SOLVENT DEPENDENT BIOEFFICACY OF AZADIRACHTA INDICA LEAF EXTRACTS AGAINST HETEROTERMES INDICOLA (BLATTODEA: RHINOTERMITIDAE)

Abstract

The growing ecological concerns related with synthetic termiticides have provoked the exploration of botanical substitutes for sustainable wood protection. This study evaluates the efficacy of Azadirachta indica (Neem) leaf extracts, prepared using three different solvents water, ethanol, and nhexane against the subterranean termite Heterotermes indicola. Fresh Neem leaves were subjected to solvent based extraction and treated wood blocks were exposed to termite colonies for 60 days under controlled laboratory conditions. The extent of termite tempted damage was measured as the percentage weight loss of the wood, and statistical analyses were performed using one-way ANOVA and post-hoc mean comparisons to find significant differences among treatments. Results show a highly significant reduction in wood weight loss for all Neem extract treatments compared with untreated controls (p < 0.001). The ethanolic extract shown the greatest repellency, resulting in a mean weight loss of 6.83 ± 0.79 %, corresponding to a 75 % reduction relative to untreated samples. The n-hexane and aqueous extracts achieved reductions of 65.7 % and 48.6 %, respectively. Observational data confirmed noticeable termite avoidance of ethanolic treated wood, aligning with the quantitative outcomes. The enhanced performance of the ethanolic extract is accredited to ethanol’s intermediate polarity, which facilitates the extraction of both polar and nonpolar phytochemicals, particularly azadirachtin and nimbin responsible for termite deterrence. These findings underscore the potential of Neem leaf extracts, especially ethanolic preparations, as ecofriendly and sustainable substitutes to synthetic termiticides. The study provides valuable insight into solvent dependent extraction efficiency and offers a foundation for the development of natural, low toxicity wood preservatives suitable for integrated pest management strategies.