ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 100, No. 3 (2013), p. 293–302
Species diversity of weevils (Ceutorhynchus spp.), migration activity and damage in winter and spring oilseed rape
Birutė VAITELYTĖ, Irena BRAZAUSKIENĖ, Eglė PETRAITIENĖ
Species diversity of weevils (Ceutorhynchus) and their migration activity in winter and spring rape crops were studied at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry during 2010–2012. Yellow water traps were used for collecting adults of Ceutorhynchus species and their oviposition and larvae development were evaluated on the petioles, stems and pods of winter and spring rape plants. The abundance of weevils (Ceutorhynchus spp.) was much higher in the winter rape crop in comparison with spring rape. The following three species prevailed in winter and spring rape: Ceutorhynchus pallidactylus, C. typhae and C. obstrictus. The flying activity of C. pallidactylus in the winter rape crop annually started at growth stage (GS) 39 and lasted for 4–5 weeks; however, in the spring rape crop – at GS 9 and lasted for only 1–2 weeks. Oviposition of C. pallidactylus lasted for 2–4 weeks in both crops. The peak amount of C. pallidactylus larvae was recorded at GS 65–67 in winter and at GS 57–61 in spring rape crop. Larvae in petioles and stems in winter and spring rape were detected for 5–6 weeks. A high abundance of C. obstrictus adults in winter rape was recorded at GS 65–73; however, migration of this insect to the spring rape crop was week during all experimental period. In the winter rape crop, oviposition of C. obstrictus lasted for 2–3 weeks and in spring rape for 1–2 weeks. The largest number of C. obstrictus larvae was determined at GS 73–79 in winter rape, at GS 67–75 in spring rape. Strong and significant (p = 0.05*, p = 0.01**) correlations were established between the abundance of C. pallidactylus larvae/plant and percent of damaged stems (r = 0.909**), also between abundance of C. pallidactylus larvae/plant and damaged stem length (r = 0.931**). C. obstrictus larvae abundance in the pods also highly and significantly correlated with the percentage of damaged pods and seeds (r = 0.874*, r = 0.931**, respectively).
Key words: Brassica napus, Ceutorhynchus obstrictus, Ceutorhynchus pallidactylus.
Full text: 100_3_str38.pdf