Biofilm dispersal for spore release in Bacillus subtilis

The dispersal of bacterial cells from a matured biofilm can be mediated either by active or passive mechanisms. In this issue of the Journal of Bacteriology, Nishikawa and Kobayashi demonstrate that the presence of calcium influences dispersal of spores from the pellicle biofilm of Bacillus subtilis. The authors propose that temporal heterogeneity in matrix production and chelation of calcium by dipicolinic acid in spores weakens the biofilm matrix and causes passive dispersal.

Arion vulgaris (Spanish slug).

The invasiveness of A. vulgaris is related to several factors. Its ability and readiness to colonize humanly-disturbed environments is of major importance. Proschwitz (1997) observed that 99% of Swedish records were from synanthropic habitats and only 1% from natural woodlands. With a proximity to humans, comes the possibility of passive dispersal through trade, particularly in living plants. The garden centre trade and horticulture are particularly implicated (Weidema, 2006). In Poland, there is evidence from studies of molecular diversity that A. vulgaris has originated from repeated, separate introductions from other parts of Europe (Soroka et al., 2007). The ability of A. vulgaris to utilize a great variety of food sources and types has been well-documented and must aid dispersal and colonization. Other than its country of origin (France), it is considered to be invasive across western and central Europe, from the Pyrenees to eastern Poland and from southern France to north Italy, Austria and Slovakia and within an isolated range in eastern Bulgaria.

Survival and Recovery of the Pine-Tree Lappet Dendrolimus pini When Subjected to Simulated Starvation

There are many reasons to study the survival and recovery of animals after starvation in simulated transport conditions or other passive dispersal methods. To do so, we chose Dendrolimus pini, an economically important pest of Scots pine with great potential in terms of passive dispersal outside its territory. In this work, we sought to answer the following questions: What is the maximum survival of different instar larvae after total starvation? Does access to dry tissues of the preferred host plant extend the lifespan of the larvae? Does the possibility of larvae recovery exist after starvation for various periods? We found that older larvae survived longer without food than younger larvae. Moreover, dry food did not extend the lifespan of the larvae. Our observations showed that insects were interested in food and tasted it at the beginning, but they did not feed on it for long. Furthermore, larvae recovery was indeed possible, and the time of starvation did not significantly affect this. We generally concluded that the D. pini larvae were characterized by the ability to survive without food for up to one month, which confirms that this species is able to survive long durations of transport to almost anywhere in the world.

Discrete stochastic marine metapopulation disease model

Some marine microparasitic pathogens can survive several months in the water column to make contact with or to be absorbed or filtered by hosts. Once inside, pathogens invade the host if they find suitable conditions for reproduction. This transmission from the environment occurs via pathogens released from infected and dead infected animals. Some recent modeling studies concentrated on the disease dynamic imposed by this complex interaction between population and water column at the host-pathogen level in single populations. However, only when a marine disease can be understood at the metapopulation scale effective approaches to management will become routinely achievable. The discrete-time disease model in this paper investigates both spatial and temporal dynamics of hosts and waterborne pathogens in a metapopulation system of three patches. This system with a patch providing infective particles and susceptible and infected individuals by dispersal tries to imitate the effect of current forces in the ocean on the passive dispersal of organisms. The model detects behaviours that are not present in single population continuous-time and deterministic models.

Discrete stochastic marine metapopulation disease model

Some marine microparasitic pathogens can survive several months in the water column to make contact with or to be absorbed or filtered by hosts. Once inside, pathogens invade the host if they find suitable conditions for reproduction. This transmission from the environment occurs via pathogens released from infected and dead infected animals. Some recent modeling studies concentrated on the disease dynamic imposed by this complex interaction between population and water column at the host-pathogen level in single populations. However, only when a marine disease can be understood at the metapopulation scale effective approaches to management will become routinely achievable. The discrete-time disease model in this paper investigates both spatial and temporal dynamics of hosts and waterborne pathogens in a metapopulation system of three patches. This system with a patch providing infective particles and susceptible and infected individuals by dispersal tries to imitate the effect of current forces in the ocean on the passive dispersal of organisms. The model detects behaviours that are not present in single population continuous-time and deterministic models.

Zooplankton associated with phytotelms and treefrogs in a neotropical forest

ABSTRACT Assumptions about the distribution of zooplankton communities in various ecosystems are often limited by lack of data on dispersal mechanisms. Many studies on frog-mediated passive dispersal have been developed in bromeliads, but they usually focus on ostracods and annelids. We investigated the potential for external phoresy of zooplankton (rotifers, cladocerans, copepods) by treefrogs in bromeliad phytotelms. Our hypotheses are that (1) zooplankton composition on frogs’ skin and in phytotelm tanks is similar, and (2) frogs with larger body size carry more propagules of these invertebrates. We filtered phytotelm water (10 to 150 mL) using plankton net (45 µm), and fixed invertebrates with 4% formalin. Frogs were actively collected in and around bromeliads (up to ~1.5 m radius) and then washed with distilled water. Fourteen species of rotifers and three of crustaceans were registered in phytotelm water and frog bodies. We captured 17 frogs with a snout-vent length (SVL) ranging from 2 to 5 cm and belonging to five species: Pristimantis ramagii (Boulenger, 1888), Dendropsophus decipiens (A. Lutz, 1925), Scinax auratus (Wied-Neuwied,1821), S. pachycrus (Miranda-Ribeiro, 1937) and S. x-signatus (Spix, 1824). Among them, 12 (70.59%) had propagules adhered to their bodies, of which the majority (ten individuals) had active zooplankton forms, while only two had dormant eggs. Ten rotifer and two microcrustacean species were recorded adhered to frogs. The zooplankton composition differed between phytotelms and anuran skin, and frog body size does not explain the number of propagules carried, refuting both hypotheses. However, evidence of dispersal was found due to the high number of propagules adhered to anurans. Our study provides evidence that frogs may be potential dispersers of dormant and active forms of zooplankton in bromeliads, through external phoresy.

Discrete stochastic marine metapopulation disease model

Some marine microparasitic pathogens can survive several months outside the host in the water column to make contact with hosts or to be absorbed or filtered by hosts. Once inside, pathogens invade the host if they find suitable conditions for reproduction within the host. This transmission from the environment occurs via pathogens released from infected animals and dead infected animals. Some recent modeling studies concentrated on the disease dynamic imposed by this complex interaction between population and water column at the host-pathogen level in single populations. However, only when a marine disease can be understood at the metapopulation scale effective approaches to management will become routinely achievable. In this paper we explore the disease dynamics at the metapopulation applying a stochastic version. The discrete-time disease model in this paper investigates both spatial and temporal dynamics of hosts and waterborne pathogens in a three patch system. This metapopulation with a patch providing infective particles and susceptible and infected individuals by dispersal tries to imitate the effect of current forces in the ocean on the passive dispersal of organisms. The model detects system behaviors that are not present in single population continuous-time and deterministic models.