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

Abstract

Abstract: Egg parasitoids (Hym., Chalcidoidea) and egg parasitism were studied in 132 egg batches of the pine processionary moth collected from stands of Pinus nigra Arnold and P. brutia Ten. in SW Turkey, at four places in heights of 800–1010 m a.s.l. in October 1998, beyond the caterpillars’ hatch. The egg batches deposited on P. nigra were high‐significantly smaller than those found on P. brutia. In this mountainous regions, Baryscapus servadeii (Dom.) and Ooencyrtus pityocampae (Mercet) were the most abundant egg parasitoids of Thaumetopoea pityocampa (Den. & Schiff.). Considering the different sampling places, Trichogramma sp. was found maximally in 3.1% of the parasitized eggs. Additionally, the hyper‐parasitoid Baryscapusransversalis Graham (mean infestation 1.8%) and Pediobius bruchicida (Rond.) (0.1%), both occurring in both sexes, and Anastatus bifasciatus (Fonsc.) (0.1%), only females, were established. The primary parasitoid O. pityocampae dominantly parasitized the eggs placed near the top of the batches, and B. servadeii was found mainly in eggs near the base. The rate of parasitism of the egg batches was very variable. The impact of egg parasitoids and predators varied from 24 to 35.9% depending on the sampling place. The hatching rate of the caterpillars was reduced to 50.7–65.6%. Under laboratory conditions, the emergence dynamics of the parasitoids showed a peak of B. tranversalis in December of the year, in which the host eggs were laid. Baryscapus servadeii emerged mainly in March–May of the following year, when the second part of O. pityocampae appeared. A large part of both parasitoids emerged before sampling of the batches. In O. pityocampae 1.65% and in B. servadeii 2.23% males developed under laboratory conditions. A rate of 15.7% of O. pityocampae and 7.9% of B. servadeii died in the eggs. The polyembryonic Trichogramma sp. (see also Tsankov et al., 1996a) attacked 1.8% of the eggs. Up to 20 (mean 12) dead pupae were found in one egg. Minor parts of eggs were undeveloped (2.9%) and 0.6% totally empty.