Search results for "swarming"

Sex pheromone identified after solid phase microextraction from tergal glands of female alates in Cornitermes bequaerti (Isoptera, Nasutitermitinae)

2002

For the first time, a termite sex pheromone secreted by tergal glands has been isolated and identified. In the mandibulate nasute termite Cornitermes bequaerti, pairing of swarming imagoes is mediated by a sex pheromone secreted by females from their tergal glands. These well developed sexual glands located in front of tergites 8, 9, 10 are essentially composed of class 1 and 2 cells, but also of some glandular units of class 3 cells. The major volatile compound of tergal secretion was isolated by solid phase microextraction (SPME) and identified by GC-MS as (3Z, 6Z, 8E)-dodecatrien-1-ol. Sex attraction bioassays with synthetic (3Z, 6Z, 8E)-dodecatrien-1-ol showed that this alcohol was the …

Laurel extracts inhibit quorum sensing, virulence factors and biofilm of foodborne pathogens

2020

Antimicrobial, antibiofilm, anti-Quorum sensing (QS) and virulence factors inhibitory capacity of different polarity Laurus nobilis extracts against several pathogenic microorganisms were studied. Some extracts exhibited antibiotic effect against Staphylococcus aureus multidrug-resistant strains. However, all extracts (100 µg/mL) inhibited to some extent the biofilm of most bacteria tested (until 40% for Gram-negative and 76% for Gram-positive). Hexane (HE) and chloroform extract (CE) were potent inhibitors of S. aureus biofilm and the microscopies further confirmed an important reduction in adherent cells. Polystyrene surfaces coated with these extracts showed a decrease in bacterial adhes…

Application of A Precision Apiculture System to Monitor Honey Daily Production †

2020

Precision beekeeping or precision apiculture is an apiary management strategy based on the monitoring of individual bee colonies to minimize resource consumption and maximize the productivity of bees. Bees play a fundamental role in ensuring pollination

Lemon Oils Attenuate the Pathogenicity of Pseudomonas aeruginosa by Quorum Sensing Inhibition

2021

The chemical composition of three Citrus limon oils: lemon essential oil (LEO), lemon terpenes (LT) and lemon essence (LE), and their influence in the virulence factors production and motility (swarming and swimming) of two Pseudomonas aeruginosa strains (ATCC 27853 and a multidrug-resistant HT5) were investigated. The main compound, limonene, was also tested in biological assays. Eighty-four compounds, accounting for a relative peak area of 99.23%, 98.58% and 99.64%, were identified by GC/MS. Limonene (59–60%), γ-terpinene (10–11%) and β-pinene (7–15%) were the main compounds. All lemon oils inhibited specific biofilm production and bacterial metabolic activities into biofilm in a dose-dep…

A numerical study of attraction/repulsion collective behavior models: 3D particle analyses and 1D kinetic simulations

2013

39p; International audience; We study at particle and kinetic level a collective behavior model based on three phenomena: self-propulsion, friction (Rayleigh effect) and an attractive/repulsive (Morse) potential rescaled so that the total mass of the system remains constant independently of the number of particles N . In the first part of the paper, we introduce the particle model: the agents are numbered and described by their position and velocity. We iden- tify five parameters that govern the possible asymptotic states for this system (clumps, spheres, dispersion, mills, rigid-body rotation, flocks) and perform a numerical analysis on the 3D setting. Then, in the second part of the paper…

The role of swarming sites for maintaining gene flow in the brown long-eared bat (Plecotus auritus)

2004

Bat-swarming sites where thousands of individuals meet in late summer were recently proposed as 'hot spots' for gene flow among populations. If, due to female philopatry, nursery colonies are genetically differentiated, and if males and females of different colonies meet at swarming sites, then we would expect lower differentiation of maternally inherited genetic markers among swarming sites and higher genetic diversity within. To test these predictions, we compared genetic variance from three swarming sites to 14 nursery colonies. We analysed biparentally (five nuclear and one sex-linked microsatellite loci) and maternally (mitochondrial D-loop, 550 bp) inherited molecular markers. Three m…

Ultrastructure and formation of the physogastric termite queen cuticle

1982

0040-8166 (Print) Journal Article; The physogastric termite queen is the most striking example in insects of growth in size without cuticular moulting. This phenomenon has been studied with electron microscopy and histochemical tests in two species of higher termites, Cubitermes fungifaber and Macrotermes bellicosus. The abdominal hypertrophy (physogastry) is allowed by growth of the arthrodial membranes of the swarming imago. The growth is slow (over several years) but important: the cuticular dry weight is multiplied by 20 in C. fungifaber, by 100-150 in M. bellicosus. The termite queen cuticle arises from the transformation of the cuticle of the swarming imago or imaginal cuticle (unfold…

Synchronized rotation in swarms of magnetotactic bacteria.

2017

Self-organizing behavior has been widely reported in both natural and artificial systems, typically distinguishing between temporal organization (synchronization) and spatial organization (swarming). Swarming has been experimentally observed in systems of magnetotactic bacteria under the action of external magnetic fields. Here we present a model of ensembles of magnetotactic bacteria in which hydrodynamic interactions lead to temporal synchronization in addition to the swarming. After a period of stabilization during which the bacteria form a quasiregular hexagonal lattice structure, the entire swarm begins to rotate in a direction opposite to the direction of the rotation of the magnetic …

2020

Abstract RNA modifications are a well-recognized way of gene expression regulation at the post-transcriptional level. Despite the importance of this level of regulation, current knowledge on modulation of tRNA modification status in response to stress conditions is far from being complete. While it is widely accepted that tRNA modifications are rather dynamic, such variations are mostly assessed in terms of total tRNA, with only a few instances where changes could be traced to single isoacceptor species. Using Escherichia coli as a model system, we explored stress-induced modulation of 2′-O-methylations in tRNAs by RiboMethSeq. This analysis and orthogonal analytical measurements by LC-MS s…

Mini-drones swarms and their potential in conflict situations

2021

Drones are currently used for a wide range of operations, such as border surveillance, general surveillance, reconnaissance, transport, aerial photography, traffic control, earth observation, communications, broadcasting, and armed attacks. This paper examines the swarming and associated abilities to overwhelm a combatant as well as bring extra functionality by means of extra sensors spread throughout the swarm. The strategy of stealth is becoming increasingly less effective. Combatants can not only sense them, but can also successfully destroy them (although this cannot be said for nano-drones). For mini-drones, objectives can be enhanced by the strategy of overwhelming. peerReviewed