The pine processionary caterpillar Thuumetopoea pityocumpa is one of the pine defoliators of high economic importance, especially in forests of the Mediterranean. Various species of Pinus serve as food plants to this polyphagous forest pest. To observe the effects of different pines on the development and mortality, newly hatched larvae from egg batches collected at Kassandra/Greece were treated with 13 different species of pines and with one species of larch. Pinus mugo Turra was taken as the standard host plant and the effects shown by the caterpillars feedin on other pine needles were compared with those feeding on P. mugo. The pine twigs used for t8e current study were made available by *Berggarten" of Hannover.Cateroillars fed with the needles of P. strobus L.. P. oarvzfloru S. & Z.. P. cembru L.. P.wullichiaha Jacks and Lurix kaempferi (Lamb.) Car;. sh'owed a delayed larval development.Moreover, a 100 Yo mortality could be observed within the first instar in the larvae feeding on P. purvifora and within the second instar in those feeding on P. strobus and L. kaempferi. The larvae fed with P. cernbru needles could live till third instar. Though some of the mature larvae fed on P. wallichiunu (= P. excelsu Wall.) migrated into the soil (larval mortality 96.7 Yo), none of the pupae could survive.The difference in the mean pupal weight could not be statistically verified in pupae of those cater illars which had fed on P. contortu Dougl., P. nigru Am., and P. leucodermis Ant., although the larvafmortality was recorded to be 11.7 YO, 43.3 YO and 33.3 YO, respectively. The mean pupal weight of other groups ranged from weakly to highly significant level.
Studies on nests of the pine processionary caterpillar were carried out in different parts of Greece in the years 1985 to 1988. Most of the nests could be found at the southeast, south and southwest of pine trees. Deviations in the distribution could be due to the slope of forests and a high population pressure. Registering of temperature data verified that the inner temperature of the caterpillar nests could rise quite high. Such a warming is clearly dependent on the intensity of the insolation and the thickness of the nest webs. The biogenic heat production has not a significant role.
The thermoeconomy of nests of the 5th instar larvae of Tbaumetopoea pityocampa was studied under laboratory conditions. Measurements over a period of several days showed an up and down in the inner temperature corresponding to the activities of the caterpillars: As the animals left the nest, the temperature inside the nest decreased quickly below than that of the surroundings, which is explained as an effect of transpiration. When the cater illars returned to the nest, the temperature increased to a maximum value of about 1.5"C over that ofthe surroundings. This rise in temperature is contributed by the biogenic heat production.Using an infrared lamp as light and heat source, the inner temperature of the nest was measured which rose very high. Although the nest temperature was above 32 "C neither the caterpillars came out nor a higher mortality could be observed. After switching the lamp off, as contributed by the web insulation and the aggregation of caterpillars, a storing of thermal energy could be recorded for several hours.As evidenced by the present and earlier studies, a great role of web thickness and solar energy on the development of pine processionary caterpillar could be revealed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.