Occurrence, biology and harmfulness of Galerucella lineola (F.) (Coleoptera, Chrysomelidae) - Part 1. Last year's (parent) beetles

Abstract

In Moravia in 1995 to 2006, the abundant occurrence of <i>Galerucella lineola</i> (F.) was used to study its occurrence, biology and harmfulness. An “alder” biological form was studied in <i>Alnus glutinosa</i> and <i>A. incana</i> mainly in Polnička Forest District (Žďár region) and a “willow” form in <i>Salix viminalis</i>, <i>S. triandra</i> and <i>S. caprea</i> in riparian and accompanying stands of the Svitava river near Bílovice nad Svitavou (Brno region). Imagoes leave their sites usually in the 1st half of May. In the course of 2.5 to 3 months, they damage on average 22.6 cm<sup>2</sup> leaves of <i>A. glutinosa</i> and <i>S. caprea</i> (of this value, males 3.2 times less than females). Males eat on average 15 times during 24 hours for a period of 3.5 minutes, i.e. in total 52 minutes (3.6% day). Females eat on average 36 times for a period of 7 min, i.e. 252 min (17.5% day). Imagoes copulate on average 10.2 times per day for a period of 67 min. For the whole period of reproduction (about 42 days), they copulate on average 428 times, i.e. for 20 days. Eggs are laid into groups of 3 to 20 (on average 14) pieces. Females lay 457 to 791 (on average 612) eggs, i.e. about 15 eggs per day. <i>Medina collaris</i> (Fall.) (Tachinidae) and <i>Townesilitus fulviceps</i> (Ruthe) (Braconidae) belong, among others, to the enemies of imagoes.