Robbie G Rae

• Lecturer at Liverpool John Moores University

The large pine weevil (Hylobius abietis L.) is a major pest in European and Asian coniferous forests, particularly in managed plantations where clear-felling practices create ideal conditions for its population growth. Traditional management practices involving synthetic insecticides have limited efficacy in terms of reducing pest populations and p...

Several slug species are highly pestiferous and threaten global sustainable agriculture. Current control methods rely heavily on metaldehyde pellets, which are often ineffective, harm nontarget organisms and have been banned in some countries. A viable alternative is the parasitic nematode Phasmarhabditis hermaphrodita (and recently P. californica)...

Animals’ gut microbiomes affect a wide array of biological processes including immunity and protection from pathogens. However, how the microbiome changes due to infection by parasites is still largely unknown, as is how the microbiome changes in hosts that differ in their susceptibility to parasites. To investigate this, we exposed two slug specie...

Avoidance of pathogens and parasites is the first line of defense to survive. Several slug species avoid the parasitic nematode Phasmarhabditis hermaphrodita to reduce infection however, there is nothing known about whether slugs avoid other members of the Phasmarhabditis genus. I exposed two slug species (Deroceras invadens and Limax maculatus) to...

p>High-throughput sequencing (HTS) is a powerful tool that enables the simultaneous detection and potential identification of any organisms present in a sample. The growing interest in the application of HTS technologies for routine diagnostics in plant health laboratories is triggering the development of guidelines on how to prepare laboratories f...

A parasitological survey of terrestrial slugs and snails was conducted at popular dog walking locations across the city of Nottingham, with the intensions of finding gastropods infected with parasites of medical (or veterinary) importance such as lungworm (metastrongyloid nematodes) and trematodes. A total of 800 gastropods were collected from 16 s...

High-throughput sequencing (HTS) technologies have the potential to become one of the most significant advances in molecular diagnostics. Their use by researchers to detect and characterize plant pathogens and pests has been growing steadily for more than a decade and they are now envisioned as a routine diagnostic test to be deployed by plant pest...

High-throughput sequencing (HTS) technologies have the potential to become one of the most signi cant advances in molecular diagnostics. Their use by researchers to detect and characterize plant pathogens and pests has been growing steadily for more than a decade and they are now envisioned as a routine diagnostic test to be deployed by plant pest...

Nematodes and bacteria are prevalent in soil ecosystems, and some have evolved symbiotic relationships. In some cases, symbionts carry out highly specialized functions: a prime example being entomopathogenic nematodes (EPNs), which vector bacteria (Xenorhabdus or Photorhabdus) into insect hosts, killing them to provide a food source for the nematod...

There is very little published information about how to culture slugs. There are at least 36 species of slug in the UK (Anderson, 2008) and as many as 44 (Rowson et al., 2014), many of which are nonnative (Cameron, 2016). They are important in terms of causing economic damage to crops (South, 1992), as well as hosts for medically important parasite...

High-throughput sequencing (HTS) technologies have the potential to become one of the most significant advances in molecular diagnostics. Their use by researchers to detect and characterize plant pathogens and pests has been growing steadily for more than a decade and they are now envisioned as a routine diagnostic test to be deployed by plant pest...

Phasmarhabditis hermaphrodita is a parasitic nematode of terrestrial gastropods that has been formulated into a successful biological control agent used on farms and gardens across Europe. There are reports of members of the Phasmarhabditis genus affecting the survival of non-target organisms under lab conditions e.g. earthworms. Therefore, we expo...

Slugs and snails are agricultural pests usually controlled by chemical bait pellets however an alternative method is the commercially produced malacopathogenic nematode Phasmarhabditis hermaphrodita, which is sold across northern Europe. P. hermaphrodita can kill several slug species but is unable to affect larger pestiferous snails. Therefore, we...

The gastropod parasitic nematode Phasmarhabditis hermaphrodita has been formulated into a successful biological control agent (Nemaslug ® , strain DMG0001) used to kill slugs on farms and gardens. When applied to soil, P. hermaphrodita uses slug mucus and faeces to find potential hosts. However, there is little information on what cues other specie...

Many parasites and hosts are embroiled in an on-going arms race that affects the evolution of each participant. One such battle is between parasitic nematodes and terrestrial gastropods which have co-evolved for 90–130 MY. Recently, snails have been shown to encase and kill invading nematodes using their shell as a defence mechanism. However, there...

Essential oils are being increasingly utilised as a biorational element in integrated pest management regimes. Whereas there has been much research on the effects of these oils on mortality and behaviour of pestiferous molluscs, insects and nematodes, there has (to the present authors’ knowledge) been no research into their effects on the mortality...

