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[Gas chromatography and mass spectrometry method for detection of selected pyrethroid metabolites in urine].

Pyrethroids are increasingly used indoors, because of their low mammalian toxicity but high insecticidal activity. Indoor application of pyrethroids, which is often carried out without adequate expert knowledge, may lead to high pesticide residues, often combined with health hazards for the people concerned. Objective of the present study is the development of a method for a biological monitoring to determine internal exposure to pyrethroids. Major pyrethroid metabolites were detected in urine by capillary gas chromatography in combination with mass selective detection (MSD). For the metabolites, the limits of determination range between 0.5 and 1 microgram/L urine. Our results so far demonstrate the detectability of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (DVCA) and 3-phenoxybenzoic acid (3-PBA) in urine during a period of elimination of 48 hours after exposure to cypermethrin. In this paper the method is exemplary illustrated by one exposed person (pest control operator).

Adult↗

Potential use of essential oils from Cameroon applied as fumigant or contact insecticides against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae).

Essential oils from seven plants species currently found in Cameroon were extracted by steam distillation and tested for their insecticidal activities against Sitophilus zeamats Motsch. Responses varied with the test applied and the plant species. For the contact toxicity, the acetone was used in order to dilute the pure essential oil. Formulations of 1% of essential oils of Xylopia aethiopica and Ocimum gratissimum were the most toxic and led to 96 and 98% of mortality respectively after 24 h. There was no death in control (0% of mortality). Fumigation test were done by applying 300 microl of pure essential oils in the bottom of closed 800 ml glass containers. In that case, the essential oil of Hyptis spicigera was the most toxic (fumigant) after 48 hours of fumigation followed by Annona seregalensis and Xylopia aethiopica 96 and 95% of mortality respectively. Some of the essential oils of plant species tested are promising for pest control in farmer granaries. However, further investigations are to be done on formulation and side effects.

Animals↗

Crystal structure of a fungal elicitor secreted by Phytophthora cryptogea, a member of a novel class of plant necrotic proteins.

BACKGROUND: Elicitins form a novel class of plant necrotic proteins which are secreted by Phytophthora and Pythium fungi, parasites of many economically important crops. These proteins induce leaf necrosis in infected plants and elicit an incompatible hypersensitive-like reaction, leading to the development of a systemic acquired resistance against a range of fungal and bacterial plant pathogens. No crystal structures of this class of protein are available. The crystal structure determination of beta-cryptogein (CRY), secreted by Phytophthora cryptogea, was undertaken to identify structural features important for the necrotic activity of elicitins. RESULTS: The structure of CRY was determined using the multiwavelength anomalous diffraction technique and refined to 2.2 A resolution. The overall structure has a novel fold consisting of six alpha helices and a beak-like motif, whose sequence is highly conserved within the family, composed of an antiparallel two-stranded beta sheet and an omega loop. This motif is assumed to be a major recognition site for a putative receptor and/or ligand. Two other distinct binding sites seem to be correlated to the level of necrotic activity of elicitins. CONCLUSIONS: The determination of the crystal structure of a member of the elicitin family may make it possible to separate the activity that causes leaf necrosis from that inducing systemic acquired resistance to pathogens, making it feasible to engineer a non-toxic elicitin that only elicits plant defences. Such studies should aid the development of non-toxic agricultural pest control.

Algal Proteins↗

Manipulating sex pheromones for insect suppression.

A review is given of different methods of using sex pheromones in pest control programs. Survey and monitoring traps have been used extensively for determining the presence and abundance of pest populations are commercially available. Pheromone trapping studies for insect suppression have shown success with some species and could be a useful tool in some situations. The technique of attracting insects to the host for insect removal or exposure to insecticide has also proved to be useful in some programs. Mating disruption studies using widely-separated pheromone evaporators or encapsulated pheromone distributed throughout an area have indicated a great potential for this technique in insect suppression programs.

Agriculture↗

Biorational approaches for insect control by enzymatic inhibition.

