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At least 199 records · Page 11Linked to original sources
PubMed1999

Sequencing and characterization of the citrus weevil, Diaprepes abbreviatus, trypsin cDNA. Effect of Aedes trypsin modulating oostatic factor on trypsin biosynthesis.

Trypsin mRNA from the citrus weevil, Diaprepes abbreviatus, was reverse transcribed and amplified by PCR. A cDNA species of 513 bp was cloned and sequenced. The 3' and 5' ends of the gene (262 bp and 237 bp, respectively) were amplified by rapid amplification of cDNA ends, cloned and sequenced. The deduced sequence of the trypsin cDNA (860 bp) encodes for 250 amino acids including 11 amino acids of activation and signal peptides and exhibited 16.8% identity to trypsin genes of selected Lepidoptera and Diptera. A three-dimensional model of Diaprepes trypsin contained two domains of beta-barrel sheets as has been found in Drosophila and Neobellieria. The catalytic active site is composed of the canonical triad of His41, Asp92 and Ser185 and a specificity pocket occupied by Asp179 with maximal activity at pH 10.4. Southern blot analysis indicated that at least two copies of the gene are encoded by Diaprepes midgut. Northern blot analysis detected a single RNA band below 1.35 kb at different larval ages (28-100 days old). The message increased with age and was most abundant at 100 days. Trypsin activity, on the other hand, reached a peak at 50 days and fell rapidly afterwards indicating that the trypsin message is probably regulated translationally. Feeding of soybean trypsin inhibitor and Aedes aegypti trypsin modulating oostatic factor affected trypsin activity and trypsin biosynthesis, respectively. These results indicate that Diaprepes regulates trypsin biosynthesis with a trypsin modulating oostatic factor-like signal.

Aedes↗
PubMed2002

Evaluation of pseudostem trapping as a control measure against banana weevil, Cosmopolites sordidus (Coleoptera: Curculionidae) in Uganda.

Controlled studies to determine the efficacy of pseudostem trapping in reducing adult populations of the banana weevil, Cosmopolites sordidus (Germar), were conducted under farmer conditions in Ntungamo district, Uganda. Twenty-seven farms were stratified on the basis of C. sordidus population density (estimated by mark and recapture methods) and divided among three treatments: (i) researcher-managed trapping (one trap per mat per month): (ii) farmer-managed trapping (trap intensity at discretion of farmer); and (iii) controls (no trapping). Intensive trapping (managed by researchers) resulted in significantly lower C. sordidus damage after one year. Over the same period, C. sordidus numbers declined by 61% on farms where trapping was managed by researchers, 53% where farmers managed trapping and 38% on farms without trapping; however, results varied greatly among farms and, overall, there was no significant effect of trapping on C. sordidus numbers. Moreover, there was only a weak relationship between the number of C. sordidus removed and the change in population density. Trapping success appeared to be affected by management levels and immigration from neighbouring farms. Although farmers were convinced that trapping was beneficial, adoption has been low due to resource requirements.

Animals↗
PubMed2002

The influence of crop management on banana weevil, Cosmopolites sordidus (Coleoptera: Curculionidae) populations and yield of highland cooking banana (cv. Atwalira) in Uganda.

A field study was undertaken in Uganda using highland cooking banana (cv. Atwalira) to test the hypothesis that bananas grown under stressed conditions are more susceptible to attack by Cosmopolites sordidus (Germar). Four banana treatments were employed to create different levels of host-plant vitality: (1) high stress: intercrop with finger millet; (2) moderate stress: monoculture without soil amendments; (3) low stress: monoculture with manure; (4) high vigour: monoculture with continuous mulch and manure. Adult C. sordidus were released at the base of banana mats 11 months after planting and populations were monitored for three years using mark and recapture methods. Cosmopolites sordidus density was greatest in the mulched plots which may have reflected increased longevity and/or longer tenure time in moist soils. Lowest C. sordidus numbers were found in intercropped banana. Damage, estimated as percentage corm tissue consumed by larvae, was similar among treatments. However, the total amount of tissue consumed was greater in mulched banana than in other systems. Plants supporting the heaviest levels of C. sordidus damage displayed bunch size reductions of 40-55%. Banana yield losses ranged from 14-20% per plot with similar levels in the intercropped and mulched systems. Yield reductions, reported as t ha-1, were twice as high in the mulched system as in the intercrop. The results from this study indicate that C. sordidus problems are not confined to stressed banana systems or those with low levels of management, but that the weevil can also attain pest status in well-managed and productive banana stands.

