Thaumetopoea wilkinsoni Tams
Taxonomic placing: Insecta, Holometabola, Lepidoptera, Thaumetopoeidae.
Common name: Cyprus processionary caterpillar.
Geographical distribution: Cyprus, Israel, Jordan and Lebanon.
The vicariants Thaumetopoea wilkinsoni and Thaumetopoea pityocampa (Denis and Schiffermüller) were often confused in the past. A recent molecular study showed clear differences between the two species, which became separated before the Quaternary ice ages. Thaumetopoea wilkinsoni is restricted to the Middle East, whereas T. pityocampa is a more western species.
Host plants: Feeding of the pest is restricted to pines (Pinus spp.). In the Middle East young P. eldarica trees are preferred to P. brutia Tenore and P. halepensis Miller.
Morphology: The brownish adults, whose length is 17-22 mm, bear transverse dark stripes and their bodies are decorated with dense hairs. The young larvae are brown-yellow, becoming darker with each molt. At maturity they are almost black and attain a size of 40 mm. They bear tubercles with yellow-white detachable setae with hooked tips.
Life cycle: The pest is univoltine. Adults emerge in the autumn and lay their eggs in early winter. Each female lays many eggs, arranging them in rows around pine needles and covering them with reddish scales. The larvae emerge after 6-7 weeks and immediately form processions that march off to seek food. The young larvae feed only on the needles’ epidermis, but later consume entire needles. After a few days of feeding the larvae form a temporary communal nest, moving to another site as they crawl to look for fresh needles. Larval development lasts 4-6 months, pupation is in the soil and takes about 5 months.
Economic importance: The larvae feed on the needles, which causes their shedding; saplings may entirely be defoliated, causing die back and even (in dry years) tree death. Larger trees may recover, although totally defoliated branches remain. The external parts of the trees, especially young ones, are usually preferred. The larvae are armed with stinging setae that easily break off and release a protein, thaumetopoein, which causes inflammations of eyes and of the respiratory system in humans and domestic animals, as well as allergies. Large-scale pine reforestation programs undertaken in Cyprus and Israel have increased the importance of the pest.
Management
Cultural control: Mass male trapping is feasible with the pheromone pityolure.
Chemical control: Stem injections with an organophosphate cause about 100% mortality, as do implants of similar pesticides.
Biological control: Various stages of the pest are attacked by several natural enemies, the more common being the egg parasitoids Ooencyrtus pityocampae and Baryscapus servadeii.Ttogether these egg parasitoids reduced hatching rate to 51-65%.
References
Halperin, J. 1985. Detection and control of the pine processionary caterpillar, Thaumetopoea wilkinsoni , with pityolure. Phytoparasitica 13: 148-149.
Halperin, J. 1986. Acephate implants for control of the pine processionary caterpillar. Phytoparasitica 14: 97-100.
Kitt, J. and Schmidt, G. H., 1993: Parasitism of egg-batches of the pine processionary moth Thaumetopoea wilkinsoni (Lep., Thaumetopoeidae) in the mountains of Lahav (Israel). Journal of Applied Entomology 115: 484-498.
Mendel, Z. 1988. Host selection by the pine processionary caterpillar, Thaumetopoea wilkinsoni. Phytoparasitica 16: 101-108.
Mendel, Z. 1990. On the origin of the pine processionary caterpillar, Thaumetopoea wilkinsoni Tams (Lep., Thaumetopoeidae) in Israel. Journal of Applied Entomology 109: 311-314.
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.