Bioefficacity of mixed powders of Vepris heterophylla and Syzygium aromaticum on the developing stages of Callosobruchus maculatus (Coleoptera: Bruchidae) pest control of Vigna unguiculata (Fabacae) in storage in the Far-North region of Cameroun

Abstract

The effect of mixed powders of Vepris heterophylla and Syzygium aromaticum on the developing stages of Callosobruchus maculatus was investigated. Quantities of 0.25, 0.50, 0.75 and 1.00g of mixed plant powders were measured: a= 1/2VS +1/2VL, b= 1/2VS +1/2SA, c=1/2VL + 1/2SA and d=1/3VS+1/3VL+1/3SA (VS= Vepris stem bark, VL= Vepris leaves, SA= Syzygium aromticum). They were applied to 100g of cowpea seeds, followed by infestation with ten pairs of 48 hours old of Callosobruchus maculatus. The highest mortality (100%) was obtained with 1.00g of the mixture d while the least (82.5%) was recorded with 0.25g of the mixture a. The increase in the doses led to the decrease of the number of eggs laid with the highest mean percentage of oviposition deterrence been 98.44% at 1.00g/100mg due to powder b and the least 93.43% with 0.25g due to powder a. The mixtures reduced adult emergence of F1 from 90.83% (powder b) to 82.5% (powder a). It also reduced the percentage of attack from 98% (control) to 0% for powder b which was the best. The rate of germination increased with the quantities of powder applied.