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At least 631 records · Page 35Linked to original sources
PubMed2004

Antitermitic quinones from Diospyros sylvatica.

Six quinones were isolated from the chloroform extract of the roots of Diospyros sylvatica and identified as 2-methyl-anthraquinone, plumbagin, diosindigo, diospyrin, isodiospyrin and microphyllone. The effect of the root extract on the orientation and survival of the subterranean termite, Odontotermes obesus was tested. In addition, four of these quinones were tested on the survival of the subterranean termite. In a direct-choice experiment, exposure to an extract-treated filter disc had a significantly repellent effect over the solvent-treated filter disc. The no-choice experiment revealed the toxic property of the extract as well as the tested quinones and showed high mortality of the O. obesus workers after 48 h on forced exposure. The major termiticidal components identified were plumbagin, isodiospyrin and microphyllone while diospyrin was not toxic to termites at the concentration tested. All the quinones are reported for the first time from D. sylvatica.

Animals↗
PubMed2004

Determination of solid-liquid partition coefficients (K(d)) for diazinon, propetamphos and cis-permethrin: implications for sheep dip disposal.

Two groups of chemicals are currently licensed for use in sheep dip products in the UK. These are organophosphate (OP) insecticides and synthetic pyrethroid (SP) insecticides. SPs are deemed to be less toxic to human health than OPs, although they are approximately 100 times more toxic to some elements of the aquatic environment. Three insecticides were selected for experimental investigation: diazinon, propetamphos (OPs) and cis-permethrin (SP), representative of the active ingredients used in sheep dip formulations, with additional uses in insect control in crops, and for domestic control of flies, mosquitoes, cockroaches, lice, ticks and spiders. The UK Government has recently reviewed agricultural practices relating to the disposal of used sheep dip, because the constituent insecticides are frequently detected in UK watercourses and the presence of these compounds is a severe hazard to the aquatic environment. Standard batch sorption experiments were carried out to investigate insecticide partitioning from water to soil, and the relationship between sorption and soil organic carbon content is discussed. Sorption isotherms and K(d) values showed that cis-permethrin adsorption was fastest on all five soils investigated, exhibiting the greatest total partitioning to the soil phase (83.8-94.8%) and high resistance to desorption. In comparison, the OP insecticides exhibited moderately strong soil adsorption as evidenced by their K(d) coefficients (diazinon K(d) 12-35 and propetamphos K(d) 9-60), with low sorption reversibility (< 15%). Calculation of a hydrological retardation factor in a scenario representative of a typical UK environment suggested that SP insecticides such as cis-permethrin will not migrate in the soil profile due to their virtual immobility and strong soil retention, and thus waste sheep dip disposal to agricultural land should not pose a risk to aquatic life if applied with appropriate controls.

Agriculture↗
PubMed2004

Effects of endosulfan on B cells of Langerhans islets in rat pancreas.

Endosulfan is widely used in insect control and it is absorbed by both humans and animals through ingestion, inhalation, and percutaneously. The purpose of this work was to study blood glucose levels and ultrastructural changes that might occur in the pancreas of adult male Wistar rats as a result endosulfan intoxication. The treated group (n = 60) received endosulfan orally via gavage 2.0 mg/kg per day in corn oil for 6 weeks, while the control group (n = 10) was given equal amount of corn oil for the same period. The substances were administrated once a day. Blood glucose levels were significantly increased at the end of 3rd and 4th week (P < 0.05), and 5th and 6th week (P < 0.01) after administration of endosulfan to rats compared with the control group. In electron microscopy studies, at the end of 2nd and 3rd weeks, swelling of mitochondria; at the end of 4th week, vacuoles in cytoplasm; at the end of 5th week, dissolution of mitochondrial matrix; and at the end of 6th week, picnotic nucleus in B cells in Langerhans islet were observed after endosulfan treatment.

Animals↗
PubMed2004

Endosulfan-induced cardiotoxicity and free radical metabolism in rats: the protective effect of vitamin E.

