Pine processionary: Difference between revisions
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== History of study == |
== History of study == |
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[[Dioscorides]] noted the urticating hairs <ref name="Roques 2015">{{cite book |last=Roques |first=Alain |title=Processionary moths and climate change : an update |publisher=Springer |publication-place=Dordrecht |year=2015 |isbn=978-94-017-9339-1 |oclc=893559920 | page=1}}</ref>of the pine-dwelling ''pityocampes'' caterpillar in his 77 AD book ''[[De materia medica]]''. |
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The French entomologist [[Jean-Henri Fabre]] conducted a famous study on the pine processionary caterpillar where a group of them followed head-to-tail in a circle around the rim of a flower pot; they continued marching in the circle for a week. He described the experiment in his 1916 book ''The Life of the Caterpillar''.<ref name="Fabre 1916 Procession">{{cite book |last=Fabre |first=Jean-Henri |author-link=Jean-Henri Fabre |title=The Life of the Caterpillar |year=1916 |url=http://www.efabre.net/chapter-iii-the-pine-processionary-the-procession |at=Chapter III: The Procession}}</ref> The study has been cited innumerable times by inspirational and religious speakers who view it as a metaphor for blindly following a leader or for confusing activity with accomplishment.<!--<ref name="Fitzgerald 2003"/>--> Fabre considered his caterpillars to be mindless automatons, trapped because they were pre-programmed to blindly follow trails, in this case the endless one that they had laid down around the circular rim of the pot.<ref name="Fitzgerald 2003"/> |
The French entomologist [[Jean-Henri Fabre]] conducted a famous study on the pine processionary caterpillar where a group of them followed head-to-tail in a circle around the rim of a flower pot; they continued marching in the circle for a week. He described the experiment in his 1916 book ''The Life of the Caterpillar''.<ref name="Fabre 1916 Procession">{{cite book |last=Fabre |first=Jean-Henri |author-link=Jean-Henri Fabre |title=The Life of the Caterpillar |year=1916 |url=http://www.efabre.net/chapter-iii-the-pine-processionary-the-procession |at=Chapter III: The Procession}}</ref> The study has been cited innumerable times by inspirational and religious speakers who view it as a metaphor for blindly following a leader or for confusing activity with accomplishment.<!--<ref name="Fitzgerald 2003"/>--> Fabre considered his caterpillars to be mindless automatons, trapped because they were pre-programmed to blindly follow trails, in this case the endless one that they had laid down around the circular rim of the pot.<ref name="Fitzgerald 2003"/> |
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Revision as of 10:52, 2 October 2021
| Pine processionary | |
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| Pine processionary larvae marching in characteristic fashion | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Superfamily: | Noctuoidea |
| Family: | Notodontidae |
| Genus: | Thaumetopoea |
| Species: | T. pityocampa
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| Binomial name | |
| Thaumetopoea pityocampa (Denis & Schiffermüller, 1775)
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The pine processionary (Thaumetopoea pityocampa) is a moth of the subfamily Thaumetopoeinae in the family Notodontidae. The species was first described by Michael Denis and Ignaz Schiffermüller in 1775. It is one of the most destructive species to pines and cedars in Central Asia, North Africa and the countries of southern Europe.[1] The urticating hairs of the caterpillar larvae cause harmful reactions in humans and other mammals. The species is notable for the behaviour of its caterpillars, which overwinter in tent-like nests high in pine trees, and which proceed through the woods in nose-to-tail columns, protected by their severely irritating hairs,[2] as described in 1916 by the French entomologist Jean-Henri Fabre. The species is one of the few insects where the larva develops in winter.
History of study
Dioscorides noted the urticating hairs [3]of the pine-dwelling pityocampes caterpillar in his 77 AD book De materia medica.
