H. KRUSTEVA, and O. KARADJOVA,
Plant Protection Institute, BG - 2230 Kostinbrod, Bulgaria
KRUSTEVA, H. and O. KARADJOVA, 2011. Impacts of triticale crop sowing date on the insect pest species composition and damage caused. Bulg. J. Agric. Sci., 17: 411-416
The effect of three sowing dates of triticale in the autumn of 2008 (September 30, October 10 and October 22) and 2009 (September 25, October 9 and October 26) on insect pest abundance and degree of damage to the crop by the main pest species was evaluated. Twenty-four insect species belonging to the orders Hemiptera (18 species), Coleoptera (1 species) and Diptera (5 species) were found to damage triticale shoots. Cereal flies have a major share in damaging triticale stems. The autumn wheat-shoot fly (Phorbia fumigata Meigen), and the frit flies Oscinella frit (Linnaeus) and Oscinella pusilla (Meigen) were the most damaging pests during the autumn vegetation period and Ph. fumigata was the dominant pest in both years of the study. The dipteran larvae mainly damaged triticale crops sown in the last decade of September and, in case of favorable climatic conditions, the first decade of October. Twelve leafhopper species of 3 families of the order Hemiptera were identified, among which family Cicadellidae was represented by the highest number of species. In 2008 the leafhoppers Psammotettix provincialis (Ribaut) and Psammotettix striatus (Linnaeus) were the dominant species, while in 2009 Empoasca pteridis (Dahlbom) and Hardya anatolica Zachvatkin were dominant. Infestation by aphids was reported only in the crops with earliest sowing dates (September), where the dominant species was Sitobion avenae (Fabricius). During the two years of the study most of the identified insects have demonstrated highest harmfulness in triticale crops from the first sowing period. Sowing the crop in later periods (second and third decades of October) could therefore be recommended in order to prevent or diminish pest damages on triticale.