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 685 records · Page 38Linked to original sources
PubMed2006

Invasion and the evolution of speed in toads.

Cane toads (Bufo marinus) are large anurans (weighing up to 2 kg) that were introduced to Australia 70 years ago to control insect pests in sugar-cane fields. But the result has been disastrous because the toads are toxic and highly invasive. Here we show that the annual rate of progress of the toad invasion front has increased about fivefold since the toads first arrived; we find that toads with longer legs can not only move faster and are the first to arrive in new areas, but also that those at the front have longer legs than toads in older (long-established) populations. The disaster looks set to turn into an ecological nightmare because of the negative effects invasive species can have on native ecosystems; over many generations, rates of invasion will be accelerated owing to rapid adaptive change in the invader, with continual 'spatial selection' at the expanding front favouring traits that increase the toads' dispersal.

Animals↗
PubMed1997

Molecular population studies of Simulium damnosum s.l. (Diptera: Simuliidae) using a novel interspersed repetitive DNA marker.

Simulium damnosum s.l., the vector of West African onchocerciasis, has been the target of a major insect control initiative for the past 20 years. However, attempts to study the migration patterns of reinvading infective flies into controlled areas have been restricted by the lack of suitable genetic markers. Here, the results of the first population-level study of S. damnosum s.l. using a repetitive DNA marker, pSO11, are presented. Sequence analysis of pSO11 revealed a complex internal pattern of repetition and an open reading frame with 56.8 per cent similarity to a mouse retrotransposon protein. Combined with an interspersed genomic distribution, the internal structure of pSO11 suggested that it represents the 5' half of a transposable element. The genomic diversity of the sequence was analysed using Southern blot analysis of genomic DNA. Data were collected from 475 individuals from the island of Bioko (in Equatorial Guinea), Cameroon, Côte d'Ivoire and Sierra Leone. The results indicate that pSO11 is useful as an indicator of genomic diversity and that the experimental design used here permits comparison of an approximately random sample of chromosomal loci. Making this assumption, estimates of homozygosity based on pSO11 diversity were used to study inter- and intraspecific variability. The results indicate that pSO11 is potentially useful for studying population-level processes in S. damnosum s.l.

Animals↗
PubMed2001

Genes for the biosynthesis of spinosyns: applications for yield improvement in Saccharopolyspora spinosa.

Spinosyns A and D are the active ingredients in an insect control agent produced by fermentation of Saccharopolyspora spinosa. Spinosyns are macrolides with a 21-carbon, tetracyclic lactone backbone to which the deoxysugars forosamine and tri-O-methylrhamnose are attached. The spinosyn biosynthesis genes, except for the rhamnose genes, are located in a cluster that spans 74 kb of the S. spinosa genome. DNA sequence analysis, targeted gene disruptions and bioconversion studies identified five large genes encoding type I polyketide synthase subunits, and 14 genes involved in sugar biosynthesis, sugar attachment to the polyketide or cross-bridging of the polyketide. Four rhamnose biosynthetic genes, two of which are also necessary for forosamine biosynthesis, are located outside the spinosyn gene cluster. Duplication of the spinosyn genes linked to the polyketide synthase genes stimulated the final step in the biosynthesis--the conversion of the forosamine-less pseudoaglycones to endproducts. Duplication of genes involved in the early steps of deoxysugar biosynthesis increased spinosyn yield significantly.

Anti-Bacterial Agents↗
PubMed1995

Free radicals and food irradiation.

Ionizing radiation can be used to control insect and microbial infestation of foodstuffs, inhibit sprouting, delay ripening and reduce the dangers from food-poisoning bacteria. Irradiation produces free radicals, most of which decay rapidly, although some are more persistent. These latter radicals can be detected and characterized by electron spin resonance (ESR). In bone and other calcified tissues, the radiation-induced radicals are distinguishable from naturally occurring radicals, and their stability makes them ideal for radiation dosimetry. The radicals induced in plant material, such as seeds and dried spices, are generally indistinguishable from the endogenous radicals and decay over a period of days or weeks. However, in many of these materials, a radiation-specific radical can be detected at low concentration, thereby permitting identification of irradiated samples, although precluding accurate dosimetry. ESR, although not universally applicable, currently provides the most specific method for the detection of irradiated food.

Electron Spin Resonance Spectroscopy↗
PubMed2002

Analysis of expressed sequence tags from subtracted and unsubtracted Ctenocephalides felis hindgut and Malpighian tubule cDNA libraries.