Conventional insecticides are highly toxic to many living organisms as well as to the environment; consequently, new biorational and more specific approaches to pest control have been developed. In this paper, we present an update of those approaches resulting from studies on inhibition of enzymes involved in key processes of insects life, particularly growth, molting and development of larvae and intraspecific communication of adults. The enzymes covered include pheromone degrading enzymes, pheromone biosynthetic enzymes, oxidoreductases, juvenile hormones, juvenile hormone epoxide hydrolases, proteases, molting hormones and phenoloxidases. Although these approaches refer to control of insect pests, many of them can be in principle also considered suitable for medicinal chemistry studies, since the mechanism of action of these inhibitors on related enzymes is quite similar, if not equal, in both fields.

Animals↗

Orchard netting impacts on biodiversity leading to cascading effects at the ecosystem level.

Agriculture must ensure food production without further compromising the ecosystem functions upon which it depends. Agricultural practices should therefore avoid harming farmland biodiversity, especially of taxa that supply the key ecosystem services (e.g. pollination, pest control and nutrient uptake) that ultimately support crop production. Orchards are among the largest permanent plantations worldwide and are increasingly characterised by the spread of plastic nets used to protect fruits/nuts from either abiotic (anti-hail, anti-rain, shade nets) or biotic (exclusion nets) hazards. Despite having received little attention to date, these nets may impact natural communities, acting both as physical barriers and as drivers of habitat changes to which biota must respond. Species-level responses to netting depend on the organism's ability to enter the netted environment and successfully exploit available resources. Net-mediated ecological filtering and plastic behavioural responses may alter species interactions, leading to cascading ecological impacts that may create species-poorer 'netted communities' with simplified ecological networks. Such changes may erode biological control potential, other ecosystem functions, and overall system stability. We conducted a systematic review on the effects of protection nets on biota, and reported novel empirical evidence on anti-hail nets' impacts on communities of orchard-dwelling birds, flower-visiting insects, and rodents. In total, we identified 48 studies from the literature, however this literature was strongly biased towards apple orchards, western countries, and pest taxa. Net deployment was highly effective in deterring target pest species, in some cases regardless of their original function, as even weather-protection nets limited pest populations. Side effects on non-target taxa were also often reported, such as decreases in pollinators and natural enemies, and/or increases in secondary pests or microbial diseases. However, most assessments largely disregarded non-pest taxa and the broader ecological consequences of netting. The few studies that addressed the effects of nets at the guild/community level, including our empirical study, confirmed that orchard netting resulted in species-poor assemblages, with possible ecosystem-level consequences. We propose that future assessments should pay more attention to the indirect effects of netting on non-target taxa, and on the supply of crop-supporting ecosystem services mediated by wild species occurring in agroecosystems. Due to the trade-offs between these services and net-mediated crop protection, integrated alternatives should be tested to improve the environmental sustainability of food production and biodiversity conservation in farmed landscapes.

Biodiversity↗

Molecular and insecticidal characterization of a Cry1I protein toxic to insects of the families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae.

The most notable characteristic of Bacillus thuringiensis is its ability to produce insecticidal proteins. More than 300 different proteins have been described with specific activity against insect species. We report the molecular and insecticidal characterization of a novel cry gene encoding a protein of the Cry1I group with toxic activity towards insects of the families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae. PCR analysis detected a DNA sequence with an open reading frame of 2.2 kb which encodes a protein with a molecular mass of 80.9 kDa. Trypsin digestion of this protein resulted in a fragment of ca. 60 kDa, typical of activated Cry1 proteins. The deduced sequence of the protein has homologies of 96.1% with Cry1Ia1, 92.8% with Cry1Ib1, and 89.6% with Cry1Ic1. According to the Cry protein classification criteria, this protein was named Cry1Ia7. The expression of the gene in Escherichia coli resulted in a protein that was water soluble and toxic to several insect species. The 50% lethal concentrations for larvae of Earias insulana, Lobesia botrana, Plutella xylostella, and Leptinotarsa decemlineata were 21.1, 8.6, 12.3, and 10.0 microg/ml, respectively. Binding assays with biotinylated toxins to E. insulana and L. botrana midgut membrane vesicles revealed that Cry1Ia7 does not share binding sites with Cry1Ab or Cry1Ac proteins, which are commonly present in B. thuringiensis-treated crops and commercial B. thuringiensis-based bioinsecticides. We discuss the potential of Cry1Ia7 as an active ingredient which can be used in combination with Cry1Ab or Cry1Ac in pest control and the management of resistance to B. thuringiensis toxins.

