The oak processionary caterpillar as the cause of an epidemic airborne disease: survey and analysis

Ocular involvement of oak processionary caterpillar hairs: Clinical outcome up to one year

PURPOSE

To evaluate a consecutive series of patients that presented with ocular findings after contact with the oak processionary caterpillar (OPC) during an epidemic reproduction of the OPC in Germany in 2019 and to assess the 1-year outcome of those eyes with persisting OPC hairs in the cornea.

METHODS

Retrospective analysis of 11 eyes (11 patients) that presented in June/July 2019 with acute ocular symptoms after outdoor activity or caterpillar nest removal. Evaluation of patients charts and slit-lamp images up to one year. Assessment of the incidence of patients with OPC-associated ocular complaints in the subsequent years (2020-2023).

RESULTS

All patients had conjunctival injection, foreign body sensation, pain, itching and/or burning sensation. In 9/11 eyes, multiple caterpillar hairs could be detected in the superficial and deeper cornea. Hair removal was attempted in 8/9 eyes; in one eye hair removal was impossible due to its deep stromal location (lost-to-follow-up). Entire hair removal was successful in 2/9 eyes, hence, six eyes with persisting hairs within the cornea were followed. Stromal haze developed adjacent to the hairs in all eyes and individual hairs disappeared (n = 4) and/or showed migration within the cornea (n = 3). Until 2023, the number of patients with OPC-associated ocular complaints decreased continuously.

CONCLUSIONS

Ophthalmologists should be aware of the possibility of caterpillar hairs in patients with acute eye symptoms after outdoor acitivities, especially in early summer; the incidence may fluctuate, though. Hair removal is recommended to avoid possible intraocular migration, still residing hairs did not cause any serious long-term complications in our cohort.

KEY MESSAGES

What is known Within the late spring and early summer season, mass reproduction of the oak processionary carterpillar (OPC) can lead to an increased number of patients with OPC-related eye complaints (pain, itching and burning sensation) caused by OPC hairs within a very short period of time. Within that season, people should be (more) actively sensitized to avoid trees with OPC hairs, take precautions and avoid eye rubing when having complaints What is new Complete surgical removal of the hairs can be difficult and is often unsuccessful due to their tiny size and often stromal location most possibly resulting from eye rubbing In the longer-term, residing hairs have shown to develop haze adjacent to the hair, migrate within the cornea or disappear/resolve. Since this may go along with an inflammatory reaction, long-term follow-up and topical steroids may be useful.

Venoms of Lepidoptera: Evolution, Composition, and Molecular Modes of Action

Animal venoms are a focus of research due to the hazards they represent and to their relationship to evolution and ecology, pharmacology, biodiscovery, and biotechnology. Venoms have evolved multiple times in Lepidoptera, mostly as defensive adaptations that protect the larval life stages. While venoms are always produced in structures derived from cuticle and setae, they are diverse in their composition and bioactivity, reflecting their multiple evolutionary origins. The most common result of envenomation by lepidopterans is pain and inflammation, but envenomation by some species causes fatal hemorrhagic syndromes or chronic inflammatory conditions in humans or veterinary pathologies such as equine amnionitis and fetal loss. The handful of lepidopteran venom toxins that have been characterized includes coagulotoxins from Lonomia obliqua (Saturniidae) and pain-causing cecropin-like peptides from Doratifera vulnerans (Limacodidae). However, our knowledge of lepidopteran venoms remains comparatively poor, with further studies required to yield a clear picture of the evolution, composition, and function of venoms produced by Lepidoptera.

Injuries and deaths due to tree failure in The Netherlands: analysis of observational data from 1998-2021

Urban and roadside trees contribute to health and resilience. However, when trees or branches fall, it can cause injuries or deaths. This study examined trends and variations of injuries and deaths due to tree failure in The Netherlands from 1998 to 2021, considering urban-rural location, sex, age and traffic mode. This study is the first to describe long-term trends in injuries and deaths due to tree failure from 1998-2021. The standardised rate of injuries per 1,000,000 population increased from 0.14 (SE 0.10) in 1998 to 0.91 (SE 0.21) in 2021, with an annual percentage increase of 5.3% (p = 0.002). The data shows a strong increase for rural areas, contrary to urban ones. The annual percentage increase in rural areas was 13.2% (p < 0.001) while injuries in urban areas increased with 3.0% (p = 0.026), which revealed large urban-rural disparities. A trend was absent in the frequency of deaths. More attention needs to be given to investigating causes, drivers and stressors associated with tree failure-related injuries. In particular, efforts should be made to reduce the prevalence in rural areas. The increase in injuries over time makes it necessary to create awareness and share knowledge among residents and local governments about tree failure risks.