Insect hindgut and Malpighian tubule (HMT) tissues regulate the contents of the haemolymph through the excretion of waste products and the specific reabsorption of nutrients. As such, they perform a role that is essential for survival and may contain molecular targets for insect control strategies. In order to discover genes expressed in the HMT tissues of the cat flea, Ctenocephalides felis, expressed sequence tags (ESTs) were generated from an unsubtracted HMT cDNA library and from a subtracted HMT cDNA library that had been enriched for HMT-specific cDNAs. A total of 4844 ESTs were analysed from both libraries: 3657 from the subtracted library and 1187 from the unsubtracted library. Of the 1418 distinct ESTs identified from both libraries, 953 had significant similarity to other sequences reported in the GenBank database. A comparison of the results from the two libraries confirmed that the percentages of genes likely to be involved with metabolism, cell structure, and digestion were reduced by the subtraction procedure, whereas genes likely to be involved with ion transport were enriched. Analysis of the prevalence of three individual cDNAs in each library revealed that the actin cDNA was reduced in the subtracted library whereas the cDNAs encoding allantoinase and a peritrophin-like protein were greatly enriched in the subtracted library. Northern blot analysis demonstrated that the actin cDNA was expressed in both the HMT and carcass tissues, whereas the allantoinase and peritrophin-like cDNAs were detected exclusively in the HMT tissues. In total, 97 distinct ESTs that appear to encode proteins involved with ion transport were analysed. Some of these proteins may be directly involved with diuresis or the specific reabsorption of salts and nutrients, and thus may be potential molecular targets for flea control strategies.

Animals↗
PubMed1998

Distribution of the Simulium damnosum complex on Bioko island, Equatorial Guinea, and the potential for onchocerciasis elimination by vector eradication.

Onchocerciasis is endemic on the island of Bioko, Equatorial Guinea, where it is transmitted by the 'Bioko form' of the Simulium damnosum complex, a cytospecies unique to the island. To determine the distribution of vector breeding, three dry season and two wet season expeditions were made in 1989, 1996 and 1997, and 226 of the island's 247 rivers (91.5%) were visited. Of these 226 rivers, 130 (58%) were flowing during the dry season, forty-five (20%) supported aquatic stages of Simuliidae of any species and twenty-five (11%) contained larvae or pupae of the S. damnosum complex. The twenty-one rivers not prospected were in the mountainous south of the island, where an additional seventeen rivers were reached but not satisfactorily prospected. Of these thirty-eight rivers, twenty-nine were considered highly likely to support vector breeding, bringing the total number of rivers which could harbour the vector during the dry season to fifty-four (21.9% of the island's total). Breeding was believed to be limited to river stretches below 1000 m altitude, and during the dry season the total length of those stretches which could support breeding on Bioko was estimated to be 1020 km. A combination of factors, including low river discharges during the dry season, the relatively low water temperature on Bioko, the suitability of limited stretches of most rivers as vector breeding sites and the close proximity of many rivers within a small geographical area, render the vector vulnerable to eradication by aerial treatment of rivers with insecticide. The isolation of the Bioko form of the S. damnosum complex suggests that reinvasion following treatment would be unlikely, and eradication of the vector might be achieved by a dry season larviciding programme in one or two years.

Altitude↗
PubMed1999

Protective efficacy of lambdacyhalothrin-impregnated bednets against Phlebotomus orientalis, the vector of visceral leishmaniasis in Sudan.

Field investigations on the sandfly Phlebotomus orientalis (Diptera: Psychodidae), the vector of Leishmania donovani causing visceral leishmaniasis (VL) in Sudan, were undertaken in two villages (Bellow and Elgamel) and Dinder National Park, to determine the protective value of bednets (polyester, 100 denier) impregnated with lambda-cyhalothrin 10 mg a.i./m2 pyrethroid insecticide. After exposure to treated netting for 30 s, P. orientalis females all died within 1 h. When field-tested in Acacia woodland, treated bednets provided complete protection from bites of the vector. Numbers of P. orientalis females landing on human collectors without bednets or using untreated bednets averaged 32.0 +/- 8.3 or 6.9 +/- 2.7 per man-night, respectively, whereas collectors using treated bednets experienced no sandfly bites during the same period (18.00-06.00 hours, 12 nights in June 1995). Socio-behavioural observations on the bed-time of people living in both study villages indicated that the use of impregnated bednets against P. orientalis would give more potential protection for women and children than for male adults. Overall the proportions of people and their durations of exposure to the risk of sandfly bites (i.e. after sunset until they went to bed) were 40% unprotected for< 1h, 50% for 1-2h and >10% for > or = 2h. Because visceral leishmaniasis in Sudan occurs mainly in children, the use of impregnated bednets (outdoors as well as indoors), and going to bed early could provide a high degree of personal protection against this zoonotic infection.

Adult↗
PubMed2000

Tissue distribution and prevalence of Wolbachia infections in tsetse flies, Glossina spp.

