Insecticidal effect of Jatropha curcas oil on the aphid Aphis fabae (Hemiptera: Aphididae) and on the main insect pests associated with cowpeas (Vigna unguiculata) in Niger

The insecticidal activity of Jatropha curcas has been evaluated on various crop pests. Oil concentrations
of 0.5, 1, 2.5, 5, 10 and 15% were first tested on the black bean aphid (Aphis fabae Scop.) as part of
an efficacy test conducted in the laboratory. During a second stage, the insecticidal efficacy of 5 and
7.5% oil concentrations was evaluated on the main pests infesting cowpea crops (Vigna unguiculata L.)
as part of a field test conducted at the University of Niamey (Niger). The results obtained in the two tests
demonstrate the biocidal effect of the treatments applied, which increases with the concentration. On
the black bean aphid, the biocidal effect increases during the hours following the application of oil
before reaching a peak after 4 days. On cowpeas, J. curcas oil concentrations of 5% and 7.5% make it
possible to reduce the level of attack by aphids (Aphis craccivora) by 10 and 50% respectively compared to
the control. A 50% and 75% fall in the number of thrips (Megalurothrips sjöstedti) and bugs (Anoplocnemis
curvipes), respectively, can be observed under the same conditions. This treatment made it possible to
greatly increase yields compared to the untreated control.