Approaches to blister beetle control on millet: Botanical and biological agents, associational resistance, varietal resistance, and light and pheromone traps

Several approaches to management of insect pests of pearl millet (Pennisetum americum) were compared in on-farm trials in four villages in north central Mali. Light traps were used for assessment of insect pest populations, installed in millet and fallow fields, and illuminated each night from 5 August to 14 October 1997. The blister beetles Psalydolytta spp. and Mylabris spp. reached their highest numbers in late August and early September, the same time period as in 1996. The insect pest captured in greatest numbers was the scarab bettle Ryinyptia infuscata. Neem decreased blister beetle counts on millet heads by 75-76 percent and increased yield by 86 percent (391 kg ha ) over the farmer control. Bacillus thuringiensis decreased blister beetle counts on millet heads by 52-57 percent and increased yield by 56 percent (256 kg ha ) over the control. Mean blister beetle counts were 12.3 beetles/head in 1996, 1995, and 1994, respectively. Millet grown in association with sorghum had fewer beetles/head and higher yield, compared with millet grown in pure stand. Two varieties with tolerance to blister beetles, 'GRP1' and 'M2D2', had higher yields than the local control. Pheromone traps reduced stem boring by A. ignefusalis and increased millet yield out to 50 m. Yield was 50 percent higher at 5 m from the traps compared with fields without traps. Blister beetles were 3.4 times greater in number and millet yields higher in fields without light traps compared to counts taken 5 m from traps, and an effect was seen out to 50 ft from the trap.