Endosulfan is widely used in insect control and it is absorbed by both humans and animals through ingestion, inhalation and percutaneously. The aim of this work was to study antioxidant enzyme system which include superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) and malondialdehyde (MDA), the end product of lipid peroxidation and ultrastructural changes that might occur in the heart tissue of adult male Wistar rats as a result of endosulfan intoxication. Vitamin E (200 mg/kg, twice a week), endosulfan (2 mg/kg, per day, once a day in corn oil) and vitamin E (200 mg/kg, twice a week)+endosulfan (2 mg/kg, per day, once a day in corn oil) combination were given to rats (n = 10/group) orally via gavage for 6 weeks. SOD, GPx, CAT activities and MDA level increased in the endosulfan-treated group heart tissue compared to control group (P < 0.01, P < 0.01, P < 0.05 and P < 0.01, respectively). SOD, GPx activities and MDA level decreased in the vitamin E + endosulfan-treated group compared to endosulfan-treated group (P < 0.05, P < 0.05 and P < 0.05, respectively). Decrease of CAT activity was not significant statistically in the vitamin E + endosulfan-treated group compared to endosulfan-treated group. CAT activity increased in the vitamin E + endosulfan treated group compared to control group (P < 0.05). Increase of SOD, GPx activities and MDA levels were not significant statistically in the vitamin E + endosulfan-treated group compared to control group. In electron microscopic investigations while cytoplasmic edema and swelling and vacuolization of mitochondria of myocardial cells in endosulfan-treated group was observing, only a weak swelling of mitochondria of myocardial cells in vitamin E + endosulfan-treated group was observed. We conclude that vitamin E significantly reduce endosulfan-induced cardiotoxicity in rats.

Administration, Oral↗
PubMed2006

Comparison of the acute toxicity for gamma-cyhalothrin and lambda-cyhalothrin to zebra fish and shrimp.

Gamma-cyhalothrin 15CS (GCH) contains only the active stereoisomer of the two isomers found in lambda-cyhalothrin 25EW (LCH). GCH (0.5 x rate) provides equivalent overall insect control as LCH (1 x rate). Both formulations showed high acute toxicity to zebra fish (Brachydanio rerio H.B.) and shrimp (Macrobrachium nippoensis de Haan). The 96-h LC(50(zebra fish,GCH)) is 1.93 microg a.i/L and LC(50(zebra fish,LCH)) is 1.94 microg a.i/L. LC(50(shrimp,GCH)) is 0.28 microg a.i./L and LC(50(shrimp,LCH)) 0.04 microg a.i./L. This indicates that the toxicity to shrimp is likely stereochemistry-dependent. The fates of GCH and LCH are similar in laboratory simulated rice paddy water and their concentrations decrease rapidly, with no GCH or LCH detected after 3 or 4 days. Both are toxic to shrimp in a simulated paddy irrigation reservoir even though treated return water is diluted 5 times. No shrimp fatality is shown in the GCH-treated paddy water after a 4-day holding period, and longer than 5 days is necessary to reach a zero fatality rate for LCH. This is compatible with the 7-day water holding period considered reasonable in agricultural practice.

Animals↗
PubMed2003

Studies on trap effectiveness of tsetse flies (Glossina spp. (Diptera: Glossinidae)) in the Tanga Region of north eastern Tanzania.

At Mkwaja and Mivumoni ranches in NE Tanzania the catches of Glossina pallidipes Austen, G. brevipalpis Newstead, G. morsitans morsitans Westwood and G. austeni Newstead were usually about two to three times greater in traps of the NGU, Epsilon and F3 types than in the Blue Biconical and Pyramidal traps when used with odours. Catches from moving men were improved about three times when the men carried a black screen, and increased by about another seven times for female G. pallidipes when a vehicle was the bait. The sensitivity of surveys for tsetse was estimated to be improved about 300 times for G. pallidipes and two to five times for G. brevipalpis and G. m. morsitans when surveys use traps instead of vehicles as baits. The needs for further research and field trials with survey methods are discussed.

