Thaumetopoea pityocampa (Denis and Schiffermüller)
Taxonomic placing: Insecta, Holometabola, Lepidoptera, Thaumetopoeidae.
Common name: Winter pine processionary moth.
Geographical distribution: The western Mediterranean region, reaching south-western Turkey in the Middle East, colonizing over 1,500,000 ha.
In the past the vicariants Thaumetopoea pityocampa and Thaumetopoea wilkinsoni Tams were often confused. However, a molecular study showed differences between the two species, which became separated before the Quaternary ice ages. CIE Entomology Map #366, 1977.
Host plants: Pines (Pinus spp.) and cedars (Cedrus spp.).
Morphology: The greyish adults bear transverse dark stripes and their heads are decorated with dense hairs. The young larvae are brown-yellow, becoming darker with each molt. All larvae bear red-brown tubercles with yellow-white detachable setae that bear hooked tips that break off easily. Their average length comes to 30 mm.
Life cycle: Thaumetopoea pityocampa is univoltine. Adults emerge and fly in August, laying eggs in September; the larvae hatch by the end of that month and the next (October). They form processions as they crawl along pine branches to find feeding sites and then rest in nests; an average nest holding about 210 larvae. They pass through five instars, pupating in the soil during May, June and July. Pine secondary plant constituents seem to determine the pest’s host selection processes.
Economic importance: The larvae feed on the needles which then drop; saplings may be entirely defoliated, causing tree dieback and even death. Fourth- and fifth-instar larvae consume all the needles of pine trees, so that they have to be burned. The average decrease in annual diameter increment for Calabrian trees in damaged areas, compared with healthy trees, can reach about 22%. This is a relatively new pest in Turkey, whose emergence has been attributed to the intense cultivation of conifers for afforestation of degraded soils and as ornamentals, and the recent expansion of the pest to upper elevations and latitudes. Outbreaks seem to be associated with dry winter and spring weather prior to the autumn and winter in which feeding occurs.
The stinging setae of the larvae break off easily and release a protein, thaumetopoein, which causes inflammations of eyes and of the respiratory system in humans and domestic animals, as well as allergies.
Management
Monitoring: The synthetic female sex pheromone of the pest is used for early detection of new infestation foci, timing of pesticide sprays and macromapping of infested and non-infested areas.
Chemical control: Organophosphates were formerly applied against the pest. Steam-distilled wood sulfate turpentine was the best of several essential plant oils tried in Turkey to control the pest. Preparations of Bacillus thuringiensis (Bt) may control the pest but two applications are required for satisfactory control. This is due to the prolonged, month-long emergence of the vulnerable young larvae, whose late members avoid the treatment, which does not persist on the needles.
Biological control: In Turkey the pest is attacked by several natural enemies, the more common being the egg parasitoids Ooencyrtus pityocampae and Baryscapus servadeii. The former attacks eggs near the top of the batches, whereas the latter was found mainly in eggs near the base of the batches. These egg parasitoids together reduced hatching rate to 51-65%. Entomopathogenic fungi applied against the pest in Turkey killed about 50% of the larvae.
References
Akinci,H.A., Ozman-Sullivan, S.K., Diler,H., Celik,N., Sullivan, G.M. and Karaca, G. 2017. Entomopathogenic fungi isolated from Thaumetopoea pityocampa and their efficacies against its larvae. Fresenius Environmental Bulletin 26: 5251-5257.
Battisti, A., Longo, S., Tiberi, R. and Triggiani, O. 1998. Results and perspectives in the use of Bacillus thuringiensis Berl. var. kurstaki and other pathogens against Thaumetopoea pityocampa (Den. et Schiff.) in Italy (Lep., Thaumetopoeidae). Anzeiger für Schädlingskunde, Pflanzenschutz, Umweltschutz 71: 72-76.
Carus, S. 2004. Impact of defoliation by the pine processionary moth (Thaumetopoea pityocampa) on radial, height and volume growth of Calabrian pine (Pinus brutia) trees in Turkey. Phytoparasitica 32: 459-469.
Devkota, B. and Schmidt, G. H., 1990. Larval development of Thaumetopoea pityocampa (Den. & Schiff) (Lep., Thaumetopoeidae) from Greece as influenced by different host plants under laboratory conditions. Journal of Applied Entomology 109: 321-330.
Halperin, J. 1986. Application of pityolure for detection and control of Thaumetopoea pityocampa in Israel. EPPO Bulletin 16: 627–632.
Kanat, M. and Alma, M.H. 2004. Insecticidal effects of essential oils from various plants. against larvae of pine processionary moth (Thaumetopoea pityocampa Schiff) (Lepidoptera : Thaumetopoeidae). Pest Management Science 60: 173-177.
Kanat, M., Sivrikaya, F. and Serez, M. 2002. A research on the effects of pine processionary moth (Thaumetopoea pityocampa Schiff), Pinus brutia, on trees and tending activities on the diameter increment of calabrian pine in Kahramanmaras. Symposium on the Pine Processionary Moth, Kahramanmaras, Turkey.
Mirchev, P., Schmidt, G. H., Tsankov, G. and Avci M. 2004. Egg parasitoids of Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae) and their impact in SW Turkey. Journal of Applied Entomology 128: 533-542.
Salvato, P., Battisti, A., Concato, S., Masutti, L., Partanello, T. and Zane, L. 2002. Genetic differentiation in the winter pine processionary moth (Thaumetopoea pityocampa-wilkinsoni complex), inferred by AFLP and mitochondrial DNA markers. Molecular Ecology 11: 2435-2444.
Solt, I. and Mendel Z. 2002. The pine processionary caterpillar Thaumetopoea pityocampa. Harefuah 141: 810-814 (in Hebrew).
Türkmen, H. and Ali Öner, Y. 2004. A human dermatitis caused by _ Thaumetopoea pityocampa (Denis and Schiffermüller, 1775) (order: Lepidoptera) caterpillars in Istanbul, Turkey. Allergy 59: 232-233.
Zhang, Q.-H., Schlyter, F., Battisti, A., Birgersson, G. and Anderson, P. 2003. Electrophysiological responses of Thaumetopoea pityocampa females to host volatiles: implications for host selection of active and inactive terpenes. Anzeiger für Schädlingskunde Pflanzenschutz, Umweltschutz 76: 103-107.