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At least 325 records · Page 18Linked to original sources
PubMed2002

Factors affecting the field performance of an attracticide against the codling moth Cydia pomonella.

Factors affecting the efficacy of an attracticide strategy for the control of the codling moth Cydia pomonella L (Lepidoptera: Tortricidae) were investigated using laboratory and field experiments. The sex-pheromone-based insect-control strategy utilises 100-microliters droplets of a sticky, paste-like formulation containing 1 mg g-1 (E,E)-8,10-dodecadien-1-ol (codlemone) as an attractant for male moths and 40 mg g-1 cyfluthrin, a contact insecticide, applied to branches in the upper parts of the tree crown. The longevity of the treatment under field conditions was assessed in the laboratory by biological testing of variously aged samples of the attracticide formulation which had been applied to the bark of apple trees growing in commercial orchards. Electroantennogram responses of male moth antennae were used to compare codlemone release from the attracticide after different lengths of environmental exposure. Changes in insecticidal efficacy of the same samples were assessed with reference to the speed of knockdown (KT50) and the mortalities after 48 h among populations of male moths confined in cages containing samples of fresh and field-aged formulations. Gradual declines in both the amount of pheromone released and insecticidal activity were observed over the 10-week period of the experiments. Various factors associated with the behaviour of codling moths in the field which might influence the attracticide strategy were also investigated. Although the vertical position of attracticide sources within apple trees had a strong influence on their attractiveness, their horizontal position had none. Results of field trials showed that efficacy of the attracticide depends on the population density of the pest. Under the conditions of the current study a density of three or more sources per tree (= 4500 sources per ha) was required to attain satisfactory levels of codling moth control.

Agriculture↗
PubMed2000

Field evaluation of deet and a piperidine repellent against Aedes communis (Diptera: Culicidae) and Simulium venustum (Diptera: Simuliidae) in the Adirondack Mountains of New York.

Repellent efficacy of N,N-diethyl-3-methyl-benzamide (deet), the piperidine, 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine (AI3-37220), and a 1:1 ratio of deet + AI3-37220 were evaluated topically (0.25 mg/cm2 applied in ethanol solution) on human volunteers against the mosquito Aedes communis (DeGeer) and the black fly Simulium venustum Say. The average repellency of all three formulations was > 95% at 4 h. For both mosquitoes and black flies, deet alone provided < 90% protection at 6 h, whereas AI3-37220 provided > 95% protection. Although repellent treatments were not significantly different overall, the contrasts between AI3-3720 versus deet were significant at 6 and 8 h. The 95% confidence interval on percent repellency at 6 h ranged from 90.1 to 98.9% for AI3-37220 versus 64.3 to 82.2% for deet, and at 8 h ranged 76.1 to 88.5% for AI3-37220 versus 47.8 to 64.0% for deet. Similarly, the confidence interval for protection against black flies at 6 h by (AI3-37220 ranged from 86.3 to 99.5% and did not overlap with the confidence interval provided by deet alone (51.2 to 78.8%). There was no evidence of synergistic repellency from a combination of the two compounds; i.e., protection from combined compounds was no better than either repellent used alone.

Aedes↗
PubMed1999

Bacillus sphaericus interferes with the development of Brugia malayi in Aedes aegypti.

Aedes aegypti (black-eyed Liverpool strain) were exposed to a sublethal dose (LD25) of Bacillus sphaericus and were fed to Mastomys coucha infected with Brugia malayi. The development of the filarial parasite was found to be arrested mostly at the second larval stage. The infection (P < 0.05), infectivity rates (P < 0.001) and L3 load (P < 0.001) were found to be reduced significantly in the treated group.

Aedes↗
PubMed2001

[The prescription of repellents].

Repellents are chemical products designed to ward off insects. They are effective against a wide range of arthropods including mosquitoes and flies but not against bees and wasps. Choosing the proper repellent can be difficult because no single product repels all pests. This article compares the performance and toxicity of various repellents based on reports describing systemic, topical, or physical repellents made from natural or synthetic ingredients. Essential oils are the most common natural ingredient. Synthetic ingredients range from dimethyphtalate, ethylexanediol, and diethyltoluamide (DEET) to new molecules such as 35/35, piperidine, bayerepel, and KBR 3023. Our findings indicate that DEET, used as the gold standard in most studies, is still the most effective repellent. There is no synergy between any of these products but combinations (e.g. ethylhexanediol and DEET) can optimize protection. In conclusion we propose guidelines for prescribing repellents to achieve the required level of protection in function of the duration of exposure and benefit-to-risk ratio. Several recommendations are made on the safe use repellents for adults and children.

Animals↗
PubMed2001

Insect neuropeptide antagonists.

The development of a new integrated approach to the generation of a novel type of insect neuropeptide (Np) antagonists and putative insect control agents based on backbone cyclic compounds is described. The approach, termed the backbone cyclic neuropeptide-based antagonist (BBC-NBA), was applied to the insect pyrokinin (PK)/pheromone biosynthesis activating neuropeptide (PBAN) family as a model, and led to the discovery of a potent linear lead antagonist and several highly potent, metabolically stable BBC antagonists, devoid of agonistic activity, which inhibited PBAN-mediated activities in moths in vivo. This review briefly summarizes our knowledge of insect Nps, describes the PK/PBAN Np family, presents the basic concepts behind the BBC-NBA approach, and introduces the advantages of this method for generation of Np agonists, antagonists and insecticide prototype molecules.

