aoife dillon | National University of Ireland, Maynooth (original) (raw)

Papers by aoife dillon

<strong>Data used to generate Figures 2 to 7 </strong> Figure 2. Bactericidal activit... more <strong>Data used to generate Figures 2 to 7 </strong> Figure 2. Bactericidal activity of poly-L-lysine polymers against <em>S. aureus</em> and <em>P. aeruginosa</em> laboratory strains compared to antibiotics. Figure 3. Bactericidal activity of poly-L-lysine polymers against <em>S. aureus</em> and <em>P. aeruginosa</em> laboratory strains. Figure 4. Comparative bactericidal activity of poly-L-lysine G3(16) copolymers series with hydrophobic amino acid isoleucine, tyrosine and phenylalanine. Figure 5. Comparison of Bactericidal activity of poly-L-lysine polymers, PLL₁₆₀and G2(8)PLL₂₀ against <em>S. aureus</em> clinical isolates from wound infections. Figure 6. Bactericidal activity of linear PLL₁₆₀against <em>S. aureus</em> and <em>P. aeruginosa </em>isolates from suspected diabetic foot infections. Figure 7. Investigation of PLL polymer-induced loss of biofilm viability by resazurin staining of 24 h biofilms.

HRB Open Research, 2022

Background: Wound infections occur as sequelae to skin trauma and cause significant hospitalizati... more Background: Wound infections occur as sequelae to skin trauma and cause significant hospitalizations, morbidity and mortality. Skin traumas arise more frequently in those with diabetes or cardiovascular disease and in these settings, may be chronic with poorer outcomes including lower limb amputation. Treatment of chronic wound infection is challenging due to antibiotic resistance and biofilm formation by bacteria including S. aureus and P. aeruginosa, which are among the most frequent causative pathogens. Managing these challenging infections requires new molecules and modalities. Methods: We evaluated antimicrobial and anti-biofilm activity of star-shaped poly(L-lysine) (PLL) polymers against S. aureus and P. aeruginosa strains and clinical isolates recovered from wounds including diabetic foot wounds (DFW) in a Dublin Hospital in 2019. A star-shaped PLL polypeptide series, specifically G2(8)PLL20, G3(16)PLL10, G4(32)PLL5 with variation in polypeptide chain length and arm-multipli...

Pest Management Science, 2017

BACKGROUND: The efficacy of a Beauveria bassiana-based formulation (Bb38) with Entostat, an elect... more BACKGROUND: The efficacy of a Beauveria bassiana-based formulation (Bb38) with Entostat, an electrostatically charged powder, was investigated as surface treatment against Cryptolestes ferrugineus, Oryzaephilus surinamensis and Sitophilus granarius adults. In lab bioassays, the efficacy of Bb38 against the aforementioned This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ps.4522 Accepted Article species was examined on concrete, plywood, steel and ceramic, whereas its residual efficacy against the same species was assessed on concrete and steel in the presence or absence of illumination. Finally, the efficacy of Bb38 against O. surinamensis and S. granarius adults was assessed in a commercial grain storage facility under realistic field conditions. RESULTS: In the lab trials, O. surinamensis and C. ferrugineus were much more susceptible to Bb38 than S. granarius, on all types of surfaces. Moreover, Bb38 was, at least for O. surinamensis and C. ferrugineus, as effective as the chemical standard (deltamethrin) for at least two months after the application, regardless of the presence or absence of illumination. Finally, in the field trial Bb38 provided a satisfactory level of control against O. surinamensis. CONCLUSION: Bb38 is an effective surface treatment, but its efficacy varies according to the target species, the type of surface and the time post-application. This is the first published report that examines the efficacy of Bb38 as a surface treatment for wider uses in empty warehouses and related storage facilities.