Exploring oak processionary caterpillar induced lepidopterism (Part 1): unveiling molecular insights through transcriptomics and proteomics

Lepidopterism, a skin inflammation condition caused by direct or airborne exposure to irritating hairs (setae) from processionary caterpillars, is becoming a significant public health concern. Recent outbreaks of the oak processionary caterpillar (Thaumetopoea processionea) have caused noteworthy health and economic consequences, with a rising frequency expected in the future, exacerbated by global warming promoting the survival of the caterpillar. Current medical treatments focus on symptom relief due to the lack of an effective therapy. While the source is known, understanding the precise causes of symptoms remain incomplete understood. In this study, we employed an advanced method to extract venom from the setae and identify the venom components through high-quality de novo transcriptomics, venom proteomics, and bioinformatic analysis. A total of 171 venom components were identified, including allergens, odorant binding proteins, small peptides, enzymes, enzyme inhibitors, and chitin biosynthesis products, potentially responsible for inflammatory and allergic reactions. This work presents the first comprehensive proteotranscriptomic database of T. processionea, contributing to understanding the complexity of lepidopterism. Furthermore, these findings hold promise for advancing therapeutic approaches to mitigate the global health impact of T. processionea and related caterpillars.

Pathogens of the oak processionary moth Thaumetopoea processionea: Developing a user-friendly bioassay system and metagenome analyses for microorganisms

The oak processionary moth (OPM) Thaumetopoea processionea is a pest of oak trees and poses health risks to humans due to the urticating setae of later instar larvae. For this reason, it is difficult to rear OPM under laboratory conditions, carry out bioassays or examine larvae for pathogens. Biological control targets the early larval instars and is based primarily on commercial preparations of Bacillus thuringiensis ssp. kurstaki (Btk). To test the entomopathogenic potential of other spore-forming bacteria, a user-friendly bioassay system was developed that (i) applies bacterial spore suspensions by oak bud dipping, (ii) targets first instar larvae through feeding exposure and (iii) takes into account their group-feeding behavior. A negligible mortality in the untreated control proved the functionality of the newly established bioassay system. Whereas the commercial Btk HD-1 strain was used as a bioassay standard and confirmed as being highly efficient, a Bacillus wiedmannii strain was ineffective in killing OPM larvae. Larvae, which died during the infection experiment, were further subjected to Nanopore sequencing for a metagenomic approach for entomopathogen detection. It further corroborated that B.wiedmannii was not able to infect and establish in OPM, but identified potential insect pathogenic species from the genera Serratia and Pseudomonas.

Exploring oak processionary caterpillar induced lepidopterism (part 2): ex vivo bio-assays unmask the role of TRPV1

As human skin comes into contact with the tiny hairs or setae of the oak processionary caterpillar, Thaumetopoea processionea, a silent yet intense chemical confrontation occurs. The result is a mix of issues: skin rashes and an intense itching that typically lasts days and weeks after the contact. This discomfort poses a significant health threat not only to humans but also to animals. In Western Europe, the alarming increase in outbreaks extends beyond areas near infested trees due to the dispersion of the setae. Predictions indicate a sustained rise in outbreaks, fueled by global changes favoring the caterpillar's survival and distribution. Currently, the absence of an efficient treatment persists due to significant gaps in our comprehension of the pathophysiology associated with this envenomation. Here, we explored the interaction between the venom extract derived from the setae of T. processionea and voltage- and ligand-gated ion channels and receptors. By conducting electrophysiological analyses, we discovered ex vivo evidence highlighting the significant role of TPTX1-Tp1, a peptide toxin from T. processionea, in modulating TRPV1. TPTX1-Tp1 is a secapin-like peptide and demonstrates a unique ability to modulate TRPV1 channels in the presence of capsaicin, leading to cell depolarization, itch and inflammatory responses. This discovery opens new avenues for developing a topical medication, suggesting the incorporation of a TRPV1 blocker as a potential solution for the local effects caused by T. processionea.

