Plant-derived semiochemical strategy for sustainable management of coconut whitefly (Aleurodicus Cocois) using trunk injection techniques

Abstract

In Sri Lanka, the coconut industry, which is a major contributor to the national economy, is under severe threat from the recently introduced pest, the coconut whitefly (Aleurodicus cocois). This pest’s resistance to conventional pesticides combined with the height of coconut trees has highlighted the need for sustainable management alternatives. The aim of this study is to develop and evaluate a plant semiochemical-based strategy for coconut whitefly control, using stem injection as a systemic alternative to chemical pesticides. The approach offers a sustainable solution by reducing pest populations without negatively impacting the ecosystem. Plant extracts of seeds and leaves of Strychnos nux vomica (Goda kaduru), neem, mint and clove oil were formulated and tested. Four successful formulations were identified and initially tested by direct spraying. Building on these results, the formulations were combined with systemic recipients such as urea, NaCl, KCl and citric acid and evaluated by strain injection methods. Field trials showed significantly higher mortality rates (68%, 95.85%, 93.27% and 94.66%) for formulations 1 to 4 compared to the untreated control (p < 0.005). Stem-injected palms showed a gradual decline in whitefly populations, although adverse weather conditions prevented continuous monitoring. These findings suggest that repeated applications are necessary for long term success.