Published online by Cambridge University Press: 26 September 2012
Introduction. In the water-savingand income-generating agroforestry cropping systems developed andpromoted by the ICRISAT in the Sudano-Sahelian zone of West Africa, particularlyin Niger, fruits of domesticated Ziziphus mauritiana (“applesof the Sahel”) are severely damaged by fruit flies (Carpomya incompleta),and chemical pesticide application poses economic, environmentaland human health problems. In the Bio-reclamation of Degraded Lands (BDL)system, apple of the Sahel is the main high-value crop, while inthe Dryland Eco-Farm (DEF), it is grown alongside watermelon. Sclerocaryabirrea (marula plum) is presently being investigated asa dryland tree species for fruit and oil production, either in orchardsor such systems as BDL. Materials and methods. To completepreliminary results of earlier studies published elsewhere, we collectedand incubated in 2010 ripe fruits of marula plum and watermelonin Sadoré, Niger, where the above-mentioned agroforestry systemsare developed, and we recorded emerging fruit flies. We also conducteda spot-spraying experiment (using GF-120) in an apple of the Sahel orchardin Niamey in 2010; we recorded undamaged and damaged fruits and incubatedthe latter. In the same orchard, we set up in 2011 a fruit fly trappingsurvey targeting the invasive species Bactrocera invadens (Chempac®traps using methyl eugenol as the attractant). Results and discussion.The results showed that only Ceratitis cosyra emergedfrom marula plums, and only Dacus spp. from watermelon.The GF-120 spot-spraying experiment showed that C. incompleta was notattracted / intoxicated, contrary to Ceratitis spp.and Dacus spp.; the sprayed trees yielded significantly moremarketable fruits than unsprayed ones; only C. incompleta emergedfrom damaged fruit. Detection trapping revealed for the first timethe presence of B. invadens in the Sahelian zone ofNiger, including at the time of apple of the Sahel fruit production. Conclusion. This, alongside results of earlier studies,suggests a repellent effect of GF-120 on the monophagous C. incompleta species(Trypetinae), while it is attractive to oligophagous/polyphagousDacinae fruit flies; some of them (e.g., Dacus spp.)damage watermelon, which is part of the DEF system, and producefruit at the same time as the jujube tree. The prospects for harnessingthese two opposite regulation pathways are discussed.