Animals↗
PubMed1999

Monitoring house reinfestation by vectors of Chagas disease: a comparative trial of detection methods during a four-year follow-up.

Domestic reinfestations by triatomine bugs were monitored after application of deltamethrin and apparent elimination of Triatoma infestans in Amama and other nearby rural villages, north-west Argentina, from 1992 to 1996. The five methods used were sensor boxes, sheets of pink typing-paper, timed manual catches by a skilled three-person team aided by a flushing-out agent, collections by house-dwellers, and knockdown using insecticide fumigant canisters. In bedrooms, house-dwellers collected T. infestans significantly more frequently than the flushing-out method, but the reverse occurred in peridomestic sites. Both methods and sensor boxes revealed the frequent invasion of adult Triatoma guasayana and T. infestans, but neither T. guasayana nor Triatoma sordida colonized bedroom areas in spite of their rising abundance in nearby peridomestic sites. Sensor boxes were significantly more sensitive than the matched paper-sheets in three of five cross-sectional surveys. On average, each box recorded 2.0-3.2 times more triatomine fecal smears than each paper sheet. The frequency of dejecta in sensor boxes correlated positively with the proportion of houses where T. infestans, T. guasayana or T. sordida were captured by any method in bedroom areas. Triatomine fecal smears in sensor boxes were the earliest and most frequent sign of domiciliary infestation, followed by dwellers' collections of adult bugs. Analyzing the data prospectively, we provide a quantitative, predictive understanding of detection methods and review the validity and interpretation of the different signs of infestation obtained. The most sensitive and cost-effective combination of detection methods for vector surveillance in domestic areas was the use of sensor boxes and house-dwellers collections.

Animals↗
PubMed2001

The role of a proline-induced broken-helix motif in alpha-helix 2 of Bacillus thuringiensis delta-endotoxins.

Bacillus thuringiensis delta-endotoxins (Cry proteins), are widely used for insect control and plant protection. They are water-soluble proteins that insert into membranes forming ion channels. In most Cry toxins alpha-helix 2 is broken by a highly conserved proline residue (Pro70 in Cry1Ab), generating a broken-helix motif. The flexibility of the motif was altered through site-directed mutagenesis. It was found that increasing the flexibility of the motif decreased the stability, the ion transport ability and the toxicity of the protein. By removing the broken-helix motif, the biological properties were restored to a wild type level.

Alanine↗
PubMed2003

Further enhancement of baculovirus insecticidal efficacy with scorpion toxins that interact cooperatively.

We have studied whether the cooperative insecticidal effect of certain scorpion toxin pairs, namely either a combination of excitatory and depressant, or alpha and depressant scorpion toxins, would improve the efficacy of Autographa californica nucleopolyhedrovirus (AcMNPV) over a virus expressing only a single toxin, towards Heliothis virescens, Helicoverpa armigera, and Spodoptera littoralis larvae. The best result was achieved by combined expression of the excitatory toxin, LqhIT1, and the depressant toxin, LqhIT2, that provided an ET(50) value of 46.9 h on H. virescens neonates, an improvement of 40% over the efficacy of wild-type AcMNPV, and of 18% and 22% over baculoviruses that express each of the toxins independently. These results demonstrate that significant improvement in efficacy of recombinant baculoviruses is obtainable with toxins that exhibit a cooperative effect, and may contribute to employ baculoviruses to replace hazardous chemicals in insect control.

Animals↗
PubMed2001

Proteolytic breakdown of the Neb-trypsin modulating oostatic factor (Neb-TMOF) in the hemolymph of different insects and its gut epithelial transport.