Animals↗
PubMed2004

Allozyme markers to help define the South American origins of Microctonus hyperodae (Hymenoptera: Braconidae) established in New Zealand for biological control of Argentine stem weevil.

The thelytokous parasitoid, Microctonus hyperodae Loan, was collected from eight South American locations and introduced to New Zealand in 1991 for biological control of Argentine stem weevil, Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae). Parasitoids from each population were released in equal numbers at each New Zealand site to give them the same opportunities to establish. Population markers have been sought to identify the South American geographic populations that have become most successful in New Zealand. These would assist in determining the importance of concepts such as climate matching and host-parasitoid coevolution to the establishment of natural enemies in new regions for biological control. Vertical polyacrylamide electrophoresis was used to survey 16 enzymes and ten calcium binding proteins, and this paper reports variation at three putative loci. Malate dehydrogenase, a dihydrolipoamide dehydrogenase isozyme and a calcium binding protein exhibited clear genetic variation, each with two alleles. All M. hyperodae isofemale lines from east of the Andes mountains shared one genotype, all but one from west of the Andes shared another, while a population from within the Andes contained both genotypes. This variation was highly congruent with previously described morphometric variation. At two loci, the maintenance of heterozygotes, and the absence of homozygotes, within isofemale lines suggested M. hyperodae thelytoky is apomictic.

Animals↗
PubMed2004

Host plant recognition by the root feeding clover weevil, Sitona lepidus (Coleoptera: Curculionidae).

This study investigated the ability of neonatal larvae of the root-feeding weevil, Sitona lepidus Gyllenhal, to locate white clover Trifolium repens L. (Fabaceae) roots growing in soil and to distinguish them from the roots of other species of clover and a co-occurring grass species. Choice experiments used a combination of invasive techniques and the novel technique of high resolution X-ray microtomography to non-invasively track larval movement in the soil towards plant roots. Burrowing distances towards roots of different plant species were also examined. Newly hatched S. lepidus recognized T. repens roots and moved preferentially towards them when given a choice of roots of subterranean clover, Trifolium subterraneum L. (Fabaceae), strawberry clover Trifolium fragiferum L. (Fabaceae), or perennial ryegrass Lolium perenneL. (Poaceae). Larvae recognized T. repens roots, whether released in groups of five or singly, when released 25 mm (meso-scale recognition) or 60 mm (macro-scale recognition) away from plant roots. There was no statistically significant difference in movement rates of larvae.

Animals↗
PubMed2003

A waveguide irradiation chamber for destruction of red palm weevils (Rhynchophorus ferrugineus) inside a block sample of a palm tree trunk.

A simple waveguide irradiation chamber at 2.45 GHz. was locally constructed for controlled laboratory experiments to assess the potentiality of using microwave heating for irradiation of weevils (RPW) inside healthy and infected palm tree trunks. The chamber consists of an aluminum rectangular waveguide with one of its broad sides removed for easy insertion of the block samples of the palm tree trunk. A rectangular aluminum plate, with the same dimensions as the removed wall section was made to slide-in and cover the tree block sample after its insertion in the waveguide to insure continuity of metallic walls. Temperature rise in the samples were monitored by thermocouples inserted through holes drilled at different positions along one of the waveguide side walls. Results showed that 100% mortality rate could be obtained with the RPW samples at distances not more than 2-3 cm from the leading edge of healthy tree block samples and 4-5 cm from leading edge of infected samples. Hot spots were observed at the leading edge of the tree samples due to high absorption of microwave at these regions.

Animals↗
PubMed2003

Wood digestion in Pselactus spadix Herbst--a weevil attacking marine timber structures.

