Investigating the potential of an autodissemination system for managing populations of vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae) with entomopathogenic fungi.

Vine weevil, also known as black vine weevil, (Otiorhynchus sulcatus) is an economically important pest affecting soft fruit and nursery stock in temperate regions. We used laboratory and polytunnel experiments to investigate a novel control system based on autodissemination of spores of an entomopathogenic fungus to populations of adult vine weevils. The fungus was applied as a conidial powder, used on its own or formulated with talc, to a simple plastic refuge for vine weevils. The potential for adult weevils to disseminate the fungus was investigated first in polytunnel experiments using fluorescent powders applied to the refuge in lieu of fungal conidia. In this system, 88% of adult weevils came in contact with the powder within 48 h. When the powder was applied to five adult weevils that were then placed within a population of 35 potential recipients, it was transmitted on average to 75% of the recipient population within 7 days. Three isolates of entomopathogenic fungi (Beauveria bassiana isolate codes 433.99 and 1749.11 and Metarhizium brunneum isolate code 275.86), selected from a laboratory virulence screen. These three isolates were then investigated for efficacy when applied as conidial powders in artificial refuges placed among populations of adult weevils held in experimental boxes in the laboratory at 20 °C. Under this regime, the fungal isolates caused 70-90% mortality of adult weevils over 28 days. A final polytunnel experiment tested the efficacy of conidial powders of M. brunneum 275.86 placed in artificial refuges to increase vine weevil mortality. Overall weevil mortality was relatively low (26-41%) but was significantly higher in cages in which the conidial powders were placed in refuge traps than in cages with control traps. The lower weevil mortality recorded in the polytunnel experiment compared to the laboratory test was most likely a consequence of the greater amounts of inoculum required to kill adult weevils when conditions fluctuate between favourable and unfavourable temperatures e.g. below 15 °C. The potential of an autodissemination system for entomopathogenic fungi as a means of controlling vine weevil as part of an integrated pest management programme is discussed.

The cycloaspeptides: uncovering a new model for methylated nonribosomal peptide biosynthesis.

The cycloaspeptides are bioactive pentapeptides produced by various filamentous fungi, which have garnered interest from the agricultural industry due to the reported insecticidal activity of the minor metabolite, cycloaspeptide E. Genome sequencing, bioinformatics and heterologous expression confirmed that the cycloaspeptide gene cluster contains a minimal 5-module nonribosomal peptide synthetase (NRPS) and a new type of trans-acting N-methyltransferase (N-MeT). Deletion of the N-MeT encoding gene and subsequent feeding studies determined that two modules of the NRPS preferentially accept and incorporate N-methylated amino acids. This discovery allowed the development of a system with unprecedented control over substrate supply and thus output, both increasing yields of specific metabolites and allowing the production of novel fluorinated analogues. Furthermore, the biosynthetic pathway to ditryptophenaline, another fungal nonribosomal peptide, was shown to be similar, in that methylated phenylalanine is accepted by the ditryptophenaline NRPS. Again, this allowed the directed biosynthesis of a fluorinated analogue, through the feeding of a mutant strain. These discoveries represent a new paradigm for the production of N-methylated cyclic peptides via the selective incorporation of N-methylated free amino acids.

Towards new sources of resistance to the currant-lettuce aphid (Nasonovia ribisnigri).

Domesticated lettuce varieties encompass much morphological variation across a range of crop type groups, with large collections of cultivars and landrace accessions maintained in genebanks. Additional variation not captured during domestication, present in ancestral wild relatives, represents a potentially rich source of alleles that can deliver to sustainable crop production. However, these large collections are difficult and costly to screen for many agronomically important traits. In this paper, we describe the generation of a diversity collection of 96 lettuce and wild species accessions that are amenable to routine phenotypic analysis and their genotypic characterization with a panel of 682 newly developed expressed sequence tag (EST)-linked KASP™ single nucleotide polymorphism (SNP) markers that are anchored to the draft Lactuca sativa genome assembly. To exemplify the utility of these resources, we screened the collection for putative sources of resistance to currant-lettuce aphid (Nasonovia ribisnigri) and carried out association analyses to look for potential SNPs linked to resistance.