Biological control (biocontrol) as a component of pest management strategies reduces reliance on synthetic chemicals, and seemingly offers a natural approach that minimizes environmental impact. However, introducing a new organism to new environments as a classical biocontrol agent can have broad and unanticipated biodiversity effects and conservat...

Many terrestrial gastropods are pestiferous and pose a significant threat to agriculture, horticulture and floriculture. They are usually controlled by metaldehyde based pellets but an alternative control method is the slug parasitic nematode Phasmarhabditis hermaphrodita, which has been formulated into a biological control agent (Nemaslug®) for us...

Many nematode species are parasitic and threaten the health of plants and animals, including humans, on a global scale. Advances in DNA sequencing techniques have allowed for the rapid and accurate identification of many organisms including nematodes. However, the steps taken from sample collection in the field to molecular analysis and identificat...

Many vector mosquito species have evolved resistance to chemical insecticides and the search for novel biological control strategies warrants further attention. Entomopathogenic nematodes (EPNs) (Heterorhabditis and Steinernema spp.) have been developed as biological control agents for use against agricultural pests but whether they could be used t...

The nematode Phasmarhabditis hermaphrodita can infect and kill many species of slugs and has been formulated into a biological control agent for farmers and gardeners. P. hermaphrodita can manipulate the behaviour of slugs, making those infected move to areas where the nematode is present. Research suggests P. hermaphrodita uses manipulation of bio...

Nematodes are prolific and diverse parasites of gastropods that have evolved to use slugs and snails as definitive and intermediate hosts. Recently, several snail species have been shown to encapsulate and kill nematodes by encasing them in their shell under laboratory conditions. However, it is unknown how common this process is in wild population...

Phasmarhabditis hermaphrodita is a lethal parasite of several slug species and has been formulated into a biological control agent for farmers and gardeners. Phasmarhabditis hermaphrodita responds to slug faeces, mucus and volatile cues to find hosts in soil. However, these results have only focused on one strain of P. hermaphrodita (DMG0001). We e...

Phasmarhabditis hermaphrodita is a parasitic nematode of terrestrial gastropods that has been formulated into a biological control agent for farmers and gardeners to kill slugs and snails. In order to locate slugs it is attracted to mucus, faeces and volatile cues; however, there is no information about whether these nematodes are attracted to snai...

The terrestrial gastropod parasitic nematode Phasmarhabditis hermaphrodita is the only nematode that evolved to infect and kill slugs and snails. Because of this ability it has been formulated into a biological control agent for gardeners. In this Forum article, the author outlines several reasons why P. hemaphrodita is a nematode that is worth stu...

Entomopathogenic nematodes (EPN) of the families Steinernematidae and Heterorhabditidae are lethal insect parasites that have been commercialised as biological control agents. EPN have been isolated from across the world but it has been more than 20 years since the last survey of the UK, and species like Steinernema carpocapsae have never been foun...

The genetic mechanisms of how free-living nematodes evolved into parasites are unknown. Current genetic model nematodes (e.g. Caenorhabditis elegans ) are not well suited to provide the answer, and mammalian parasites are expensive and logistically difficult to maintain. Here we propose the terrestrial gastropod parasite Phasmarhabditis hermaphrodi...

The ability of parasites to manipulate the behaviour of their hosts has evolved multiple times, and has a clear fitness benefit to the parasite in terms of facilitating growth, reproduction and transfer to suitable hosts. The mechanisms by which these behavioural changes are induced are poorly understood, but in many cases parasite manipulation of...

There are 108 species of nematode that are known to have co-evolved with gastropods and use them as definitive, intermediate or paratenic hosts. One nematode (Phasmarhabditis hermaphrodita) is lethal to eight species of snail, but nine species are resistant for unknown reasons. This study investigated whether a previously untested snail species, Ar...

Chironomidae, or non-biting midges, are found worldwide in a wide variety of aquatic habitats. During periods of mass adult eclosion they can become a nuisance and health hazard. Current control methods target the aquatic larval stage and include the use of insect growth regulators or insecticides, which may be prohibited in certain environments or...

Exoskeletons have evolved 18 times independently over 550 MYA and are essential for the success of the Gastropoda. The gastropod shell shows a vast array of different sizes, shapes and structures, and is made of conchiolin and calcium carbonate, which provides protection from predators and extreme environmental conditions. Here, I report that the g...

