A contribution to the knowledge of biology and harmfulness of Deporaus betulae (L.) (Coleoptera, Attelabidae)

Abstract

The paper deals with the occurrence, development and harmfulness of Deporaus betulae (L.). The majority of field studies was carried out at Training Forest Enterprise (TFE) Masaryk Forest in Křtiny (District Brno-venkov) in 2010 and 2011. In addition to this, the species was studied in detail also in a laboratory. It occurred mostly on Betula pendula and Carpinus betulus. Rarely, the species was found on Alnus glutinosa and Corylus avellana and only sporadically on Fagus sylvatica, Quercus petraea, Tilia cordata and T. platyphyllos. In the studied area, larvae and pupae hibernate. Beetles occur on trees from the end of April to the beginning of July, sporadically later. Females lay on average 2.5 (in the laboratory 4.4) eggs into rolls on B. pendula, on C. betulus 2.2 eggs. During two months, they damage on average 5.3 cm2 leaves creating 14 rolls and laying 35 eggs into the rolls. Larvae consume only 1.7 cm2 leaf blade. The development of the species takes three to four months from egg laying to the departure of larvae into soil. On leaves of B. pendula of an average area of 14.2 cm2, females roll up the same area (about 11.2 cm2) as on leaves of C. betulus of an area of 21.7 cm2. Into the rolls, they lay on average the same number of eggs. The average number of eggs in rolls increases with the increased area of B. pendula leaf blade. Trees partly compensate for the reduction of assimilatory area also by the growth of the area of neighbouring undamaged leaves (on average by 12.7 %).