The French entomologist Jean-Henri Fabre conducted a famous study on the pine processionary caterpillar where a group of them followed head-to-tail in a circle around the rim of a flower pot; they continued marching in the circle for a week. He described the experiment in his 1916 book The Life of the Caterpillar.[4] The study has been cited innumerable times by inspirational and religious speakers who view it as a metaphor for blindly following a leader or for confusing activity with accomplishment. Fabre considered his caterpillars to be mindless automatons, trapped because they were pre-programmed to blindly follow trails, in this case the endless one that they had laid down around the circular rim of the pot.[5]
More recent studies, however, indicate that Fabre's caterpillars were actually physically trapped on the narrow rim of the pot, their feet unable to gain the secure purchase that would be needed to descend its steep, vertical walls. In one experiment, groups of processionary caterpillars of the same age as those observed by Fabre were placed on a flat table top and surrounded be a circular glass ring, 8 inches (20 cm) in diameter and 1 inch (2.5 cm) high. The caterpillars soon moved to the edge of the arena where they began to circle, one behind another. They were allowed to process like this until they had a well-established trail along the edge of the ring. The ring was then removed; the circular processions persisted for an average of just two minutes before the caterpillars marched off in a straight line. However, when circular trails were established by younger caterpillars they continued to circle for as long as 12 hours after the physical constraint was removed.[5][6]
Life cycle
Though most pine processionary moths only live one year, some in high altitudes or more northern areas may survive for over two years. The adult moths lay their eggs near the tops of pine trees. After hatching, the larva eat pine needles while progressing through five stages of development (instars). To survive through the winter, the caterpillars construct a nest of silk threads, making them one of the few species of insect where the larvae develop in winter. Around the beginning of April, the caterpillars leave the nests in the procession for which the species is known. They burrow underground and emerge at the end of summer.[7]
The eggs are laid in cylindrical bodies ranging from 4 to 5 centimetres (1.6 to 2.0 in) in length. The eggs are covered with scales which come from the female and mimic pine shoots.[7]
The larva is a major forest pest, living communally in large "tents", usually in pine trees but occasionally in cedar or larch, marching out at night in single file (hence the common name) to feed on the needles. There are often several such tents in a single tree. When they are ready to pupate, the larvae march in their usual fashion to the ground, where they disperse to pupate singly on or just below the surface.[8][9]
The moth's pupal stage occurs in a white silken cocoon under soil. The pupae measure around 20 millimetres (0.79 in) and are a pale brownish-yellow that changes into a dark reddish brown.[7][9]
As an adult, T. pityocampa has predominantly light brown forewings with brown markings. The moth's hindwings are white. Females have larger wingspans of 36 to 49 millimetres (1.4 to 1.9 in), compared to a male's 31 to 39 millimetres (1.2 to 1.5 in).[7] Adults only live for a single day, when they mate and lay eggs. How far they are able to spread depends on how far the female is able to fly during her short time as an adult. Her average flying distance is 1.7 kilometres (1.1 mi), with a maximum recorded of 10.5 kilometres (6.5 mi). The species flies from May to July.[8]
Behaviour
Shelter building
T. pityocampa is highly social. Throughout its life cycle, an individual makes several shelters. The first of these is flimsy and temporary, but in the third instar, they build a permanent nest. Once the permanent nest is built, the caterpillars become foragers, staying in the vicinity of the nest. The nest has no openings, so caterpillars force themselves through the layers of the shelter. The waste from the larvae's diet falls as frass and accumulates at the bottom of the nest.[8][9]
Processions
Lengthy processions are formed when fully grown caterpillars abandon their host tree in search of pupation sites, when as many as three hundred caterpillars may travel long distances from the natal tree looking for soft soil in which to bury themselves and form cocoons. During processions, stimuli from setae on the tip of the abdomen of the caterpillar in front serve to hold processions together, taking priority over the trail pheromone or silk.[5][8]
Interactions with humans
Skin and eye irritation
In the third and subsequent instars of their development, pine processionary caterpillars defend themselves from predators with conspicuous hairs containing an irritant chemical. Simple contact with the hairs of the caterpillar can cause severe rashes (urticaria) and eye irritation in humans and other mammals, and some individuals may have an allergic reaction.[9][10] When stressed or threatened, fifth-stage larvae eject hairs shaped like harpoons, which penetrate all areas of exposed skin nearby and irritate them with an urticating protein.[9]
Forestry damage
The pine processionary is a major economic pest in coniferous forests in southern Europe,[9] where the caterpillar is responsible for most of the defoliation seen in coniferous trees; outbreaks are somewhat cyclical, with a period of 7 to 9 years.[11] Although pines are the most susceptible, other conifer trees such as larches are also vulnerable. The caterpillars can completely defoliate trees if large quantities are present.[8]
Natural controls
The species is controlled to some extent by predators, parasites and viruses which attack the moth at many stages of its life cycle.[9] For example, eggs are eaten by the orthopteran Ephippiger ephippiger, while larvae are eaten by birds such as great tit (Parus major) and great spotted cuckoo (Clamator glandarius). Larvae are parasitised by solitary wasps (Ichneumonidae, Braconidae) and some species of flies (Tachinidae), and may be infected by the processionary moth virus Smithiavirus pityocampae. Pupae are eaten by hoopoes (Upupa epops), while adults are eaten by bats.[9]
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Mantis religiosa eating caterpillar, Pyrenees
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Calosoma sycophanta beetle eating caterpillar, Turkey
Artificial control
Efforts to control the pine processionary have included biological control using Bacillus thuringiensis, which is effective on eggs and first- or second-stage caterpillars (in September or October), or insecticides such as diflubenzuron, an insect growth regulator, which can be sprayed from aircraft. Monitoring can include the use of pheromone traps. Older methods used insecticides in oil, inserted directly into nests, or mechanical removal of nests.[12] [13]
References
- ^ Kerdelhué, Carole; Zane, Lorenzo; Simonato, Mauro; Salvato, Paola; Rousselet, Jérôme; Roques, Alain; Battisti, Andrea (2009). "Quaternary history and contemporary patterns in a currently expanding species". BMC Evolutionary Biology. 9 (1): 220. doi:10.1186/1471-2148-9-220. ISSN 1471-2148. PMC 2753568. PMID 19732434.
