Factors affecting Thaumetopoea pityocampa emergence in laboratory conditions

Abstract

To investigate the factors affecting the emergence of the pine processionary moth (Thaumetopoea pityocampa) in laboratory conditions, a number of 1487 larvae, prepupae and pupae were collected in the period February-May 2019 from five pest habitats: Fotinovo and Kandilka villages (inhabited by a summer phenological form), Sandanski and Klisura towns (winter phonological form occurs) and Sarnak village (both forms occur). At the date of collection, the rate of parasitism was very low (0-0.1%). Throughout the study, significant differences in the characteristics of pupal stage and mortality between both phenological forms were established. The rate of emerged adults varied from 21.4% to 77.6% in the observed habitats. The sex ratio between female and male specimens was almost equal. Only 0.6% of samples emerged in the second year, after diapause. In four localities (Fotinovo, Kandilka, Sandanski and Sarnak), the rate of infection by entomopathogens was between 6.0% and 20.8%, and the parasitism caused by tachinids – between 0.9% and 3.4%. The flight period of the summer and winter phenological forms of T. pityocampa were clearly differentiated with about a month. In summer form, the flight began in late May and ended in the last decade of June, and in winter form – from early July to the end of August. The duration of the flight period in both forms lasted 30 to 50 days with an equal number of emerged male and female specimens.