Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INSECT CONTROL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2000

Modes of control of insect Malpighian tubules: synergism, antagonism, cooperation and autonomous regulation.

Rates of fluid and ion secretion by insect Malpighian tubules are controlled by peptides, including CRF-related peptides and kinins, and in some species by serotonin. It now appears to be a general rule that tubule secretion rate is controlled through the interaction of two or more haemolymph-borne factors. In this review we suggest that these interactions may be classified as synergistic, cooperative, or antagonistic. When presented together, two diuretic factors may act in synergism, so that fluid secretion is stimulated to a greater extent than the sum of their individual effects. Synergism may involve one or more second messenger systems. Alternatively, diuretic factors may act in cooperation, so that although their overall effects are additive, cation and anion transport pathways are controlled separately by distinct second messenger systems. There is also one example of antagonism between factors controlling tubule secretion and between their respective second messengers; one factor is stimulatory, the other is inhibitory. In addition to the complex control of fluid and ion transport by haemolymph-borne factors, sophisticated autonomous regulatory mechanisms have been identified in Malpighian tubules. When triggered by appropriate stimuli, these mechanisms play homeostatic roles, preserving haemolymph osmolality or ionic composition.

Journal Article↗
PubMed1996

G-protein-coupled receptors in insect cells.

The main classes of transmembrane signaling receptor proteins are well conserved during evolution and are encountered in vertebrates as well as in invertebrates. All members of the G-protein-coupled receptor superfamily share a number of basic structural and functional characteristics. In both insects and mammals, this receptor class is involved in the perception and transduction of many important extracellular signals, including a great deal of paracrine, endocrine, and neuronal messengers and visual, olfactory and gustatory stimuli. Therefore, most of the receptor subclasses appear to have originated several hundred million years ago, before the divergence of the major animal Phyla took place. Nevertheless, many insect-specific molecular interactions are encountered and these could become interesting tools for future applications, e.g., in insect pest control. Insect cell lines are well suited for large-scale expression and characterization of cloned receptor genes. Furthermore, novel methods for the production of stably transformed insect cells may form a major breakthrough for insect signal transduction research.

Amino Acid Sequence↗
PubMed2003

Extinction and permanence of a two-prey one-predator system with impulsive effect.

In this paper, we investigate a two-prey one-predator system with impulsive effect on the predator of fixed moment. By using Floquet's theorem and small-amplitude perturbation skills, we show that there exists a globally asymptotically stable two-pest eradication periodic solution when the impulsive period is less than some critical value. Further, we prove that the system is permanent if the impulsive period is larger than some critical value, and meanwhile the conditions for the extinction of one of the two prey and permanence of the remaining two species are given. Finally, numerical simulation shows that there exists a stable positive periodic solution with a maximum value no larger than a given level. Therefore, we can use the stability of the positive periodic solution and its period to control insect pests at acceptably low levels.

Animals↗
PubMed2002

Essential oil formulations useful as a new tool for insect pest control.

This study investigated the effects of some essential oils on Limantria dispar (Lepidoptera: Lymantridae, gypsy moth) larvae, one of the most serious pests of cork oak forests. The essential oils were first formulated as oil in water (o/w) emulsions and used in laboratory bioassays to assess their lethal concentration (LC50). Microcapsules containing the most promising oils (Rosmarinus officinalis and Thymus herba-barona) were then prepared by a phase separation process, followed by freeze-drying. The formulations thus obtained, characterized in terms of essential oil content and composition, morphology, storage stability, and release profile, were tested on gypsy moth larvae. The results showed that the tested oils possess interesting larvicidal effects that make them suitable for application in integrated control strategies. The microencapsulation process gave high encapsulation yields (over 98%) with both essential oils, which have different chemical compositions. The microcapsules had toxic effects at a concentration similar to that usually employed for localized treatments with microgranular synthetic pesticides. Toxicity appeared to be maximized when the microparticles adhered to the typical hair structures of several defoliator families. These formulations seem to be able to protect the core material against environmental agents and could be considered for use in controlled drug release systems. The natural active principles they contain could provide an alternative system in insect pest control.

Animals↗
PubMed2005

[Evaluation of non-host plant ethanol extracts against Plutella xylostella population].

