Lemon peel oil extract as mosquito larvicide

Tests on lemon peel oil extract as a mosquito larvicide were carried out. The oil was found to be toxic on larvae, pupae and eggs of Culex quinquefasciatus. The oil also fulfilled other required specifications like suitable specific gravity, spreading pressure and viscosity. It was also toxic at a wide pH range, stable to heat and light in terms of chemical change which could alter larvicidal action. However, it was volatile and did not form a permanent film on water surfaces for long periods. This affected the larvicidal action.     

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A novel Clostridium bifermentans strain toxic to mosquito larvae on ingestion was isolated from a soil sample collected from secondary forest floor. This strain was designated as serovar paraiba (C. b. paraiba) according to its specific H antigen. Clostridium bifermentans paraiba is most toxic to Anopheles maculatus Theobald larvae (LC50 = 0.038 mg/liter), whereas toxicity to Aedes aegypti (Linn.) (LC50 = 0.74 mg/liter) and Culex quinquefasciatus Say (LC50 = 0.11 mg/liter) larvae was 20 and 3 times lower, respectively. The toxicity to An. maculatus larvae is as high as that of Bacillus thuringiensis serovar israelensis. C. b. paraiba was also found to exhibit significant per os insecticidal activity toward adult Musca domestica (Linn.).     

Inhibition of growth and aflatoxin production of Aspergillus parasiticus by citrus oils

Aspergillus parasiticus was inoculated into grapefruit juice and a glucose-yeast extract medium; both contained 500-7000 ppm of citrus oils that were incorporated into the media by sonication. Orange and lemon oil were more inhibitory to mold growth and aflatoxin production than was dlimonene, the main constituent of the two peel oils. After 7 days at 28 degrees C, 2000 ppm of lemon and 3000 ppm of orange oil in grapefruit juice afforded maximum suppression of mold growth and toxin formation. When the glucose-yeast extract medium was used, 3000 ppm of either oil were needed to achieve the same result. After 4 days at 28 degrees C, orange oil at 3500 ppm in either medium markedly inhibited mold growth (as evidenced by dry weight of mold mycelium) and aflatoxin production (only 14 and 1% of the amount normally produced in the juice and artificial medium, respectively). Higher concentrations of orange oil further reduced mold growth and aflatoxin production and also delayed the onset of sporulation, if it occurred. Although aflatoxin was detected in all samples, only 0.2 to 0.5% of the amount found in controls (without the citrus oil) was present when the medium contained 7000 ppm orange oil. The mold consistently grew, albeit very poorly, on the glass at the liquid-atmosphere interface even when the substrate contained a large amount of citrus oil.     

Insect-control chemicals from plants. III. Toxic lignans from Libocedrus bidwillii

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.     

Development of Wuchereria bancrofti in Culex pipiens L. (Diptera: Culicidae) exposed in the larval instar to sublethal dosages of insecticides and one insect growth regulator and their influence on reproduction of filaria-infected mosquitoes

The effects of exposure of Culex pipiens larvae to sublethel concentrations of larvicides on uptake, development of Wuchereria bancrofti, survival rate and reproduction of filaria-infected mosquitoes were investigated. Fourth instar larvae of Cx. pipiens were exposed to LC40 of the surfactant Triton X-100, the insect growth regulator DPX alone or combined with LC10 of the surfactant and permethrin alone or combined with LC10 of the surfactant. Adults that survived insecticide treatments and controls were infected by allowing them to feed on microfilaremic volunteers. Significant reduction in the uptake of microfilaria was observed in groups treated with Triton X-100 alone or combined either with permethrin or DPX when compared to control. The overall infection and infective rates were significantly reduced in mosquitoes treated with Triton X-100 either alone or combined with permethrin. Treatment with Triton X-100 and DPX prolonged the extrinsic incubation period (EIP) and retarded the development of filarial larvae, while permethrin either alone or combined with Triton X-100 and DPX combined with Triton X-100 shortened the EIP. All larvicides reduced the number of infective larvae (L3)/mosquito and induced deformities among he different parasite stages, especially in mosquitoes treated with combination of permethrin and Triton X-100 or mixture of DPX and Triton X-100 where 36% and 54.9% respectively of L3S were deformed. In treated mosquitoes, a low percentage of L3S was detected in the head and proboscis region while the majority was trapped in the thoracic region. The survival rates of mosquitoes were reduced in cases treated with permethrin, DPX and Triton X-100 while treatment with mixture of DPX and Triton X-100 induced higher rate of mortalities when compared to control. Egg production of filaria- infected Cx. pipiens was significantly reduced in mosquitoes treated with DPX and Triton X-100. It was observed that the addition of Triton X-100 to DPX or to permethrin significantly reduced egg production. The results suggest that sublethal concentrations of larvicides especially Triton X-100 applied to 4th instar larvae of Cx. pipiens could effectively interfere with the development of W. bancrofti in Cx. pipiens and reduced the survival rate and fecundity of the vector.     

