellogenin production was decreased by up to 75% (day 24 post-infection) and, at all times investigated, vitellogenin synthesis was significantly below control levels (days 3-30 post-infection). Incubating fat bodies from control insects with isolated metacestodes indicated that this may be a direct effect by the parasite which is developmental stage-specific. Stage II, but not Stage III-IV, not heat-killed parasites could bring about this decrease in vitellogenin. In addition, these effects may be density dependent within the range of 2-20 parasites per fat body; only 2 metacestodes were necessary to cause a significant decrease. Since metacestodes do not take up vitellogenin, nor limit the amount of [14C]leucine available to the fat body for vitellogenin production, it is conceivable that the parasite produces a potent inhibitor of vitellogenin synthesis, or a molecule which induces cells within the fat body.

Animals↗
PubMed2000

Volatile aldehydes are promising broad-spectrum postharvest insecticides.

A variety of naturally occurring aldehydes common in plants have been evaluated for their insecticidal activity and for phytotoxicity to postharvest fruits, vegetables, and grains. Twenty-nine compounds were initially screened for their activity against aphids on fava bean leaf disks. Application under reduced pressure (partial vacuum) for the first quarter of fumigation increased insecticidal activity severalfold. The 11 best aldehydes were assayed against aphids placed under the third leaf of whole heads of iceberg lettuce using the same two-tier reduced-pressure regime, which caused no additional detriment to the commodity over fumigation at atmospheric pressure. Phytotoxicity to naked and wrapped iceburg lettuce, green and red table grapes, lemon, grapefruit, orange, broccoli, avocado, cabbage, pinto bean, and rice at doses that killed 100% of aphids was recorded for three promising fumigants: propanal, (E)-2-pentenal, and 2-methyl-(E)-2-butenal. These three compounds have excellent potential as affordable postharvest insect control agents, killing 100% of the aphids with little or no detectable harm to a majority of the commodities tested. Preliminary assays indicate that similar doses are also effective against mealybugs, thrips, and whitefly.

Aldehydes↗
PubMed2000

Determination of spinosad and its metabolites in food and environmental matrices. 2. Liquid chomatography-mass spectrometry.

A selective and sensitive method utilizing liquid chromatography-mass spectrometry (LC-MS) has been developed for determining residues of the natural insect control agent spinosad in several crop matrices that are difficult to analyze by HPLC with UV detection. The method determines the active ingredients (spinosyns A and D) and three minor metabolites (spinosyns B and K and N-demethylspinosyn D) in alfalfa hay, wheat hay, wheat straw, sorghum fodder, and corn stover. The analytes are extracted from the samples with an acetonitrile/water solution, and the extracts are purified by solid phase extraction with a C(18) disk and a silica cartridge. All five analytes are determined simultaneously in a single injection using positive atmospheric pressure chemical ionization LC-MS with selected ion monitoring. The average recoveries ranged from 69 to 96% with standard deviations ranging from 4 to 15%. The method has a validated limit of quantitation of 0. 01 microgram/g and a limit of detection of 0.003 microgram/g. The LC-MS method can also provide residue confirmation in addition to quantitation.

Agriculture↗
PubMed2002

Environmental fate of spinosad. 1. Dissipation and degradation in aqueous systems.

Spinosad is a bacterially derived insect control agent consisting of two active compounds, spinosyns A and D. The objective of this paper is to describe the environmental fate of spinosad in aquatic systems. To this end, several studies performed to meet regulatory requirements are used to study the fate and degradation in individual environmental media. Specifically, investigations of abiotic (hydrolysis and photolysis) and biotic (aerobic and anaerobic aquatic) processes are described. Understanding developed from the laboratory-based studies has been tested and augmented by an outdoor microcosm study. Understanding of aquatic fate is a building block for a complete environmental safety assessment of spinosad products (Cleveland, C. B.; Mayes, M. A.; Cryer, S. A. Pest Manag. Sci. 2001, 58, 70-84). From individual investigations, the following understanding of dissipation emerges: (1) Aqueous photolysis of spinosad is rapid (observed half-lives of <1 up to 2 days in summer sunlight) and will be the primary route of degradation in aquatic systems exposed to sunlight. (2) Biotic transformations contribute to spinosad's dissipation, but less so than photolysis; they will be of primary importance only in the absence of light. (3) Spinosad partitions rapidly (within a few days) from water to organic matter and soil/sediment in aquatic systems but not so rapidly as to replace sunlight as the primary route of dissipation. (4) Abiotic hydrolysis is relatively unimportant compared to other dissipation routes, except under highly basic (artificial) conditions and even then observed half-lives are approximately 8 months. Degradation pathways are understood are follows: (1) Degradation primarily proceeds by loss of the forosamine sugar and reduction of the 13,14-bond on the macrolide ring under aqueous photolytic conditions. (2) Degradation to several other compounds occurs through biotic degradation. Degradation under anaerobic conditions primarily involves changes and substitutions in the rhamnose ring, eventually followed by complete loss of the rhamnose ring. Degradation under aerobic conditions was more extensive (to smaller compounds) with the loss of both the forosamine and rhamnose sugars to diketone spinosyn aglycon degradates. (3) Hydrolytic degradation involves loss of the forosamine sugar and water and reduction on the macrolide ring to a double bond at the 16,17-position.

