Synergistic Insecticidal Activity of Cynanchum acutum and Sonchus maritimus Extracts against Aphids

Background: This study evaluated the insecticidal effectiveness of aqueous extracts from Cynanchum acutum L. (climbing vine swallowworts), Sonchus maritimus L. (Sow Thistle) and their 1:1 mixture against aphids collected in El Oued Province. Methods: Plant materials were prepared using standard extraction techniques and bioassays were conducted on adult and larval aphids at five different concentrations, with mortality noted after 24 and 48 hours. Result: Probit analysis showed significant, dose- and time-dependent mortality for all extracts, with larvae generally more vulnerable than adults. The mixture was the most effective, showing the lowest LC50 values: from 0.73 mg/mL (adults, 24 h) to 0.56 mg/mL (adults, 48 h) and from 0.49 mg/mL to 0.12 mg/mL for larvae. Sonchus maritimus L. alone exhibited potent activity against larvae (LC50 = 0.025 mg/ml at 48 h), while Cynanchum acutum L. was less powerful. Nearly complete larval mortality was observed at concentrations above 0.666 mg/ml for all extracts. These findings suggest that mixed botanical extracts have great potential as sustainable, potent agents for aphid control, justifying further field testing and safety evaluations.