Insecticidal activity of Bacillus laterosporus

The Bacillus laterosporus strains 921 and 615 were shown to have toxicity for larvae of the mosquitoes Aedes aegypti, Anopheles stephensi, and Culex pipiens. The larvicidal activity of B. laterosporus was associated with spores and crystalline inclusions. Purified B. laterosporus 615 crystals were highly toxic for Aedes aegypti and Anopheles stephensi.     

Contribution of the 65-kilodalton protein encoded by the cloned gene cry19A to the mosquitocidal activity of Bacillus thuringiensis subsp. jegathesan

Two new crystal protein genes, cry19A and orf2, isolated from Bacillus thuringiensis subsp. jegathesan were cloned and characterized. The cry19A gene encodes a 74.7-kDa protein, and the orf2 gene encodes a 60-kDa protein. Cry19A contains the five conserved blocks present in most B. thuringiensis delta-endotoxins. The ORF2 amino acid sequence is similar to that of the carboxy terminus of Cry4 proteins. The cry 19A gene was expressed independently or in combination with orf2 in a crystal-negative B. thuringiensis host. The proteins accumulated as inclusions. Purified inclusions containing either Cry19A alone or Cry19A and ORF2 together were toxic to Anopheles stephensi and Culex pipiens mosquito larvae. They were more toxic to C. pipiens than to A. stephensi. However, inclusions containing Cry19A and ORF2 together were more toxic than inclusions of Cry19A alone but less toxic than the wild-type inclusions of B. thuringiensis subsp. jegathesan.     

Evaluation of three (Z)-9-tricosene formulations for control of Musca domestica (Diptera: Muscidae) in caged-layer poultry units

A field trial comparing the effectiveness of toxic targets impregnated with different formulations of the Musca domestica L. female sex pheromone (Z)-9-tricosene was conducted in a caged-layer, deep-pit poultry unit in southern England. Targets baited with 5 g of technical grade (Z)-9-tricosene, or 5 g of a 40% polymer bead formulation, caught significantly greater numbers of M. domestica than control targets. This increase in attractiveness of the pheromone-impregnated targets persisted for at least 24 wk. However, mean daily catch rates of M. domestica at targets baited with 5 g of a 2% wettable powder formulation did not significantly differ from control levels. Technical grade and bead formulations of the pheromone attracted significantly more males than females. However, the catches of female M. domestica at these pheromone-impregnated targets were significantly greater than female catches at control targets. Monitoring with sticky cards indicated that the introduction of toxic targets successfully suppressed adult M. domestica population density for up to 13 wk. Possible hypotheses explaining the effect of (Z)-9-tricosene on female attraction are discussed.     

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Anopheles sacharovi, An. atropatvus, An. pulcherrimus, An. superpictus. An. stephensi, Culex pipiens females to prefer fresh water for their oviposition. The differences between them are that the An.stephensi and Culex pipiens avoid high salinity values more frequently than other species. The eggs of a all the species studied do not survive at 2% salinity. The An. sacharovi eggs are more resistant to salinity while the An. pulcherrimus ones are less resistant. Nevertheless, the females of all the species oviposited a quantity into the significant salinity water obviously unsuited to the development of preimaginal stages.     

Determinants of perceived health in patients with left ventricular dysfunction: a structural modeling analysis

The species composition, abundance, and distribution of mosquito larvae in tires were determined on 3 dates at a relatively large rural tire dump (about 300,000 tires) in southeastern IL (Jasper County). Several observations at this site differed from those in previous reports about mosquitoes in tireyards, including 1) a relatively high percentage of tires positive for Aedes triseriatus larvae in an open-field area, 2) a greater abundance of Culex pipiens than Cx. restuans in late-season collections, 3) a seasonal change in the distribution of Aedes atropalpus larvae in tires from open field and edge of woods areas, and 4) the presence of Ae. albopictus as a major late-season species. Ae. albopictus adults were captured in sod-baited gravid traps along the edge of a wooded riparian area 200 m from the tire pile.     

The toxicity of different crude oils on mussel larva

Five natural oils of varied origins, mixed with sea water by stirring, have been shown to be toxic for mussel larvae, which have been contaminated during one hour. This toxicity, expressed by the mortality percentage and the growth rate after contamination, was dependent on the type and the concentration of oil. The tests were carried out on 20 h old and 5 days old larvae, and were similar and complementary.     