Strategies for public health adaptation to climate change in practice: social learning in the processionary Moth Knowledge Platform

Social learning theory can support understanding of how a group of diverse actors addresses complex challenges related to public health adaptation. This study focuses on one specific issue of public health adaptation: oak processionary moth (OPM) adaptation. With a social learning framework, we examined how public health adaption strategies gradually develop and are adjusted on the basis of new knowledge and experiences. For this qualitative case study, data were collected through 27 meetings of the Processionary Moth Knowledge Platform in the Netherlands and six additional interviews. Results indicate that relations between stakeholders, including experts played a major role in the learning process, facilitating the development and implementation of OPM adaptation and connecting local challenges to national adaptation strategies. Uncertainties regarding knowledge and organization were recurrent topics of discussion, highlighting the iterative and adaptive nature of public health adaptation. The study emphasizes the importance of building relationships among stakeholders and small steps in the learning process that can lead to the creation of new strategies and, if successful, the prevention of negative health impacts.

Occupational Exposure of Forest Workers to the Urticating Setae of the Pine Processionary Moth Thaumetopoea pityocampa

The larvae of the pine processionary moth are a threat to public health because they produce detachable setae that are about 200 µm long and 6 µm wide, reaching a total number of up to 1 million per mature individual. The setae are intended to be released to protect the larvae from predators but become a public health issue when in contact with humans and warm-blooded animals. Symptoms associated with the setae are typically urticaria and local swelling erythema, although edema of the skin, conjunctivitis or respiratory mucosa may occur. Occupational exposure concerns mainly forest workers but also farmers and gardeners. In the present study, we quantify the exposure to the setae of forest workers in a district of Northern Italy. The pine processionary moth represents a real case of occupational exposure as the urticating setae produced by the larvae caused symptoms in most forest workers directly in contact with the infested trees. In addition, the urticating setae were detected on the body of the chainsaw operators and in the surroundings of the felled trees during the operations. The non-exposed workers of the same agency did not report symptoms, with only one exception, likely linked to a non-occupational exposure. As the risk is not immediately perceived by the workers because direct contact with the larvae is unlikely, a campaign of information to workers and the general population living nearby infested forestry areas about the risk associated with airborne exposure is recommended. This becomes especially important in the areas of recent expansion of the insect, where people are inexperienced.

Tree insect pests and pathogens: a global systematic review of their impacts in urban areas

Trees contribute greatly to urban environments and human well-being, yet relatively little is known about the extent to which a rising incidence of tree insect pests and pathogens may be affecting these contributions. To address this issue, we undertook a systematic review and synthesis of the diverse global empirical evidence on the impacts of urban tree insect pests and pathogens, using bibliographic databases. Following screening and appraisal of over 3000 articles from a wide range of fields, 100 studies from 28 countries, spanning 1979–2021, were conceptually sorted into a three-part framework: (1) environmental impacts, representing 95 of the studies, including those reporting on tree damage, mortality, reduced growth, and changes in tree function; (2) social impacts were reported by 35 of studies, including on aesthetics, human health, and safety hazards; and (3) economic impacts, reported in 24 of studies, including on costs of pest management, and economic losses. There has been a considerable increase in urban impact studies since 2011. Evidence gaps exist on impacts on climate-regulating capacity, including temperature regulation, water retention, soil erosion, and wind protection, but also on specific hazards, nuisances, human well-being, property damages, and hazard liabilities. As a knowledge synthesis, this article presents the best available evidence of urban tree insect / pathogen impacts to guide policy, management and further research. It will enable us to better forecast how growing threats will affect the urban forest and plan for these eventualities.

Processionary caterpillar reactions in Southern Italy forestry workers: description of three cases

Background

Processionary caterpillar (PC), also named Thaumatopea pityocampa, has been reported to cause hypersensitivity reactions after contact with a toxin contained in hair-like bristles which cover this insect. Occupational exposure to PC is underestimated in outdoor workers and especially in forestry workers (FW) and is globally diffusing because of rising temperatures.

Cases presentation

We present the first three cases of FW from Sicily, a Southern Italy (SI) region, which reported hypersensitivity reactions due to exposure to PC infested trees. These cases were identified by the occupational health physician during the annual screening of FW working in the Mountains of north-eastern Sicily. Interviewing a population of 630 FW, 1 male and 2 females reported direct contact skin reactions together with airborne contact reactions to PC hairs causing mild respiratory symptoms in two cases and ocular symptoms in one case, which needed treatment with systemic corticosteroids and antihistamines.

Conclusions

This is the first report of hypersensitivity reactions in SI FW due to occupational exposure to PC. Further screenings not only in FW but also in other populations of outdoor workers are needed in order to assess the real incidence of contact and airborne reactions due to occupational exposure to PC. Though so far no correlation has been found with atopy, it seems apparent that the reactions occur in susceptible subjects; further research is needed for a correct diagnosis and to identify possible desensitization procedures.

