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At least 1,153 records · Page 64Linked to original sources
PubMed2005

A dominant lethal genetic system for autocidal control of the Mediterranean fruitfly.

The Sterile Insect Technique (SIT) used to control insect pests relies on the release of large numbers of radiation-sterilized insects. Irradiation can have a negative impact on the subsequent performance of the released insects and therefore on the cost and effectiveness of a control program. This and other problems associated with current SIT programs could be overcome by the use of recombinant DNA methods and molecular genetics. Here we describe the construction of strains of the Mediterranean fruit fly (medfly) harboring a tetracycline-repressible transactivator (tTA) that causes lethality in early developmental stages of the heterozygous progeny but has little effect on the survival of the parental transgenic tTA insects. We show that these properties should prove advantageous for the implementation of insect pest control programs.

Animals↗
PubMedDate not supplied

Simulated digestion status of intact and exoskeletally-punctured insects and insect larvae: a spectroscopic investigation.

In this study, we tested the hypothesis that puncturing the chitin exoskeleton of insect and insect larvae food sources aids the ingress of digestive fluids and increases the rate of digestion and energy uptake in insectivorous mammals. For this purpose 10 crickets (Acheta domesticus) and 10 mealworms (Tenebrio molitor larvae) were divided into two groups of 5; one group was punctured using a small blade to mimic the effect of a single bite, the remainder serving as controls. The insects were then individually immersed in 5 ml of a 1 x 10(-2) mol.dm(-3) solution of hydrochloric acid (pH 2.0) for a period of 2 h in order to mimic digestion in the stomach. The matrix was then centrifuged and the supernatant fluid subjected to spectrophotometric and high-resolution proton (1H) NMR analysis. Electronic absorption spectra of these supernatants revealed that puncturing the exoskeleton of mealworms and crickets gave rise to substantial elevations (up to 14-fold) in the concentrations of UV-absorbing biomolecules (p < 0.025 for both species). The 400-MHz 1H NMR profiles of supernatants derived from mealworm and cricket specimens with punctured exoskeletons contained a wide variety of prominent biomolecule resonances, whereas those from unpunctured (control) insects contained signals of a much lower intensity, ascribable only to selected biomolecules. We conclude that puncturing the cuticle of insects and insect larvae prior to swallowing confers significant nutritional advantages over swallowing prey whole.

Animal Nutritional Physiological Phenomena↗
PubMed1959

Aspects of black-fly control and entomology in the New World in relation to the Simulium problem in Nigeria.

A general account is given of insecticidal control of black-flies in North and Central America, and the problems are contrasted with those arising in the control of Simulium damnosum Theo. in Nigeria. Some recent biological observations on Canadian black-flies are described, and it is emphasized that these have materially contributed to successful control. It is pointed out that S. damnosum control is being practised in the absence of much fundamental biological knowledge of this pest. Entomological aspects of onchocerciasis in Mexico and Guatemala are discussed, and compared with S. damnosum and its relationship to onchocerciasis in Nigeria.

Animals↗
PubMed2004

Fusion proteins containing insect-specific toxins as pest control agents: snowdrop lectin delivers fused insecticidal spider venom toxin to insect haemolymph following oral ingestion.

The mannose-specific snowdrop lectin (Galanthus nivalis agglutinin: GNA), when fed to insects, binds to the gut epithelium and passes into the haemolymph. The ability of GNA to act as a carrier protein to deliver an insecticidal spider venom neurotoxin (Segestria florentina toxin 1: SFI1) to the haemolymph of lepidopteran larvae was investigated. Constructs encoding SFI1 and an SFI1/GNA fusion protein were expressed in Pichia pastoris. The insecticidal activity of purified recombinant proteins on injection was found to be comparable to published values for SfI1 purified from spider venom [Toxicon 40 (2002) 125]. Whereas neither GNA nor SFI1 alone showed acute toxicity when fed to larvae of tomato moth (Lacanobia oleracea), feeding SFI1/GNA fusion at 2.5% of dietary proteins was insecticidal to first stadium larvae, causing 100% mortality after 6 days. The protein also showed a significant, dose dependent, toxicity towards fourth and fifth stadium larvae, with growth reduced by up to approximately 90% over a 4-day assay period compared to controls. Delivery of intact SFI1/GNA to the haemolymph in these insects was shown by western blotting; haemolymph samples from fusion-fed larvae contained a GNA-immunoreactive protein of the same molecular weight as the SFI1/GNA fusion. SFI1/GNA and similar fusion proteins offer a novel and effective approach for delivering haemolymph active toxins by oral administration, which could be used in crop protection by expression in transgenic plants.

