Structure, ooparasitoid spectrum and rate of parasitism of egg‐batches of Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae) in Greece¹²

Abstract

In the years 1988/89,222 egg-batches of the pine processionary caterpillar Thaumetopoea pityocampa (Den. & Schiff.) collected in Greece were studied in the laboratory for one year. Data on structure and size of the batches as well as a method rendering quite accurate estimates of the number of eggs per batch are presented. Altogether 10 871 parasitoids belonging to 6 species of Chalcidoidea emerged from the samples. The three most abundant species were Eutetrastichus servadeii (Dom.), Ooencyrtus pityocampae Mercet and Eutetrastichus sp. near servadeii. In the samples collected on Kassandra (KI) and on the Peloponnes (P) in autumn 1988 shortly after oviposition, the number of emer ing primary arasitoids was largely related to the duration of field exposure of the batches. Caterpiflars hatched from 67 YO of the eg s of these sample units. In egg-batches collected on Kassandra after 7 months of exposure in the f i e d (KII) a much greater parasitoid impact was observed. Not only did they yield more adult parasitoids throughout the first year; a striking difference was the much higher proportion of eggs without hatching or emergence holes, a majority of which showed signs of parasitoid attack.Only 4 % of the eggs appeared to be sterile after one year. Host mortality in the KII egg-batches was calculated to be 63 %.

Egg parasitoids of Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae) and their impact in SW Turkey

“…The distance from the base of the needles varied from 0 to 22 mm, as known from the other regions mentioned. The mean number of eggs per batch was slightly lower in Bulgaria than at Marikostino ( Tsankov et al., 1995, 1996a, 1998) and more similar to the numbers found in the Rhodopes ( Mirchev et al., 1998b) and in Greece ( Bellin et al., 1990; Schmidt , 1990). Much lower numbers of eggs per batch were found in Israel ( Kitt and Schmidt , 1993), Algeria ( Tsankov et al., 1995) and Morocco ( Schmidt et al., 1997a), where mean of 165–180 eggs per batch were counted.…”

“…In SW Turkey, only two species of egg parasitoids were mainly responsible for the reduced survival of the embryonic stages of the host; both can occur in the same egg batch. As in other mountainous regions ( Bellin et al., 1990; Tsankov et al., 1995; Schmidt et al., 1997b; Mirchev et al., 1998b, 1999), B. servadeii was most abundant, except at Igdecik, where O. pityocampae was more densely populated reaching 65.1% of the total impact of egg parasitoids. Considering both O. pityocampae and B. servadeii , most of the parasitized eggs, from which adults emerged before sampling of the egg batches, showed a light meconium, indicating that the host embryo was attacked at an early developing stage, because no remains of the caterpillar were found, except in very few eggs.…”

“…In eggs of T. pityocampa , parasitism starts directly after host oviposition and is maintained almost until termination of the embryogenesis of the host ( Kitt and Schmidt , 1993; Tsankov et al., 1996b). The probability of the parasitoids to find and attack egg batches will be increased with their abundance and the exposure time of the egg batches ( Bellin et al., 1990). If the abundance of parasitoids is low, their impact will be reduced and not all egg batches of the region will be parasitized, as shown in the eastern Rhodopes ( Mirchev et al., 1998b) and in Israel ( Kitt and Schmidt , 1993).…”

“…In the mountainous part of NE Albania 15.2–23.2% of egg parasitism was recorded ( Mirchev et al., 1999). In Greece, a lower rate of eggs was found parasitized ranging from 14.7 to 28.3% ( Bellin et al., 1990; Schmidt et al., 1997a; Tsankov et al., 1999). For Italy, Tiberi (1990) reported a range of egg parasitoid impact from 6% to little more than 30%, depending on the region.…”

Establishment and expansion of a Thaumetopoea pityocampa (Den. & Schiff.) (Lep. Notodontidae) population with a shifted life cycle in a production pine forest, Central-Coastal Portugal

“…The hatching rate of both T. pityocampa populations in the Leiria Forest was in fact high -above 85% -when compared to egg-batches collected around the Mediterranean basin -15-80% -most mortality being due to parasitoids (Bellin et al, 1990;Tsankov et al, 1995;Tsankov et al, 1998;Schmidt et al, 1999). The SP egg mortality was the lowest ever found for the species, and most of the egg-batches had no parasitized eggs at all.…”