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Immunologic reactivity on one year follow-up of subjects without allergy to Hymenoptera stings.

We studied Hymenoptera stings in 72 pest-control operators without any previous systemic reactions to Hymenoptera stings, and investigated their venom-specific IgE levels in serial specimens collected over one year. At the initial evaluation, venom-specific IgE was present in 25 (34.7%) of 72 pest-control operators, and venom-specific IgE titer significantly decreased as the time interval from the last sting increased (p < 0.001). In most cases, venom-specific IgE disappeared less than 3 years after the last sting. On the other hand, the ratio of subjects with positive CAP for venom-specific IgE was significantly increased with an elevation of total serum IgE level (p < 0.001). After the one year follow-up, venom-specific IgE titer in the 25 subjects with positive CAP decreased significantly (p = 0.026). Total serum IgE level modified the decline significantly (p = 0.011), but the time interval from the last sting did not. In elevated total IgE level (>250 IU/ml), the decline of venom-specific IgE tended to be slow.

Adult↗

Abiotic conditions can modify the penetrance of transgene-based lethality systems for insect population control.

Modern genetic biocontrol techniques for insect pest management, when compared to chemical insecticide spraying, offer high species specificity and reduced environmental impact, and some of these methods require the environmental release of genetically modified (GM) insects. Because organisms exposed to different environments often show variability in phenotype and gene expression, it is likely that GM insects will also experience environmentally mediated variation, potentially compromising pest control efficiency. This study examines the impact of temperature and nutrition on the early embryonic Tet-off conditional lethality system in Drosophila melanogaster. By independently manipulating parental and offspring environments, we assessed how exposure to variable environments influenced the probability of larval hatching and the transcript abundance of the transgenic system. Our findings revealed that: (i) transgene performance distinctly responds to temperature and nutrition; (ii) thermal stress has a greater impact when embryos, rather than parents, are exposed; and (iii) extreme nutritional conditions can markedly reduce the penetrance of transgenic lethality. Although changes in transgene transcript abundance were observed across environments, these changes did not fully explain the phenotypic variation, suggesting that factors downstream of transcription probably drive variation in transgenic lethality.

Animals↗

Do earthworms help to sustain the slug predator Pterostichus melanarius (Coleoptera: carabidae) within crops? Investigations using monoclonal antibodies.

Earthworms provide a major potential source of alternative food for polyphagous predators, such as carabid beetles, that are natural enemies of slugs, aphids and other agricultural pests. Non-pest prey may foster larger numbers of natural enemies, which then help to control pests, or alternatively may help to divert the predators away from pest control. An earthworm-specific monoclonal antibody was developed to study carabid-earthworm interactions in the field and assess the role of earthworms as alternative prey. The antibody could identify as little at 7 ng of earthworm protein in an ELISA, and could detect earthworm remains in the foregut of the carabid beetle Pterostichus melanarius for 64 h after consumption. Thirty-six per cent of field-collected beetles contained earthworm remains. Quantities of earthworm proteins in the beetle foreguts were negatively related to total foregut biomass, suggesting that earthworm consumption increased as total prey availability declined. There was also a negative relationship between foregut biomass and beetle numbers, but both quantities and concentrations of earthworm proteins in beetle foreguts were positively related to beetle numbers. This suggests that as beetle activity-density increased, total prey availability declined, or, as prey availability declined, beetles spent more time searching. In these circumstances, beetles fed to a greater extent on earthworms, an acceptable but nonpreferred food item. Earthworms may, therefore, provide an ideal alternative prey for P. melanarius, helping to sustain it when pest numbers are low but allowing it to perform a 'lying-in-wait' strategy, ready to switch back to feeding on pests when they become available.

Animals↗

Insect chitinases: molecular biology and potential use as biopesticides.

Chitin, an insoluble structural polysaccharide that occurs in the exoskeletal and gut linings of insects, is a metabolic target of selective pest control agents. One potential biopesticide is the insect molting enzyme, chitinase, which degrades chitin to low molecular weight, soluble and insoluble oligosaccharides. For several years, our laboratories have been characterizing this enzyme and its gene. Most recently, we have been developing chitinase for use as a biopesticide to control insect and also fungal pests. Chitinases have been isolated from the tobacco hornworm, Manduca sexta, and several other insect species, and some of their chemical, physical, and kinetic properties have been determined. Also, cDNA and genomic clones for the chitinase from the hornworm have been isolated and characterized. Transgenic plants that express hornworm chitinase constitutively have been generated and found to exhibit host plant resistance. A transformed entomopathogenic virus that produces the enzyme displayed enhanced insecticidal activity. Chitinase also potentiated the efficacy of the toxin from the microbial insecticide, Bacillus thuringiensis. Insect chitinase and its gene are now available for biopesticidal applications in integrated pest management programs. Current knowledge regarding the molecular biology and biopesticidal action of insect and several other types of chitinases is described in this mini-review.

