Occurrence, development and economic importance of Phratora (=Phyllodecta) vitellinae (L.) (Coleoptera, Chrysomelidae)
2006
Urban, J.(Mendelova Zemedelska a Lesnicka Univ., Brno (Czech Republic). Lesnicka a Drevarska Fakulta) E-mail:[email protected]
The studies of the occurrence, development and harmfulness of Phratora (= Phyllodecta) vitellinae were carried out in riparian and accompanying stands of the Svitava and Svratka rivers in the region of Brno, Czech Republic, and in a laboratory during the years 1998-2005. Imagoes leave hibernation places at the end of April and at the beginning of May. In captivity, they lived on Salix fragilis about 2.5 months damaging on average 28.6 cm2 leaf blades and laying on average 293 eggs. In the excessively warm growing season of 2005, imagoes lived about 3.5 months after hibernation, however, already after one month of feeding they fell in a month diapause at the beginning of June. Before its start, they damaged on average 12.8 cm2 (after the diapause 14.4 cm2) leaves and laid on average 389 eggs. Larvae damaged about 4 cm2 leaves during 2 to 3 weeks (in the laboratory during 12 to 13 days). After 2 to 3 weeks (in the laboratory after 10 to 12 days) from the cessation of feeding young beetles appeared on trees. Imagoes of the 1st generation occurred from mid-June to the beginning of October. During about 55 days of life, they damaged 19 cm2 leaves and laid on average 182 eggs. Imagoes of the 2nd generation occur from mid-August to the end of the growing season. After 10 to 14 days of feeding, they take shelter in wintering places. In the laboratory, however, these imagoes damaged about 19 cm2 leaves during 2 months and laid about 190 eggs. Wintering places were looked up by imagoes of the 3rd generation which damaged on average 4.2 cm2 leaves before hibernation. In the Czech Republic, P. vitellinae is usually bivoltine, the 2nd generation being always incomplete.
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