Laboratory evaluation of the biocontrol potential of Mesocyclops thermocyclopoides (Copepoda: Cyclopidae) against mosquito larvae

Biocontrol potential of Mesocyclops thermocyclopoides against first instar larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus was studied under laboratory conditions. It was found that M. thermocyclopoides had the highest predation efficacy against Ae. aegypti followed by An. stephensi and Cx. quinquefasciatus. There was a significant reduction in the predation efficacy of M. thermocyclopoides against Cx. quinquefasciatus in the presence of alternate food (p < 0.01). The cage simulation trial indicated that M. themocyclopoides has the potential to control Ae. aegypti breeding effectively in a container type of habitat.     

The potential effectiveness of essential oils as a treatment for headlice, Pediculus humanus capitis

Essential oils of aniseed, cinnamon leaf, red thyme, tea tree, peppermint, nutmeg, rosemary, and pine were tested in vitro against lice, Pediculus humanus. All the oils except for rosemary and pine were found to be effective in the laboratory when applied in an alcoholic solution and followed by a rinse the following morning in an essential oil/vinegar/water mixture. Peppermint and nutmeg were only used as a blend rather than as individual oils. Problems of solubility and toxicity are discussed, as are possible mechanisms of action. Phenols, phenolic ethers, ketones, and oxides (1,8-cineole) appear to be the major toxic components of these essential oils when used on lice. Aldehydes and sesquiterpenes may also play a role.     

Efficacy of an ivermectin controlled-release capsule against nematode and arthropod endoparasites in sheep

Five controlled trials were conducted in Germany or in the United Kingdom, using 74 female sheep of merino or Dorset horn breeds, to evaluate the efficacy of an ivermectin controlled-release capsule against naturally acquired or induced infections of gastrointestinal nematodes, lungworms and nasal bot larvae and against incoming infections with gastrointestinal and pulmonary nematodes. Half of the animals were treated with one ivermectin controlled-release capsule that delivered ivermectin at the rate of 1.6 mg per day for 100 days while the other half remained untreated. Parasites were counted 21, 28, 35 or 56 days after administration of the capsule. The treatment was highly effective (> or = 99 per cent) against established parasites of the following species: Haemonchus contortus (adults and fourth-stage larvae), Ostertagia circumcincta, O pinnata, O trifurcata, Ostertagia species fourth-stage larvae, Trichostrongylus axei, T colubriformis, T vitrinus, Cooperia curticei, Nematodirus battus, N filicollis, Strongyloides papillosus, Chabertia ovina, Oesophagostomum venulosum, Trichuris ovis, Tr skrjabini, Dictyocaulus filaria, Protostrongylus rufescens and Oestrus ovis (larvae). The treatment prevented the establishment of the gastrointestinal nematodes H contortus, O circumcincta, T axei, T colubriformis, C curticei, N battus, N filicollis, Ch ovina, Oe vennulosum and the establishment of the lungworm D filaria by > 99 per cent compared with untreated controls (P < or = 0.01).     

Deletion mapping in breast tumor cell lines points to two distinct tumor-suppressor genes in the 1p32-pter region, one of deleted regions (1p36.2) being located within the consensus region of LOH in neuroblastoma

The nucleotide sequence of the cry11Bb1 gene from Bacillus thuringiensis subsp. medellin was determined. The corresponding protein has a deduced molecular mass of 88.2 kDa, and is 60.9% and 83% identical to the proteins Cry11Aa1 and Cry11Ba1, respectively. The Cry11Bb1 protein contains five repetitive blocks of 16 amino acids at the C terminal part. It is highly toxic to first instar laboratory reared Aedes aegypti, Anopheles albimanus and Culex quinquefasciatus larvae.     

Albendazole versus ricobendazole (albendazole-sulphoxide) against enteral and parenteral stages of Trichinella spiralis in mice

Comparison of the anthelmintic activity and pharmacokinetic profiles following albendazole (ABZ) and albendazole-sulphoxide (ricobendazole = RBZ) administration was made in a mouse model for helminthic infections. Swiss CD-1 mice were experimentally infected with Trichinella spiralis and treated with either ABZ or RBZ at 3 different stages of the parasite life-cycle: pre-adult (day 1 p.i.), migrating larvae (days 13, 14 and 15 p.i.) and encysted muscle larvae (days 34, 35 and 36 p.i.). Plasma concentrations of albendazole-sulphoxide (ABZSO) were measured in age matched non-infected mice by high performance liquid chromatography (HPLC), after administration of ABZ or RBZ dosed at 50 mg ABZ equivalent kg-1. ABZSO pharmacokinetic profiles following ABZ or RBZ administration were similar, although the Tmax (1.83 +/- 0.30 and 0.41 +/- 0.28, respectively) were significantly different (P < 0.01). Against pre-adult stages ABZ was significantly (P < 0.05) more effective than RBZ when administered at 10 mg kg-1 (96.5% and 78.0% reduction with respect to the control group). Migrating and encysted larvae were less sensitive to both compounds and dose rates had to be increased to 100 mg kg-1 to achieve significant efficacies. Against parenteral stages, ABZ was significantly more effective than RBZ when both were given at 100 mg kg-1 (64.0% and 44.2% reduction against migrating larvae and 94.7% and 65.5% reduction against encysted larvae, respectively). In conclusion, RBZ was not more effective than ABZ against enteral and parenteral stages of Trichinella spiralis.     