Cockroaches are major pests, vectors of pathogenic bacteria and induce allergies. Current control methods use chemical pesticides, but they can be ineffective and costly and there are reports of resistance in the field; hence new control methods are needed. There are conflicting reports about the susceptibility of cockroaches to entomopathogenic ne...

The evolutionary genetic mechanisms that are responsible for the transition of free-living nematodes to parasites are unknown and current nematode models used to study this have limitations. The gastropod parasite Phasmarhabditis hermaphrodita could be used as a new model to dissect the molecular mechanisms involved in the evolution of parasitism....

The impact of selected entomopathogenic nematodes and Phasmarhabditis hermaphrodita on the EuropeanUnion-protected slug Geomalacus maculosus and the sympatric Lehmannia marginata was investigated. There was no significant difference in mortality between slugs treated with nematodes and their controls. The presence of P. hermaphrodita in two G. macu...

RNA interference is a rapid, inexpensive, and highly effective tool used to inhibit gene function. In C. elegans, whole genome screens have been used to identify genes involved with numerous traits including aging and innate immunity. RNAi in C. elegans can be carried out via feeding, soaking, or injection. Here we outline protocols used to maintai...

The nematode Phasmarhabditis hermaphrodita has been developed as a biological control agent for slugs and snails. Slugs avoid areas where P. hermaphrodita is present. We investigated whether behavioural avoidance of P. hermaphrodita is a common feature of slugs and snails by exposing eight species to P. hermaphrodita. We showed that slugs generally...

Phasmarhabditis hermaphrodita is a lethal parasite of several slug and snail species that has been formulated into a biological control agent. However, the complete host range of this nematode is poorly understood, in particular its potential to affect non-target aquatic snail species. Here we exposed three species of juvenile and adult freshwater...

The Giant African snail (Achatina fulica) is a major pest in tropical countries. Current control methods involve the use of slug pellets (metaldehyde) but they are ineffective, therefore new methods of control are needed. We investigated whether A. fulica is susceptible to the gastropod parasitic nematode Phasmarhabditis hermaphrodita, which has be...

Nematodes and bacteria are the most numerous organisms on Earth with numbers of nematodes thought to exceed 1 million per square metre (Floyd et al., 2002) and bacterial cells in 1 g of soil estimated to be 100 billion (Faegri et al., 1977). These two groups of organisms have evolved numerous relationships ranging from strict symbiosis, whereby nem...

While there has been intense study on entomopathogenic nematodes (EPNs) by numerous research groups throughout the world, there has been much less work on nematodes that can control slugs. A survey of academic research papers listed in the Scopus database in December 2014 using the search terms “Steinernema or Heterorhabditis” revealed over 2,100 h...

The reproductive system regulates lifespan in insects, nematodes and vertebrates. In Caenorhabditis elegans removal of germline increases lifespan by 60% which is dependent upon insulin signaling, nuclear hormone signaling, autophagy and fat metabolism and their microRNA-regulators. Germline-deficient C. elegans are also more resistant to various b...

The evolution of genetic mechanisms used to combat bacterial infections is critical for the survival of animals and plants, yet how these genes evolved to produce a robust defense system is poorly understood. Studies of the nematode Caenorhabditis elegans have uncovered a plethora of genetic regulators and effectors responsible for surviving pathog...

Relative proportions of pioneer genes versus non-pioneer genes in the active transcriptome of P. pacificus on each of the four pathogens. The P. pacificus genome contains about 30% pioneer genes. Compared to the random expectation of the same proportion of pioneer genes in different expression profiles, they are found to significantly under-represe...

Pioneer genes are expressed at higher levels than non-pioneer genes in each of the pathogen-induced expression profiles on P. pacificus. Cumulative distributions of fold-changes of pioneer genes (red curves) and non-pioneer genes (blue curves) for genes differentially expressed on (A) B. thuringiensis DB27 (B) S. aureus (C) S. marcescens and (D) X....

Overlap between pioneer genes regulated in P. pacificus in response to the four pathogens. Of the 832 pioneer genes differentially expressed on any of the pathogens in P. pacificus, 160 genes are common between two or more than two expression profiles. (PDF)

Pfam domains enriched in C. elegans expression profiles in response to different pathogens. (XLSX)

Expression clusters enriched in genes up- and down-regulated in P. pacificus upon exposure to each of the four pathogens. (XLSX)

Genes common across expression profiles of C. elegans and P. pacificus upon exposure to the gram-negative bacteria (A) S. marcescens (B) X. nematophila , and (C) common to both S. marcescens and X. nematophila expression profiles. (XLSX)

Summary statistics of P. pacificus ablation experiments monitoring survival when fed S. marcescens and X. nematophila. Mean survival and standard errors for all conditions tested, and p-values from log Rank test assessing significance of difference between various comparisons. The rows 8 and 9 (marked with an “*”) correspond to the pathogen X. nema...