Pselactus spadix tunnels timber structures in the marine environment. Recent studies reported a cosmopolitan distribution for this weevil, which is frequently found in harbour and port areas. P. spadix feeds on timber (hardwood and softwood) in immature and adult life stages, but its digestion of wood components had not been investigated. Using dry weight analyses of tunnel walls and frass produced, P. spadix adults consumed Scots pine with soft rot decay at a rate of 1.59 +/- 0.37 mg d-1 and the digestibility of this substrate was 57.96 +/- 5.89 (i.e. for 100 mg consumed SR-pine, 58 mg was digested). Using gravimetric analysis to quantify structural wood components in tunnel walls and frass, P. spadix adults were found to digest cellulose, lignin and hemicellulose with digestibility coefficients of 82.2, 41.2 and 14.5 respectively. Fourier Transform Infrared (FTIR) spectroscopy analyses of tunnel walls and frass of adults and larvae from soft rotted pine also indicated digestion of all structural components, with larvae digesting cellulose and lignin more efficiently than adults. When FTIR was employed to analyse adult tunnel walls and frass from undecayed pine, cellulose and hemicellulose were digested, but no evidence of lignin digestion was found. This study shows that adults digest lignin when soft rot is present and suggests a symbiotic function of wood degrading microorganisms.

Animals↗
PubMed1998

Incongruence between morphological and mitochondrial-DNA characters suggests hybrid origins of parthenogenetic weevil lineages (Genus aramigus).

An expanded matrix of morphological characters for the genus Aramigus (Coleoptera: Curculionidae), which includes numerous polyploid parthenogenetic lineages, was compared and combined with a published matrix of mitochondrial DNA (mtDNA) characters. The matrix of morphological characters provides little resolution of the A. tessellatus and A. uruguayensis species complexes but does resolve previously unresolved relationships among other morphologically defined species (A. globoculus + A. intermedius, A. curtulus + A. planioculus). The morphological and mtDNA characters are significantly incongruent (0.435 < or = IM < or = 0.463; IMF = 0.0735), according to the tests of Farris et al. (P = 0.010) and Templeton (P < 0.005), probably because of hybrid origins of polyploid parthenogenetic lineages. For the few sexual lineages included in both matrices, morphology and mtDNA provide congruent estimates of phylogeny. In spite of recent injunctions against combining data sets that are incongruent because of differing histories, the results of the combined analyses were used to select one of the most-parsimonious mtDNA trees as the best estimate of maternal-lineage genealogy and to reconstruct the evolution of parthenogenesis under the assumption that transitions from sexuality to parthenogenesis are irreversible. Where cytogenetically justified, as in weevils, the irreversibility assumption is useful for producing conservative estimates of the age of parthenogenetic lineages in spite of potential sampling bias against sexuals.

Animals↗
PubMedDate not supplied

Water-balance characteristics respond to changes in body size in subantarctic weevils.

Several environmental factors leading to size-dependent mortality influence insect body size. Few investigations have been concerned with the ways in which the mechanisms underlying variation in water-balance characteristics evolve in response to changes in body size that occur independently of water-balance requirements. Using an explicitly phylogenetic analysis, we show how body size has changed over time in the Ectemnorhinus group of weevils and how water-balance characteristics have evolved in response to this change and changes in habitat use. The basal species in the group are all large bodied and from moist environments. In response to a change in resource availability, there was a marked decline in size within the group. Despite the reduction in water content and dehydration tolerance that this meant, evolution of low whole-animal water-loss rates and high tolerance of dehydration resulted in conservation of desiccation resistance. The return to moist habitats in the group resulted in a reduction in dehydration tolerance and an increase in water-loss rate. Thus, dehydration tolerance and water-loss rate respond rapidly both when there is selection for water conservation and when this requirement is relaxed. Future laboratory selection experiments might usefully explore both directions of water-balance evolution.

Animals↗
PubMedDate not supplied

Inheritance of null alleles for microsatellites in the white pine weevil (Pissodes strobi [Peck] [Coleoptera: Curculionidae]).