Through establishing experimental and natural population life tables, and by using the index of population trend (1) and interference index of population control (IIPC), this paper evaluated 8 kinds of non-host plant ethanol extracts against experimental population of Plutella xylostella, and 3 kinds of these extracts and their mixture against Plutella xylostella natural population. The experimental population life table of DBM showed that the index of population trend (I) was 69. 8964 in control, and decreased dramatically to 5.3702, 4.4842, 8.0945, 11.1382, 6.8937, 6.1609, 5.5199 and 9.8052, respectively in treatments of Zanthoxylum bungeanum, Eucalyptus tereticornis, Nicotiana tabacum, Broussonetia papyrifera, Bauhinia variegata, Duranta repens, Euphorbia hirta and Camellia oleifera ethanol extracts, while the corresponding IIPC was 0.0768, 0.0642, 0.1158, 0.1594, 0.0986, 0.0881, 0.0790 and 0. 1403, respectively. The natural population life tables of DBM showed that the index of population trend (I) was 21.6232 in control, and decreased dramatically to 5.1997, 7.4160, 7. 3644 and 3.1399, respectively in treatments of the ethanol extracts of E. tereticornis, N. tabacum, C. oleifera and their mixture, while the corresponding IIPC was 0.2405, 0.3695, 0.3549 and 0.1608, respectively. All of these indicated that the test plant extracts could interfere the development of P. xylostella population significantly, and had the potential as an effective measure for controlling insect pest.

Animals↗
PubMed1994

[Ectoparasites of animals: methods of ecological, biological, genetic and mechanical control].

The use of insecticides is still the basic procedure for controlling most ectoparasites, but various methods are being developed to act in addition to, or in synergy with these products, so as to enhance the efficacy and reduce the adverse effects of insecticides, by contributing to ecologically acceptable strategies. These methods are classified as ecological control (modification of the environment of the parasite), biological control (predation, parasitism, action of pathogens, etc.), genetic control (release of sterile males, hybridisation, genetic manipulations) and mechanical control (insect traps, use of repellents). The application of such methods depends on the biological and ecological characteristics of the ectoparasite, and they may act directly or indirectly, affecting mortality and/or reproduction. The authors review the principal methods applicable to major groups of ectoparasites of veterinary interest. Non-chemical methods are the subject of wide-ranging and promising research, particularly in view of recent developments in biotechnology.

Animals↗
PubMed1992

Microbiological and biotechnological aspects of metabolism of carbamates and organophosphates.

Several carbamate and organophosphate compounds are used to control a wide variety of insect pests, weeds, and disease-transmitting vectors. These chemicals were introduced to replace the recalcitrant and hazardous chlorinated pesticides. Although newly introduced pesticides were considered to be biodegradable, some of them are highly toxic and their residues are found in certain environments. In addition, degradation of some of the carbamates generates metabolites that are also toxic. In general, hydrolysis of the carbamate and organophosphates yields less toxic metabolites compared with the metabolites produced from oxidation. Although microorganisms capable of degrading many of these pesticides have been isolated, knowledge about the biochemical pathways and respective genes involved in the degradation is sparse. Recently, a great deal of interest in the mechanisms of biodegradation of carbamate and organophosphate compounds has been shown because (1) an efficient mineralization of the pesticides used for insect control could eliminate the problems of environmental pollution, (2) a balance between degradation and efficacy of pesticides could result in safer application and effective insect control, and (3) knowledge about the mechanisms of biodegradation could help to deal with situations leading to the generation of toxic metabolites and bioremediation of polluted environments. In addition, advances in genetic engineering and biotechnology offer great potential to exploit the degradative properties of microorganisms in order to develop bioremediation strategies and novel applications such as development of economic plants tolerant to herbicides. In this review, recent advances in the biochemical and genetic aspects of microbial degradation of carbamate and organophosphates are discussed and areas in need of further investigation identified.

Bacteria↗
PubMed1997

Transgenic plants: an emerging approach to pest control.

Insect pests are a major cause of damage to the world's commercially important agricultural crops. Current strategies aimed at reducing crop losses rely primarily on chemical pesticides. Alternatively transgenic crops with intrinsic pest resistance offer a promising alternative and continue to be developed. The first generation of insect-resistant transgenic plants are based on insecticidal proteins from Bacillus thuringiensis (Bt). A second generation of insect-resistant plants under development include both Bt and non-Bt proteins with novel modes of action and different spectra of activity against insect pests.