Forest Ecology and Management, 2016

Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. The... more Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. Their widespread use makes environmental risk assessment important, but very few comprehensive post-application risk assessments have been conducted for EPN. We apply a rigorous risk analysis procedure to the use of EPN applied in a forest ecosystem to suppress the large pine weevil (Hylobius abietis). In this synthesis, we provide a quantitative evaluation of five risk categories: a) establishment, b) dispersal, c) host range, d) direct non-target effects and e) indirect non-target effects. A low level of risk was identified (35-51 out of a possible total of 125). Species exotic to the clear-fell forest ecosystem (Steinernema carpocapsae and Heterorhabditis downesi) were accorded a lower overall risk status than native species and strains (Steinernema feltiae), largely as a result of their shorter persistence in the target environment. We conclude that EPN are a low risk viable alternative control for pine weevil compared to the higher risk conventional control using pyrethroid or neonicotinoid insecticides.

BioControl, 2015

The large pine weevil Hylobius abietis is a serious pest of reforestation in northern Europe. Dev... more The large pine weevil Hylobius abietis is a serious pest of reforestation in northern Europe. Development takes place in the stumps of felled conifer trees and emerging adults feed on and kill newly planted trees. Application of entomopathogenic nematodes around tree stumps has been shown to reduce the emergence of adult weevils. In order to target application at the most susceptible stage, the susceptibility of larvae and pupae to Heterorhabditis downesi and Steinernema carpocapsae was compared in a close-contact assay on filter paper. An average of 95.8 % of larvae were killed by H. downesi and 82.1 % by S. carpocapsae while only 16.3 and 15.0 % of pupae were killed by these two species, respectively. However, many of the H. abietis that were exposed as pupae died after metamorphosis to callow adult, with mortality of pupae and callow adults combined reaching 62.5 % for H. downesi and 69.9 % for S. carpocapsae. For both nematode species significantly more insects died as larvae than as either pupae or pupae/callow adults. When pupae were exposed to infective juveniles (IJs) for 2 days and were then washed while still pupae to remove surface IJs, adults were later found to be infected indicating that IJs can infect pupae, survive metamorphosis and subsequently kill adults.

Biological Control, 2021

Abstract The relatively short shelf life of many entomopathogenic nematode (EPN) based products i... more Abstract The relatively short shelf life of many entomopathogenic nematode (EPN) based products is a major constraint which limits their widespread usage in IPM programs. The two primary factors that affect survival of the infective juveniles (IJs) during storage (i.e. shelf life) are the rate at which the IJs utilize their energy reservoirs during storage and the effect of microbial contamination in formulation. In the present study, the suitability of Carboxymethyl cellulose (CMC) as an inert substrate for EPNs formulation was evaluated. Survival and virulence of dehydrated and non-dehydrated CMC formulated IJs of Heterorhabditis bacteriophora and Steinernema carpocapsae in the presence and absence of an antimicrobial agent was evaluated at two temperatures, 15 and 25 °C, over a six-month storage period. After six months of storage at 25 °C, levels of survival of H. bacteriophora and S. carpocapsae (77% and 93%, respectively) were highest where dehydrated IJs where in CMC which contained an antimicrobial agent. The effect of storage temperature (15 versus 25 °C) with respect to this formulation was species specific: a significant effect was seen in the case of H. bacteriophora, though not for S. carpocapsae. In both species, efficacy of anhydrobiosis on IJs survival emerged as foraging strategy dependent factor; this situation was observed for the efficacy of formaldehyde too. EPNs mortality across all treatments revealed two-stage survival curves, stage I with a steep slope and high mortality rate and stage II with a gentle slope and low rate of mortality. In our results CMC emerged as an efficient substrate for formulation of evaluated EPNs, mainly S. carpocapsae, though the use of antimicrobial agents other than formaldehyde may also make this formulation tool more appropriate for H. bacteriophora. Regarding the two-stage model, we propose that when assessing the suitability of new isolates for mass production, screening IJs from the 2nd stage of this mortality curves could be useful in terms of predicting the long-term viability of EPNs-based products.

Biocontrol Science and Technology

Scientific Reports

Biopesticides are biological pest control agents that are viewed as safer alternatives to the syn... more Biopesticides are biological pest control agents that are viewed as safer alternatives to the synthetic chemicals that dominate the global insecticide market. A major constraint on the wider adoption of biopesticides is their susceptibility to the ultraviolet (UV: 290–400 nm) radiation in sunlight, which limits their persistence and efficacy. Here, we describe a novel formulation technology for biopesticides in which the active ingredient (baculovirus) is micro-encapsulated in an ENTOSTAT wax combined with a UV absorbant (titanium dioxide, TiO2). Importantly, this capsule protects the sensitive viral DNA from degrading in sunlight, but dissolves in the alkaline insect gut to release the virus, which then infects and kills the pest. We show, using simulated sunlight, in both laboratory bioassays and trials on cabbage and tomato plants, that this can extend the efficacy of the biopesticide well beyond the few hours of existing virus formulations, potentially increasing the spray inter...

Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. The... more Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. Their widespread use makes environmental risk assessment important, but very few comprehensive post-application risk assessments have been conducted for EPN. We apply a rigorous risk analysis procedure to the use of EPN applied in a forest ecosystem to suppress the large pine weevil (Hylobius abietis). In this synthesis, we provide a quantitative evaluation of five risk categories: (a) establishment, (b) dispersal, (c) host range, (d) direct non-target effects and (e) indirect non-target effects. A low level of risk was identified (35–51 out of a possible total of 125). Species exotic to the clear-fell forest ecosystem (Steinernema carpocapsae and Heterorhabditis downesi) were accorded a lower overall risk status than native species and strains (Steinernema feltiae), largely as a result of their shorter persistence in the target environment. We conclude that EPN are a low risk viable alternative control for pine weevil compared to the higher risk conventional control using pyrethroid or neonicotinoid insecticides.

Animal Behaviour, 2010

antiparasite defence entomopathogenic nematode grooming Heterorhabditis downesi Hylobius abietis ... more antiparasite defence entomopathogenic nematode grooming Heterorhabditis downesi Hylobius abietis large pine weevil parasite avoidance parasite recognition Steinernema carpocapsae

Hylobius abietis, a major problem for seedling survival on forested land, develops under the bark... more Hylobius abietis, a major problem for seedling survival on forested land, develops under the bark of stumps of felled conifers. We investigated the efficacy of entomopathogenic nematodes (EPN) and fungi (EPF) applied to stumps to suppress adult emergence. We performed five field trials over three years and assessed results through destructive sampling and emergence trapping. We used two strategies in application: eradicant, where treatments were applied after weevil colonisation and prophylactic, where treatments were applied prior to colonisation. At prophylactic sites no treatment significantly reduced weevil emergence. At all eradicant sites, treatments including nematodes were more efficacious than those not. EPF-only treatment did not significantly reduce weevil emergence compared to controls, but there was a non-significant (P = 0.058) numerical reduction at one site. The effects of EPF and EPN were additive. There was evidence of mortality due to native Beauveria sp. at all three eradicant sites, identified as Beauveria caledonica at one. A proportion of weevils at depths of up to 18 cm in the soil were infected by the applied Beauveria bassiana showing that applied fungi can reach this cryptic pest. If choice of EPF strain and application technologies are optimised, EPF may present a viable control method for pine weevil in the future.

The large pine weevil is the most serious pest of conifer reforestation in Ireland. The adult wee... more The large pine weevil is the most serious pest of conifer reforestation in Ireland. The adult weevil causes damage by feeding on the bark of young transplants. With up to 100,000 adult weevils emerging per hectare on recently felled conifer sites, it is not uncommon for 100% of young plants to be killed. Pine weevils are susceptible to attack from a number of natural enemies such as fungi, parasites and predators. Of these, insect killing nematodes (microscopic worms) are the most promising biological control agent: capable of reducing weevil populations by up to 70%. The practicalities of using nematodes, their environmental safety and their potential for use as part of an integrated pest management strategy are discussed. The large pine weevil, Hylobius abietis (Figure 1) is the most important pest of replanted conifer sites in Ireland. This beetle has been recognised as a pest in Europe since the nineteenth century, but reports of damage were relatively rare in Ireland and Britai...