Amino Acid Sequence↗

[Wild domestic pigeons--a public health problem of increasing significance in East Germany].

In many cities of the GDR the number of wild house pigeons is increasing. Because of their distribution, noxious effects and hygienic importance they are considered by law as health pests. Therefore, their populations have to be regulated in such a way to minimize the noxious effects caused by them. The State Hygiene inspectorate is responsible for organization and surveillance of health pest control. At present in the GDR two procedures are allowed applying chemical substance for pest control by specialists. A catching procedure, applicable everywhere, is well proving a success. By restauration of old buildings and closing of lofts in new ones it is possible to take prophylactic measures against the increasing number of pigeons. The municipal administration should coordinate the possible measures in the respective territory.

Animal Welfare↗

Population dynamics of small mammals in semi-arid regions: a comparative study of demographic variability in two rodent species.

The seasonally determined demographic structure of two semi-arid rodents, both agricultural pest species (the leaf-eared mouse (Phyllotis darwini) in Chile and the multimammate mouse (Mastomys natalensis) in Tanzania), is analysed using capture-mark-recapture (CMR) statistical models and measures for elasticity (the relative change in the growth rate due to a relative unit change in the parameter of concern) derived from projection linear matrix models. We demonstrate that reproduction and survival during the breeding season contribute approximately equally to population growth in the leaf-eared mouse, whereas the multimammate mouse is characterized by a more clearly defined seasonal structure into breeding and non-breeding seasons and that reproduction contributes far more than survival during the breeding season. On this basis, we discuss evolutionary and applied (pest control) issues. Regarding the evolution of life histories (leading to a maximization of the overall net annual growth rate), we suggest that for the leaf-eared mouse, features favouring survival throughout the year will provide selective value, but that during the main breeding season, features favouring reproduction and survival are about equally favourable. For the multimammate mouse, features favouring survival are particularly important outside the breeding season, whereas during the breeding season features favouring reproduction are more important. Regarding pest control (aiming at reducing the overall net annual growth rate), we suggest that (ignoring economic considerations) affecting survival outside the main breeding season is particularly effective for the leaf-eared mouse, a feature that is even more the case for the multimammate mouse. In sum, we demonstrate through this comparative study that much is to be learnt from studying the dynamics of fluctuating small rodents-a focal issue within much of population ecology.

Animals↗

Biological monitoring of pyrethroids in blood and pyrethroid metabolites in urine: applications and limitations.

The objective of this study was to perform biological monitoring of subjects who are occupationally exposed to pyrethroids. The study group consisted of 30 pest control operators exposed to cyfluthrin, cypermethrin or permethrin. After exposure, 24-h urine samples were collected and 20 ml of blood was drawn. The pyrethroid metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzoic acid and fluorophenoxybenzoic acid were determined in the urine samples (limit of detection: 0.5 micrograms/l) by GC MS and the pyrethroids in plasma (limit of detection: 5 micrograms) GC-ECD. The concentrations of metabolites in the urine of the pest control operators ranged between < 0.5 micrograms/l and 277 micrograms/l urine. The concentrations of cyfluthrin, cypermethrin and permethrin in the plasma were below the limits of detection (< 5 micrograms/l). To test if the metabolites are specific for pyrethroid exposure, they were determined in the urine of non-exposed subjects (n = 40). In no case could pyrethroid metabolites be detected. A cyfluthrin elimination experiment showed that cyfluthrin metabolites are eliminated following first-order kinetics (t 1/2 = 6.4 h). Storage experiments demonstrate that frozen urine samples (-21 degrees C) show no significant losses of metabolites within a year. In contrast, pyrethroids stored in plasma are susceptible to further biodegeneration.

Adult↗

Assessment of risks of brodifacoum to non-target birds and mammals in New Zealand.

