Evaluation of Hyptis spicigera leaf extracts against cowpea weevil (Callosobruchus maculatus) in stored Bambara groundnut (Vigna subterranea L.)

2020

English

Laboratory study was conducted at the University for Development Studies, Tamale, Ghana in 2016 to evaluate the potency of different concentrations of aqueous leaf extracts (ALE) from Hyptis spicigera (Lam.) against Callosobruchus maculatus (F.) infestation in Bambara groundnut seeds. Two aqueous extracts concentrations were prepared at three temperatures. The treatments were; control (sterilized untreated seed), 10% ALE [w\v] applied at 25 C, 10% ALE applied at 50 C, 10% ALE applied at 100 C, 20% ALE applied at 25 C, 20% ALE applied at 50 C and 20% ALE applied at 100 C. The results showed that, application of 20% ALE at 100 C recorded a significant (p < 0.05) lower number of eggs (26.3), adults emerge (6.5), seed damage (1.6%), seed weight loss (1.1%), susceptibility index (0.4%) and a higher inhibition rate (2.3%) compared to the control. Seed viability test was also highest (89.3%) in the 20% ALE at 50 C. The formulation of 20% ALE at 100 C was the most potent against C. maculatus infestation. Seeds destined for human consumption can be treated at this concentration and temperature. We also recommend 20% ALE at 50 C for protecting seeds stored for propagation

Keteku, A. K.; Badii, B. K.; Sowley, E. N. K.