Pesticidal activity of Tithonia diversifolia (Hemsl.) A. Gray and Tephrosia vogelii (Hook f.); phytochemical isolation and characterization: A review

This paper presents a critical review on the current status of knowledge of the chemistry of Tithonia diversifolia and Tephrosia vogelii. The review explores the isolation, characterization of bioactive compounds and pesticidal evaluation of the extracts and isolates from the two plants. Existing concerns are over efficacy which indicate that most pesticidal studies on T. diversifolia have been conducted using plant extracts and a few of their fractions, which does not fully demonstrate compound effectiveness in pest control, and thus little progress in developing new products. Additionally, the variability in the occurrence of pesticidal compounds within a plant material such as that of T. vogelii can affect its end-use as botanical pesticides resulting in instances where farmers report no pesticidal activity of the same species. These challenges can result in the low adoption of pesticidal plants by farmers. The gaps in the knowledge of the chemistry of biological activity entail that the chemical basis for the activity of crude extracts needs to be comprehended while considering them as generation plants for pesticidal use on various crops pests. Furthermore discussions have been made on challenges of isolating and characterizing complex crude extracts. Emerging concerns over their toxicity and safety of bioactive compounds and their metabolites to the environment have also been explored. The review further discusses health-related aspects of bio-markers of biological activity from the crude extracts as reported in other researches. This needs to be studied in these plants' pesticidal applications which could trigger a new course of further research.