Search results for " Insect"
showing 10 items of 280 documents
Tempo and mode of early gene loss in endosymbiotic bacteria from insects
2006
Background Understanding evolutionary processes that drive genome reduction requires determining the tempo (rate) and the mode (size and types of deletions) of gene losses. In this study, we analysed five endosymbiotic genome sequences of the gamma-proteobacteria (three different Buchnera aphidicola strains, Wigglesworthia glossinidia, Blochmannia floridanus) to test if gene loss could be driven by the selective importance of genes. We used a parsimony method to reconstruct a minimal ancestral genome of insect endosymbionts and quantified gene loss along the branches of the phylogenetic tree. To evaluate the selective or functional importance of genes, we used a parameter that measures the …
Mecanismos de resistencia a piretroides en ácaros depredadores
2023
Los piretroides constituyen un grupo de plaguicidas catalogados como moduladores del canal de sodio (Grupo 3), según el comité de acción contra la resistencia a los insecticidas (IRAC). Estos plaguicidas son análogos sintéticos de las piretrinas, compuestos naturales con actividad insecticida que se encuentran en las flores de las plantas del género Chrysanthemum, popularmente conocidas como crisantemos. Actualmente, existen numerosos productos plaguicidas que contienen en su formulación piretroides, siendo ampliamente utilizados en el control de plagas en diferentes contextos como la agricultura, la ganadería, la apicultura e incluso a nivel doméstico, erigiéndose como uno de los grupos de…
Estudio de una superfamilia de genes de respuesta a patógenos (repat) en insectos
2012
El intestino de los insectos es una de las principales vías de entrada de entomopatógenos. Con el fin de minimizar los efectos negativos de los patógenos, el intestino de los insectos posee diferentes mecanismos: síntesis de péptidos antimicrobianos, producción de especies reactivas de oxígeno, activación de los sistemas de reparación y detoxificación, melanización, fagocitosis, apoptosis y la renovación celular, entre otros. Estudios de expresión tras la exposición a diferentes patógenos han mostrado cómo la expresión de ciertos genes varía en el intestino tras la infección. Previamente a la realización de esta tesis, se identificó, en el lepidóptero Spodoptera exigua, una familia de genes…
The cockroach Blattella germanica obtains nitrogen from uric acid through a metabolic pathway shared with its bacterial endosymbiont.
2014
Uric acid storedin the fat bodyof cockroaches is a nitrogen reservoirmobilized in times of scarcity. The discovery of urease in Blattabacterium cuenoti, the primary endosymbiont of cockroaches, suggests that the endosymbiont may participate in cockroach nitrogen economy. However, bacterial urease may only be one piece in the entire nitrogen recycling process from insect uric acid. Thus, in addition to the uricolytic pathway to urea, there must be glutamine synthetase assimilating the released ammonia by the urease reaction to enable the stored nitrogen to be metabolically usable. None of the Blattabacterium genomes sequenced to date possess genes encoding for those enzymes. To test the host…
Toxicity of several d-endotoxins of Bacillus thuringiensis against Helicoverpa armigera (Lepidoptera: Noctuidae) from Spain
2005
Abstract Toxicity and larval growth inhibition of 11 insecticidal proteins of Bacillus thuringiensis were evaluated against neonate larvae of Helicoverpa armigera, a major pest of important crops in Spain and other countries, by a whole-diet contamination method. The most active toxins were Cry1Ac4 and Cry2Aa1, with LC50 values of 3.5 and 6.3 μg/ml, respectively. At the concentrations tested, Cry1Ac4, Cry2Aa1, Cry9Ca, Cry1Fa1, Cry1Ab3, Cry2Ab2, Cry1Da, and Cry1Ja1, produced a significant growth inhibition, whereas Cry1Aa3, Cry1Ca2, and Cry1Ea had no effect.
Contrôle des ravageurs de cultures par les ennemis naturels : la plante hôte facteur régulateur du système immunitaire des chenilles de vers de la gr…
2013
10 pages; National audience; En raison des nombreux dégâts occasionnés par les vers de la grappe dans les vignobles, trouver un moyen de lutte efficace est devenu un réel challenge. A l’heure actuelle, la lutte biologique apparaît comme une alternative possible à la lutte chimique. Cependant, les résultats obtenus suite aux lâchers de parasitoïdes sont extrêmement variables dans leur efficacité. Des études approfondies de la biologie des vers de la grappe et de leurs parasitoïdes sont donc nécessaires afin d’affiner les méthodes de lutte biologique. Le système immunitaire des insectes représente la dernière ligne de défense des phytophages contre les parasitoïdes. Dans cette étude nous mett…
Should grape moth larval immunity help explaining resistance against natural enemies?
2011
National audience; In tritrophic systems (plants, phytophagous insects and natural enemies), host plant variation often keys the relative performance of both the herbivore and its associated natural enemies. In bottom-up effects, host plants could affect the fitness of phytophagous insects including growth rate and adult fertility. These effects are indirectly reflected in parasitoids whose success depends on their host quality. For instance, nutrient deficiency or/and toxic defensive compounds of the plants could slow-down the development of herbivorous insects, thus extending the window of vulnerability of attacks by natural enemies. The immune system is arguably the most common resistanc…
Use of two odorants to control bactrocera oleae and ceratitis capitata
2020
International audience; Many insects are considered as pests because of the damage they cause to cultures. Growers and our society are waiting for environmentally safe strategies to prevent insect damages, without arming the environment and the biodiversity. Recently we discovered an innovative solution using some odorant molecules to control Drosophila suzukii behavior. Using this knowledge we started to investigate the possibility to apply this strategy to Bactrocera oleae (olive fruit fly) and Ceratitis capitata (Mediterranean fruit fly) to modify their social behavior. This new technology, which is protected by the patent n° EP19306102, could be particularly interesting to avoid infesta…
Effet insecticide de Bacillus thuringiensis kurstaki et d’une toxine bactérienne, le Spinosad, à l’égard des blattes domestiques adultes (Blattella g…
2012
Les blattes sont très étudiées en raison de leur impact sur la santé humaine et animale, sur les cultures et l’habitat. Blattella germanica est une blatte domestique prédominante qui représente un vecteur potentiel des maladies. En raison de sa nuisance elle a fait l’objet de plusieurs études, en vue d’une lutte efficace. Ces dernières années, une nouvelle approche toxicologique est apparue, elle consiste à développer de nouveaux insecticides issus essentiellement des molécules biologiques telles que les plantes et les microorganismes comme les champignons et les bactéries. Dans cette étude on s’est intéressé aux effets induits par le Bacillus thuringiensiskurstaki sur les adultes de B. ger…
Search for biological signature of the degradation of chlordecone in soil of the French West Indies
2015
The use of chlordecone (CLD) to eradicate the weevil populations in the banana plantations in the French West Indies (Guadeloupe and Martinique) between 1972 and 1993 led to the contamination of the soil and the environment. This very hydrophobic organochlorine insecticide persists in the soil where it slowly transfers not only to the water resources but also to terrestrial and aquatic biota (plants, animals, fishes, shellfishes). Deemed “non-degradable”, CLD is resistant to photolysis, hydrolysis and biodegradation. To date, there is no method to remediate the 20,000 hectares of polluted soil with this insecticide. Given the extent of CLD pollution, biological decontamination processes app…