Journal of nematology

A destructive outbreak of the stem and bulb (bloat) nematode (Ditylenchus dipsaci) on garlic was ... more A destructive outbreak of the stem and bulb (bloat) nematode (Ditylenchus dipsaci) on garlic was first observed in a commercial field in western New York in June 2010. A follow-up survey demonstrated the widespread occurrence of the bloat nematode on garlic grown throughout the state and it was recovered from samples received from 17 counties and at populations as high as 3,609/g garlic tissues. Since then, over 300 garlic samples were processed in our laboratory and the bloat nematode was recovered from approximately 30% of the samples. Damage by this outbreak had significantly impacted garlic production in New York; with 100% yield losses occurring in some cases. Severely infected plants exhibit stunting; yellowing and collapse of outer leaves, and such plants may eventually die. Individual cloves or the entire bulb of infected plants initially exhibit light discoloration, later become dark brown in color, shrunken, soft, light in weight, and at later stages show cracks in the basal plate. Decay symptoms are usually developed on such cloves and bulbs due to the involvement of various saprophytic soil organisms. During 2011 and 2012, five workshops on the biology and management of the bloat nematode and general garlic production were offered and attended by >200 growers. A new project by the Specialty Crop Program through the NYS Dept. of Agriculture and Markets will subsidize the bloat nematode diagnostics and outreach on appropriate garlic and soil sampling protocols, interpretation of the test results obtained, and the implementation of appropriate management options against this nematode for both conventional and organic garlic growers in New York. The latter include the use of nematode-free planting seeds, planting in bloat nematode-free or treated soil, use of appropriate crop rotations (out of Allium species and other known hosts to the garlic and onion race of D. dipsaci), use of effective bio-fumigant cover crops and others.

Journal of Invertebrate Pathology, 2010

Steinernema carpocapsae can be effective against root-feeding insects despite its reputation as a... more Steinernema carpocapsae can be effective against root-feeding insects despite its reputation as a sedentary ambusher. In pot experiments, using twigs as surrogate roots and pine weevil larvae as targets, we tested the hypothesis that roots serve as physical routeways and conduits of feeding-associated stimuli, thus enhancing the success of S. carpocapsae applied at the surface against subterranean hosts. Insect mortality was lowest (25%) in the absence of plant material, increased to 48% when twigs linked nematodes and insects, and further increased to 69% when the insects were allowed feed on the twigs. This is the first experimental support for the root-routeway hypothesis.

Forest Ecology and Management, 2013

and sharing with colleagues.

Ecological Applications, 2008

Entomopathogenic nematodes (EPN) are currently marketed worldwide for use in inundative biologica... more Entomopathogenic nematodes (EPN) are currently marketed worldwide for use in inundative biological control, where the applied natural enemy population (rather than its offspring) is expected to reduce insect numbers. Unlike classical biological control, in inundative control natural enemy establishment is not crucial in order to achieve pest suppression. Field trials in Irish forestry provided the opportunity to test predictions regarding the establishment of two exotic (Steinernema carpocapsae and Heterorhabditis megidis) and two indigenous (Steinernema feltiae and Heterorhabditis downesi) species. Nematodes were inundatively applied to pine stumps to control populations of pine weevil, Hylobius abietis, on three clearcut sites, and their persistence and spread monitored for up to five years. All species were recovered three years after application but only S. feltiae was recovered in years 4 and 5. Limited horizontal dispersal to 20 cm (but not 100 cm) was observed, but the majority of nematodes were recovered close to the area of application. Steinernema feltiae was also recovered from nearby stumps to which it had not been applied, indicating possible phoretic dispersal by weevils or other stump-associated fauna. EPN were not recovered from stumps outside the treated area, suggesting that such dispersal is quite localized. Two strains of S. feltiae (Irish and exotic) were applied. Amplified fragment length polymorphism (AFLP) analysis on 11 populations isolated from soil four years later showed that all had a much closer affinity to the applied Irish strain, suggesting persistence of this genotype and extinction of the exotic one. Some strains were clustered close together, and this is interpreted in the light of possible population genetic scenarios. The findings from the field study confirm predictions based on background knowledge of the species and demonstrate the importance of mediumterm studies, as a 3-year study would have overestimated the risk of establishment of exotic species. Short-term persistence and spread of S. carpocapsae, S. feltiae, and H. downesi was also studied in pine forest mesocosms. Similar trends to field results, such as limited horizontal dispersal, even vertical distribution, and more abundant recovery of S. feltiae than of other species, point to the utility of mesocosm studies as a predictive tool.