Processing of procathepsin from Musca domestica eggs

The major source of amino acids for insect embryos are yolk proteins which accumulate in developing oocytes and are hydrolyzed during embryogenesis. Studies on Musca domestica embryogenesis indicated that a cathepsin B-like proteinase is responsible for yolk protein degradation (Ribolla et al., 1993). In this study, we report the purification of mature cathepsin and show that it is made up of a single 41 kDa polypeptide chain. The Musca domestica cathepsin NH2-terminal 11-residue sequence was determined (Ala-Pro-Lys-Tyr-Val-Asp-Tyr-Gly-Glu-Asn-Glu) and reveals homology with other cathepsins of the papain family. Experiments using serum anti-cathepsin show that the enzyme is stored in oocytes as a 55 kDa zymogen. The activation of the zymogen occurs in vitro only at low pH. In vitro activation in the presence of cysteine protease inhibitors is blocked at an intermediary polypeptide of 48 kDa. Kinetic studies of this activation process at pH 3.5 and 4.6 show that the zymogen is processed in a manner similar to that of pepsin (Foltmann, 1986) and papain (Vernet et al., 1991). We propose that Musca domestica cathepsin zymogen activation occurs in two steps. First, an intramolecular cleavage of the procathepsin polypeptide chain (55,000), induced by low pH gives rise to an intermediary polypeptide (48,000) which then undergoes autolysis to produce the mature enzyme (41,000).     

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A culture system designed to support the development of individual preantral mouse ovarian follicles has been employed to study follicle growth in the New World marsupial species Monodelphis domestica. Preantral follicles were isolated mechanically and cultured individually in microdrops under oil. Preliminary results indicate that follicle growth was positively correlated to the concentration of follicle-stimulating hormone (FSH) provided, with 1.0-1.5 IU FSH mL-1 producing the best results. Incubation at the body temperature of M. domestica (33 degrees C) was found to be preferable to that at 37 degrees C. The culture system was able to support follicle growth; however, despite follicles exceeding the size when antrum formation occurs in vivo, they remained preantral.     

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Topical treatment of the phytochemical plumbagin in doses ranging 0.005-5 micrograms prevented oocyte development and affected fecundity and fertility in M. domestica. The treatment to wandering larvae was less effective as the compound could only effect the fertility to a significant level whereas the fecundity was not significantly reduced. The effect of the compound was more pronounced in adult treatments where both fecundity and fertility reduced drastically. The compound also effected the oocyte maturation as it arrested the development of vitellogenic oocyte at stage six. As the juvenile hormone analogue methoprene and moulting hormone 20-hydroxyecdysone or the mixture of these hormones could not restore the development of the oocyte in ovaries of plumbagin treated flies, it is concluded that the compound does not effect the female houseflies through hormonal pathways, instead in all probability it acts like a cytotoxic compound.     

Antitumor effects elicited by antisense-mediated downregulation of the insulin-like growth factor I receptor (review)

The parasporal inclusion proteins of the type strain of Bacillus thuringiensis serovar higo (H44), that have moderate mosquitocidal activity, were characterized. The purified parasporal inclusions, spherical in shape, were examined for activity against the two mosquito species, Culex pipiens molestus and Anopheles stephensi and the moth-fly, Telmatoscopus albipunctatus. The LC50 values of the inclusion for the two mosquitoes were 3.41 and 0.15 microgram.ml-1, respectively. No mortality was shown for T. albipunctatus larvae by the inclusions at concentrations up to 1 mg ml-1. Solubilized parasporal inclusions exhibited no haemolytic activity against sheep erythrocytes. Parasporal inclusions consisted of eight proteins with molecular masses of 98, 91, 71, 63, 59, 50, 44 and 27 kDa. Of these, the 50 and 44 kDa proteins were the major components. Analysis with immunoblotting revealed that, among several inclusion proteins of B. thuringiensis serovar israelensis, only two proteins of 130 kDa and 110 kDa reacted weakly with antibodies against higo proteins. N-terminal amino acid sequences of the 98, 91, and 71 kDa proteins showed 85-100% identity to those of the two established Cry protein classes, Cry4A and Cry10A.