Insecticidal Effect of the Essential Oil of Eucalyptus globulus Leaves on the Aphid, Aphis craccivora (Homoptera: Aphididae) of Vigna unguiculata in Central Region of Togo

Vigna unguiculata (L.) Walp. is an important vital crop in the diet of populations, whose productivity is declining due to the pressure of pests, including Aphis cracivora Koch (Homoptera: Aphididae). To combat these pests, farmers use synthetic chemical products, which are highly toxic to human health and useful entomofauna. To remedy these problems and find alternative to these synthetic chemical pesticides, this study aims to evaluate the efficacy of a formulation based on the essential oil of E. globulus on A. craccivora.

The test was realised in the field using the Fischer experimental design with five replicates. Each replicate consisted of three treatments with the E. globulus essential oil formulation at different concentrations (0.1, 0.5 and 1%), a positive control (treatment with the synthetic insecticide K-optimal (Acetamiprid-Lamdacyhalothrin) and an untreated plot. A. craccivora population dynamics and pod yield were the parameters evaluated during the experimentation.

The essential oil of E. globulus formulation, at a concentration of 1% reduced considerably the density of A. craccivora population (4.8±0.12 aphids per plant) and induce a higher yield in terms of number of pods (12.42±1.16 pods per plant) compared to the untreated plot (48.2±1.02 aphids per plant; 6.325±0.33 pods per plant). Statistical analysis showed that the effect of the formulation based on 1% of E. globulus essential oil was similar to the synthetic insecticide effect.