Ocular complications of oak processionary caterpillar setae in the Netherlands; case series, literature overview, national survey and treatment advice

During early summer 2019, the Netherlands experienced an outbreak of the exotic oak processionary caterpillar. The vast number of caterpillars, which live in large nests on oak trees before they turn into moths, possess thousands of small, barbed hairs (setae) that are disseminated with the wind. The hairs cause a range of primarily dermatologic problems. However, Dutch ophthalmologists started reporting patients with ophthalmologic complaints caused by the penetrating hairs of the oak processionary caterpillar. This paper focuses on the ophthalmologic complications caused by the caterpillar hairs. We collected a series of four cases with reports ranging from a corneal erosion with hairs lodged into the cornea, to a sterile endophthalmitis in which hairs were found in the vitreous. A literature review for similar cases was performed using the PubMed and Embase database. Together with the Dutch Ophthalmic Society (Nederlands Oogheelkundig Gezelschap, NOG), a national survey was issued to determine the scale of this new problem. This showed that oak processionary caterpillar related complaints are primarily limited to the south of the Netherlands. Suggested ophthalmic treatment guidelines are presented. With the next summer at the doorstep, and limited preventative measures against the caterpillar hairs, we expect a new wave of ophthalmologic complaints coming year as well.

Understanding Public Health Adaptation to Climate Change: An Explorative Study on the Development of Adaptation Strategies Relating to the Oak Processionary Moth in The Netherlands

Understanding of public health adaptation (PHA) to climate change and implementation is limited. This study therefore focuses on one specific PHA issue: adaptation to the oak processionary moth (OPM). The aim is to examine the development of OPM adaptation in order to offer a problem description of the complexities involved in OPM adaptation. In this explorative case study, we investigate adaptation strategies based on semi-structured interviews with 26 actors involved in OPM adaptation in The Netherlands. The results indicate that the context of OPM adaptation is relatively complex, given the involvement of many interdependent actors. OPM adaptation was developed with limited knowledge and strategies were based on ad hoc approaches in which there was ambiguity about tasks and expertise. In addition, different actors have different perceptions and values concerning health, sustainability, risks and responsibilities influencing decision-making processes, while also posing a challenge to collaboration and the development of a coordinated approach. The generation of knowledge and its translation into practical strategies calls for interdisciplinary cooperation in knowledge development. PHA adaptation involves more than technical and organisational solutions alone. It also entails the development of a shared problem perception and solution space in which citizens are also engaged.

Was kommt dort durch die Luft geflogen …?

Die Larven des 4. bis 6. Stadiums des Eichenprozessionspinners sind mit Brennhärchen (Setae) bewehrt, welche bei Mensch und Tier heftige entzündliche Haut- und Schleimhautreaktionen (Lepidopterismus) hervorrufen. Die Übertragung erfolgt sehr häufig aerogen, oder durch direkten Kontakt. Durch den Befall von Bäumen im urbanen Grünbereich ist die Fallzahl – vor allem in Jahren mit Massenvermehrung des Forstparasiten – sehr groß. Da die Dunkelziffer sehr hoch ist, sollten Ärzte und Ärztinnen bei Patienten mit juckenden, asymmetrisch verteilten papulösen oder urtikariellen Exanthemen an die Möglichkeit des Vorliegens einer Raupendermatitis denken. Meiden der Befallsgebiete bzw. Tragen von persönlicher Schutzkleidung bei Außenarbeitern, stellen die besten präventiven Maßnahmen dar.

Incidence and causes of pregnancy loss after Day 70 of gestation in Thoroughbreds

BACKGROUND

Pregnancy loss after Day 70 of gestation manifests as abortion, stillbirth or perinatal death. While previous studies have reported the diagnoses of laboratory submissions, none have quantified the incidence and causes of abortions, stillbirths and perinatal mortality at a population level.

OBJECTIVES

To report the incidence and causes of pregnancy loss after Day 70 of gestation in a cohort of Thoroughbreds.

STUDY DESIGN

Retrospective cohort study.

METHODS

Outcomes of Day 70 pregnancies were collected from eight Thoroughbred farms over the 2013-2017 breeding seasons. Stud, veterinary and laboratory records were supplemented with publicly available data. Cause of loss was categorised using custom criteria.

