Botanicals

Abstract

Botanicals are plant-derived compounds. Despite their origin, botanicals used for pest control are typically pesticides, although some compounds are behaviorally active rather than toxic. Their natural source creates some confusion, because there is often an erroneous assumption that plant compounds are innately safer in some way. Some botanicals, for example nicotine, are as toxic as some conventional pesticides to mammals. The toxic effects of botanicals on insects can be categorized as follows: 1) kill a life stage of an insect species by oral, contact, or fumigant action; 2) prevent feeding (act as an antifeedant); 3) suppress reproduction; 4) repel insects or affect insect behavior; and 5) a combination of effects mentioned in 1-4 (Jotwani and Sircar 1967, Ignatowicz and Wesolowska 1994, Shaaya et al. 1997). Most of the references on the use of botanicals are from tropical and semi-tropical countries. The majority of these papers refer to the addition of plant material to bulk grain to suppress specific insect species. The tendency has been to assume that there is an ethno-botanical precedent for this research. This is often the case, and undoubtedly the overall idea comes from such use under subsistence conditions, but often it appears that the plants tested against insects had an ethno-pharmacological role in the culture (Weaver et al. 1992, 1994a, b; Prakash and Rao 1997). Other reasons for investigation may be the absence of damage of potential plants by phytophagous insects (Arnason et al. 1989, Weaver et al. 1995, Dev and Koul 1997), or even simply the fact that the plant was conspicuously aromatic (Weaver et al. 1995, Dev and Koul 1997).