Balanites aegyptiaca and Calotropis procera aqueous extracts exhibit ovicidal and larvicidal activity against Spodoptera frugiperda

Abstract

The use of botanical control is increasingly being reconsidered as a sustainable alternative to chemical control, especially for smallholder farmers with limited financial resources. This study aimed to evaluate the ovicidal and larvicidal effects of the aqueous extracts of Balanites aegyptiaca and Calotropis procera on fall armyworm (Spodoptera frugiperda). To this end, five concentrations of each extract were tested on one-day-old eggs and second-instar larvae. The egg hatching inhibition rate and larval mortality rate were calculated. The 50% inhibitory concentrations for egg hatching (IC₅₀) and the 50% lethal concentrations (LC₅₀) were determined. The results revealed that concentrations of 148 g/L, 185 g/L, and 222 g/L of Balanites aegyptiaca and those of 126 g/L and 152 g/L of Calotropis procera maintained egg hatching inhibition above 50% at 168 h after application, which was not the case on control treatment where 98% of eggs hatched within the same time slot. At 96 hours, the IC₅₀ of C. procera (12.70 g/L) was significantly lower than that of Balanites aegyptiaca (126.35 g/L). Regarding the larvicidal effect, the extract of Balanites aegyptiaca induced a maximum mortality of 83.93% at 222 g/L, while all concentrations of Calotropis procera induced more than 50% mortality. At 24 hours, the LC₅₀ of Balanites aegyptiaca was 120.75 g/L compared to 137.41 g/L for Calotropis procera. The aqueous extracts of Balanites aegyptiaca and Calotropis procera are therefore potential sustainable alternatives for the management of Spodoptera frugiperda.