Ecological characteristics of Thaumetopoea pityocampa Denis & Schiffermüller, 1775 (Lepidoptera: Notodontidae) in egg stage in Thasos Island, Greece

Abstract

In September 2017, 96 egg batches of Thaumetopoea pityocampa were collected from Aleppo pine (Pinus halepensis) trees at four sites of Thasos Island in Greece. In the different localities, the average number of eggs in batches varied from 196.5 to 223.9 (212.4 for the Thasos Island). The length of P. halepensis needles with egg batches differed in size - between 84 to 210 mm. Approximately 75% of batches were laid close to the middle of needles, between 121 and 180 mm. The egg masses were formed mainly on two needles (84.4%) and the rest - on one, three or four needles (13.6%) or on fine shoots (2%). In most cases (88.3%), the female moths started to lay eggs from the tip of the needle. The distance from the base of the needle to the beginning of the egg batches was established between 0 and 180 mm, as most of them (62.7%) were clustered around the average value (87.3 mm) in the diapason of 60-120 mm. The average rate of T. pityocampa survival in egg stage was 48%. The parasitized eggs were 43.8%, and the rest included unhatched eggs, predominately undeveloped eggs with dried-up yolk. No correlation was found between the percentage of parasitized eggs and the distance of the egg batches from the base of needles.