Four families of the white pine weevil (Pissodes strobi) produced by controlled breeding were used to study the mode of inheritance at four microsatellite loci. The results confirmed the Mendelian segregation of all loci. Three of the four loci showed the presence of null alleles. The observed high polymorphism of P. strobi microsatellites increased their usefulness for paternity determination. The presence of null alleles predicates the need to redesign primers before using them in population genetics studies where pedigree is unknown.

Animals↗
PubMed2003

Evolution of clonality and polyploidy in a weevil system.

The increased interest in asexual organisms calls for in-depth studies of asexual complexes that actively give rise to new clones. We present an extensive molecular study of the Otiorhynchus scaber (Coleoptera, Curculionidae) weevil system. Three forms have traditionally been recognized: diploid sexuals, triploid, and tetraploid parthenogens. All forms coexist in a small central area, but only the polyploid parthenogens have colonized marginal areas. Analyzing the phylogenetic relationship, based on three partial mitochondrial genes, of 95 individuals from 19 populations, we find that parthenogenesis and polyploidy have originated at least three times from different diploid lineages. We observe two major mitochondrial lineages, with over 2.5% sequence divergence between the most basal groups within them, and find that current distribution and phylogenetic relationships are weakly correlated. Quite unexpectedly, we also discover diploid clones that coexist with, and are morphologically indistinguishable from, the diploid sexual females. Our results support that these diploid clones are derived directly from the diploid sexuals. We also find that it is mainly an increase in ploidy level and not the benefits of asexual reproduction that confers to polyploid parthenogens the advantage over their diploid sexual relatives.

Animals↗
PubMed1969

Abscission of cotton flower buds and petioles caused by protein from boll weevil larvae.

Protein extracted from boll weevil larvae causes abscission of cotton flower buds and debladed petioles. Abscission of buds is preceded by a rapid and persistent flaring of bracts; cell proliferation is induced in the abscission zone of debladed petioles. A possible mode of transmission of the agent from larva to bud tissue is discussed.

Journal Article↗
PubMed1992

T-independent polyclonal activation of B cells in vitro by immunoglobulin binding substance (IBS) from the granary weevil.

Experiments are described for T-independent polyclonal activation of B cells in vitro by the immunoglobulin binding substance (IBS) from the granary weevil. The affinity-chromatographically purified IBS was used. IBS is a heat-, alkali- and acid-stable glucopeptide which is characterized by non-specific immunoglobulin binding to the Fab fragment. The purified IBS consists of three polymer homologues whose molecular weights are 12-14,000, 25-30,000 and more than 150,000 Da. IBS did not stimulate DNA synthesis by murine T cells, macrophages or plasma cells whereas it did stimulate that by mature B cells without any help from T cells or macrophages. IBS also stimulated both in vitro IgG production by spleen cells and in vitro sensitization of spleen cells by sheep red cells (SRBC). IBS was found to stimulate DNA synthesis by B cells mediated by binding to surface immunoglobulins of B cells. IBS is thought to be a useful amplifier for inducing human hybridomas and a valuable tool for examining mature B cells, both diagnostically and experimentally.

Animals↗
PubMed1995

Identification of important allergenic proteins in extracts of the granary weevil (Sitophilus granarius).

This paper describes the identification of important allergens from the granary weevil (Sitophilus granarius) (Sg). Sera from Danish bakers whose skin prick tests were positive to extracts of Sg were screened for IgE against Sg extracts. We found that 54% (n = 66) had elevated levels of IgE (RAST classes 1-3, by luminescent immunoassay) against whole-body extracts of Sg. The specificity of patient IgE was investigated in an inhibition-dot immunoblotting assay. IgE binding was inhibited in all sera but two, thus indicating that the patients' IgE was indeed specific for the Sg extract. In crossed immunoelectrophoresis, 23 different proteins were identified. All RAST-positive sera were investigated in crossed radioimmuno-electrophoresis. At least 11 proteins in the Sg extract were capable of binding IgE. All individual sera reacted with at least four different proteins. The two most prominent allergens bound IgE from 88% and 100%, respectively, of the patients. These two are considered to be the most important allergens from Sg, and will be useful as markers in environmental immunochemical assays to detect allergens in samples from bakeries, grain stores, etc.