The risks to non-target birds and other wildlife from the use of vertebrate pesticides, including anticoagulant rodenticides, are determined to a significant extent by species' intrinsic susceptibility, and the toxicokinetics of the compounds used. Brodifacoum is highly toxic to birds and mammals. The acute toxicity of brodifacoum to birds in New Zealand varies from <1 mg/kg in pukeko (Porphyrio p. melanotus), the native swamp hen, to >20 mg/kg in the paradise shelduck (Tadorna variegata). Like other second-generation anticoagulants brodifacoum is strongly bound to vitamin K epoxide reductase and will persist, apparently for at least 6 months, in organs and tissue containing this enzyme, e.g., liver, kidney, and pancreas. The unique toxicokinetics of this class of compound exacerbates the risk of primary and secondary poisoning of non-target species. Vertebrate pest control programmes in New Zealand using bait containing brodifacoum have resulted in the primary and secondary poisoning and sub-lethal contamination of non-target species. These include native raptors, such as the Australasian harrier (Circus approximans) and morepork (Ninox novaeseelandiae), other native birds such as the pukeko, weka (Gallirallus australis), southern black-backed gull (Larus dominicanus), and kiwi (Apteryx spp.), and introduced mammals, including game animals. There are increasing numbers of reports worldwide of wildlife contamination and toxicosis after the use of second-generation anticoagulants. All pest control activities require careful risk-benefit assessment in view of their potential to cause adverse environmental impact. Monitoring of wildlife for pesticide residues will provide data that can be used to reduce the risk of anticoagulant bioaccumulation and mortality in non-target species.

4-Hydroxycoumarins↗

Screening of the insecticidal activity of Bacillus thuringiensis strains against Lygus hesperus (Hemiptera: Miridae) nymphal population.

Lygus hesperus Knight (Hemiptera: Miridae) is an economically important insect pest controlled primarily by chemical pesticides. Bacillus thuringiensis Berliner is a gram-positive bacterium that has been developed for the control of some insect pests in the orders Lepidoptera, Coleoptera, and Diptera. In this study, whole culture extracts of 94 B. thuringiensis strains from 83 serovars were added to an artificial diet and assayed against L. hesperus first and second instars. A total of five B. thuringiensis strains, B. thuringiensis variety thuringiensis, thuringiensis exotoxin +, morrisoni, tolworthi, and darmstadiensis generated > 98% mortality after 7 d of incubation. The screening was repeated with 117 alkali-solubilized trypsin-digested B. thuringiensis cultures and the same five B. thuringiensis strains showed nearly identical results. All five strains produce beta-exotoxin, which exhibits a wide host spectrum activity. No beta-exotoxin-minus B. thuringiensis strains showed significant toxicity against L. hesperus nymphs. The present work is one of the first thorough screenings of the wide diversity of the B. thuringiensis varieties for the control of L. hesperus nymphal populations.

Adenosine↗

Relative importance of predators and parasitoids for cereal aphid control.

Field experiments with manipulations of natural enemies of plant-feeding insects may show how a diverse enemy group ensures an important ecosystem function such as naturally occurring biological pest control. We studied cereal aphid populations in winter wheat under experimentally reduced densities of: (i) ground-dwelling generalist predators (mostly spiders, carabid and staphylinid beetles); (ii) flying predators (coccinellid beetles, syrphid flies, gall midges, etc.) and parasitoids (aphidiid wasps), and a combination of (i) and (ii), compared with open controls. Aphid populations were 18% higher at reduced densities of ground-dwelling predators, 70% higher when flying predators and parasitoids were removed, and 172% higher on the removal of both enemy groups. Parasitoid wasps probably had the strongest effect, as flying predators occurred only in negligible densities. The great importance of parasitism is a new finding for aphid control in cereal fields. In conclusion, a more detailed knowledge of the mechanisms of natural pest control would help to develop environmentally sound crop management with reduced pesticide applications.

Animals↗

Plant chemistry and natural enemy fitness: effects on herbivore and natural enemy interactions.

Tremendous strides have been made regarding our understanding of how host plant chemistry influences the interactions between herbivores and their natural enemies. While most work has focused on plant chemistry effects on host location and acceptance by natural enemies, an increasing number of studies examine negative effects. The tritrophic role of plant chemistry is central to several aspects of trophic phenomena including top-down versus bottom-up control of herbivores, enemy-free space and host choice, and theories of plant defense. Furthermore, tritrophic effects of plant chemistry are important in assessing the degree of compatibility between biological control and plant resistance approaches to pest control. Additional research is needed to understand the physiological effects of plant chemistry on parasitoids. Explicit tests are required to determine whether natural enemies can act as selective forces on plant defense. Finally, further studies of natural systems are crucial to understanding the evolution of multitrophic relationships.

Animals↗

[Dichlorvos insect strips indoors: pollution and risk assessment].

Exposure to Danger and Assessing the Hazards: Application of the highly potent pest control agent dichlorvos (DDVP) involves the hazard of effects on the central nervous system and a risk of human cancer. Consumers use dichlorvos in pest strips to protect their rooms from insects. This undifferentiated pest control can lead to chronic exposure. Over several weeks we found an indoor air concentration of dichlorvos between 60 and 1300 micrograms/m3 in 34 m3-experimental-room (chamber). Textiles and foodstuffs in this room were also contaminated. Beside the inhalative intake the oral and dermal intake can also lead to an additional loading of the residents. The ADI-resp. DTA-value of 4 micrograms/kg body-weight and day is exceeded about 10-15 times on the average by inhalative exposure only.

