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At least 325 records · Page 18Linked to original sources
PubMed1997

Characterization of a gene family encoding cysteine proteinases of Sitophilus zeamais (maize weevil), and analysis of the protein distribution in various tissues including alimentary tract and germ cells.

We have identified and characterized a gene family comprising at least four genes encoding cathepsin L-like cysteine proteinases (SCPs) in Sitophilus zeamais, Coleoptera. A cDNA clone corresponding to a major mRNA species of the gene family in adult insects codes for a cysteine proteinase (CP) of 338 amino acid residues, and two genomic clones code for similar CPs of 331 residues whose COOH-terminal structures are seven amino acids shorter. These three SCPs show high sequence similarity to one another as well as to other insect and mammalian cathepsin L-like proteinases. A polyclonal antibody raised against bacterially expressed SCP was used as a probe to examine the molecular forms and distribution of the enzyme. SCP exists in both proenzyme and mature forms in larvae, pupae, and adults, and the proenzyme converts in vitro into the mature form at acidic pH. Immunohistochemical analysis showed that SCP is present in several tissues including alimentary organs and germ cells. In alimentary organs, SCP is distributed in the gastric caeca, but not the midgut. SCP is also present in genital organs, especially in oocytes and nurse cells, where it exists at high levels. These results indicate that SCP plays a variety of physiological roles including a role in food digestion.

Amino Acid Sequence↗
PubMed2000

Size-specific defensive structures in a horned weevil confirm a classic battle plan: avoid fights with larger opponents.

A rigid sheath that extends deep into the prothorax of male Parisoschoenus expositus serves to receive the horns of opponents in battles over females. The male cannot use his own horn unless he receives his opponent's horn in his sheath. The length of a male's sheath is always approximately equal to the length of his own horns, so his body design is appropriate only for horn-locking battles with males whose horns are equal to or shorter than his own. Horn length and sheath length are dimorphic with respect to each other and to an indicator of body size. The switch points between morphs are very nearly the same for several relationships, so the different aspects of fighting morphology are tightly coordinated.

Aggression↗
PubMed2003

Genetic architecture of differences between populations of cowpea weevil (Callosobruchus maculatus) evolved in the same environment.

We investigated the genetic architecture underlying differentiation in fitness-related traits between two pairs of populations of the seed beetle Callosobruchus maculatus (Coleoptera: Bruchidae). These populations had geographically distant (> 2000 km) origins but evolved in a uniform laboratory environment for 120 generations. For each pair of populations (Nigeria x Yemen and Cameroon x Uganda) we estimated the means of five fitness-related characters and a measure of fitness (net reproductive rate R0) in each of the parental populations and 12 types of hybrids (two F1 and two F2 lines and eight backcrosses). Models containing up to nine composite genetic parameters were fitted to the means of the 14 lines. The patterns of line means for all traits in the Nigeria x Yemen cross and for four traits (larval survival, developmental rate, female body weight, and fecundity) in the Cameroon x Uganda cross were best explained by models including additive, dominance, and maternal effects, but excluding epistasis. We did not find any evidence for outbreeding depression for any trait. An epistatic component of divergence was detected for egg hatching success and R0 in the Cameroon x Uganda cross, but its sign was opposite to that expected under outbreeding depression, that is, additive x additive epistasis had a positive effect on the performance of F2 hybrids. All traits except fecundity showed a pattern of heterosis. A large difference of egg-hatching success between the two reciprocal F1 lines in that cross was best explained as fertilization incompatibility between Cameroon females and sperm carrying Uganda genes. The results suggest that these populations have not converged to the same life-history phenotype and genetic architecture, despite 120 generations of uniform natural selection. However, the absence of outbreeding depression implies that they did not evolve toward different adaptive peaks.

Animals↗
PubMed1983

A unique substance from the granary weevil: nonspecific immunoglobulin binding substance.

We have studied the precipitation test as a diagnostic procedure for hypersensitivity pneumonitis or associated allergic states using Sitophilus granarius (SG) antigen. The incidence of positive reaction in the precipitation test against SG is extremely high in children and adults, not only asthmatics, but also in normal, healthy subjects. In experiments with radioimmunoassay using SG paper discs and 125I-labelled IgG fragments, SG was more strongly bound to the Fab than to the Fc fragment. However, the binding was not mediated by a true antigen-antibody reaction because the reaction was inhibited by both kappa- and lambda-type Bence-Jones proteins. Nonspecific immunoglobulin binding substance (IBS) was separated from crude SG extract by affinity chromatography using IgG immunosorbent. IBS was monocomponent on polyacrylamide gel electrophoresis in sodium dodecyl sulfate, and the molecular weight was about 12,000-14,000. We believe that IBS might be a valuable tool for immunological experiments, comparable with staphylococcal protein A.

Alveolitis, Extrinsic Allergic↗
PubMed2004

The seed coat of Phaseolus vulgaris interferes with the development of the cowpea weevil [Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)].

We have confirmed here that the seeds of the common bean (Phaseolus vulgaris, L.) do not support development of the bruchid Callosobruchus maculatus (F.), a pest of cowpea [Vigna unguiculata (L.) Walp] seeds. Analysis of the testa (seed coat) of the bean suggested that neither thickness nor the levels of compounds such as tannic acid, tannins, or HCN are important for the resistance. On the other hand, we have found that phaseolin (vicilin-like 7S storage globulin), detected in the testa by Western blotting and N-terminal amino acid sequencing, is detrimental to the development of C. maculatus. As for the case of other previously studied legume seeds (Canavalia ensiformis and Phaseolus lunatus) we suggest that the presence of vicilin-like proteins in the testa of P. vulgaris may have had a significant role in the evolutionary adaptation of bruchids to the seeds of leguminous plants.