Amino Acid Sequence↗

Manipulation of parasitoids for aphid pest management: progress and prospects.

This paper describes research at IACR-Rothamsted on aphid parasitoid responses to semiochemical foraging stimuli, aimed at developing novel ways of manipulating these behaviours to overcome ecological constraints to biological and integrated pest control. Female parasitoids respond both to aphid sex pheromones acting as kairomones, and to aphid-induced plant volatiles, acting as synomones. A range of economically important parasitoid species respond to aphid sex pheromones, and their potential for enhancing parasitization of aphid populations has been demonstrated in the field. Commercial production of the pheromone from the plant Nepeta cataria L has been developed and strategies for its use in arable crops are being investigated. Aphid-induced plant volatiles are released systemically throughout the plant and are aphid species specific, probably induced by elicitors in aphid saliva. Aphid-infested plants can induce uninfested neighbours to release damage-related volatiles, plant-to-plant communication occurring via the rhizosphere. The plant compound cis-jasmone has been identified as a plant signal with potential for aphid control, inducing plant defence mechanisms that both deter colonising aphids and attract parasitoids and predators. Such compounds may represent a new generation of crop protectants and their further investigation and development will be aided by the tools generated by genomic and post-genomic biology.

Animals↗

Distribution, occurrence and characterization of entomopathogenic fungi in agricultural soil in the Palestinian area.

The occurrence of entomopathogenic fungi was investigated in irrigated vegetable fields and citrus orchards soils, over a nine-month period (April-December 1999), using the Galleria bait method (GBM). Entomopathogenic fungi were found to occur in 33.6% of the soil samples studied, with positive samples yielding 70 fungal isolates, belonging to 20 species from 13 genera. Conidiobolus coronatus was the most frequent and abundant entomopathogenic species recovered, comprising 31.4% of the total number of isolates. Soil pH, soil moisture content and the geographical location had minor or no effect on the isolation of entomopathogenic fungi in the fields studied. On the other hand, organic matter content of soil, and vegetation type were found to significantly affect the occurrence of entomopathogenic fungi in soil habitats, with orchard fields yielding larger numbers of isolates than vegetable fields. Using Koch's postulates the pathogenicity of fungal isolates to Galleria larvae was found to range from 16-100% (mortality rate). Isolates of C. coronatus proved to be the most virulent isolates recovered. The effect of media and temperature on mycelial growth rate, conidial production and conidial germination of six entomopathogenic fungal species (C. coronatus, Entomophaga grylli, Erynia castrans, Hirsutella jonesii, Paecilomyces farinosus and Sporodiniella umbellata) was also studied. Mycelial growth rate, spore production and spore germination were significantly affected by media, temperature and isolates. In view of the present results, C. coronatus appears to be a good candidate for pest control in agricultural soils, as it has a wide tolerance to agricultural practices, has frequently been isolated from both vegetable and orchard fields, and is characterized by high mycelial growth rate, conidial production and conidial germination.

Animals↗

Cytotoxicity against insect cells of entomopathogenic fungi of the genera Hypocrella (anamorph Aschersonia): possible agents for biological control.