Animals↗
PubMed1997

Role of presynaptic inputs to proprioceptive afferents in tuning sensorimotor pathways of an insect joint control network.

The femur-tibia (FT) joint of insects is governed by a neuronal network that controls activity in tibial motoneurons by processing sensory information about tibial position and movement provided by afferents of the femoral chordotonal organ (fCO). We show that central arborizations of fCO afferents receive presynaptic depolarizing synaptic inputs. With an average resting potential of -71.9 +/- 3.72 mV (n = 10), the reversal potential of these potentials is on average -62.8 +/- 2.3 mV (n = 5). These synaptic potentials occur either spontaneously or are related to movements at the fCO. They are thus induced by signals from other fCO afferents. Therefore, the synaptic inputs to fCO afferents are specific and depend on the sensitivity of the individual afferent affected. These potentials reduce the amplitude of concurrent afferent action potentials. Bath application of picrotoxin, a noncompetitive blocker of chloride ion channels, blocks these potentials, which indicates that they are mediated by chloride ions. From these results, it is concluded that these are inhibitory synaptic potentials generated in the central terminals of fCO afferents. Pharmacologic removal of these potentials affects the tuning of the complete FT control system. Following removal, the dependence of the FT control loop on the tibia position increases relative to the dependency on the velocity of tibia movements. This is due to changes in the relative weighting of the position and velocity signals in the parallel interneuronal pathways from the fCO onto tibial motoneurons. Consequently, the FT joint is no longer able to perform twig mimesis (i.e., catalepsy), which is known to rely on a low position compared to the high-velocity dependency of the FT control system.

Afferent Pathways↗
PubMed1990

Response of nuclear polyhedrosis virus-resistant Spodoptera frugiperda larvae to other pathogens and to chemical insecticides.

Selection in the laboratory for Spodoptera frugiperda (Sf) resistant to nuclear polyhedrosis virus (NPV) affected the susceptibility of the insect to certain other mortality agents, including a chemical insecticide. Median lethal concentrations (LC50S) and associated statistics were compared for several mortality agents between colonies of NPV-resistant and -susceptible (control) insects. Compared to the susceptible insects, the NPV-resistant insects were cross-resistant to the S. frugiperda granulosis virus and to the Autographa californica NPV based on nonoverlap of 95% fiducial limits of the LC50S. The NPV-resistant insects were significantly more susceptible to methyl parathion than the control insects. The two colonies of S. frugiperda did not differ significantly in their response to Bacillus thuringiensis, Vairimorpha necatrix, or carbaryl. The cross-resistance experiments were based on per os exposure of the insects to the pathogens and insecticides; the susceptibility of the resistant and control insects did not differ significantly when the Sf NPV was injected into the hemocoel or when methyl parathion was applied topically.

Animals↗
PubMed2006

Transgenic plants for insect pest control: a forward looking scientific perspective.

One of the first successes of plant biotechnology has been the creation and commercialisation of transgenic crops exhibiting resistance to major insect pests. First generation products encompassed plants with single insecticidal Bt genes with resistance against major pests of corn and cotton. Modelling studies predicted that usefulness of these resistant plants would be short-lived, as a result of the ability of insects to develop resistance against single insecticidal gene products. However, despite such dire predictions no such collapse has taken place and the acreage of transgenic insect resistance crops has been increasing at a steady rate over the 9 years since the deployment of the first transgenic insect resistant plant. However, in order to assure durability and sustainability of resistance, novel strategies have been contemplated and are being developed. This perspective addresses a number of potentially useful strategies to assure the longevity of second and third generation insect resistant plants.

Animals↗
PubMed2001

Pesticide resistance: can we make it a renewable resource?