Enrichment for GO terms from categories (a) Biological Process (b) Molecular Function (c) Cellular Component, in genes differentially regulated upon germline ablation. The total number of genes in P. pacificus genome with a given GO term are in the “Annotated” column, the number of genes observed to be significantly differentially expressed are in...

Effect of Z2 and Z3 germline ablation on survival of P. pacificus insulin signaling mutants exposed to S. marcescens. Survival of Ppa-daf-16 (tu901) Z2 and Z3 ablated (blue) and un-ablated (red), and Ppa-daf-16 (tu302) Z2 and Z3 ablated (yellow) and un-ablated (green) exposed to S. marcescens. Error bars represent ± S.E.M. (TIFF)

Comparison of fold-changes in expression profiles E4 (ablated versus unablated animals exposed to S. marcescens) and E1 (ablated versus unablated animals exposed to E. coli). The two profiles are quite similar, with almost similar fold-changes for the majority of the genes. (Pearson correlation = 0.90, Spearman's rank correlation = 0.89). (TIFF)

Genes significantly differentially expressed in the comparison of germline-ablated animals fed on E. coli OP50 versus un-ablated animals fed E. coli OP50 (Expression profile E1). Processed microarray data for experiment E1 for each P. pacificus gene with its log2 fold change, FDR corrected p-value and average expression value (log2 scale). (XLS)

Genes significantly differentially expressed in the comparison of germline-ablated animals fed on S. marcescens versus germline-ablated animals fed E. coli OP50 (Expression profile E2). Processed microarray data for experiment E2 for each P. pacificus gene with its log2 fold change, FDR corrected p-value and average expression value (log2 scale). (...

Genes common between pathogen response of germline-ablated animals (experiment E2) and pathogen response of un-ablated animals (experiment E3). About 100 significantly differentially expressed genes are common between the expression profiles E2 and E3. All genes except one show a similar direction of fold change. The corresponding ortholog in C. el...

Genes significantly differentially expressed in the comparison of germline-ablated animals fed on S. marcescens versus un-ablated animals fed S. marcescens (Expression profile E4). Processed microarray data for experiment E4 for each P. pacificus gene with its log2 fold change, FDR corrected p-value and average expression value (log2 scale). (XLS)

List of the 292 genes exclusive to expression profile E4 (ablated versus unablated animals exposed to S. marcescens) in a comparison against profile E1 (ablated versus unablated animals exposed to E. coli). The log2 fold change, FDR corrected p-value and average expression value (log2 scale) of the 292 genes exclusive to profile E4. (XLS)

Microarray expression clusters showing significant overlap with genes up or down regulated in expression profile E4 (ablated versus unablated P. pacificus exposed to S. marcescens). The profile E4 is also enriched for genes that are known targets of DAF-16, and TGF-beta pathway in C. elegans, and genes regulated in response to various pathogens in...

Pfam domains enriched in the genes regulated upon germline ablation. The total number of genes in P. pacificus genome whose products contain a given Pfam domain are in the “Total” column, the number of genes observed to be significantly differentially expressed are in the column “Observed” and the number of genes expected by random chance are given...

Removal of the reproductive system of many animals including fish, flies, nematodes, mice and humans can increase lifespan through mechanisms largely unknown. The abrogation of the germline in Caenorhabditis elegans increases longevity by 60% due to a signal emitted from the somatic gonad. Apart from increased longevity, germline-less C. elegans is...

Bacterial pathogens have shaped the evolution and survival of organisms throughout history, but little is known about the evolution of virulence mechanisms and the counteracting defence strategies of host species. The nematode model organisms, Caenorhabditis elegans and Pristionchus pacificus, feed on a wealth of bacteria in their natural soil envi...

In the natural environment, Caenorhabditis elegans and closely related nematodes are thought to associate with invertebrate hosts for transport (phoresy) or for food (necromeny) ([Kiontke and Sudhaus, 2006][1]). Recently, Abebe et al. ([Abebe et al., 2010][2]) showed that by feeding C. briggsae (and

The main food source of free-living nematodes in the soil environment is bacteria, which can affect nematode development, fecundity and survival. In order to occupy a reliable source of bacterial food, some nematodes have formed specific relationships with an array of invertebrate hosts (where bacteria proliferate once the hosts dies), thus forming...