RESULTS

Data were collected on 3,586 pregnancies from 1,802 mares. The incidence risk of a pregnancy failing to produce a live foal at 24 hours post parturition was 7.3% (95% confidence interval (CI) 6.5-8.2, equating to 7.3 cases per 100 Day-70 pregnancies). The incidence of pregnancy loss between Day 70 and 300 of gestation, Day 301-315 and stillbirth/perinatal death was 4.0% (95% CI 3.4-4.7), 0.3% (95% CI 0.2-0.6) and 1.4% (95% CI 1.1-1.9) respectively. Of the pregnancy losses where tissue was available, 61.1% were submitted for post-mortem examination. The incidence risk of loss due to umbilical cord-related pathologies was 1.5% (95% CI 1.1-1.9), 0.4% (95% CI 0.2-0.6) for noninfectious placental disease and 0.3% (95% CI 0.2-0.6) for both infectious placentitis and Equine Herpesvirus infection. No primary diagnosis was made in 11.2% of the cases which underwent full post-mortem examination.

MAIN LIMITATIONS

It was not possible to differentiate between intra-partum stillbirth and early post-partum death.

CONCLUSION

Pregnancy loss after Day 70 of gestation is a significant source of loss in the Thoroughbred with umbilical cord-related pathologies being the most commonly diagnosed cause. Reporting the incidence of pregnancy loss at a population level with clear case definitions will allow for accurate global comparisons.

Mites, caterpillars and moths

Besides conditions such as scabies and hypersensitivity to house dust mites, other diseases caused by mites and caterpillars tend to be more uncommon in everyday practice. Nevertheless, there is a broad spectrum of medically relevant disorders associated with these arthropods. Mites may act as parasites that infect or colonize the skin (e.g., scabies, pseudoscabies, demodicosis) or they may pierce the host's skin and feed on tissue fluid and blood (trombiculosis). In the latter case, they also play a role as vectors transmitting Orientia tsutsugamushi, the pathogen that causes Tsutsugamushi fever. In addition to house dust mites, storage mites, too, are characterized by their allergenic potential. The terms erucism and lepidopterism are used for the various diseases caused by caterpillars and moths. Both terms are not used consistently. With respect to pathogenesis, various mechanisms have been described, including type I and type IV hypersensitivity as well as irritant and toxin-induced reactions. In Germany, skin reactions following exposure to the hairs of oak processionary caterpillars are particularly common. Extracutaneous manifestations including nausea, vomiting, hemorrhage, arthropathy or even life-threatening reactions have been reported in association with certain exotic species. Some species act as parasites by feeding on blood or tears. As natural silk can cause immediate and delayed-type hypersensitivity reactions, workers in the silk industry may develop allergic asthma, rhinitis, or conjunctivitis. Consumption of silkworm pupae is associated with the risk of food allergy.

Comparison of the drift potential of two application methods for the control of oak processionary moths with biocidal products in an oak avenue

The control of oak processionary moths (OPM; Thaumetopoea processionea) with biocidal products has become more important to protect humans from its urticating hairs. Two important application methods are cannon sprayers and helicopters. However, drift of insecticides to non-target areas might occur during the treatment resulting in potential risks for non-target organisms. Until now, information about the direct drift resulting from the applications are missing because equipment for the application of biocidal products is not tested or regulated within Europe. The aim of this work is to measure the direct drift in up to 100 m distance resulting from the application of biocidal products using a cannon sprayer and helicopter in an oak avenue. Furthermore, two different nozzles were tested for the helicopter application. The results show high drift potential with decreasing concentrations in relation to the distance to the treated area. Considering the 50th percentile of the results, the cannon sprayer produced generally more drift than the helicopter. Considering the 90th percentile at near distance, the helicopter equipped with ID-120-05 POM nozzles showed a significantly lower drift than both other tested techniques, the helicopter equipped with the Airmix 110 05 nozzles and the cannon sprayer. Hundred m away from the treated area, both nozzles installed at the helicopter showed a lower drift than the cannon sprayer. For the first time, this study shows the drift potential of applications of biocidal products and shows the possibilities to reduce drift into non-target areas by choosing appropriate equipment. This leads to a reduction of risks for non-target organisms in the vicinity of treated avenues.

