Search results for "littoralis"
showing 10 items of 28 documents
Effect of substitutions of key residues on the stability and the insecticidal activity of Vip3Af from Bacillus thuringiensis
2021
Modern agriculture demands for more sustainable agrochemicals to reduce the environmental and health impact. The whole process of the discovery and development of new active substances or control agents is sorely slow and expensive. Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis are specific toxins against caterpillars with a potential capacity to broaden the range of target pests. Site-directed mutagenesis is one of the most approaches used to test hypotheses on the role of different amino acids on the structure and function of proteins. To gain a better understanding of the role of key amino acid residues of Vip3A proteins, we have generated 12 mutants of the Vip3Af1 …
A taxonomic revision helps to clarify differences between the Atlantic invasive Ptilohyale littoralis and the Mediterranean endemic Parhyale plumicor…
2018
Ptilohyaleexplorator (formerly Parhyaleexplorator), described by Arresti (1989), can be considered to be a synonym of west-Atlantic Ptilohyalelittoralis (Stimpson, 1853), based on morphological observations of paratypes and specimens recently collected in the type locality of Ptilohyaleexplorator. The first collections of Ptilohyalelittoralis, from the eastern Atlantic were from the port of Rotterdam (The Netherlands) in 2009 and later in Wimereux, Opal Coast (France) in 2014; however, the synonymy of Ptilohyaleexplorator with Ptilohyalelittoralis backdates to the first European record of Ptilohyalelittoralis in 1985 at La Vigne, Bay of Arcachon (France). This indicates that Ptilohyalelitto…
Efficacy of sea fennel (Crithmum maritimum L., Apiaceae) essential oils against Culex quinquefasciatus Say and Spodoptera littoralis (Boisd.)
2017
The effective management of insect pests and vectors still represents a major challenge in current entomology. Culex quinquefasciatus Say is a key vector of lymphatic filariasis, Rift Valley fever, West Nile, St. Louis encephalitis and Western equine encephalitis virus. Recently, the importance of the eco-friendly control of C. quinquefasciatus larval population using plant-borne biopesticides, including essential oils (EOs), has been stressed. Spodoptera littoralis (Boisd.) also known as tobacco cutworm, is one of the most destructive moth agricultural pests in tropic and sub-tropic regions. Despite the fact that sea fennel (Crithmum maritimum L., Apiaceae) is considered as a promising bio…
Chemical Composition and Broad-Spectrum Insecticidal Activity of the Flower Essential Oil from an Ancient Sicilian Food Plant, Ridolfia segetum
2021
Several species of the family Apiaceae are aromatic herbs that produce essential oils usable on an industrial scale for pharmaceutical, cosmetic, and food purposes. In particular, some essential oils, such as green insecticides for example, may replace synthetic insecticides, keeping most of their efficacy and avoiding environmental pollution or human poisoning. In the present study, we explored the insecticidal potential of Ridolfia segetum (L.) Moris essential oil (EO) against three different pests: Culex quinquefasciatus Say, Musca domestica L., and Spodoptera littoralis (Boisduval). For this purpose, the EO was obtained by hydrodistillation of flowers and its composition was achieved by…
Insecticidal spectrum and mode of action of the Bacillus thuringiensis Vip3Ca insecticidal protein.
2016
The Vip3Ca protein, discovered in a screening of Spanish collections of Bacillus thuringiensis, was known to be toxic to Chrysodeixis chalcites, Mamestra brassicae and Trichoplusia ni. In the present study, its activity has been tested with additional insect species and we found that Cydia pomonella is moderately susceptible to this protein. Vip3Ca (of approximately 90 kDa) was processed to an approximately 70 kDa protein when incubated with midgut juice in all tested species. The kinetics of proteolysis correlated with the susceptibility of the insect species to Vip3Ca. The activation was faster to slower in the following order: M. brassicae (susceptible), Spodoptera littoralis (moderately…
Midgut microbiota and host immunocompetence underlie Bacillus thuringiensis killing mechanism
2016
Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered. The resulting cellular immunosuppression was characterized by a reduced …
A taxonomic revision helps to clarify differences between the Atlantic invasive
2017
Abstract Ptilohyale explorator (formerly Parhyale explorator), described by Arresti (1989), can be considered to be a synonym of west-Atlantic Ptilohyale littoralis (Stimpson, 1853), based on morphological observations of paratypes and specimens recently collected in the type locality of Ptilohyale explorator. The first collections of Ptilohyale littoralis, from the eastern Atlantic were from the port of Rotterdam (The Netherlands) in 2009 and later in Wimereux, Opal Coast (France) in 2014; however, the synonymy of Ptilohyale explorator with Ptilohyale littoralis backdates to the first European record of Ptilohyale littoralis in 1985 at La Vigne, Bay of Arcachon (France). This indicates tha…
Males Benefit from Mating with Outbred Females in Drosophila littoralis: Male Choice for Female Genetic Quality?
2015
The evolution and expression of mate choice behaviour in either sex depends on the sex-specific combination of mating costs, benefits of choice and constraints on choice. If the benefits of choice are larger for one sex, we would expect that sex to be choosier, assuming that the mating costs and constraints on choice are equal between sexes. Because deliberate inbreeding is a powerful genetic method for experimental manipulation of the quality of study organisms, we tested the effects of both male and female inbreeding on egg and offspring production in Drosophila littoralis. Female inbreeding significantly reduced offspring production (mostly due to lower egg-to-adult viability), whereas m…
Inbreeding rate modifies the dynamics of genetic load in small populations
2012
The negative fitness consequences of close inbreeding are widely recognized, but predicting the long-term effects of inbreeding and genetic drift due to limited population size is not straightforward. As the frequency and homozygosity of recessive deleterious alleles increase, selection can remove (purge) them from a population, reducing the genetic load. At the same time, small population size relaxes selection against mildly harmful mutations, which may lead to accumulation of genetic load. The efficiency of purging and the accumulation of mutations both depend on the rate of inbreeding (i.e., population size) and on the nature of mutations. We studied how increasing levels of inbreeding …
Domain shuffling between Vip3Aa and Vip3Ca: chimera stability and insecticidal activity against European, American, African, and Asian pests
2020
The bacterium Bacillus thuringiensis produces insecticidal Vip3 proteins during the vegetative growth phase with activity against several lepidopteran pests. To date, three different Vip3 protein families have been identified based on sequence identity: Vip3A, Vip3B, and Vip3C. In this study, we report the construction of chimeras by exchanging domains between Vip3Aa and Vip3Ca, two proteins with marked specificity differences against lepidopteran pests. We found that some domain combinations made proteins insoluble or prone to degradation by trypsin as most abundant insect gut protease. The soluble and trypsin-stable chimeras, along with the parental proteins Vip3Aa and Vip3Ca, were tested…