<strong>Data used to generate Figures 2 to 7 </strong> Figure 2. Bactericidal activit... more <strong>Data used to generate Figures 2 to 7 </strong> Figure 2. Bactericidal activity of poly-L-lysine polymers against <em>S. aureus</em> and <em>P. aeruginosa</em> laboratory strains compared to antibiotics. Figure 3. Bactericidal activity of poly-L-lysine polymers against <em>S. aureus</em> and <em>P. aeruginosa</em> laboratory strains. Figure 4. Comparative bactericidal activity of poly-L-lysine G3(16) copolymers series with hydrophobic amino acid isoleucine, tyrosine and phenylalanine. Figure 5. Comparison of Bactericidal activity of poly-L-lysine polymers, PLL₁₆₀and G2(8)PLL₂₀ against <em>S. aureus</em> clinical isolates from wound infections. Figure 6. Bactericidal activity of linear PLL₁₆₀against <em>S. aureus</em> and <em>P. aeruginosa </em>isolates from suspected diabetic foot infections. Figure 7. Investigation of PLL polymer-induced loss of biofilm viability by resazurin staining of 24 h biofilms.

HRB Open Research, 2022

Background: Wound infections occur as sequelae to skin trauma and cause significant hospitalizati... more Background: Wound infections occur as sequelae to skin trauma and cause significant hospitalizations, morbidity and mortality. Skin traumas arise more frequently in those with diabetes or cardiovascular disease and in these settings, may be chronic with poorer outcomes including lower limb amputation. Treatment of chronic wound infection is challenging due to antibiotic resistance and biofilm formation by bacteria including S. aureus and P. aeruginosa, which are among the most frequent causative pathogens. Managing these challenging infections requires new molecules and modalities. Methods: We evaluated antimicrobial and anti-biofilm activity of star-shaped poly(L-lysine) (PLL) polymers against S. aureus and P. aeruginosa strains and clinical isolates recovered from wounds including diabetic foot wounds (DFW) in a Dublin Hospital in 2019. A star-shaped PLL polypeptide series, specifically G2(8)PLL20, G3(16)PLL10, G4(32)PLL5 with variation in polypeptide chain length and arm-multipli...

Pest Management Science, 2017

BACKGROUND: The efficacy of a Beauveria bassiana-based formulation (Bb38) with Entostat, an elect... more BACKGROUND: The efficacy of a Beauveria bassiana-based formulation (Bb38) with Entostat, an electrostatically charged powder, was investigated as surface treatment against Cryptolestes ferrugineus, Oryzaephilus surinamensis and Sitophilus granarius adults. In lab bioassays, the efficacy of Bb38 against the aforementioned This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ps.4522 Accepted Article species was examined on concrete, plywood, steel and ceramic, whereas its residual efficacy against the same species was assessed on concrete and steel in the presence or absence of illumination. Finally, the efficacy of Bb38 against O. surinamensis and S. granarius adults was assessed in a commercial grain storage facility under realistic field conditions. RESULTS: In the lab trials, O. surinamensis and C. ferrugineus were much more susceptible to Bb38 than S. granarius, on all types of surfaces. Moreover, Bb38 was, at least for O. surinamensis and C. ferrugineus, as effective as the chemical standard (deltamethrin) for at least two months after the application, regardless of the presence or absence of illumination. Finally, in the field trial Bb38 provided a satisfactory level of control against O. surinamensis. CONCLUSION: Bb38 is an effective surface treatment, but its efficacy varies according to the target species, the type of surface and the time post-application. This is the first published report that examines the efficacy of Bb38 as a surface treatment for wider uses in empty warehouses and related storage facilities.

Forest Ecology and Management, 2016

Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. The... more Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. Their widespread use makes environmental risk assessment important, but very few comprehensive post-application risk assessments have been conducted for EPN. We apply a rigorous risk analysis procedure to the use of EPN applied in a forest ecosystem to suppress the large pine weevil (Hylobius abietis). In this synthesis, we provide a quantitative evaluation of five risk categories: a) establishment, b) dispersal, c) host range, d) direct non-target effects and e) indirect non-target effects. A low level of risk was identified (35-51 out of a possible total of 125). Species exotic to the clear-fell forest ecosystem (Steinernema carpocapsae and Heterorhabditis downesi) were accorded a lower overall risk status than native species and strains (Steinernema feltiae), largely as a result of their shorter persistence in the target environment. We conclude that EPN are a low risk viable alternative control for pine weevil compared to the higher risk conventional control using pyrethroid or neonicotinoid insecticides.