Tsetse flies Glossina spp. (Diptera: Glossinidae) harbor three different symbiotic microorganisms, one being an intracellular Rickettsia of the genus Wolbachia. This bacterium infects a wide range of arthropods, where it causes a variety of reproductive abnormalities, one of which is termed cytoplasmic incompatibility (CI) that, when expressed, results in embryonic death due to disruptions in fertilization events. We report here that in colonized flies, Wolbachia infections can be detected in 100% of sampled individuals, while infections vary significantly in field populations. Based on Wolbachia Surface Protein (wsp) gene sequence analysis, the infections associated with different fly species are all unique within the A group of the Wolbachia pipientis clade. In addition to being present in germ-line tissues, Wolbachia infections have been found in somatic tissues of several insects. Using a Wolbachia-specific PCR-based assay, the tissue tropism of infections in Glossina morsitans morsitans Westwood, Glossina brevipalpis Newstead and Glossina austeni Newstead were analysed. While infections in G. m. morsitans and G. brevipalpis were limited to reproductive tissues, in G. austeni, Wolbachia could be detected in various somatic tissues.

Animals↗
PubMed2000

Repellency of deet to nymphs of Triatoma infestans.

The repellency of N,N-diethyl-3-methylbenzamide (deet) to Triatoma infestans (Klug) (Hemiptera: Reduviidae) was evaluated using third-instar nymphs and a video tracking technique. Three experimental designs were used: (a) the test arena floor was divided into two halves, only one of which was treated with deet; (b) the arena floor was divided into an inner circle and an outer ring, only the latter treated with deet; (c) half of the test arena was covered by a filter paper roof treated with deet (out of reach of the nymphs). In all three types of experiment, a repellent effect was demonstrated proportional to the dose of deet. When a host (pigeon) was shielded by deet-treated gauze, the rate of blood-feeding by the nymphs was inhibited. Topical pre-treatment of the nymphs with N-ethylmaleimide, to block chemoreception, inhibited the repellency.

Animals↗
PubMed2000

Resistance to dieldrin + fipronil assorts with chromosome inversion 2La in the malaria vector Anopheles gambiae.

Cyclodiene insecticide resistance in malaria vector mosquitoes of the Anopheles gambiae species complex (Diptera: Culicidae) has been reported previously from several parts of Africa. We report resistance to dieldrin, a cyclodiene, in two laboratory strains of An. gambiae Giles sensu stricto code-named Ian P20 from Nigeria (1979) and CIG from Cote d'Ivoire (1997). Dieldrin resistance levels were high in adult female mosquitoes (40-75% survived exposure to 4% dieldrin for 1 h) and was closely linked with chromosomal paracentric inversion 2La. This inversion did not occur in Hardy-Weinberg proportions, but showed an excess of heterozygotes in both strains, which may account for the high levels of resistance. This linkage also suggests that dieldrin resistance in Ian P20 is dominant. After subsamples of strain Ian P20 were exposed for 1 h to dieldrin 4% or fipronil 2% (discriminating concentrations), the resultant mortality-rates (61% and 65%) were not significantly different. Most survivors after fipronil treatment also survived subsequent exposure to dieldrin (46/50=92%). This apparent cross-resistance between insecticides of two classes (cyclodiene and phenyl pyrazole) has implications for the management of insecticide resistance in wild populations of the An. gambiae complex.

Animals↗
PubMed2004

Activity of Lutzomyia pseudolongipalpis and L. longipalpis s.l. (Diptera: Psychodidae) in Venezuela.

The nocturnal activity of the phlebotomine sandfly Lutzomyia pseudolongipalpis and two populations of L. longipalpis s.l. from different American visceral leishmaniasis foci in Venezuela was studied using collection bottle rotator traps. The activity of L. pseudolongipalpis from Lara State was continuous throughout the night, while that of L. longipalpis s.l. from El Layero, Guárico State and from Santa Ana del Valle, Margarita Island, was greatest before 23:00 h. The activity of sandflies of both populations and sexes steadily decreased thereafter. These different patterns seem to correlate with genetic data that indicate the presence in Venezuela of at least two sibling species in the L. longipalpis complex. The advantages of the bottle rotator trap for this type of study are discussed.

Animals↗
PubMed2006

[Triatominae and Cactaceae: a risk for the transmission of the American trypanosomiasis in the peridomicilary space (Northeast Brazil)].

Field observations carried in semi-arid Brazil Northeast point out the frequent association, in the peridomiciliary space, between a cactus, Cereus jamacaru, the occurrence of nests in its branches and the occurrence of two species of insects vectors of Trypanosoma cruzi, pathogenic agent of Chagas disease: Rhodnius neglectus and Triatoma pseudomaculata. The analysis of the architectural variables of this Cactaceae shows that the presence of nests, and thus of insects, depends on the traditional practices of management of this cactus. This study underlines the relevance of an integrated approach of the ecology of Triatominae for the identification of factors of risk.

Agriculture↗