Adolescent↗
PubMed1975

Emodin, a toxic metabolite of Aspergillus wentii isolated from weevil-damaged chestnuts.

A diarrheagenic toxin from culture extracts of Aspergillus wentii Wehmer isolated from weevil-damaged Chinese chestnuts was identified as emodin (2-methyl-4,5,7-trihydroxyanthraquinone). The orange-red, crystalline toxin (mp 255 to 257 C) showed ultraviolet absorption maxima in ethyl alcohol at 223, 250, 267, 290, and 442 nm, and infrared absorption maxima at 3,400 cm-1 (OH), 1,635, and 1,625 CM-1. Chemical shifts and coupling constants of the proton magnetic resonance spectra of the A. wentii toxin and of authentic emodin agreed. Mean lethal dose of emodin orally administered to 1-day-old DeKalb cockerels was 3.7 mg/kg.

Animals↗
PubMed1975

Toxigenic Aspergillus and Penicillium isolates from weevil-damaged chestnuts.

Aspergillus and Penicillium were among the most common genera of fungi isolated on malt-salt agar from weevil-damaged Chinese chestnut kernels (16.8 and 40.7% occurrence, respectively). Chloroform extracts of 21 of 50 Aspergillus isolates and 18 of 50 representative Penicillium isolates, grown for 4 weeks at 21.1 C on artificial medium, were toxic to day-old cockerels. Tweleve of the toxic Aspergillus isolates were identified as A. wentii, eight as A. flavus, and one as A. flavus var. columnaris. Nine of the toxic Penicillium isolates were identified as P. terrestre, three as P. steckii, two each as P. citrinum and P. funiculosum, and one each as P. herquei (Series) and P. roqueforti (Series). Acute diarrhea was associated with the toxicity of A. wentii and muscular tremors with the toxicity of P. terrestre, one isolate of P. steckii, and one of P. funiculosum.

Animals↗
PubMed1976

Toxigenic species of Penicillium, Fusarium, and Aspergillus from weevil-damaged pecans.

Of a total of 2392 fungi isolated from weevil-damaged pecans, 46.4% were Alternaria and Epicoccum, 23.9% were Penicillium, 12.4% were Pestalotia and Monochaeta, 6.5% were Cladosporium, 6.4% were Fusarium, and less than 2% each were Phoma, Aspergillus, Rhizopus, Trichothecium, and miscellaneous. Chloroform extracts of 34 of 105 representative Penicillium isolates, 3 of 28 Fusarium isolates, and 3 of 23 Aspergillus isolates were toxic to day-old cockerels during three bioassays. Eight of the toxic extracts from Penicillium spp. were tremorgenic. One tremorgenic isolate was identified as P. paxilli, four were identified as P. lanoso-coeruleum, and three as P. cyclopium. Nine of the non-tremorgenic isolates were identified as P. citrinum, five as P. aurantio-virens, three as P. oxalicum, and two as P. meleagrinum. Others were identified as one each of P. brevi-compactum (Series), P. nigricans (Series), P. roqueforti, P. rugulosum (Series), P. terrestre, and P. stoloniferium. One was unidentified. Toxigenic Aspergillus isolates were all A. flavus. Two of the toxic Fusarium isolates were F. moniliforme, and one was unidentified.

Animals↗
PubMed2000

Synthesis of 2,2,4,4-tetramethyl-N,N'-bis(2,6-dimethylphenyl)cyclobutane-1,3-diimine , a unique compound from Arundo donax, and its analogues to test their antifeedant activity against the boll weevil, Anthonomus grandis.

2,2,4,4-Tetramethyl-N,N'-bis(2,6-dimethylphenyl) cyclobutane-1,3-diimine (1), which was isolated from the Thai plant Arundo donax as an antifeedant against the boll weevil (Anthonomus grandis), and its analogues (9-13) were synthesized and shown to possess no remarkable antifeedant activity of practical interest.

Animals↗