Animals↗
PubMed2000

Evaluation of sequential sampling plans for the larger grain borer (Coleoptera: Bostrichidae) and the maize weevil (Coleoptera: Curculionidae) and of visual grain assessment in West Africa.

Repeated sampling of rural maize stores in Benin was conducted to evaluate published parameters of a sequential sampling plan for a negative binomial distribution to determine pest status for Prostephanus truncatus (Horn) and Sitophilus zeamais Motschulsky. A computer program was used to rerandomize the data and evaluate the effects, in terms of average sample number and error rates, of different sampling plan parameter values. With respect to P. truncatus, lower and upper thresholds of 0.2 and 1.0 insects per ear and parameter values of k = 0.2 and alpha = beta = 0.1 were found to be adequate. With respect to S. zeamais, lower and upper thresholds of 10 and 20 insects per ear and parameter values of k = 1.0 and i alpha = beta = 0.1 were found to be adequate. Simplified sampling rules were proposed in which 11 ears should be sampled and if no P. truncatus are found, the population is low; otherwise the Wald plan should be followed. Owing to the lower per capita rate of damage, effective simplified sampling rules for S. zeamais were difficult to construct. An evaluation of the visual assessment scale rising whole ears showed that a visual scale estimating percentage damage rather than percentage loss, might be easy to construct and preferable for traders. Further work is needed to improve the usefulness of the visual scale in pest management decision support.

Animals↗
PubMed2001

Structure and development of ovaries in the weevil, Anthonomus pomorum (Coleoptera, Polyphaga). I. Somatic tissues of the trophic chamber.

In developing ovarioles of Anthonomus pomorum (Coleoptera, Polyphaga, Curculionidae) the trophic chambers (tropharia) are relatively large and consist of clusters (clones) of germ cells and various somatic tissues. Each ovariole is enclosed within an outer epithelial sheath (tunica externa). Throughout the pupal phase, the growth of this sheath is accelerated and precedes the development of the rest of the ovariole. As a result, the epithelial sheath proliferates anteriorly and forms an elongated "sleeve" that during the later stages of development becomes gradually filled by the growing tropharium. In the early pupal stage, a few terminal filament cells are observed in contact with the anterior end of the tropharium. These cells are separated from the rest of the trophic chamber by a transverse septum, which maintains continuity with the basal lamina. Beneath the basal lamina there is a layer of inner sheath cells, whereas inside the tropharium there are interstitial cells. These two types of cell differ morphologically in a mature ovary but they retain, until the end of the imago-B stage, a similar ultrastructure testifying to their common origin. At the posterior end of the tropharium, from the imago-B stage on, many young oocytes, surrounded by prefollicular cells, are observed. This is the so-called neck region of the tropharium. Extraction with Triton X-100 detergent showed that in a mature trophic chamber there are only individual microtubules arranged along the projections of interstitial cells. This indicates that the cytoskeleton elements (microfilaments and microtubules) participate only to a very limited extent in the spatial organisation of the tropharium in A. pomorum.

Animals↗
PubMed2001

Effectiveness of IGRS (CGA-184699) and (CGA-259205) on the respiratory metabolism of the red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae).

Prepupae of Rhynchophorus ferrugineus were topically applied with one of three dose-levels (1.00, 0.10 or 0.01 microgram/insect) of lufenuron (CGA-184699) or diofenolan (CGA-259205). The daily O2 consumption and CO2-output were determined and the respiratory quotient (RQ) was calculated. Lufenuron prohibited the pupae to consume O2, regardless of their age. Considering the CO2 release, this IGR exerted an inhibitory action on pupae increasingly correlated with the increasing dose-level. Volumes of consumed O2 reversely correlated with the dose value of diofenolan. Also, CO2 output was suffered an inhibitory effect of diofenolan which was consecutively related to the dose value. An U-shaped pattern of daily respiration was not, unfortunately, attained, irrespective of the IGR or its dose. In addition, RQ mean values were less than unity but exceeded 0.7.

Age Factors↗
PubMed2001

Respiratory metabolic responsiveness during the pupal stage of the red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae) to certain plant extracts.

The prepupae of Rhynchophorus ferrugineous were topically applied with one of three dose-levels (0.1, 0.005 or 0.001 microgram/insect) of Jojoba oil (Joj) or azadirachtin (Azt). The daily O2 consumption and CO2 respiratory output were determined and the respiratory quotient (RQ) was calculated. After Joj treatments, O2 consumption of early- and late pupae increased as the dose-level was decreased. The respiration curve did not assume an U-shaped pattern as common in the pupal stage of many insect species. Also, an inhibitory action of Azt on the pupal respiration has been clearly exhibited. A similar result of the respiration curve was observed by Azt. All dose levels of Joj, but only the higher two ones of Azt, suppressed the CO2 release. Both botanicals inhibited the RQ during the pupal stage. However, all RQ mean values of treated or control pupae were < 1.0 and > 0.7.

Animals↗