Direct and Indirect effects of Schefflera extracts (Schefflera sp.1 and Schefflera sp.2) (Araliaceae) on Aedes albopictus (Skuse) : implications for control

Lingeshwarry, Jewarethnam (2017) Direct and Indirect effects of Schefflera extracts (Schefflera sp.1 and Schefflera sp.2) (Araliaceae) on Aedes albopictus (Skuse) : implications for control. [Final Year Project Report] (Unpublished)

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Abstract

Aedes albopictus (Skuse) is classified as one of the agent responsible in transmitting deadly dengue viruses. Efforts to combat these vectors relied heavily on the use of synthetic insecticide and did not address the likely possibility that plants may also hold valuable nutrients. This study evaluated the lethal and sub lethal effects of different concentration (LC5, LC1O, LC2O & LC40) extracts from Schefflera sp.1 and Schefflera sp.2 on Ae. albopictus. Both Schefflera extracts exhibited a concentration-dependent pattern. The survival rates were less than 50% at LC40 for both extracts but 100% in control. The survivors had delayed developmental period at LC20 (9.67 ± 0.49 days) in SchEx1 and at LC40 (8.83 ± 0.40 days) in SchEx2. Exposure to Schefflera extracts also resulted in poor pupation and adult production with emergence defects at the highest concentration. This outcome strongly suggests that Schefflera extracts could be used in control strategies in reducing the population size of dengue vectors as well as their capacity of disease transmission.

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