Variation in Morphology and Airborne Dispersal of the Urticating Apparatus of Ochrogaster lunifer (Lepidoptera: Notodontidae), an Australian Processionary Caterpillar, and Implications for Livestock and Humans

True setae borne on the abdominal tergites of Ochrogaster lunifer Herrich-Schӓffer caterpillars are the agents of an irritating contact dermatitis, osteomyelitis, ophthalmia, and severe allergic reactions in humans, and are the cause of Equine Amnionitis and Fetal Loss in Australia. The setae are detached and readily dislodge from the integument whereby they disperse throughout the environment. To better understand the true setae of O. lunifer as agents of medical and veterinary concern, we studied their characteristics and distance dispersed. Whereas members of the European Thaumetopoeinae have been widely studied, their southern-hemisphere counterparts such as O. lunifer are not well known despite their harmfulness and known medical and veterinary importance. The caterpillar's investment in true setae increased with age and size, and two distinct size classes co-occurred in setae fields. A previously undescribed morphological type of true seta was found on the first abdominal segment. All true setae were calculated to travel long distances in the air even under light breeze conditions. Our results show there is a high risk of exposure to airborne urticating setae within 100 m of elevated caterpillar activity, and a likely risk of exposure for some kilometers in the direction of the prevailing breeze. This information should be used to inform management strategies in areas where urticating processionary caterpillars are active, and especially during periods of an outbreak.

Poisonous setae on a Baltic amber caterpillar

The knobbed setae on a small caterpillar in 45-55 million years old [Eocene] Baltic amber were studied and characterized as urticating, with evidence of liquid release implying the production of poisons. It is presumed that the caterpillar had been disturbed just prior to falling into the resin, as some of its setae showed defensive responses. The swollen tips of the setae are equipped with "trip hairs" and when disturbed, the tips release liquid deposits, some of which contain rod-like bodies. These setal responses to a disturbance are the first report of poisonous setal defense mechanisms in a fossil insect.

Venomous caterpillars: From inoculation apparatus to venom composition and envenomation

Envenomation by the larval or pupal stages of moths occurs when the victim presses their hairs. They penetrate the subcutaneous tissue, releasing toxins such as proteolytic enzymes, histamine and other pro-inflammatory substances. Cutaneous reactions, including severe pain, oedema and erythema are frequent local manifestations of caterpillar envenomation, but, in some cases, the reactions can evolve into vesicles, bullae, erosions, petechiae, superficial skin necrosis and ulcerations. Alternatively, some individual can develop allergic reactions, renal failure, osteochondritis, deformity and immobilization of the affected joints and intracerebral bleeding. Caterpillars produce venom to protect themselves from predators; contact with humans is accidental and deserves close attention. Their venoms have not been well studied, except for toxins from some few species. The present review brings together data on venomous caterpillars of moths, primarily addressing the available literature on diversity among the different families that cause accident in humans, the structures used in their defense, venom composition and clinical aspects of the envenomations. Understanding the molecular mechanisms of action of caterpillars' toxins may lead to the development of more adequate treatments.

Expert risk perceptions and the social amplification of risk: A case study in invasive tree pests and diseases

The Social Amplification of Risk Framework (SARF) is often used as a conceptual tool for studying diverse risk perceptions associated with environmental hazards. While widely applied, it has been criticised for implying that it is possible to define a benchmark 'real' risk that is determined by experts and around which public risk perceptions can subsequently become amplified. It has been argued that this objectification of risk is particularly problematic when there are high levels of scientific uncertainty and a lack of expert consensus about the nature of a risk and its impacts. In order to explore this further, this paper examines how 'experts' - defined in this case as scientists, policy makers, outbreak managers and key stakeholders - construct and assemble their understanding of the risks associated with two invasive tree pest and disease outbreaks in the UK, ash dieback and oak processionary moth. Through semi-structured interviews with experts in each of the case study outbreaks, the paper aims to better understand the nature of information sources drawn on to construct perceptions of tree health risks, especially when uncertainty is prevalent. A key conclusion is that risk assessment is a socially-mediated, relational and incremental process with experts drawing on a range of official, anecdotal and experiential sources of information, as well as reference to past events in order to assemble the risk case. Aligned with this, experts make attributions about public concern, especially when the evidence base is incomplete and there is a need to justify policy and management actions and safeguard reputation.

Processionary Moths and Associated Urtication Risk: Global Change-Driven Effects

Processionary moths carry urticating setae, which cause health problems in humans and other warm-blooded animals. The pine processionary moth Thaumetopoea pityocampa has responded to global change (climate warming and increased global trade) by extending its distribution range. The subfamily Thaumetopoeinae consists of approximately 100 species. An important question is whether other processionary moth species will similarly respond to these specific dimensions of global change and thus introduce health hazards into new areas. We describe, for the first time, how setae are distributed on different life stages (adult, larva) of major groups within the subfamily. Using the available data, we conclude that there is little evidence that processionary moths as a group will behave like T. pityocampa and expand their distributional range. The health problems caused by setae strongly relate to population density, which may, or may not, be connected to global change.

