Search results for "INSECT"
showing 10 items of 2033 documents
Increase in midgut microbiota load induces an apparent immune priming and increases tolerance to Bacillus thuringiensis
2010
Summary The insect immune system is comprised of both humoral and cellular components that are mobilized in response to parasitic or pathogenic infections. Activation of the immune response implies a consid- erable expenditure of energy and that is why insects rely on inducible pathways that are activated after coming into contact with the pathogenic agent. Known as immune priming, insects can prolong the activation of the immune response and transmit their immune status to the next generation. Starting from a laboratory colony of the lepidopteran Spodoptera exigua and using the lytic zone assay as a measure of the immune status, we selected for a sub-colony with high levels of immune activ…
Fructose 2,6-bisphosphate as a signal for changing from sugar to lipid oxidation during flight in locusts
1986
AbstractFlight in locusts is initially powered mainly by carbohydrate but if flight is to be sustained, as in migration, the animals have to utilize fat as the predominant fuel. The molecular basis of this metabolic switch has not been identified. Fructose 2,6-bisphosphate is a potent activator of 6-phosphofructokinase (EC 2.7.1.11) purified from locust flight muscle. After the first few minutes of flight in the locust the concentration of fructose 2,6-bisphosphate in the flight muscle falls dramatically, which should lead to a decrease in the activity of 6-phosphofructokinase as part of the mechanism to conserve carbohydrate during prolonged flight.
Optimum and Maximum Host Sizes at Parasitism for the Endoparasitoid <I>Hyposoter didymator</I> (Hymenoptera: Ichneumonidae) Differ Greatl…
2007
Host size is considered a reliable indicator of host quality and an important determinant of parasitoid fitness. Koinobiont parasitoids attack hosts that continue feeding and growing during parasitism. In contrast with hemolymph-feeding koinobionts, tissue-feeding koinobionts face not only a minimum host size for successful development but also a maximum host size, because consumption of the entire host is often necessary for successful egression. Here we study interactions between a generalist tissue-feeding larval endoparasitoid, Hyposoter didymator Thunberg (Hymenoptera: Ichneumonidae) and two of its natural hosts, Spodoptera exigua Hübner and Chrysodeixis chalcites Esper (Lepidoptera: N…
Monoclonal antibodies recognizing larval- and pupal-specific cuticular proteins of Tenebrio molitor (Insecta, Coleoptera)
1993
To study the sequential expression of insect epidermal cells during metamorphosis, a library of monoclonal antibodies (MABs) was prepared against the water-soluble proteins from preecdysial pupal cuticle of Tenebrio molitor. Six selected MABs recognizing only larval and pupal cuticular proteins (CPs) in immunoblot analysis were classified into three types. Type 1 recognized a 21.5 and a 22 kDa polypeptide, type 2, a 26 kDa polypeptide, and type 3, three polypeptides of 18.5, 19.5 and 21.5 kDa. They did not immunoreact with any protein of fat bodies or haemolymph from pharate pupae, suggesting that the antigens originate from the epidermis. The stage-specificity was confirmed by electron mic…
Study of the aminopeptidase N gene family in the lepidopterans Ostrinia nubilalis (Hübner) and Bombyx mori (L.): Sequences, mapping and expression
2010
Aminopeptidases N (APNs) are a class of ectoenzymes present in lepidopteran larvae midguts, involved in the Bacillus thuringiensis (Bt) toxins mode of action. In the present work, seven aminopeptidases have been cloned from the midgut of Ostrinia nubilalis, the major Lepidopteran corn pest in the temperate climates. Six sequences were identified as APNs because of the presence of the HEXXH(X)18E and GAMEN motifs, as well as the signal peptide and the GPI-anchor sequences. The remaining sequence did not contain the two cellular targeting signals, indicating it belonged to the puromycin-sensitive aminopeptidase (PSA) family. An in silico analysis allowed us to find orthologous sequences in Bo…
Number, identity, and sequence of the Drosophila head segments as revealed by neural elements and their deletion patterns in mutants.
1994
The development of the insect head tagma involves massive rearrangements and secondary fusions of segment anlagen during embryogenesis. Due to the lack of reliable morphological markers, the number, identity, and sequence of the head segments, particularly in the pregnathal region, are still a matter of ongoing debates. We examined the complex array of internal structures of the embryonic Drosophila melanogaster head such as the sensory structures and nerves of the peripheral and stomatogastric nervous systems, and we used embryonic head mutations causing a lack of overlapping segment anlagen to unravel the segmental identity and the sequence of the neural elements. Our results provide evid…
Development of the wing discs of Zophobas atratus under natural and experimental conditions: occurrence of a gradual larval-pupal commitment in the e…
1999
Using light and electron microscopy, we studied the development of the wing discs in the large beetle Zophobas atratus, under natural and experimental conditions. A reversible differentiation of the wing discs is usually observed during supernumerary instars of crowded larvae. Juvenile hormone analog (JHA) application during the wandering period or compelled experimental crowding during the larval-pupal switchover – or commitment – inhibits the onset of metamorphosis. Isolation, followed by recrowding, also induces the disc cells to secrete unusual cuticular material. Recrowding is able to trigger the reversal of metamorphosis during the 4-day period when larval-pupal commitment is taking p…
Developmental profiles of epidermal mRNAs during the pupal-adult molt of Tenebrio molitor and isolation of a cDNA clone encoding an adult cuticular p…
1992
0012-1606 (Print) Journal Article; Changes in translatable mRNAs from the wing epidermis of the Coleoptera Tenebrio molitor have been investigated during metamorphosis by analysis of in vitro translated products. Striking differences between the patterns obtained from mRNAs extracted during pupal and adult cuticle secretion indicated that a drastic change in gene expression occurs during the pupal-adult transition. In addition to these stage-specific modifications, the mRNA patterns changed within each cuticular synthesis program (pupal or adult), especially at ecdysis. After tritiated leucine incorporation, some of the major radiolabeled cuticular proteins showed similar changes suggesting…
Effect of Cry Toxins on Xylotrechus arvicola (Coleoptera: Cerambycidae) Larvae
2022
Simple Summary Xylotrechus arvicola is a destructive pest in vineyards (Vitis vinifera) in the main wine-producing areas of the Iberian Peninsula. X. arvicola larvae bore into the grapevine wood-making galleries, thus damaging the plant both directly and indirectly. The susceptibility of X. arvicola larvae to five coleopteran toxic Cry proteins was evaluated under laboratory conditions in order to deepen the knowledge of the effect of these proteins on this insect throughout its biological development. The Cry proteins tested could be applied to control X. arvicola larvae since they were able to kill them and cause serious alterations in the larvae during the remaining months of development…
External and internal elimination of supernumerary larvae in the whitefly parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae)
2008
Abstract The solitary parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) is one of the key biological control agents of the whitefly Bemisia argentifolii Bellows & Perring, also known as B. tabaci (Gennadius) B-biotype (Homoptera: Aleyrodidae). We present new information on its biology, and particularly about larval elimination during the first instar in cases of superparasitism. For the first time, physical elimination of supernumerary larvae was observed, both outside and inside the host. These findings are documented with confocal microscopy images and video recordings. We observed more than 350 B. argentifolii nymphs, parasitized with one, two or more than two larvae. Physi…