Aerobiosis↗
PubMed2004

Insecticidal components from field pea extracts: soyasaponins and lysolecithins.

Extracts from field peas (Pisum sativum L.) have previously been shown to have a utility to control insect pests. To identify potentially new bioinsecticides in field crops, we describe the fractionation of impure extracts (C8 extracts) derived from protein-rich fractions of commercial pea flour. The activity of separated fractions was determined by a flour disk antifeedant bioassay with the rice weevil [Sitophilus oryzae (L.)], an insect pest of stored products. Bioassay-guided fractionation showed that the triterpenoid saponin fractions were partly responsible for the antifeedant activity of C8 extracts. Soyasaponin I (soyasaponin Bb), isolated from peas and soybeans, and mixtures of soyasaponins, comprised of soyasaponins I-III and isolated from soybeans, were inactive antifeedants, but dehydrosoyasaponin I (the C-22 ketone derivative of soyasaponin I), a minor component found in C8 extracts, was shown to be an active component. Dehydrosoyasaponin I (soyasaponin Be) and soyasaponin VI (soyasaponin betag) coeluted under conditions of silica gel thin-layer chromatography and C18 high-performance liquid chromatography. However, dehydrosoyasaponin I could be isolated from saponin-enriched fractions with a reversed phase column of styrene/divinylbenzene operated at alkaline pH. Phospholipids of the lysolecithin type were also identified in saponin fractions of C8 extracts from peas. Three of the lysolecithins were inactive alone against rice weevils, but mixtures of these phospholipids enhanced the insecticidal activity of dehydrosoyasaponin I.

Animals↗
PubMed2004

Isomer selectivity in aquatic toxicity and biodegradation of cypermethrin.

Synthetic pyrethroids (SPs) are widely used in both agricultural and urban regions for insect control. Unlike many other pesticides, SPs are chiral compounds consisting of stereoisomers. However, occurrence of isomer selectivity in environmental processes is poorly understood for SPs. We evaluated isomer selectivity in toxicity of cypermethrin (CP) to Ceriodaphnia dubia and in its biodegradation by microbial isolates and in sediment. Among the eight enantiomers, two enantiomers (1R-cis-alphaS and 1R-trans-alphaS) were found to be toxic to C. dubia. Bacteria strains isolated from sediment selectively degraded CP diastereomers and enantiomers. The trans diastereomers were preferentially degraded over the cis diastereomers. Of the two active enantiomers, 1R-cis-alphaS was degraded slower, whereas 1R-trans-alphaS was degraded faster than the other stereoisomers. Similar isomer selectivity was observed during CP degradation in whole sediment. Since ecotoxicity is likely caused only by the biologically active enantiomers, knowledge on isomer selectivity may improve our understanding of the ecological risks of CP and analogous SPs.

Animals↗
PubMed2004

Insecticidal effect of phthalides and furanocoumarins from Angelica acutiloba against Drosophila melanogaster.