Adolescent↗

Food pollution.

Food can influence the human body in many ways, both positively and negatively. Several key elements of contemporary food cultivation and production are presented, along with their potential consequences to our health. The history of food cultivation and consumption is contrasted between early hunter-gatherer societies and modern day societies. Natural nutrient-rich foods produced from the soil in early societies have been replaced with artificial supplements and treated with pesticides and herbicides to control plant disease. The evolution of pesticides is chronicled from the synthesis of DDT in 1870 to present day. Several commonly used chemicals are described along with their documented side effects. A number of methods of pest control from ancient to modern day are offered as alternatives to polluting chemicals. Integrated pest management is proposed as a promising, economically feasible method of pest management, reducing pollution and risk to wildlife and human health.

Agriculture↗

Development and implementation of a reduced risk peach arthropod management program in New Jersey.

We implemented a 2-yr program to reduce organophosphorus and carbamate insecticide use and mitigate their associated risks as they relate to peach production in New Jersey and elsewhere. The main thrust integrated mating disruption with ground cover management practices to reduce oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), and tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae), abundance and damage. This Reduced Risk Peach Arthropod Management Program was compared with adjacent conventionally managed peach orchards. In 1999, we found 2.3 times fewer L. lineolaris and stink bugs (Euschistus servus (Say), E. tristigmus (Say), Acrostemum hilare (Say) (Heteroptera: Pentatomidae) and 2.0 times less heteropteran damaged peaches in reduced-risk orchards when compared with conventionally managed orchards. In 2000, we observed 4.9 times fewer heteropteran insects in reduced-risk orchards but damage levels were not significantly different between the two programs. In both years, G. molesta mating disruption gave at least 4 mo of noninsecticidal control of this major pest. The reduced-risk program provided a level of pest control that was equal to or better than conventional peach pest management programs while using fewer organophosporus and carbamate insecticides.

Animals↗

The effect of indoxacarb and five other insecticides on Phytoseiulus persimilis (Acari: Phytoseiidae), Amblyseius fallacis (Acari: Phytoseiidae) and nymphs of Orius insidiosus (Hemiptera: Anthocoridae).

A laboratory study assessed the contact toxicity of indoxacarb, abamectin, endosulfan, insecticidal soap, S-kinoprene and dimethoate to Amblyseius fallacis (Garman), Phytoseiulus persimilis Athias-Henriot and nymphs of Orius insidiosus (Say). Amblyseius fallacis is a predacious phytoseiid mite and an integral part of integrated pest management (IPM) programmes in North American apple orchards. The other two beneficials are widely used in greenhouses to manage various arthropod pests infesting vegetable and ornamental crops. Indoxacarb is a slow-acting insecticide, so toxicity data were recorded 7 days post-treatment when the data had stabilised. It showed no toxicity to O. insidiosus nymphs or to A. fallacis or P. persimilis adults. The LC50 values for O. insidiosus nymphs and P. persimilis could not be estimated with their associated confidence limits, because the g values were greater than 0.5 and under such circumstances the lethal concentration would lie outside the limits. The LC50 for A. fallacis was 7.6x the label rate. The fecundity of P. persimilis was reduced by 26.7%. The eclosion of treated eggs from both species of beneficial mites was not affected adversely. Among the other pest control products, S-kinoprene and endosulfan affected adversely at least one species of the predators, whereas dimethoate, abamectin and insecticidal soap were very toxic to all three beneficials. Indoxacarb should be evaluated as a pest control product in IPM programmes.

Animals↗

Integration of repellents, attractants, and insecticides in a "push-pull" strategy for managing German cockroach (Dictyoptera: Blattellidae) populations.

"Push-pull" is a behavior manipulation strategy in which behavior-modifying stimuli are integrated with a pest control agent. We evaluated the efficacy of an insecticide bait in combination with attractants ("pull"), repellents ("push"), or both ("push-pull") using a hydramethylnon-based bait, feces-contaminated surfaces as an attractant, and methyl neodecanamide-treated surfaces to repel cockroaches. Both adult males and first-instar German cockroaches, Blattella germanica (L.), chose shelters nearest the attractant-treated surfaces and farthest from the repellent-treated surfaces. Food consumption was highest from food nearest the preferred shelters, and mortality was highest when the insecticide bait was near the preferred shelter. These patterns were more apparent in first instars than in adults. Our results from large arena studies in the laboratory show that the push-pull strategy can be used to displace pests from resources or commodities that are to be protected, and simultaneously lure the pest to an attractant source coupled with a pest control agent. Concentrating cockroaches into a limited area should facilitate the precision-targeting of the pest population and promises to reduce insecticide use.

Animals↗