BioControl, 2015

The large pine weevil Hylobius abietis is a serious pest of reforestation in northern Europe. Dev... more The large pine weevil Hylobius abietis is a serious pest of reforestation in northern Europe. Development takes place in the stumps of felled conifer trees and emerging adults feed on and kill newly planted trees. Application of entomopathogenic nematodes around tree stumps has been shown to reduce the emergence of adult weevils. In order to target application at the most susceptible stage, the susceptibility of larvae and pupae to Heterorhabditis downesi and Steinernema carpocapsae was compared in a close-contact assay on filter paper. An average of 95.8 % of larvae were killed by H. downesi and 82.1 % by S. carpocapsae while only 16.3 and 15.0 % of pupae were killed by these two species, respectively. However, many of the H. abietis that were exposed as pupae died after metamorphosis to callow adult, with mortality of pupae and callow adults combined reaching 62.5 % for H. downesi and 69.9 % for S. carpocapsae. For both nematode species significantly more insects died as larvae than as either pupae or pupae/callow adults. When pupae were exposed to infective juveniles (IJs) for 2 days and were then washed while still pupae to remove surface IJs, adults were later found to be infected indicating that IJs can infect pupae, survive metamorphosis and subsequently kill adults.

Biological Control, 2021

Abstract The relatively short shelf life of many entomopathogenic nematode (EPN) based products i... more Abstract The relatively short shelf life of many entomopathogenic nematode (EPN) based products is a major constraint which limits their widespread usage in IPM programs. The two primary factors that affect survival of the infective juveniles (IJs) during storage (i.e. shelf life) are the rate at which the IJs utilize their energy reservoirs during storage and the effect of microbial contamination in formulation. In the present study, the suitability of Carboxymethyl cellulose (CMC) as an inert substrate for EPNs formulation was evaluated. Survival and virulence of dehydrated and non-dehydrated CMC formulated IJs of Heterorhabditis bacteriophora and Steinernema carpocapsae in the presence and absence of an antimicrobial agent was evaluated at two temperatures, 15 and 25 °C, over a six-month storage period. After six months of storage at 25 °C, levels of survival of H. bacteriophora and S. carpocapsae (77% and 93%, respectively) were highest where dehydrated IJs where in CMC which contained an antimicrobial agent. The effect of storage temperature (15 versus 25 °C) with respect to this formulation was species specific: a significant effect was seen in the case of H. bacteriophora, though not for S. carpocapsae. In both species, efficacy of anhydrobiosis on IJs survival emerged as foraging strategy dependent factor; this situation was observed for the efficacy of formaldehyde too. EPNs mortality across all treatments revealed two-stage survival curves, stage I with a steep slope and high mortality rate and stage II with a gentle slope and low rate of mortality. In our results CMC emerged as an efficient substrate for formulation of evaluated EPNs, mainly S. carpocapsae, though the use of antimicrobial agents other than formaldehyde may also make this formulation tool more appropriate for H. bacteriophora. Regarding the two-stage model, we propose that when assessing the suitability of new isolates for mass production, screening IJs from the 2nd stage of this mortality curves could be useful in terms of predicting the long-term viability of EPNs-based products.

Biocontrol Science and Technology

Scientific Reports

Biopesticides are biological pest control agents that are viewed as safer alternatives to the syn... more Biopesticides are biological pest control agents that are viewed as safer alternatives to the synthetic chemicals that dominate the global insecticide market. A major constraint on the wider adoption of biopesticides is their susceptibility to the ultraviolet (UV: 290–400 nm) radiation in sunlight, which limits their persistence and efficacy. Here, we describe a novel formulation technology for biopesticides in which the active ingredient (baculovirus) is micro-encapsulated in an ENTOSTAT wax combined with a UV absorbant (titanium dioxide, TiO2). Importantly, this capsule protects the sensitive viral DNA from degrading in sunlight, but dissolves in the alkaline insect gut to release the virus, which then infects and kills the pest. We show, using simulated sunlight, in both laboratory bioassays and trials on cabbage and tomato plants, that this can extend the efficacy of the biopesticide well beyond the few hours of existing virus formulations, potentially increasing the spray inter...

Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. The... more Entomopathogenic nematodes (EPN) are globally important inundative biological control agents. Their widespread use makes environmental risk assessment important, but very few comprehensive post-application risk assessments have been conducted for EPN. We apply a rigorous risk analysis procedure to the use of EPN applied in a forest ecosystem to suppress the large pine weevil (Hylobius abietis). In this synthesis, we provide a quantitative evaluation of five risk categories: (a) establishment, (b) dispersal, (c) host range, (d) direct non-target effects and (e) indirect non-target effects. A low level of risk was identified (35–51 out of a possible total of 125). Species exotic to the clear-fell forest ecosystem (Steinernema carpocapsae and Heterorhabditis downesi) were accorded a lower overall risk status than native species and strains (Steinernema feltiae), largely as a result of their shorter persistence in the target environment. We conclude that EPN are a low risk viable alternative control for pine weevil compared to the higher risk conventional control using pyrethroid or neonicotinoid insecticides.

Animal Behaviour, 2010

antiparasite defence entomopathogenic nematode grooming Heterorhabditis downesi Hylobius abietis ... more antiparasite defence entomopathogenic nematode grooming Heterorhabditis downesi Hylobius abietis large pine weevil parasite avoidance parasite recognition Steinernema carpocapsae

Hylobius abietis, a major problem for seedling survival on forested land, develops under the bark... more Hylobius abietis, a major problem for seedling survival on forested land, develops under the bark of stumps of felled conifers. We investigated the efficacy of entomopathogenic nematodes (EPN) and fungi (EPF) applied to stumps to suppress adult emergence. We performed five field trials over three years and assessed results through destructive sampling and emergence trapping. We used two strategies in application: eradicant, where treatments were applied after weevil colonisation and prophylactic, where treatments were applied prior to colonisation. At prophylactic sites no treatment significantly reduced weevil emergence. At all eradicant sites, treatments including nematodes were more efficacious than those not. EPF-only treatment did not significantly reduce weevil emergence compared to controls, but there was a non-significant (P = 0.058) numerical reduction at one site. The effects of EPF and EPN were additive. There was evidence of mortality due to native Beauveria sp. at all three eradicant sites, identified as Beauveria caledonica at one. A proportion of weevils at depths of up to 18 cm in the soil were infected by the applied Beauveria bassiana showing that applied fungi can reach this cryptic pest. If choice of EPF strain and application technologies are optimised, EPF may present a viable control method for pine weevil in the future.

The large pine weevil is the most serious pest of conifer reforestation in Ireland. The adult wee... more The large pine weevil is the most serious pest of conifer reforestation in Ireland. The adult weevil causes damage by feeding on the bark of young transplants. With up to 100,000 adult weevils emerging per hectare on recently felled conifer sites, it is not uncommon for 100% of young plants to be killed. Pine weevils are susceptible to attack from a number of natural enemies such as fungi, parasites and predators. Of these, insect killing nematodes (microscopic worms) are the most promising biological control agent: capable of reducing weevil populations by up to 70%. The practicalities of using nematodes, their environmental safety and their potential for use as part of an integrated pest management strategy are discussed. The large pine weevil, Hylobius abietis (Figure 1) is the most important pest of replanted conifer sites in Ireland. This beetle has been recognised as a pest in Europe since the nineteenth century, but reports of damage were relatively rare in Ireland and Britai...

