Evaluation of Plant Extracts on Mortality and Tunneling Activities of Subterranean Termites in Pakistan

Plant extracts offer a vast, virtually untapped reservoir of chemical compounds with many potential uses. One of these uses is in agriculture to manage pests with less risk than with synthetic compounds that are toxicologically and environmentally undesirable. Increasing evolution of resistance in pest population further derives the need to search for new bioactive compounds with a wide range of new modes of action. Various experiments using plant extracts in human and animal health protection, agriculture and household pest management have been particularly promising (Pascual-Villalobos & Robledo, 1999; Scott et al., 2004). The apparent societal hope for using plant extracts in place of more traditional pesticides has also increased the attention paid to natural products in the past decade (Duke et al., 2003). Plant products have been exploited as insecticides, insect-repellents, antifeedants and insect growth and development regulators (Saxena, 1998). The deleterious effects of phytochemcials or crude plant extracts on insects are manifested in several ways, including suppression of calling behaviour (Khan & Saxena, 1986), growth retardation (Breuer & Schmidt, 1995), toxicity (Hiremath et al., 1997), oviposition deterrence (Zhao et al., 1998), feeding inhibition (Wheeler & Isman, 2001) and reduction of fecundity and fertility (Muthukrishnan & Pushpalatha, 2001). Many plants have been recognized to have anti-termitic activities (Sakasegawa et al., 2003, Park & Shin, 2005, Jembere et al., 2005, Cheng et al., 2007, Ding & Hu, 2010, Supriadi and Ismanto, 2010) or repellent to the termites i.e., Eucalyptus globules, lemmon grass, Eucalyptus citrodora, cedar wood, clove bud and vetiver grass (Zhu et al., 2001a, b), Taiwania cryptomerioides Hayat (Chang et al., 2001), Dodonaea viscosa (Purple hop bush) a termite resistant shrub (Anonymous, 2001), Ocimum basilicum L., Cymbopogon winterianus Jowitt, Cinammomum camphora, Rosmarinus officinalis (Sbeghen et al., 2002) and Coleus ambionicus (Singh et al., 2004) are less extensively studied against termites.