Dispersion in time and space affect mating success and Allee effects in invading gypsy moth populations

1. Understanding why invading populations sometimes fail to establish is of considerable relevance to the development of strategies for managing biological invasions. 2. Newly arriving populations tend to be sparse and are often influenced by Allee effects. Mating failure is a typical cause of Allee effects in low-density insect populations, and dispersion of individuals in space and time can exacerbate mate-location failure in invading populations. 3. Here we evaluate the relative importance of dispersal and sexual asynchrony as contributors to Allee effects in invading populations by adopting as a case study the gypsy moth (Lymantria dispar L.), an important insect defoliator for which considerable demographic information is available. 4. We used release-recapture experiments to parameterize a model that describes probabilities that males locate females along various spatial and temporal offsets between male and female adult emergence. 5. Based on these experimental results, we developed a generalized model of mating success that demonstrates the existence of an Allee threshold, below which introduced gypsy moth populations are likely to go extinct without any management intervention.     

Electron-Microscopic Studies of the Colonies of an Alkylsulfonate-utilizing Bacterial Consortium

The light- and electron-microscopic analysis of the colonies of a bacterial consortium capable of utilizing alkylsulfonates, which are the main ingredients of waste from the synthetic rubber industry, revealed the presence of eight types of cells. All types of cells were gram-negative and differed in shape, size, and the presence of capsule and cytoplasmic inclusions. Three types of cells were present in all the colonies studied. The presence of the other types of cells depended on the inoculum used and on the composition of the growth medium.     

Male fitness of honeybee colonies (Apis mellifera L.)

Honeybees (Apis mellifera L.) have an extreme polyandrous mating system. Worker offspring of 19 naturally mated queens was genotyped with DNA microsatellites, to estimate male reproductive success of 16 drone producing colonies. This allowed for estimating the male mating success on both the colony level and the level of individual drones. The experiment was conducted in a closed population on an isolated island to exclude interferences of drones from unknown colonies. Although all colonies had produced similar numbers of drones, differences among the colonies in male mating success exceeded one order of magnitude. These differences were enhanced by the siring success of individual drones within the offspring of mated queens. The siring success of individual drones was correlated with the mating frequency at the colony level. Thus more successful colonies not only produced drones with a higher chance of mating, but also with a significantly higher proportion of offspring sired than drones from less successful colonies. Although the life cycle of honeybee colonies is very female centred, the male reproductive success appears to be a major driver of natural selection in honeybees.     

The Architectonics of Colonies of Bacillus subtilis 2335

Colonies grown from vegetative Bacillus subtilis 2335 cells had a standard structure, with bacillar cells occupying the whole colony volume. At the same time, the colonies of this bacterium grown from germinated spores had an abnormal structure characterized by the location of cells in a surface layer 100–200 m thick at the colony boundary with the air. The glycocalyx of the colonies grown from spores was characterized by a wetting angle _e of 120°–160°, whereas that of the colonies grown from vegetative cells had an angle _eas low as 5°–30°. It is suggested that spores and vegetative cells follow different strategies of substrate colonization and that the architectonics of bacterial colonies is determined by the physicochemical properties of the glycocalyx.     

Inference about the Number of Resident Bacterial Strains when Sampling from Plate Colonies

This paper deals with making inferences about the number of resident bacterial strains in mice gut based on the number of strains of bacteria found in a random sample of colonies derived from plated faecal material. It is shown that for what seems to be a natural way to test the hypothesis that there is only one resident bacterial strain against the alternative that there is more than one resident strain the probability of a Type II error may be unacceptably large. It is also shown that given the sample contains only one bacterial strain the probability that the animal has only one resident strain converges to unity at a geometric rate as the sample size increases.     

Colonial organization and intercellular communication in microorganisms

This review covers the modern concepts and recent data demonstrating the integrity and coherence of microbial populations (colonies, biofilms, etc.) as peculiar “superorganisms.” Special attention is given to such relevant phenomena as apoptosis, bacterial altruism, quorum effects, collective differentiation of microbial cells, and the formation of population-level structures such as an extracellular matrix. Emphasis is placed on the channels and agents of intercellular communication in microbial populations. The involvement of a large number of evolutionarily conserved communicational facilities and patterns of intercellular interactions is underscored. Much attention is also given to the role of colonial organization and intercellular communication in parasite/commensal/symbiont-multicellular host organism systems.     

Nest recognition in neighboring colonies: a comparison of two European species of Polistes wasps (P. dominulus and P. nimphus, Hymenoptera: Vespidae)

The ability of two species of Polistes wasps to distinguish their own from nearby nests was tested, following the procedure used by Espelie et al. Our experiments demonstrated that, in the laboratory, females of Polistes dominulus and Polistes nimphus preferentially selected their own nests rather than nearby nests. We also evaluated the role of odor cues in nest recognition by washing nests in hexane to remove the apolar solvent-soluble components of nest odor. Although P. nimphus females continued to discriminate nests even after washing, P. dominulus individuals failed to discriminate between their own and a foreign neighboring nest. In both species, wasps were able to recognize their own nests when nest extracts were subsequently reapplied to the nest surface. These results indicate that P. dominulus wasps recognize their nests through perception of nest odor. The ability of P. nimphus wasps to distinguish their own nests even after presumed removal of the nest odor is discussed. Received: January 27, 2000 / Accepted: May 22, 2000     

The genesis of secondary reproductive structures in streptomycete colonies as revealed by confocal microscopy

Streptomycete colonies were examined by confocal microscopy to elucidate the origin of the secondary structures that form the concentric rings of aerial mycelium. These reproductive structures but no the vegetative ones were found to luminesce upon safranine staining. It is shown that the secondary reproductive structures emerge within the substrate mycelium by lateral branching or apical extension of vegetative hyphae, further developing into numerous secondary branches filled with protospores.     

A Bryophyte flora of Kent. I

Abstract

Gender expression and sporophyte frequency of Frullania tamarisci were compared between epiphytic woodland and exposed coastal colonies in an Atlantic region of western Britain. Corticolous colonies exhibited very high sporophyte frequency in mixed-sex colonies. Samples from well-grown epiphytic patches commonly had intimate mixtures of highly fertile female and male shoot networks, and fertilisation reduced gynoecia number. In marked contrast, colonies in exposed coastal habitats were found to be sub-fertile or non sex-expressing and sporophytes were rare. There was a distinct female bias among colonies on the coast where spatial segregation of the sexes and male scarcity appear to limit sporophyte frequency. It is suggested that the close association of males and sporophytic females in epiphytic colonies may be influenced by within-colony sporophyte frequency.