{{cite journal}}: CS1 maint: unflagged free DOI (link)
- ^ Oliveira, P. (2003). "Cinco casos clínicos de intoxicação por contacto com a larva Thaumetopoea pityocampa em cães" [Report of poison in five dogs after contact with Thaumetopoea pityocampa] (PDF). Revista Portuguesa de Ciências Clinicas (in Portuguese). 89 (547). Arnaldo, P. S.; Araújo, M.; Ginja, M.; Sousa, A. P.: 81–84. Archived from the original (PDF) on 28 July 2007. Retrieved 2 October 2021.
- ^ Roques, Alain (2015). Processionary moths and climate change : an update. Dordrecht: Springer. p. 1. ISBN 978-94-017-9339-1. OCLC 893559920.
- ^ Fabre, Jean-Henri (1916). The Life of the Caterpillar. Chapter III: The Procession.
- ^ a b c Fitzgerald, Terrence D. (2003). "The role of a trail pheromone in the foraging and processionary behavior of Thaumetopoea pityocampa". Journal of Chemical Ecology. 29 (3): 513–532. doi:10.1023/a:1022875102682. ISSN 0098-0331.
- ^ Fitzgerald, Terrence D. (September 2008). "Lethal Fuzz: Toxic hairs enable some caterpillars to venture forth in conspicuous processions". Natural History Magazine. 177 (7): 28–33.
- ^ a b c d "Pest profile: pine processionary moth" (PDF). Impact Project. Archived from the original (PDF) on 4 March 2016. Retrieved 2 July 2013.
- ^ a b c d e "Pine processionary moth (Thaumetopoea pityocampa)". Forest Research. Retrieved 2 October 2021.
- ^ a b c d e f g h Bonnet, Catherine; Martin, Jean-Claude; Mazet, René (2008). "La Processionnaire du Pin" [The Pine Processionary] (PDF). Stantari (in French) (14 (August–October 2008)). INRA: 29–33. Archived from the original (PDF) on 4 October 2011. Retrieved 2 October 2021.
- ^ Fabre, Jean-Henri (1916). The Life of the Caterpillar. Chapter VI: The Stinging Power. Archived from the original on 9 July 2013.
- ^ Li, S.; Daudin, J.J.; Piou, D.; Robinet, C.; Jactel, H. (9 June 2015). "Periodicity and synchrony of pine processionary moth outbreaks in France". Forest Ecology and Management. 354: 309–317. doi:10.1016/j.foreco.2015.05.023.
- ^ "Processionaria do Pinheiro: Diagnostico e Meios de Controlo" [Pine Processionary: Diagnostics and means of control] (PDF) (in Portuguese). ICNF.pt. Retrieved 2 October 2021.
- ^ "Enquadramento Legal do Regime Florestal" [Legal Framework of the Forest Regime] (in Portuguese). ICNF.pt. Retrieved 2 October 2021.
External links
- Kimber, Ian. "71.002 BF2021 Pine Processionary Thaumetopoea pityocampa ([Denis & Schiffermüller], 1775)". UKMoths. Retrieved 4 July 2019.
- INRA website: Processionnaire du pin (in French)
- Wildlife in France: Pine processionary moth
- https://orugaprocesionaria.org/ (in Spanish)