Phasmarhabditis hermaphrodita is a nematode parasite of slugs that is commercially reared in monoxenic culture with the bacterium Moraxella osloensis and sold as a biological molluscicide. However, its bacterial associations when reared in vivo in slugs are unknown. We show that when reared in vivo in slugs, P. hermaphrodita does not retain M. oslo...

Pristionchus spp. nematodes exhibit several traits that might serve as pre-adaptations to parasitism. Under harsh environmental conditions, these nematodes can arrest development and form dauer larvae. In addition, they have been shown to live in necromenic association with a range of beetles, including dung beetles ( Geotrupes stercorosus ) on whi...

Slugs are serious pests of a range of crops worldwide and are commonly controlled using chemical bait molluscicides. Phasmarhabditis hermaphrodita is a slug parasitic nematode that can be an effective alternative to chemical pellets. We conducted a field trial with Chinese cabbage to assess the potential of new nematode application techniques (dipp...

The commercially available parasitic nematode Phasmarhabditis hermaphrodita is an effective biocontrol agent for slugs and particularly Deroceras reticulatum, a widespread pest species. Use of the nematode is currently limited by cost and it may be that by developing a fuller understanding of the ecology and behaviour of this nematode, more cost ef...

Phasmarhabditis hermaphrodita is a parasitic nematode that has been formulated into a biological control agent for slugs. The nematode responds to slug-associated cues such as mucus and feces in order to locate potential hosts. We assessed the olfactory response of P. hermaphrodita to mucus from 9 species of slugs, 2 snails, and 2 earthworms (non-h...

INTRODUCTION Pristionchus pacificus is a nematode that has been established as a model system for evolutionary developmental biology. Initially, P. pacificus was used as a convenient nematode with which to compare the processes of vulva and gonad development as well as sex determination to Caenorhabditis elegans , one of the best-studied animal mod...

INTRODUCTION In this procedure, nematodes disembark from a beetle carcass and feed on Escherichia coli OP50. The nematodes are then monitored for a few days and identified using simple morphological characteristics. This method is rapid, easy, and biased for Pristionchus species.

INTRODUCTION In the soil environment, nematodes must rely on a number of host-specific chemical cues in order to find potential beetle hosts. They must also discriminate among different food choices (i.e., bacteria), which is important because if the nematodes concentrate on an unsuitable food source, they may die. To detect the bacteria and host-s...

Nematodes and bacteria are major components of the soil ecosystem. Many nematodes use bacteria for food, whereas others evolved specialized bacterial interactions ranging from mutualism to parasitism. Little is known about the biological mechanisms by which nematode-bacterial interactions are achieved, largely because in the laboratory nematodes ar...

We exposed three slug species (Deroceras reticulatum (Müller), Milax gagates (Draparnaud) and Limax pseudoflavus L.) to the parasitic nematode Phasmarhabditis hermaphrodita Schneider. P. hermaphrodita was able to cause mortality and feeding inhibition to both D. reticulatum and M. gagates but did not negatively affect L. pseudoflavus. On dissection...

Phasmarhabditis hermaphrodita Schneider (Nematoda: Rhabditidae) is a nematode that parasitises a wide range of slug and snail species. It has been formulated into a biological control agent (Nemaslug) and was commercialised in 1994. It is now available in fourteen European countries. A review is given of all research on P. hermaphrodita, including...

Phasmarhabditis hermaphrodita is a parasitic nematode capable of killing several species of slugs including Deroceras reticulatum, the most widespread slug pest in the world. This nematode can control slug infestations in a wide range of crops such as wheat, lettuce and strawberries. Optimization of this biocontrol agent depends on a proper underst...

Entomopathogenic nematodes use a range of cues released by insects to locate hosts but there has been no research on how the slug-parasitic nematode, Phasmarhabditis hermaphrodita, finds potential hosts. We exposed P. hermaphrodita to a range of cues associated with the highly susceptible host Deroceras reticulatum. Cues included foot and mantle mu...

Summary Phasmarhabditis hermaphrodita is a lethal slug parasitic nematode that has been for- mulated into an effective biological control agent called Nemaslug®. We investigated the possibility of using different application methods of P. hermaphrodita to reduce cost and the number of nematodes applied. We also compared P. hermaphrodita with a new...

We exposed five earthworm species, one flatworm species and the susceptible slug Deroceras reticulatum to the recommended field application rate and five times this rate of Phasmarhabditis hermaphrodita. P. hermaphrodita caused significant mortality to D. reticulatum at the recommended rate and five times the recommended rate. Survival of the earth...

Robbie Rae, Jamie Robertson and Mike Wilson, outline the problems that slugs cause in many temperate crops and introduce new treatment strategies for their control.