Negative cross-resistance (NCR) occurs when a mutant allele confers (i) resistance to one toxic chemical and (ii) hyper-susceptibility to another. Sequential deployment of NCR toxins is useful for insect control in few situations (Pittendrigh et al., 2000). Using Monte Carlo simulations, we investigated the concurrent use of a pair of NCR toxins to control a hypothetical insect pest population. When the toxins killed more heterozygotes than homozygotes, the resistance allele became either extremely common or rare depending on starting allelic frequency. If the NCR toxins did not kill the two homozygous groups equally, then the toxin with lesser toxicity eventually played a greater role in the control of the pest population. Based on our results, we present an approach for the systematic development of an NCR toxin after the commercial release of the first toxin. First, large-scale screens are performed to find chemicals that kill the resistant homozygous insects, but not the susceptible ones. Chemicals that preferentially kill resistant insects are then tested for toxicity to the heterozygotes. Those highly toxic to both homo- and heterozygotes are given the highest priority for development. This screen can be adapted to identify compounds useful in controlling antibiotic-, herbicide- or fungicide-resistant organisms.

Animals↗
PubMed2006

Transgenic tobacco plants producing caffeine: a potential new strategy for insect pest control.

Caffeine (1,3,7-trimethylxanthine) is one of the most widely used plant secondary metabolites, primarily as a stimulant and an ingredient in drugs. In nature, caffeine is believed to function in chemical defense, acting as an antiherbivory and allelopathic agent, and therefore it might be employed to protect agriculturally important crop plants. In coffee plants, caffeine is synthesized from the precursor xanthosine in four steps, three N-methylations and removal of ribose. We had previously isolated genes encoding three distinct N-methyltransferases, and we demonstrated production of recombinant enzymes that yielded caffeine in in vitro reconstitution experiments. When these caffeine biosynthetic pathway genes were simultaneously expressed in tobacco plants (Nicotiana tabacum), caffeine was successfully produced up to 5 microg/g fresh weight in leaves. The leaves were unpalatable to tobacco cutworms (Spodoptera litura). This repellent action appeared to be more widely applicable to lepidopteran caterpillars as observed with small white (Pieris rapae) fed on Chinese cabbages that had been top-treated with caffeine. Our recent results suggest a novel approach to strengthen anti-herbivore traits by producing caffeine in crop plants.

Animals↗
PubMed1993

Superoxide formation preceding flight muscle histolysis in Solenopsis: fine structural cytochemistry and biochemistry.

In Solenopsis spp., muscle histolysis or breakdown is a normal process in females and is initiated in the flight muscles only immediately after a mating flight. Information regarding the presence of the oxyradical scavenging enzyme superoxide dismutase (SOD) and the formation of the radical oxygen intermediate superoxide (SO) during the early stages of flight muscle histolysis in this insect was investigated. In normal fibrillar flight muscles from control animals, SOD was immunolocalized to vesicular and tubular components of the sarcotubular system. Lanthanum tracer studies indicated that some of these SOD-positive structures might be tubulovesicles continuous with the extracellular space. Following the injection of virgin alates with experimental haemolymph obtained from artificially inseminated females, the membrane delimited elements of the sarcotubular system became increasingly swollen and dilated with time (from 60 to 120 minutes postinjection) with a concomitant decrease in SOD activity and an increase in oxyradical formation. Many similar vesicles were lanthanum-positive. SO was not seen in the sarcoplasmic vesicles and tubules of control insects. The biochemical quantification of SO release over a 2-hour period showed a marked increase in oxyradical formation following treatment with the experimental haemolymph in comparison to control insects. Also, the addition of superoxide dismutase depressed SO formation under these conditions. Despite the histochemical and biochemical changes seen in the muscles of experimental insects, by 2 hours post-treatment there was no evidence of muscle necrosis. From these studies on flight muscle histolysis/necrosis in Solenopsis it appears that the formation of oxyradicals might represent an early event in myopathogenesis and subsequent tissue involution. The generation of SO is more than likely to be associated with alterations in the normal structure, biochemistry and permeability of the biomembranes which delimit the sarcotubular system.

Animals↗
PubMed2000

Insect population control using a dominant, repressible, lethal genetic system.

A major modification to the sterile insect technique is described, in which transgenic insects homozygous for a dominant, repressible, female-specific lethal gene system are used. We demonstrate two methods that give the required genetic characteristics in an otherwise wild-type genetic background. The first system uses a sex-specific promoter or enhancer to drive the expression of a repressible transcription factor, which in turn controls the expression of a toxic gene product. The second system uses non-sex-specific expression of the repressible transcription factor to regulate a selectively lethal gene product. Both methods work efficiently in Drosophila melanogaster, and we expect these principles to be widely applicable to more economically important organisms.

Animals↗