Extracts from entomopathogenic fungi of the genus Hypocrella (7 species) and its anamorph Aschersonia (11 species) were screened for cytotoxicity to Sf9 and C6/36 insect cells and L929, BHK(21)C13 and HepG2 mammalian cells. Cytotoxic extracts to insect cells (ID50's < or = 10 microg ml(-1)) but not to mammalian cells (ID50's > or = 10 microg ml(-1)) conformed to the criteria of the project and were considered 'lead' extracts for further investigation. 'Leads' were found in two of the Hypocrella species: H. discoidea, and H. tamurai and in three of the Aschersonia species: A. samoensis, A. badia, and A. tamurai. Bioassay-guided fractionation of the cell extract of the fungus A. samoensis BCC 1393 led to the identification of two known anthraquinone dimers, (+)rugulosin (1) and skyrin (2) which showed selective toxicity towards insect cells. (+)Rugulosin (1) and skyrin (2) exhibited strong cytotoxic activity against the insect cell line Sf9 with respective ID50 values of 1.2 and 9.6 microg ml(-1), but showed weak activity toward mammalian cells. This first report of (+)rugulosin (1) and skyrin (2) in A. samoensis is confirmed and demonstrated in another four strains of A. samoensis isolated in Thailand. The preferential cytotoxicity against Sf9 insect cells gives evidence that these insect-pathogenic fungi of the Hypocrella/Aschersonia group might be useful as an agent for pest control.

Aedes↗

Composition and insect attracting activity of the essential oil of Rosmarinus officinalis.

The essential oil and a number of extracts of Rosmarinus officinalis L. in solvents of increasing polarity were isolated, and their components identified and tested as pest control agents. Ethanol and acetone extracts attract grape berry moth Lobesia botrana. However, none of the extracts had a significant effect on western flower thrips Frankliniella occidentalis, which is attracted by 1,8-cineole, a major essential oil component.

Animals↗

AcMNPV ChiA protein disrupts the peritrophic membrane and alters midgut physiology of Bombyx mori larvae.

Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) chitinase A (ChiA) is a protein which promotes the final liquefaction of infected host larvae. The potential of this viral molecule as a new tool for insect control is explored here. The ChiA gene was isolated from the AcMNPV genome by PCR and expressed in E. coli. The recombinant protein, purified by affinity chromatography, showed both exo- and endo-chitinase activities and produced perforations on the peritrophic membrane (PM) of Bombyx mori larvae which increased in number and in size, in a dose-dependent manner. This structural alteration resulted into a significant increase of PM permeability to methylene blue and to the small neuropeptide proctolin. When the fifth instar larvae of B. mori were fed on a artificial diet supplemented with the recombinant ChiA, 100% mortality was observed at a dose of 1 microg/g of larval body weight (LW), while at sub-lethal doses of 0.56 microg/g LW, a reduced larval growth was recorded. These results indicate that AcMNPV-ChiA may offer interesting new opportunities for pest control.

Animals↗

MicroRNA-driven regulatory networks in aphid ecological adaptation: integrating stress tolerance, dispersal plasticity, and population expansion.

Aphids (Hemiptera: Aphididae) are important agricultural pests and exhibit strong ecological adaptability, allowing them to persist under stress, disperse to new habitats, and rapidly increase population size. Recent advances in functional genomics have identified microRNAs (miRNAs) as key post-transcriptional regulators involved in these processes, yet their roles have remained fragmented across studies. Here, we synthesize current evidence into a "three-stage framework", encompassing population maintenance under stress, dispersal to new habitats, and population expansion upon establishment. We highlight how miRNAs regulate detoxification pathways (e.g., P450s, UGTs, ABC transporters), mediate interactions with host plants and symbionts, and integrate hormonal signaling networks including insulin, juvenile hormone, and ecdysteroid pathways. This framework identifies candidate miRNAs, target genes, and signaling pathways that may recur across different ecological contexts, including stress responses, dispersal-related plasticity, and reproductive regulation. However, direct evidence demonstrating that candidate shared miRNA regulators coordinate multiple life-history stages remains limited and requires further experimental validation. We critically evaluate the strength of functional evidence, distinguishing experimentally validated miRNA-target interactions from prediction- or expression-based associations. Finally, we discuss emerging applications of miRNA-based pest control, including artificial miRNAs, RNAi technologies, and nanocarrier delivery systems. By linking molecular mechanisms with ecological outcomes, this review provides a synthesis and highlights miRNAs as important regulators of aphid adaptation and candidate targets for sustainable management strategies.

Aphids↗

Viral pesticides : biohazard evaluation on the cytogenetic level.

