Evaluation of host plant resistance, sowing date modification and intercropping as methods for the control ofMylabris and Coryna species (Coleoptera: Meloidae) infesting pearl millet in the Nigerian Sudan savanna

Three experiments were laid out in 1997 and 1998 cropping seasons in Maiduguri (Sudan savanna), north-eastern Nigeria to assess damage by meloid beetles in six varieties (Ex-borno, Wame, Zongori, Gargasori, Mboderi and GB8735) of pearl millet sown as sole crops on 14, 21, 28 July and 5 August and as intercrops with cowpea (cv. Borno brown) or sorghum (cv. Gooseneck). Damage in pearl millet (cv. Ex-borno) arranged within rows of cowpea or sorghum in cropping patterns of 3:1, 2:1, 1:1 and 1:0 were also assessed. Four species, Mylabris afzelli (Bilb.), M. fimbriatus (Mars.), Coryna chevrolati (Blair.) and C. hermanniae (Fab.), were the only meloid beetles that attacked millet panicles in the duration of the study. Percentage damage by meloid beetles and grain yield loss were significantly higher in millets sown on 21 July or earlier (early sown millet) than in those sown later in both 1997 and 1998; damage and grain yield loss were also significantly higher in GB8735 than in the other varieties in both years. Grain yields were significantly higher in Wame in 1997 and in Gargasori in 1998. Grain yields were significantly higher in sole millet but lower in the millet-sorghum cropping system in 1997. Damage and grain yield loss caused by Mylabris spp. in GB8735 in both 1997 and 1998 and in Wame in 1998 and byCoryna spp. in GB8735 and Mboderi in 1998 were significantly higher than in the other varieties. Grain yields were significantly higher in Zongori but lower in GB8735 in both years; grain yields were highest in Zongori and Gargasori sown as sole crops or as intercrops in 1997 and 1998. Damage by Coryna spp. was significantly higher in the 1:0 cropping pattern in 1998 but grain yields were significantly higher in this cropping pattern in 1997. Grain yields were lowest in the 1:1 cropping pattern in both 1997 and 1998.