Insecticidal activity of Angelica acutiloba extract and its constituents was investigated and compared with that of rotenone. Bioassay-guided isolation of the chloroform extract of A. acutiloba against larvae of Drosophila melanogaster afforded two phthalides, (Z)-butylidenephthalide (1) and (Z)-ligustilide (2), and two furanocoumarins, xanthotoxin (3) and isopimpinellin (4). The structures of these compounds were established by spectroscopic analysis. The isolated compounds 1, 2, 3, and 4 exhibited LC(50) values of 0.94, 2.54, 3.35, and 0.82 micromol/mL of diet concentration against larvae of D. melanogaster, respectively. Against both sexes (males/females, 1:1) of adults (5-7 days old), compound 1 showed the most potent activity with a LD(50) value of 0.84 microg/adult. Compound 1 is a more active insecticide than rotenone (LD(50) = 3.68 microg/adult) and has potential as a novel insect control agent. However, compound 2 was inactive against adults. The structure-activity relationship of phthalides isolated indicated that the aromaticity appeared to play an important role in the activity of both larvae and adults. To determine the insecticide mode of action for acute adulticidal activity, acetylcholinesterase (AChE) inhibitory activity was also investigated in vitro, and the result indicated that the acute adulticidal activity of compounds 3 and 4 was due to the inhibition of AChE.

Angelica↗
PubMed1999

Fluorescent excitation transfer immunoassay for the determination of spinosyn A in water.

A fluorescent excitation transfer immunoassay for spinosyn A, a fermentation derived insect control agent, has been developed and applied to the analysis of tap water and wastewater effluent from manufacturing plants. Fluorescein (F) and tetramethylrhodamine (TMR) were chosen as donor and quencher, respectively, for the excitation transfer. Fluorescence quenching was observed from the binding of F-labeled antigen to TMR-labeled antibody. By employing nonlabeled antigen in a competitive immunoassay format, we reversed fluorescence quenching. The assay provides a limit of detection of 0. 01 ppb and a working range of 0.05-1 ppb and allows for the rapid determination of spinosyn A in water with recovery values ranging from 96% to 120%. With the exploitation of the small size of optical fibers, fluorescence from an assay volume of 24 microL could be measured without special vessels.

Anti-Bacterial Agents↗
PubMed2000

Determination of spinosad and its metabolites in citrus crops and orange processed commodities by HPLC with UV detection.

Spinosad is an insect control agent that is derived from a naturally occurring organism and is effective on a wide variety of crops, including citrus crops. A method is described for the determination of spinosad and its metabolites in citrus crops and orange processed commodities. The method determines residues of the active ingredients (spinosyns A and D) and three minor metabolites (spinosyn B, spinosyn K, and N-demethylspinosyn D). For dried orange pulp and orange oil, the method has a limit of quantitation (LOQ) of 0.02 microg/g and a limit of detection (LOD) of 0.006 microg/g. For all other sample matrices (whole fruit, edible fruit, juice, and peel), the method has an LOQ of 0.01 microg/g and an LOD of 0.003 microg/g. The analytes are extracted from the various sample types using appropriate solvents, and the extracts are purified by liquid-liquid partitioning and/or solid-phase extraction. All five analytes are determined simultaneously in the purified extracts by reversed-phase high-performance liquid chromatography with ultraviolet detection at 250 nm.

Anti-Bacterial Agents↗
PubMed2000

Insecticidal and fumigant activities of Cinnamomum cassia bark-derived materials against Mechoris ursulus (Coleoptera: attelabidae).

The insecticidal and fumigant activities of Cinnamomum cassia (Blume) bark-derived materials against the oak nut weevil (Mechoris ursulus Roelofs) were examined using filter paper diffusion and fumigation methods and compared to those of the commercially available Cinnamomum bark-derived compounds (eugenol, salicylaldehyde, trans-cinnamic acid, and cinnamyl alcohol). The biologically active constituent of the Cinnamomum bark was characterized as trans-cinnamaldehyde by spectroscopic analysis. In a test with the filter paper diffusion method, trans-cinnamaldehyde showed 100 and 83.3% mortality at rates of 2.5 and 1.0 mg/filter paper, respectively. At 2.5 mg/paper, strong insecticidal activity was produced from eugenol (90.0% mortality) and salicylaldehyde (88. 9%), whereas trans-cinnamic acid revealed moderate activity (73.3%). At 5 mg/paper, weak insecticidal activity (50.0%) was produced from cinnamyl alcohol. In a fumigation test, the Cinnamomum bark-derived compounds were much more effective against M. ursulus larvae in closed cups than in open ones. These results indicate that the insecticidal activity of test compounds was attributable to fumigant action, although there is also significant contact toxicity. As a naturally occurring insect-control agent, the Cinnamomum bark-derived materials described could be useful as a new preventive agent against damage caused by M. ursulus.

Aldehydes↗
PubMed2006

Engineering of the spinosyn PKS: directing starter unit incorporation.