Promising agents for integrated pest control are naturally occuring insect pathogenic viruses that belong to the group of baculoviruses. We have performed experiments using mammalian cells from different species in vivo and in vitro to test a possible effect of baculoviruses on chromosome aberration rates and sister chromatid exchanges. No cytogenetic effects were found.

Animals↗

Effect of occupational exposure to aldrin on urinary D-glucaric acid, plasma dieldrin, and lymphocyte sister chromatid exchange.

The effects of exposure to the chlorinated cyclodiene termiticide aldrin was evaluated in pest control workers potentially exposed to this material. Sister chromatid exchange (SCE) frequencies were not elevated in workers handling aldrin. This is consistent with the fact that chlorinated cyclodienes are not genotoxic. Plasma dieldrin concentrations (up to 250 ng/ml) confirmed exposure in workers actively performing termiticide treatments and in maintenance and store workers, when compared with unexposed control workers (median concentration, 4.8 ng/ml). Urinary D-glucaric acid (DGA), an index of hepatic enzyme activity, was elevated in pesticide-exposed groups but urinary DGA was poorly correlated with plasma dieldrin level. This indicates that concurrent exposures of these groups to other pesticides may have influenced mixed-function oxidase metabolic activity.

Adolescent↗

Genetic variability of Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) populations from Latin America is associated with variations in susceptibility to Bacillus thuringiensis cry toxins.

Bacillus thuringiensis strains isolated from Latin American soil samples that showed toxicity against three Spodoptera frugiperda populations from different geographical areas (Mexico, Colombia, and Brazil) were characterized on the basis of their insecticidal activity, crystal morphology, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of parasporal crystals, plasmid profiles, and cry gene content. We found that the different S. frugiperda populations display different susceptibilities to the selected B. thuringiensis strains and also to pure preparations of Cry1B, Cry1C, and Cry1D toxins. Binding assays performed with pure toxin demonstrated that the differences in the toxin binding capacities of these insect populations correlated with the observed differences in susceptibility to the three Cry toxins analyzed. Finally, the genetic variability of the three insect populations was analyzed by random amplification of polymorphic DNA-PCR, which showed significant genetic diversity among the three S. frugiperda populations analyzed. The data presented here show that the genetic variability of S. frugiperda populations should be carefully considered in the development of insect pest control strategies, including the deployment of genetically modified maize in different geographical regions.

Animals↗

Safety of Pochonia chlamydosporia var catenulata in acute oral and dermal toxicity/pathogenicity evaluations in rats and rabbits.

The nematophagous fungus, Pochonia chlamydosporia var. catenulata (Kamyschlco ex Barron & Onions) Zare & W-Gams, was investigated as a potential biocontrol agent in integrated pest management strategy for Meloidogyne incognita (Kofoid and White) Chitwood in vegetable crops in Cuba. An acute oral and dermal toxicity/patogenicity study was performed to determine the safety of this fungus in non-target organisms. In the first study, a 1-dose level of 5 x 10(8) units of the microbial pest control agent/treated rat was used. Mortality or clinical signs were not evident and no adverse effects on body weight, hematology, microbiology and gross or microscopic pathology were observed. Food and water consumption was not significantly different between control and treated groups. In the acute dermal toxicity study, there was neither mortality nor clinical signs of toxicity, and no toxic effects in gross and microscopic pathology were detected. Thus, Pochonia chlamydosporia var. catenulate (Vcc-108, IMI SD 187), administered oral and dermally to rats and rabbits respectively, was safe in toxicity/pathogenicity studies.

Administration, Cutaneous↗

[Clustering analysis and optimal cut-apart of arthropod community in megranate orchard].

Based on the principles of community ecology and by the method of fuzzy clustering, this paper studied the temporal and quantitative dynamics of the arthropod community and sub-community in megranate orchard, aimed to utilize natural enemy resources for pests control. The results showed that both of total community and natural enemy sub-community could be grouped into 4 clusters, and non-natural enemy sub-community could be grouped into 3 clusters. This clustering reflected the complexity of the community structure. The optimal cut-apart could divide the total community and sub-community into 3 stages, i. e., April-August, September-October, and November.

Animals↗