The degradation of the unblocked hexapeptide, trypsin modulating oostatic factor of the flesh fly Neobellieria (Sarcophaga) bullata (Neb-TMOF) was studied in vitro in the hemolymph of the lepidopteran Spodoptera frugiperda, the orthopteran Schistocerca gregaria and the dictyopteran Leucophaea maderae. The half-life in the different species varied from approximately 3min in L. maderae to approximately 25min in S. gregaria. Purification of the degradation products and ESI-Qq-oa-Tof mass spectrometry revealed the fragments Asn-Pro-Thr-Asn, Leu-His and Asn-Pro, which were the same in the hemolymph of all species. Except in Leucophaea, Neb-TMOF was cleaved in dipeptides starting from the C-terminus and the reaction could be, at least partially, inhibited by captopril. These observations suggest that a dipeptidase, which has very similar enzymatic properties as mammalian angiotensin converting enzyme (ACE) and which circulates in the hemolymph, apparently is involved in the breakdown of Neb-TMOF and might be a common but not a universal enzyme in insect hemolymph.The introduction of Neb-TMOF into the gut of S. gregaria with the help of a capillary tube (intubation) demonstrated that the intact peptide is able to cross the gut epithelium and to appear in the hemolymph compartment. Since [3H]-inulin, which is too large to cross cell membranes, was found to penetrate the gut walls at a measurable rate, the paracellular pathway might be also permeable to smaller peptides. There was indeed a clear correlation between the molecular weight of inulin, Neb-TMOF, and inositol and the rate of penetration of these compounds through the gut epithelium to the hemolymph. These are promising findings in view of a potential use of such peptides for insect control purposes.

Journal Article↗
PubMed2002

Prey-mediated effects of the protease inhibitor aprotinin on the predatory carabid beetle Nebria brevicollis.

To investigate the potential non-target impacts of transgenic pest-resistant plants, prey-mediated impacts of a protease inhibitor (PI) on the predatory carabid, Nebria brevicollis, were investigated. The PI used was aprotinin, a serine PI of mammalian origin with insecticidal properties when incorporated in artificial diet or expressed in transgenic plants. Field-collected N. brevicollis adults, kept at 23 degrees C, 16:8 L:D, were fed, over their pre-aestivation activity period of 24 days, with Helicoverpa armigera larvae reared on an artificial diet containing 0.5% (w:w, fresh mass) aprotinin. These larvae contained 22.62 &mgr;g aprotinin/g insect. Control prey was reared on diet without aprotinin. Beetle survival and body mass were unaffected by prey type. Beetles consuming PI-fed prey lost significantly more mass than the control beetles during two periods of mass loss, but gained significantly more mass during the final period of mass gain. This was not due to differences in amounts of prey supplied or consumed. The final mass gain coincided with increased consumption of PI-prey. Female beetles were significantly heavier than males, but we found no consistent gender-based differences in response to PI-prey. At the end of the experiment, body mass of all beetles was similar to field-collected ones (approximately 55 mg). All experimental beetles had significantly lower activities of digestive cysteine proteases and the serine proteases chymotrypsin and trypsin than field-collected ones. Beetles consuming PI-fed prey had significantly lower levels of trypsin and higher levels of chymotrypsin and elastase than the control beetles.

Journal Article↗
PubMed1997

The effects of azadirachtin on the testes of the desert locust, Schistocerca gregaria (Forskål).

Testes removed from Schistocerca gregaria, injected with 5 or 7&mgr;g azadirachting(-1) body wt on day 0-2 of the Vth instar and killed by decapitation 20days after treatment, showed significant reductions between the widths, lengths and volumes of the treated groups, compared to control insects. Under cytological examination these testes, from insects exhibiting classical signs of azadirachtin poisoning, showed arrested spermatogenic meiosis at Metaphase I.

Journal Article↗
PubMed1998

Role of the head in the ultrastructural midgut organization in Rhodnius prolixus larvae: evidence from head transplantation experiments and ecdysone therapy.