Animals↗
PubMed1994

Use of hexaflumuron, an insect growth regulator in the control of Aedes albopictus (Skuse).

An attempt was made to assess the control potency of an insect growth regulator (IGR), hexaflumuron, against Aedes albopictus, a potent dengue vector, both in the laboratory and under field conditions. Emergence inhibition activity of this IGR against laboratory reared and field collected larvae of Ae. albopictus showed EI50 values of 1.9 x 10(-4) and 1.80 x 10(-4) mg(ai)/l respectively. Under field conditions, no appreciable reduction in immature density occurred at the lowest application rate of 0.001 mg(ai)/l whereas at the rate of 0.01 mg(ai)/l 100% reduction could be seen in earthern pots placed in a garden for 9 days. A reduction of 100% in pupal density was observed for 21 and 18 days at an application rate of 0.1 mg(ai)/l in pots and tyres respectively. Considering that this IGR was effective for about three weeks, it can be used successfully at the rate of 0.1 mg(ai)/l for controlling Ae. albopictus breeding in container habitats.

Aedes↗
PubMed2002

Comparative analysis of quantitative trait loci controlling glucosinolates, myrosinase and insect resistance in Arabidopsis thaliana.

Evolutionary interactions among insect herbivores and plant chemical defenses have generated systems where plant compounds have opposing fitness consequences for host plants, depending on attack by various insect herbivores. This interplay complicates understanding of fitness costs and benefits of plant chemical defenses. We are studying the role of the glucosinolate-myrosinase chemical defense system in protecting Arabidopsis thaliana from specialist and generalist insect herbivory. We used two Arabidopsis recombinant inbred populations in which we had previously mapped QTL controlling variation in the glucosinolate-myrosinase system. In this study we mapped QTL controlling resistance to specialist (Plutella xylostella) and generalist (Trichoplusia ni) herbivores. We identified a number of QTL that are specific to one herbivore or the other, as well as a single QTL that controls resistance to both insects. Comparison of QTL for herbivory, glucosinolates, and myrosinase showed that T. ni herbivory is strongly deterred by higher glucosinolate levels, faster breakdown rates, and specific chemical structures. In contrast, P. xylostella herbivory is uncorrelated with variation in the glucosinolate-myrosinase system. This agrees with evolutionary theory stating that specialist insects may overcome host plant chemical defenses, whereas generalists will be sensitive to these same defenses.

Animals↗
PubMed2005

Effects of UV-absorbing plastic films on greenhouse whitefly (Homoptera: Aleyrodidae).

Studies were conducted to investigate the effects of ultraviolet (UV)-absorbing plastic films on the orientation and distribution behavior of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). In field experiments, small tunnels were constructed and covered with either an UV-transmitting (Thermilux) or UV-absorbing (K-Rose) plastic film. Results show that significantly more whiteflies were recorded in the tunnels with high compared with those with low UV intensities. Moreover, whitefly penetration and dispersion were less inside the UV-deficient tunnels. These results suggest that the type of plastic film used for greenhouse covers may have a significant influence on both the initial immigration and distribution of T. vaporariorum into greenhouses. The possibilities of using UV-absorbing plastic films for whitefly integrated pest management in greenhouses are discussed.

Agriculture↗