Influence of spacing on the feeding activities of major pests of sunflower and their associated damage

Abstract

The experiment was conducted in the Floriculture experimental field of National Horticultural Research Institute (NIHORT) Ibadan, Oyo State, Nigeria (3 0 52’E and 7 0 25’N) between August and November 2009 and repeated between July and October 2010. Sunflower seeds were sown directly on prepared field using the following spacing: 65 cm x 75 cm, 75 cm x 75 cm, 85 cm x 75 cm and 100 cm x 75 cm on 3 m by 3 m plot size with 1m distance between and within plot and laid out in a randomized complete block design (RCBD) with three replicates. The insects observed were: the Sunflower beetle (Zygogramma exclamationis Fabricius (Coleoptera: Chrysomelidae), Spittlebug (Poophilus adustus Walker (Hemiptera: Cercopoidae), Variegated grasshopper (Zonocerus variegatus Linnaeus Orthoptera: Pyrgomorphidae), Sunflower stem weevil (Cylindrocopturus adspersus Leconte (Coleoptera: Curculionidae), Pachnoda cordata Drury (Coleoptera: Cetoniidae) and Atelocera raptoria Germar (Hemiptera: Pentatomidae). Spacing 65 cm x 75 cm significantly gave a high insect population than other treatments while lowest insect population and highest seed yield were observed in spacing 100cm x 75cm. The highest damaged leaves (48.60, 51.25), stems (22.25, 25.10), and flower heads (23.50 and 27.20) in 2009 and 2010 respectively were observed in plants with 65 cm x 75 cm spacing.