Amino Acid Sequence↗
PubMed1999

Genetic mapping of resistance to Bacillus thuringiensis toxins in diamondback moth using biphasic linkage analysis.

Transgenic plants producing environmentally benign Bacillus thuringiensis (Bt) toxins are deployed increasingly for insect control, but their efficacy will be short-lived if pests adapt quickly. The diamondback moth (Plutella xylostella), a worldwide pest of vegetables, is the first insect to evolve resistance to Bt toxins in open-field populations. A recessive autosomal gene confers resistance to at least four Bt toxins and enables survival without adverse effects on transgenic plants. Allelic variants of this gene confer resistance in strains from Hawaii, Pennsylvania, and the Philippines. Here we exploited the biphasic nature of Lepidopteran genetic linkage to map this gene in diamondback moth with 207 amplified fragment length polymorphisms as DNA markers. We also cloned and sequenced an amplified fragment length polymorphism marker for the chromosome containing the Bt resistance gene. The results provide a powerful tool for facilitating progress in understanding, monitoring, and managing resistance to Bt.

Animals↗
PubMed1998

Insecticidal toxins from the bacterium Photorhabdus luminescens.

Transgenic plants expressing Bacillus thuringiensis (Bt) toxins are currently being deployed for insect control. In response to concerns about Bt resistance, we investigated a toxin secreted by a different bacterium Photorhabdus luminescens, which lives in the gut of entomophagous nematodes. In insects infected by the nematode, the bacteria are released into the insect hemocoel; the insect dies and the nematodes and bacteria replicate in the cadaver. The toxin consists of a series of four native complexes encoded by toxin complex loci tca, tcb, tcc, and tcd. Both tca and tcd encode complexes with high oral toxicity to Manduca sexta and therefore they represent potential alternatives to Bt for transgenic deployment.

Amino Acid Sequence↗
PubMed1992

Expression of the mosquitocidal toxins of Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis by recombinant Caulobacter crescentus, a vehicle for biological control of aquatic insect larvae.

In the quest for effective control of mosquitoes, attention has turned increasingly to strains of the bacteria Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis, which produce potent toxins with specific mosquitocidal activities. However, sedimentation of the bacterial spores limits the duration of effective control after field application of these bacilli. We describe here the cloning of genes encoding the 51.4- and 41.9-kDa toxins from B. sphaericus 2297, the 100-kDa toxin from B. sphaericus SSII-1, and the 130-kDa toxin from B. thuringiensis subsp. israelensis into the broad-host-range plasmid pRK248 and the transfer of these genes for expression in Caulobacter crescentus CB15. The recombinant C. crescentus cells were shown to be toxic to mosquito larvae. Caulobacter species are ubiquitous microorganisms residing in the upper regions of aquatic environments and therefore provide the potential for prolonged control by maintaining mosquitocidal toxins in larval feeding zones.

Animals↗
PubMed1998

[Study on the physiological activities of the metabolites from Paecilomyces arovirens].

The metabolites of Paecilomyces arovirens exhibited insecticidal activities to many inscct pcsts, including cotton aphid, Aphis gossypii, hawthorn Ispidcr mitc, Tetranychus viennensis and larvae of imported cabbage worm, Pietis rapae. A comparison was made between the metabolites of P. arovirens and naphthyl acetic acid (NAA) in wheat (Triticum aestivum) and water melon (Cucumis sativus) bioassays on their physiological effects. Results demonstrated that some of the metabolites physiological activities of P. arovirens are same to that of NAA, some are different between them. It indicate that there is a new kind or many kinds of plant growth regulator in the metabolites and need further analysized. The results can offer reference for exploiting a new insecticid which not only can control insect pests, but also increase plant growth.

Cucumis sativus↗
PubMed1985

[Physical preservation of food].

Physical preservation procedures are mostly aimed at prolonging the durability of foods by slowing down or repressing the spoilage mechanisms by the alteration of relevant parameters. Of these mechanisms of microbiological, enzymatic, chemical and mechanical type, especially the first-named are dealt with. Growth and multiplication of micro-organisms can be influenced by temperature, water activity and high-energy radiation. Depending on the susceptibility to deterioration of the products and the intensity of the processes based on these parameters, different degrees of durability are obtained. Micro-organisms are killed by the application of high temperatures in conjunction with the treatment times required in a given case. Relatively mild treatments affect only the vegetative forms (pasteurization), whereas more aggressive treatments are required to kill spores as well (sterilization). Recontamination of the products which were subjected to the two procedures must be avoided. Pasteurized foods require additional cold storage to prevent the spores from sprouting. Low temperatures reduce and repress the growth of micro-organisms (refrigeration) or prevent any activity of the micro-organisms (deep-freezing). The latter deprives the micro-organisms of the water they need for their growth. The same principle applies to another method of preservation where so much water is extracted from the product that the residual humidity no longer allows the micro-organisms to be active (drying). Ionising radiation can be used to reduce a potential risk to hygiene, to influence physiological processes, to control insects and to lengthen the durability of fresh food in the short term. Finally optimum product quality can be maintained by combining various procedures. If such methods cope with controlling the microbiological situation, attention must nevertheless be given to the other spoilage mechanisms as well, as they may prove to be limiting factors with respect to product quality.

Bacteria↗
PubMed2001

Entomopathogenic nematodes for the biocontrol of ticks.

Entomopathogenic steinemematid and heterorhabditid nematodes are increasingly used to control insect pests of economically important crops. Laboratory and field simulation trials show that ticks are also susceptible to these nematodes. The authors review the potential of entomogenous nematodes for the control of ticks.

Animals↗