The allergenic protein Tha p 2 of processionary moths of the genus Thaumetopoea (Thaumetopoeinae, Notodontidae, Lepidoptera): Characterization and evolution

The allergenic Tha p 2 protein has been extracted recently from the urticating setae of the pine processionary moth Thaumetopoea pityocampa. In the present paper, we test for the occurrence of this protein in other Thaumetopoeinae, with a particular focus on members of the genus Thaumetopoea, as well as unrelated moth species, to better understand the physicochemical properties of the protein, the nature of encoding genes and their evolutionary history. Tha p 2 is encoded by the intronless gene Tha p 2 that is restricted to the processionary moths (Thaumetopoeinae, Notodontidae, Lepidoptera). Most of the species present two isoforms of Tha p 2 that can be interpreted as the result of heterozygosity in the single gene. The only exception is represented by Thaumetopoea wilkinsoni, in which 20 different isoforms occur in a single specimen, leading to the conclusion that, at least in this species, multiple copies of Tha p 2 exist. Serine, glycine, cysteine and leucine are abundant in Tha p 2, a protein well conserved among processionary moths. The predicted secondary structures of Tha p 2 indicate the presence of 3 α-helices and six β-barrels. Finally, the evolution of the gene and the protein was characterized by a combination of positive and negative selection, with the latter being more evident.

Size and dispersion of urticating setae in three species of processionary moths

Larvae of the processionary moths of the Palaearctic region bear urticating setae that are released against vertebrate predators, especially insectivorous birds. A few species are pests of forest and urban trees and, consequently, may threaten human and animal health during outbreaks, causing dermatitis, conjunctivitis and respiratory distress. Although some studies provide detailed information about the setae, particularly those of the pine processionary moth Thaumetopoea pityocampa, there is little knowledge on the morphological traits of the setae and their release by the larvae. In the present study we identify major traits of the setae of 3 species of processionary moth, T. pityocampa, T. pinivora and T. processionea, which are potentially helpful in the understanding of setae dynamics in the environment: (i) diameter and length of setae and (ii) analysis of dynamical properties of the setae in the airborne state. Setae are highly variable in size, with bimodal distribution in T. pityocampa and T. pinivora; in these 2 species, short and long setae are interspersed within the integument fields where they occur. The difference in the seta size has important consequences in dispersion, as smaller setae can spread 5 times further than their bigger counterparts. This information is relevant for a full understanding of the defensive importance of larval setae against natural enemies of the processionary moths, as well for elucidating the importance of the processionary setae as air pollutants, both close to the infested trees and at longer distances.

Setae from larvae of the northern processionary moth (Thaumetopoea pinivora, TP) stimulate proliferation of human blood lymphocytes in vitro

Larvae of the Northern pine processionary moth (Thaumetopoea pinivora, TP) carry microscopic needles (setae), which by penetrating skin and mucous membranes, may cause inflammatory/immune derived symptoms in man. In the present study the stimulatory effects of setae on human blood lymphocytes in vitro was investigated. Blood mononuclear cells were separated from venous blood or buffy coat of ten healthy individuals, six previously exposed to setae and four with no known exposure. Lymphoproliferation was measured as uptake of ³H-thymidine. Setae were prepared from TP larvae. Setae and saline setae extracts stimulated proliferation of T-lymphocytes in the presence of monocytic cells. Stimulation was pronounced in cells from persons who had been exposed to setae, and weak in cells from non-exposed donors. Chitin also induced lymphocyte proliferation in most donors, but to a lesser extent and independently of donor's previous exposure to setae. In conclusion, setae contain molecules that in the presence of monocytes activate human T-lymphocytes to proliferation. The antigenic nature of stimulatory molecules was supported by the significantly stronger lymphocyte response in persons previously exposed to setae than in non-exposed donors. The nature of such molecules remains to be defined.

The consequence of tree pests and diseases for ecosystem services

Trees and forests provide a wide variety of ecosystem services in addition to timber, food, and other provisioning services. New approaches to pest and disease management are needed that take into account these multiple services and the different stakeholders they benefit, as well as the likelihood of greater threats in the future resulting from globalization and climate change. These considerations will affect priorities for both basic and applied research and how trade and phytosanitary regulations are formulated.