Studies on the effects of decapitation, head transplantation and ecdysone therapy on the ultrastructural organization of the midgut in 5th-instar larvae of Rhodnius prolixus, were carried out. Control insects had a typical and significant organization of the epithelial cells (mainly microvilli, extracellular membrane layers and basal portion of the epithelial cells) of the midgut (stomach and intestine) during the entire period of the experiment. However, the host larvae, when decapitated 1 day after feeding, demonstrated significant changes in the ultrastructural organization of the epithelial cells of these compartments. In converse experiments, head transplantations from untreated donors 4-5 days after feeding into headless larvae sustained the ultrastructural organization of the epithelial cells in the midgut. Oral therapy with ecdysone (5 &mgr;g/mL of blood meal) in decapitated insects significantly reversed the altered organization of the stomach and intestine. These results point to a brain factor, possibly the prothoracicotropic hormone (PTTH) which stimulates ecdysteroid production in the prothoracic glands, may be a factor responsible, directly or indirectly, for the midgut cell organization in R. prolixus.

Journal Article↗
PubMed2003

Strain-specific detection of introduced Beauveria bassiana in agricultural fields by use of sequence-characterized amplified region markers.

Field studies on the efficacy and persistence of an introduced strain of Beauveria bassiana for insect control require detection assays to differentiate the non-native strain from indigenous populations. In this study we developed strain-specific molecular markers based on polymerase chain reaction amplification of sequence-characterized amplified regions (SCAR) in combination with dilution plating on semi-selective medium to detect and estimate density of propagules of a commercial strain of B. bassiana (strain GHA) in field samples. Using random amplified polymorphic DNA (RAPD) analysis, unique fragments that distinguished GHA from other strains of B. bassiana were obtained. Three amplicons, OPA-14(0.44), OPA-15(0.44), and OPB-9(0.67), generated with RAPD primers were cloned and sequenced and used as bases for designing SCAR primers OPA14 F/R(445), OPA15 F/R(441), and OPB9 F/R(677), respectively. All three SCAR primers were highly sensitive, capable of detecting 100pg B. bassiana GHA genomic DNA, and thus could be used to detect varying levels of the fungus in the field.

Agriculture↗
PubMed1996

Infraspecific taxonomy and essential oil chemotypes in sweet basil, Ocimum basilicum.

Essential oil compositions of fresh and freeze-dried leaves were determined for 16 accessions of Ocimum basilicum belonging to different varieties to see whether they could be used as infraspecific taxonomic characters. One accession of O. x citriodorum was also studied. Some 30 monoterpenoids, sesquiterpenoids and phenylpropanoids were identified, the major components (more than 20% of the total essential oil composition in one or more accessions) being geranial and neral in O. x citriodorum, and linalool, methyl chavicol, eugenol, methyl eugenol and geraniol in O. basilicum. Based on a combination of the latter compounds, five major essential oil profiles could be distinguished in the accessions studied for O. basilicum. These profiles were largely the same for fresh and freeze-dried material of the same plant, although in the dried leaves, methyl chavicol and eugenol concentrations had generally declined in comparison to those of linalool. There appeared to be little correlation between essential oil patterns and varietal classification within O. basilicum. In view of the chemical heterogeneity of O. basilicum and its use as an essential oil-producing crop, culinary herb, medicinal plant and insect-controlling agent, in all of which chemicals play an important role, the infraspecific classification of this taxon should take chemical characters into consideration. A system for the classification of essential oil chemotypes in O. basilicum is proposed.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Chemical industry reduces emissions--from production to the consumer.

Responsible care has always been an important issue at a chemical industry like Bayer. In recent years, the company has made extensive efforts to further improve its products and processes with regard to environmental protection and safety. In this contribution, a number of examples will highlight recent achievements of Bayer in the field of low or no emission processes and products. Examples are given in the fields of production-integrated environmental protection measures (new and improved processes e.g., for the production of adipic acid), the application of integrated environmental protection measures (2K-PUR water-borne coatings for cars) and product-integrated environmental protection measures (targeted application of insecticides/Attract and Kill) as a new low emission method to control insect pests.

Air Pollution↗