Gregarine and Beauveria bassiana Infections of the Grey Corn Weevil, Tanymecus dilaticollis (Coleoptera: Curculionidae)

摘要

As an economically important insect pest, the adults of the grey corn weevil, Tanymecus dilatlcollis (Coleoptera: Curculionidae) were investigated for presence of pathogens. In 2009 and 2011, 1069 specimens were collected from maize and sunflower crops in 6 localities in Northern Bulgaria and studied in the laboratory. As a result of this study infections caused by a septate gregarine and Beauveria bassiana were established. In 2009, the prevalence of gregarine was 29.8% and of the fungi was 26.8%. Protozoan diseases were not found in the populations of T. dilaticollis investigated in 2011 but the weevils killed by mycosis were 52.55% ± 7.04 from all 901 analysed adults of the grey corn weevil. Morphometrical data about the gregarine found in the weevils were presented. Some isolates of B. bassiana were obtained in pure cultures. Occurrence of pathogens in T. dilaticollis populations was discussed with the view to their role as natural regulators of pest population density. The gregarine parasiteis reported for first time for T. dilaticollis.