Corneal inflammation from pine processionary caterpillar hairs

PURPOSE

Hairs from the caterpillar of the pine processionary moth, Thaumetopoea pityocampa, located in the pine forests of southern Europe and elsewhere, can become embedded in the cornea and conjunctiva. Disorders produced by the urticating hairs can be classified into a broad spectrum of severity from mild keratoconjunctivitis to anaphylactic shock. This report presents 3 cases that illustrate the range of corneal responses to embedded hairs of the processionary moth caterpillar.

METHODS

Case series and review of the literature.

RESULTS

A 51-year-old man (case 1), a 46-year-old woman (case 2), and a 67-year-old man (case 3) presented different manifestations as a result of contact with pine processionary caterpillar hairs. Case 1 had acute keratitis with decreased vision. He was treated with a corneal depot steroid 4 times daily for 3 months. After 4 months, he was asymptomatic. Case 2 had acute keratitis without vision symptoms. She was released without treatment, and 1 month later was asymptomatic. Case 3 experienced dry gritty sensations, probably because of blepharitis, but also presented asymptomatic caterpillar hairs embedded in the corneal stroma. He was instructed regarding lid hygiene for his blepharitis, and after 3 months the embedded caterpillar hairs had disappeared.

CONCLUSIONS

The most common ocular presentation of embedded hairs from the pine processionary moth caterpillar is keratitis. The urticating hairs can cause corneal infiltrates that disappear progressively over time. Steroid eye drops accelerate the resorption of these infiltrates.

Insect stings: clinical features and management

BACKGROUND

In human beings, local and systemic reactions can be caused both by blood-sucking insects and by venomous insect stings. In Central Europe, the insects that most commonly cause such reactions are honeybees, certain social wasps, mosquitoes, and flies.

METHODS

This article is based on a selective literature review, including guidelines from Germany and abroad.

RESULTS

Insect venom induces a toxic reaction at the site of the sting. Large local reactions are due to allergy and occur in up to 25% of the population; as many as 3.5% develop IgE-mediated, potentially life-threatening anaphylaxis, of which about 20 people die in Germany each year. Mastocytosis is found in 3% to 5% of patients with sting anaphylaxis, rendering these patients prone to very severe reactions. Blood-sucking by hematophagous insects can elicit a local allergic reaction, presenting as a wheal or papule, in at least 75% of the population. Large local reactions may ensue, but other diseases are rare. The acute symptoms of an insect sting are treated symptomatically. Patients who have had a systemic reaction or a large local reaction due to insect allergy must take permanent measures to avoid further allergen contact, and to make sure they can treat themselves adequately if stung again. Most patients with systemic anaphylactic reactions to bee or wasp stings need specific immunotherapy.

CONCLUSION

Insect stings can cause severe disease. Anaphylaxis due to bee or wasp stings is not a rare event; specific immunotherapy protects susceptible persons from further, potentially life-threatening reactions.

Urticating hairs in arthropods: their nature and medical significance

The ecological phenomenon of arthropods with defensive hairs is widespread. These urticating hairs can be divided into three categories: true setae, which are detachable hairs in Lepidoptera and in New World tarantula spiders; modified setae, which are stiff hairs in lepidopteran larvae; and spines, which are complex and secretion-filled structures in lepidopteran larvae. This review focuses on the true setae because their high density on a large number of common arthropod species has great implications for human and animal health. Morphology and function, interactions with human tissues, epidemiology, and medical impact, including inflammation and allergy in relation to true setae, are addressed. Because data from epidemiological and other clinical studies are ambiguous with regard to frequencies of setae-caused allergic reactions, other mechanisms for setae-mediated disease are suggested. Finally, we briefly discuss current evidence for the adaptive and ecological significance of true setae.

Pruritic dermatitis on an oil tanker after a visit to French Guyana

A 40-year-old seaman presented to our emergency department with a severe pruritic skin reaction on his limbs and neck after visiting French Guyana on an oil tanker. Twenty crewmembers had had the same complaints. The harbor in French Guyana had been devastated by an invasion of Hylesia metabus, a moth that can cause a serious dermatitis due to contact with the hairs (setae) of the female moth. Complaints due to contact with caterpillars, butterflies, or moths is called lepidopterism. The complaints are self-limiting, and treatment is symptomatic. Due to the increasing amount of travelers and the normally harmless character of butterflies and moths, we would like to heighten the awareness of this relatively unknown condition.