Abstract

A field bioassay was conducted at Ndashi Etche, Rivers State, Nigeria to evaluate the biocidal potential of selected plant extracts against a millipede species(Spirostreptus assiniensis (Diplopoda: Spirostreptidae), infesting cassava (Manihot esculenta Crantz). The treatments comprised plant extracts from neem (Azadirachata indica), uziza (Piper guineense) and dragon tree (Dracenea arborea) and were arranged in a randomized complete block fashion. The cassava variety employed was Etche Local best. The plot size was 4 × 4 m and there were a total of 11 plots replicated three times including control. Cuttings treated with neem (A. indica) at 150 g/l and D. arborea at 150 g/l had fewer numbers of holes (2.5 - 6.0) compared with control (10.0). Similarly, treated cuttings significantly produced taller plants (30 - 44.5 cm) than untreated ones. Furthermore, mortality of the millipedes was highest among plants treated with neem (A. indica) (3.9), D. arborea (3.7) and uziza (P. gunineense) (3.4) in contrast to the control (0.0).

Key words: Spirostreptus assiniensis, Manihot esculenta, plant extracts, mortality.