Pine processionary

Abstract: The genus Thaumetopoea contains the processionary moths, a group of lepidopteran associated with forest trees, well known for the social behaviour of the larvae and for carrying urticating setae. The taxonomy of the genus is partly unresolved and a phylogenetic approach is lacking. The goal of this work is to produce a phylogeny for Thaumetopoea and to identify the main traits driving the evolution of this group. Eighteen mitochondrial and three nuclear genes were fully/partly sequenced. Markers were aligned and analysed singularly or in various combinations. Phylogenetic analyses were performed according to maximum likelihood and Bayesian inference methods. Trees obtained from largest data sets provided identical topologies that received strong statistical support. Three main clades were identified within Thaumetopoea and were further supported by several signatures located in the mitochondrial tRNAs and intergenic spacers. The reference topology was used to investigate the evolution of life history traits related to biogeography, host plant, ecology, and morphology. A multigenic approach allowed to produce a robust phylogenetic analysis of the genus Thaumetopoea, with the identification of three major clades linked to different ecological and life history traits. The first clade is associated with Angiosperm host plants and has a fast spring development of larvae on young foliage. The other clades have originated by one event of host plant shift to Gymnosperm Pinaceae, which implied a longer larval developmental time due to the lower nutritional quality of leaves. These clades showed different adaptations to such a constraint, the first with a switch of larval feeding to cold season (winter pine processionary moths), and the second with a retraction to high altitude and latitude and a development cycle extended over two years (summer pine processionary moths). Recent global warming is affecting all species and seems able to further shape the evolution of the group.

Abstract: Contact with the pine processionary caterpillar induces dermatitis, usually located in exposed areas, and, less frequently, ocular lesions through a toxic-irritative mechanism. Recently, the existence of an immediate hypersensitivity mechanism has been demonstrated, mainly in occupationally exposed patients Objective To present four patients who experienced allergic reactions (urticaria-angioedema and rhinitis-asthma) after non-occupational exposure to pine processionary caterpillar Patients and methods The four patients underwent allergy testing through skin prick tests (SPT), specific IgE detection and SDS-PAGE immunoblotting. One patient also underwent a specific bronchial challenge test with the pine processionary antigen Results In all patients, both SPT with the caterpillar extract and specific IgE were positive. Western blotting showed several IgE-binding bands with molecular mass values ranging from 18 to 107 kDa. A shift in the electrophoretic mobility of some of the relevant allergens occurred under the presence of a reductive agent (β-mercaptoethanol). The specific bronchial challenge test with pine processionary antigen performed in one of the patients also produced positive results. Conclusions The results of this study show an immunologic IgE-mediated immediate hypersensitivity mechanism in these reactions. The processionary caterpillar’s airborne urticating hairs or spicules should be considered, at least in some locations, not only as contact and occupational allergens, but also as seasonal aeroallergens

Abstract: Optimal group size of gregarious larvae is the result of a trade-off between the costs and benefits undergone by individuals living in groups of different sizes. Thus, females should adjust their clutch size to an optimal-minimum group size. In this study, we experimentally manipulated the size of colonies of pine processionary caterpillars, a capital breeder species, to test the hypothesis that a large group size enhances larval growth and survival. We also explored whether this relationship fits a quadratic or an asymptotic curve and estimated an optimum or a minimal-optimum group size. The results showed significant differences in the final larval sizes in the various treatments, being greater in the larger groups. In addition, according to the existence of a minimal-optimum group size, we found that a Piecewise Linear Regression fits the above relationship better than does a linear regression. Groups larger than 32 individuals did not differ in growth or survival parameters. Although the number of dead larvae per group did not differ between experimental treatments, large experimental colonies suffered a lower percentage of mortality. Thus, the probability of reaching the pupal stage was greater for larvae from large colonies because of dilution effects. Our results demonstrated a minimum group size, above which group size did predict larval growth or mortality, thereby explaining why pine processionary caterpillars live in large groups.

Abstract: This chapter presents the evolutionary history of Thaumetopoea species associated with pines, at different temporal and spatial scales. It corresponds to recent discoveries and ongoing works using sequencing technologies and population genetics. Most of the subchapters focus on the winter pine processionary moths T. pityocampa/T. wilkinsoni including a population with a shifted life cycle. Results concerning the summer pine processionary moth T. pinivora and the evolution of the whole genus are also presented. This chapter gives insights about the effects of Quaternary climate changes in different regions, and allow to study the contemporary changes due to the present climate warming.