A review of Trichogramma Westwood parasitoids on eggs of Thaumetopoea pityocampa (Denis & Schiffermüller) in habitats of the Balkan Peninsula and Asia Minor

Abstract

Studies on egg parasitoids of the pine processionary moth (Thaumetopoea pityocampa) were conducted during the period 1991-2018 in native localities of the pest on the Balkan Peninsula and in Asia Minor. In Bulgaria the biological material (2510 egg batches and 579273 eggs) was collected in 48 host localities. A number of 650 egg batches and 135611 eggs were studied from the Balkan countries (North Macedonia, Bosnia and Herzegovina, Albania and Greece), and in the Asian part of Turkey (Asia Minor), the biological material was examined from nine habitats. Eight species of egg parasitoids (Ooencyrtus pityocampae, Baryscapus servadeii, B. transversalis, Pediobius bruchicida, Anastatus bifasciatus, Eupelmus vesicularis, E. vladimiri and Trichogramma sp.) were found. The total regulating effect of egg parasitoids in Bulgaria was on average 17.6%, and in the other Balkan countries – 24.9%. Trichogramma sp. was found in 63.1% of the analysed samples in Bulgaria and in 55.6% from the neighboring countries. The percent of parasitism of T. pityocampa eggs by Trichogramma sp. was low - on average 0.39% for Bulgaria and 0.73% for the other Balkan countries. The relative share of the species in the total percentage of parasitised eggs for Bulgaria and the other countries was 2.2% and 2.9%, respectively.