Search results for "INSECT"
showing 10 items of 2033 documents
Caracterización molecular del mecanismo de patogénesis de las toxinas Cry de Bacillus thuringiensis activas contra insectos coleópteros
2013
Los bioinsecticidas basados en Bacillus thuringiensis (Bt) constituyen una herramienta de gran valor para el control de plagas de insectos, ya que presentan una forma de aplicación muy específica e inocua para los usuarios y el medio ambiente. Entender, tanto el mecanismo de toxicidad de estos bioinsecticidas como la respuesta desencadenada en los insectos diana, tiene como objetivo proporcionar una base útil para el desarrollo de insecticidas mejorados dirigidos contra estas importantes plagas agrícolas, permitiendo ampliar el rango y los niveles de toxicidad de las proteínas insecticidas y abordar problemas como la aparición de resistencia. La presente tesis se ha centrado en el estudio d…
Convergent Loss of Chemoreceptors across Independent Origins of Slave-Making in Ants
2022
The evolution of an obligate parasitic lifestyle often leads to the reduction of morphological and physiological traits, which may be accompanied by loss of genes and functions. Slave-maker ants are social parasites that exploit the work force of closely related ant species for social behaviours such as brood care and foraging. Recent divergence between these social parasites and their hosts enables comparative studies of gene family evolution. We sequenced the genomes of eight ant species, representing three independent origins of ant slavery. During the evolution of eusociality, chemoreceptor genes multiplied due to the importance of chemical communication in societies. We investigated ev…
The nasus gland: A new gland in soldiers of Angularitermes (Termitidae, Nasutitermitinae)
2015
Termites have developed many exocrine glands, generally dedicated to defence or communication. Although a few of these glands occur in all termite species, or represent synapomorphies of larger clades, others are morphological innovations of a single species, or a few related species. Here, we describe the nasus gland, a new gland occurring at the base of the nasus of Angularitermes soldiers. The nasus gland is composed of class 1, 2, and 3 secretory cells, a rare combination that is only shared by the sternal and tergal glands of some termites and cockroaches. The ultrastructural observations suggest that the secretion is produced by class 2 and 3 secretory cells, and released mostly by cl…
Zoonotic Dirofilaria immitis and Dirofilaria repens infection in humans and an integrative approach to the diagnosis
2021
Abstract Dirofilariosis by Dirofilaria immitis and Dirofilaria repens is endemic in dogs from countries of the Mediterranean basin. Both species may infect humans, with most of the infected patients remaining asymptomatic. Based on the recent description of the southernmost hyperendemic European focus of heartworm disease in dogs from the Pelagie archipelagos, we performed a serological and molecular survey in human population of that area. Human blood samples were collected in the islands of Linosa (n=101) and Lampedusa (n=296) and tested by ELISA and molecular test for the detection of D. immitis and D. repens. Samples were also screened for filarioid-associated endosymbionts, Wolbachia s…
Estructura de comunidades de Odonata en sistemas mediterráneos
2015
En ecología, una comunidad es un conjunto de especies que coexiste en un mismo momento y lugar (Mittelbach 2012) pero la forma en que se han conceptualizado las comunidades ecológicas ha cambiado con el tiempo. A principios del siglo XX, la comunidad se consideró una entidad discreta principalmente regulada por factores ambientales lo que condujo al debate entre las visiones clementsiana y gleasoniana de las comunidades. Más tarde, el debate se centró en los mecanismos que permitían la coexistencia de especies en función de la manera en la que las diferentes especies explotaban los recursos disponibles. Fue la época en la que Hutchinson (1957) enunció su teoría del nicho. En esa línea, Diam…
Alien Insect Impact on Cultural Heritage and Landscape: an Underestimated Problem
2017
The impact of alien invasive insects on cultural heritage and landscapes is very often neglected; even though, more than 50% of species that threaten cultural heritage in Europe are of exotic origin. In addition they are more aggressive. Several examples and a description, are given of the most dangerous alien insects present in heritage sites that constitute a risk for the conservation of cultural property: museum collections, libraries, archives and historic buildings. Globalisation has increased this phenomenon but traces of the accidental introduction of insect pests have occurred since Roman times. The paper discusses the need to implement an estimation of the costs that arise from the…
Lack of cross‐resistance to otherBacillus thuringiensiscrystal proteins in a population ofPlutella xylostellahighly resistant to cryia(b)
1994
Competition experiments were performed with brush border membrane vesicles of diamondback moth larvae using 125I‐labelled CryIA(b) and unlabelled CryIA(a), CryIA(b) and CryIA(c). The results suggested a model with a single binding site for CryIA(b). Heterologous competition showed that CryIA(c) competed as effectively as CryIA(b) for the CryIA(b) binding site, whereas CryIA(a) competed less effectively. Toxicity tests were performed on third instar larvae with trypsin‐activated insecticidal crystal proteins (ICPs) and a commercial formulation of Bacillus thuringiensis (Bt) (Dipel). A laboratory colony was found to be susceptible to all four ICPs tested and to Dipel. CryIA(b), CryIA(c) and C…
Providing insights into browntail moth local outbreaks by combining life table data and semi-parametric statistics
2011
1. Life table studies have been an essential tool for the comprehension of insect population dynamics, although their use has been methodologically biased by a primary focus on mortality factors, especially natural enemies. Thus, studies in natural populations may relegate important mortality sources to the ‘unknown’ or ‘residual’ mortality categories. To overcome this limitation, life tables may be complemented by combining them with other approaches. 2. The aim of the present study was to provide insights into browntail moth Euproctis chrysorrhoea L. (Lepidoptera: Lymantriidae) local outbreaks by combining life table data and statistical modelling. First, E. chrysorrhoea population densit…
Susceptibility to Cry proteins of a SpanishOstrinia nubilalisglasshouse population repeatedly sprayed withBacillus thuringiensisformulations
2013
Ostrinia nubilalis Hubner (Lepidoptera: Crambidae), a major pest of corn in temperate climates, can feed on other crops due to its polyphagous behaviour. In particular, this species became a serious problem in some sweet pepper commercial glasshouses in south-eastern Spain repeatedly sprayed with Bacillus thuringiensis (Bt) products to control Spodoptera exigua Hubner (Lepidoptera: Noctuidae). The susceptibility of an O. nubilalis colony established from individuals collected in these Bt-sprayed glasshouses was compared with a reference laboratory colony. Differences in susceptibility between the two colonies to Cry1Aa, Cry1Ab, Cry1Ac and Cry2Aa proteins were found. However, our results ind…
Larval Arrest in Development of Tribolium castaneum (Coleoptera: Tenebrionidae)
1986
Arrested larval development (in the last larval instar) of part of the total larval population has been detected in moderately crowded situations (40 larvae in 2 g food) in Tribolium castaneum (Herbst) cultures This phenomenon is the same found previously in highly crowded cultures of Drosophila melanogaster (Meigen) and other related species. The arrest may be viewed as a mechanism of physiological adaptation of organisms to competitive situations.