Journal of nematology

A destructive outbreak of the stem and bulb (bloat) nematode (Ditylenchus dipsaci) on garlic was ... more A destructive outbreak of the stem and bulb (bloat) nematode (Ditylenchus dipsaci) on garlic was first observed in a commercial field in western New York in June 2010. A follow-up survey demonstrated the widespread occurrence of the bloat nematode on garlic grown throughout the state and it was recovered from samples received from 17 counties and at populations as high as 3,609/g garlic tissues. Since then, over 300 garlic samples were processed in our laboratory and the bloat nematode was recovered from approximately 30% of the samples. Damage by this outbreak had significantly impacted garlic production in New York; with 100% yield losses occurring in some cases. Severely infected plants exhibit stunting; yellowing and collapse of outer leaves, and such plants may eventually die. Individual cloves or the entire bulb of infected plants initially exhibit light discoloration, later become dark brown in color, shrunken, soft, light in weight, and at later stages show cracks in the basal plate. Decay symptoms are usually developed on such cloves and bulbs due to the involvement of various saprophytic soil organisms. During 2011 and 2012, five workshops on the biology and management of the bloat nematode and general garlic production were offered and attended by >200 growers. A new project by the Specialty Crop Program through the NYS Dept. of Agriculture and Markets will subsidize the bloat nematode diagnostics and outreach on appropriate garlic and soil sampling protocols, interpretation of the test results obtained, and the implementation of appropriate management options against this nematode for both conventional and organic garlic growers in New York. The latter include the use of nematode-free planting seeds, planting in bloat nematode-free or treated soil, use of appropriate crop rotations (out of Allium species and other known hosts to the garlic and onion race of D. dipsaci), use of effective bio-fumigant cover crops and others.

Journal of Invertebrate Pathology, 2010

Steinernema carpocapsae can be effective against root-feeding insects despite its reputation as a... more Steinernema carpocapsae can be effective against root-feeding insects despite its reputation as a sedentary ambusher. In pot experiments, using twigs as surrogate roots and pine weevil larvae as targets, we tested the hypothesis that roots serve as physical routeways and conduits of feeding-associated stimuli, thus enhancing the success of S. carpocapsae applied at the surface against subterranean hosts. Insect mortality was lowest (25%) in the absence of plant material, increased to 48% when twigs linked nematodes and insects, and further increased to 69% when the insects were allowed feed on the twigs. This is the first experimental support for the root-routeway hypothesis.

Forest Ecology and Management, 2013

and sharing with colleagues.

Ecological Applications, 2008

Entomopathogenic nematodes (EPN) are currently marketed worldwide for use in inundative biologica... more Entomopathogenic nematodes (EPN) are currently marketed worldwide for use in inundative biological control, where the applied natural enemy population (rather than its offspring) is expected to reduce insect numbers. Unlike classical biological control, in inundative control natural enemy establishment is not crucial in order to achieve pest suppression. Field trials in Irish forestry provided the opportunity to test predictions regarding the establishment of two exotic (Steinernema carpocapsae and Heterorhabditis megidis) and two indigenous (Steinernema feltiae and Heterorhabditis downesi) species. Nematodes were inundatively applied to pine stumps to control populations of pine weevil, Hylobius abietis, on three clearcut sites, and their persistence and spread monitored for up to five years. All species were recovered three years after application but only S. feltiae was recovered in years 4 and 5. Limited horizontal dispersal to 20 cm (but not 100 cm) was observed, but the majority of nematodes were recovered close to the area of application. Steinernema feltiae was also recovered from nearby stumps to which it had not been applied, indicating possible phoretic dispersal by weevils or other stump-associated fauna. EPN were not recovered from stumps outside the treated area, suggesting that such dispersal is quite localized. Two strains of S. feltiae (Irish and exotic) were applied. Amplified fragment length polymorphism (AFLP) analysis on 11 populations isolated from soil four years later showed that all had a much closer affinity to the applied Irish strain, suggesting persistence of this genotype and extinction of the exotic one. Some strains were clustered close together, and this is interpreted in the light of possible population genetic scenarios. The findings from the field study confirm predictions based on background knowledge of the species and demonstrate the importance of mediumterm studies, as a 3-year study would have overestimated the risk of establishment of exotic species. Short-term persistence and spread of S. carpocapsae, S. feltiae, and H. downesi was also studied in pine forest mesocosms. Similar trends to field results, such as limited horizontal dispersal, even vertical distribution, and more abundant recovery of S. feltiae than of other species, point to the utility of mesocosm studies as a predictive tool.