Natural enemies from South Africa for biological control of Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae) in Europe

The non-native invasive plant, Lagarosiphon major (Hydrocharitaceae) is a submersed aquatic macrophyte that poses a significant threat to water bodies in Europe. Dense infestations prove difficult to manage using traditional methods. In order to initiate a biocontrol programme, a survey for natural enemies of Lagarosiphon was conducted in South Africa. Several phytophagous species were recorded for the first time, with at least three showing notable promise as candidate agents. Amongst these, a leaf-mining fly, Hydrellia sp. (Ephydridae) that occurred over a wide distribution causes significant leaf damage despite high levels of parasitism by braconid wasps. Another yet unidentified fly was recorded mining the stem of L. major. Two leaf-feeding and shoot boring weevils, cf. Bagous sp. (Curculionidae) were recorded damaging the shoot tips and stunting the growth of the stem. Several leaf-feeding lepidopteran species (Nymphulinae) were frequently recorded, but are expected to feed on a wide range of plant species and are not considered for importation before other candidates are assessed. The discovery of several natural enemies in the country of origin improves the biological control prospects of L. major in Europe

Larvae of Nymphulinae (Lepidoptera: Pyralidae) associated with Hydrilla verticillata (Hydrocharitaceae) in North Queensland

Australian Nymphulinae are a diverse group of moths with aquatic caterpillars that probably play an important role in determining the composition and abundance of aquatic macrophytes in Australian freshwater systems. Less than 10% of the nymphuline larvae in Australia have been described. As part of a project to develop biological control agents for hydrilla, Hydrilla verticillata, we encountered a variety of Nymphulinae larvae feeding on this and other aquatic plants. We illustrate, describe and provide a key to five species of Nymphulinae larvae (Ambia ptolycusalis (Walker), Parapoynx diminutalis Snellen, Hygraula nitens Butler, Margarosticha repititalis (Warren) and Theila siennata (Warren)) that feed on hydrilla in North Queensland. Information on their host plants also is included. Our field research indicates that none of these species should be considered as potential biological control agents for hydrilla

A transposon-based tool for transformation and mutagenesis in trypanosomatid protozoa

The ability of transposable elements to mobilize across genomes and affect the expression of genes makes them exceptional tools for genetic manipulation methodologies. Several transposon-based systems have been modified and incorporated into shuttle mutagenesis approaches in a variety of organisms. We have found that the Mos1 element, a DNA transposon from Drosophila mauritiana, is suitable and readily adaptable to a variety of strategies to the study of trypanosomatid parasitic protozoa. Trypanosomatids are the causative agents of a wide range of neglected diseases in underdeveloped regions of the globe. In this chapter we describe the basic elements and the available protocols for the in vitro use of Mos1 derivatives in the protozoan parasite Leishmania

Refining the process of agent selection through understanding plant demography and plant response to herbivory

Understanding plant demography and plant response to herbivory is critical to the selection of effective weed biological control agents. We adopt the metaphor of 'filters' to suggest how agent prioritisation may be improved to narrow our choices down to those likely to be most effective in achieving the desired weed management outcome. Models can serve to capture our level of knowledge (or ignorance) about our study system and we illustrate how one type of modelling approach (matrix models) may be useful in identifying the weak link in a plant life cycle by using a hypothetical and an actual weed example (Parkinsonia aculeata). Once the vulnerable stage has been identified we propose that studying plant response to herbivory (simulated and/or actual) can help identify the guilds of herbivores to which a plant is most likely to succumb. Taking only potentially effective agents through the filter of host specificity may improve the chances of releasing safe and effective agents. The methods we outline may not always lead us definitively to the successful agent(s), but such an empirical, data-driven approach will make the basis for agent selection explicit and serve as testable hypotheses once agents are released

Morphological changes in Salmonella Typhimurium caused by the lantibiotic bovicin HC5 in association with EDTA

Bacteriocins, particularly those produced by Gram-positive bacteria, have in recent years been considered promising antimicrobial agents to inhibit bacterial growth in food, and thus are potential food preservatives. These peptides generally exhibit a spectrum of action limited to Gram-positive bacteria. However, their action can be extended to Gram-negative bacteria through association with chelating agents. In the present study, we evaluated the occurrence of morphological changes on the cell envelope of Salmonella Typhimurium cells treated with bovicin HC5—a lantibiotic from Streptococcus bovis HC5—in association with EDTA. The morphological changes of the cells were visualized by atomic force microscopy (AFM), and the increase in cell membrane permeability was confirmed by the leakage of potassium ions (K+). The images displayed changes in the cell envelope, with increased surface roughness and a decreased cell volume. These changes indicate that EDTA plays a role in the destabilization of the outer membrane, allowing bovicin HC5 to act on the cytoplasmic membrane through the formation of pores, which was confirmed by the detection of potassium in the cell supernatant. These results suggest that bovicin HC5 combined with EDTA has potential for use on Salmonella cells

Functional Studies of the Yeast Med5, Med15 and Med16 Mediator Tail Subunits

The yeast Mediator complex can be divided into three modules, designated Head, Middle and Tail. Tail comprises the Med2, Med3, Med5, Med15 and Med16 protein subunits, which are all encoded by genes that are individually non-essential for viability. In cells lacking Med16, Tail is displaced from Head and Middle. However, inactivation of MED5/MED15 and MED15/MED16 are synthetically lethal, indicating that Tail performs essential functions as a separate complex even when it is not bound to Middle and Head. We have used the N-Degron method to create temperature-sensitive (ts) mutants in the Mediator tail subunits Med5, Med15 and Med16 to study the immediate effects on global gene expression when each subunit is individually inactivated, and when Med5/15 or Med15/16 are inactivated together. We identify 25 genes in each double mutant that show a significant change in expression when compared to the corresponding single mutants and to the wild type strain. Importantly, 13 of the 25 identified genes are common for both double mutants. We also find that all strains in which MED15 is inactivated show down-regulation of genes that have been identified as targets for the Ace2 transcriptional activator protein, which is important for progression through the G1 phase of the cell cycle. Supporting this observation, we demonstrate that loss of Med15 leads to a G1 arrest phenotype. Collectively, these findings provide insight into the function of the Mediator Tail module