Insecticidal activity of certain medicinal plants

Area of Science:

• Agricultural Science
• Entomology
• Phytochemistry

Background:

• The Egyptian cottonworm (Spodoptera littoralis) is a significant agricultural pest.
• Developing eco-friendly pest control methods is crucial for sustainable agriculture.
• Medicinal plants are a potential source of natural insecticides.

Purpose of the Study:

• To evaluate the insecticidal activity of methanol extracts from eight medicinal plant species.
• To identify plants with high toxicity against Spodoptera littoralis larvae.
• To assess the impact of these extracts on larval growth and feeding efficiency.

Main Methods:

• Methanol extracts of eight medicinal plant species were prepared.
• Third instar larvae of Spodoptera littoralis were exposed to the plant extracts.
• Larval mortality and growth indexes (RGR, ECI, ECD) were measured.

Main Results:

• All tested plant extracts exhibited some level of toxicity against Spodoptera littoralis larvae.
• Extracts from Ocimum basilicum, Origanum majorana, and Salvia officinalis demonstrated high insecticidal activity.
• Significant negative effects on relative growth rate (RGR), efficiency of conversion of ingested food (ECI), and efficiency of conversion of digested food (ECD) were observed.

Conclusions:

• Ocimum basilicum, Origanum majorana, and Salvia officinalis possess potent insecticidal properties against Spodoptera littoralis.
• These plant extracts offer a promising natural alternative for managing Egyptian cottonworm infestations.
• Further research into the active compounds and mechanisms of action is warranted.