Search results for "INSECT"
showing 10 items of 2033 documents
Comparison of quantitative Holocene temperature reconstructions using multiple proxies from a northern boreal lake
2017
Four biotic proxies (plant macrofossils, pollen, chironomids and diatoms) are employed to quantitatively reconstruct variations in mean July air temperatures ( Tjul) at Lake Loitsana (northern Finland) during the Holocene. The aim is to evaluate the robustness and biases in these temperature reconstructions and to compare the timing of highest Tjul in the individual reconstructions. The reconstructed Tjul values are evaluated in relation to local-scale/site-specific processes associated with the Holocene lake development at Loitsana as these factors have been shown to significantly influence the fossil assemblages found in the Lake Loitsana sediments. While pollen-based temperatures follow…
Structural Studies Reveal that Endosomal Cations Promote Formation of Infectious Coxsackievirus A9 A-Particles, Facilitating RNA and VP4 Release
2022
Coxsackievirus A9 (CVA9), an enterovirus, is a common cause of pediatric aseptic meningitis and neonatal sepsis. During cell entry, enterovirus capsids undergo conformational changes leading to expansion, formation of large pores, externalization of VP1 N termini, and loss of the lipid factor from VP1. Factors such as receptor binding, heat, and acidic pH can trigger capsid expansion in some enteroviruses. Here, we show that fatty acid-free bovine serum albumin or neutral endosomal ionic conditions can independently prime CVA9 for expansion and genome release. Our results showed that CVA9 treatment with albumin or endosomal ions generated a heterogeneous population of virions, which could b…
Evaluating Resistance to Bt Toxin Cry1Ab by F<SUB>2</SUB> Screen in European Populations of Ostrinia nubilalis (Lepidoptera: Crambidae)
2010
ABSTRACT The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F2 screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the CrylAb toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the CrylAb toxin. The cost of F2 screen performed in the four countries varie…
Diuron mineralisation in a Mediterranean vineyard soil: impact of moisture content and temperature
2010
BACKGROUND: The diuron-mineralising ability of the microbiota of a Mediterranean vineyard soil exposed each year to this herbicide was measured. The impact of soil moisture and temperature on this microbial activity was assessed. RESULTS: The soil microbiota was shown to mineralise diuron. This mineralising activity was positively correlated with soil moisture content, being negligible at 5% and more than 30% at 20% soil moisture content. According to a double Gaussian model applied to fit the dataset, the optimum temperature/soil moisture conditions were 27.9 °C/19.3% for maximum mineralisation rate and 21.9 °C/18.3% for maximum percentage mineralisation. The impact of temperature and soil…
Evidence for 2,4-D mineralisation in Mediterranean soils: impact of moisture content and temperature
2009
BACKGROUND: The 2,4-D degradation ability of the microbiota of three arable Mediterranean soils was estimated. The impact of soil moisture and temperature on 2,4-D degradation was investigated. RESULTS: The microbiota of the three soils regularly exposed to 2,4-D were able rapidly to mineralise this herbicide. The half-life of 2,4-D ranged from 8 to 30 days, and maximum mineralisation of 14C-2,4-D ranged from 57 to 71%. Extractable 14C-2,4-D and 14C-bound residues accounted for less than 1 and 15% respectively of the 14C-2,4-D initially added. The highest amounts of 14C-2,4-D bound residues were recorded in the soil with the lowest 2,4-D-mineralising ability. Although all three soils were a…
Versatile and Dynamic Symbioses Between Insects and Burkholderia Bacteria
2020
Symbiotic associations with microorganisms represent major sources of ecological and evolutionary innovations in insects. Multiple insect taxa engage in symbioses with bacteria of the genus Burkholderia, a diverse group that is widespread across different environments and whose members can be mutualistic or pathogenic to plants, fungi, and animals. Burkholderia symbionts provide nutritional benefits and resistance against insecticides to stinkbugs, defend Lagria beetle eggs against pathogenic fungi, and may be involved in nitrogen metabolism in ants. In contrast to many other insect symbioses, the known associations with Burkholderia are characterized by environmental symbiont acquisition …
Gap perception in bumblebees
2018
ABSTRACT A number of insects fly over long distances below the natural canopy, where the physical environment is highly cluttered consisting of obstacles of varying shape, size and texture. While navigating within such environments, animals need to perceive and disambiguate environmental features that might obstruct their flight. The most elemental aspect of aerial navigation through such environments is gap identification and ‘passability’ evaluation. We used bumblebees to seek insights into the mechanisms used for gap identification when confronted with an obstacle in their flight path and behavioral compensations employed to assess gap properties. Initially, bumblebee foragers were train…
Mining of new insecticidal protein genes plus determination of the insecticidal spectrum and mode of action of Bacillus thuringiensis Vip3Ca protein
2019
Bacillus thuringiensis és un bacteri que pertany al grup de Bacillus cereus i produeix una gran varietat de proteïnes insecticides juntament amb altres factors de virulència que contribueixen a la seva patogenicitat. Bacillus thuringiensis s'ha considerat com el agent bioinsecticida amb més èxit durant el segle passat. Actualment, és àmpliament utilitzat com agent microbià per a les principals plagues d'insectes com a formulat (selecció de aïllats de B. thuringiensis escollits per la seua combinació de proteïnes insecticides present en el cristall parasporal) o mitjançant l’expressió de les proteïnes insecticides (cultius Bt) en plantes d’interès agronòmic (dacsa, cotó, soja, etc.). En quan…
Evolutionary genomics and functional studies on the metabolic role of Blattabacterium, primary endosymbiont of cockroaches
2013
Introducció La simbiosi, entesa com la relació de interdependència entre dos o més individus de diferents espècies, ha tingut un profunda influència al llarg de l’evolució de la vida. De fet, hi ha un ampli consens respecte a la importància de les associacions simbiòtiques, en l’aparició i evolució primerenca de la cèl•lula eucariota, així com en l’evolució del sistema immunitari en eucariotes complexos o en l’adquisició de noves capacitats metabòliques en plantes i animals, permetent-los així explorar noves fonts d’aliments o ocupar nous nínxols ecològics. Segons l’efecte de la interacció sobre els membres de l’associació, es poden distingir tres tipus: comensalisme, quan un dels membres e…
Plant-animal interactions in fire-prone ecosystems
2018
SÍNTESIS Estudiar cómo responden las interacciones ecológicas a las perturbaciones es clave para abordar la creciente pérdida de biodiversidad en diferentes ecosistemas. En la Tierra existen especies que han evolucionado ante la presencia recurrente de perturbaciones naturales, como ocurre en ecosistemas con incendios frecuentes. En ellos el fuego se originó poco después de la aparición de las primeras plantas terrestres y también algunos de los patrones de incendios característicos que todavía permanecen. Sin embargo, las actividades humanas están alterando los patrones naturales de incendios, lo que puede suponer una amenaza incluso para las especies que presentan una rápida recuperación …