The spinosyns are a family of potent and highly selective insect control agents that display a favorable environmental profile. As some regions of the spinosyn molecule are recalcitrant to chemical modification, a targeted genetic approach was carried out to generate new analogues. The polyketide synthase (PKS) loading modules from the avermectin PKS of Streptomyces avermitilis and the erythromcyin PKS of Saccharopolyspora erythraea were each used to replace the spinosyn PKS loading module. Both of the resulting strains containing hybrid PKS pathways produced the anticipated spinosyn analogues. Supplementation of the culture media with a range of exogenous carboxylic acids led to the successful incorporation of these novel elements to yield further novel spinosyn molecules, some of which demonstrated potent and new insecticidal activities. Furthermore, it has been demonstrated that semisynthesis of such novel metabolites can then be used to generate active analogues, demonstrating the effectiveness of utilizing these complementary methods to search the chemical space around this template.

Amino Acid Sequence↗
PubMed2001

Why short-term bioassays are not meaningful--effects of a pesticide (Imidacloprid) and a metal (cadmium) on pea aphids (Acyrthosiphon pisum Harris).

The life-table study on effects of a heavy metal, Cd (100 and 200 mg kg-1 soil), and an insecticide, imidacloprid (4 and 40 g a.i. ha-1), on pea aphids revealed significant effects of both chemicals on life history traits and population dynamics. Substantial differences in the action of the two chemicals and between the two doses of imidacloprid were observed. The pesticide caused high mortality at the beginning of the experiment, however some aphids were able to live for as long as control insects. In contrast, Cd-induced mortality was low at the beginning but increased during the experiment. Analysis of data collected during the first 10 days of the experiment, the first 20 days, or for the whole life-time of the cohort gave different results. While highly significant effects of imidacloprid were detected already after 10 days of the experiment, Cd treatment resulted in no effect for this time of exposure. Higher dose of imidacloprid decreased growth and development rates along with delayed reproduction (9th or 10th day). In contrast, the aphids treated with the low dose of imidacloprid and with both concentrations of Cd started their reproduction at the same day as untreated insects (6th or 7th day), but the reproduction tended to cease earlier. This indicates that too short ecotoxicological tests may result in serious underestimation of some effects, while overestimating others.

Animals↗
PubMed2004

The effects of seed quality and pipecolic and djenkolic acids on bruchid beetle infestation in water deficit-stressed Acacia trees.

Acacia trees in the Negev desert and the Arava valley of Israel are suffering high levels of mortality due to water stress. Additionally, recruitment is negatively affected by bruchid beetles. We hypothesized that water-stressed trees would be less able to produce secondary defense compounds, such as the nonprotein amino acids, pipecolic acid and djenkolic acid, in their seeds to decrease seed herbivory. We further hypothesized that the high seed infestation reported is due to increased fitness of beetles infesting trees that are in a poor physiological state. Contrary to our prediction, pipecolic acid concentration was higher in water-stressed Acacia raddiana trees. We found that infestation rates and beetle fitness were higher in trees in a poor physiological state, despite the higher levels of pipecolic acid in these trees. There was a significant positive correlation between infestation level and the amounts of djenkolic acid in the seeds, indicating that the beetles may have found a means of utilizing djenkolic acid for their own benefit.

Acacia↗
PubMed2001

[Protection against biting mosquitoes].

The protection against arthropods especially disease transmitting mosquitoes is becoming more and more important. The problems with drugs used for treatment and prophylactic of malaria are rapidly growing due to emergence of resistant parasites and unwanted side effects. Furthermore the population living in endemic area often can't afford the new expensive drugs. A safe and effective way of preventing insect bites is needed. One can prevent arthropod born diseases by avoiding insect bites through physical and chemical means or a combination of both. Repellents are substances applied to the skin, which effectively prevent insects from biting. The gold standard is still Diethylbenzamine (DEET), which is highly effective, well documented and in use for more than 50 years. The new repellent Bayrepel (hydroxyethyl isobutyl piperidin carboxylate) available to the consumer since 1998, seems to have an efficacy comparable with DEET. Insecticides have a direct toxic effect on the nervous system of arthropods. Mainly synthetic pyrethroids, which produce less ecological problems than the older products, are used. They are supplied in form of sprays, vaporising mats or coils. An important progress is the combination of insecticides with physical means. Insecticide treated bed nets or clothes give an excellent protection. Topical or systemic Vitamin B1, acoustic devices and electrocuters are still sold and widely used although their complete ineffectivity is documented in many studies.

Animals↗