Phytochemical composition and insecticidal potentials of some plant aqueous extracts in suppressing Podagrica spp. (Coleoptera: Chrysomelidae) Infestation on Okra (Abelmoschus esculentus L. Moench)

Abstract

Foliar application of 25% w/v crude aqueous extracts Calotrophus procera (Aiton) W.T. Aiton, Canarium schweinfurthii (Engl.) and Bryscocarpus coccineus (Schum. & Thonn.) were evaluated for their insecticidal activity in reducing Podagrica infestation on okra. Results showed that plants extracts significantly suppress Podagrica spp. infestation and protect okra plant from severe leaves defoliation, with C. schweinfurthii (21.67 and 20.14) and B. coccineus (23.07 and 24.55) showing promising insecticidal activity. The yield attributes from okra sprayed with Lambda cyhalothrin did not differ significantly compared to those sprayed with botanical insecticide despite having highest yield attributes. Qualitative phytochemical screening revealed the presence of Triterpenoids, Steroids, Flavonoids, Phlobatanins, Saponins, Tannins, Cardiac glycoside and Anthraquinones. Alkaloids and Anthraquinones were not detected in C. procera and C. schweinfurthii while Triterpenoids and Phlobatanins were absent C. schweinfurthii. The presence of these phytochemicals indicates that the plants possess insecticidal properties responsible for significant reduction in Podagrica spp. infestation, severity of leaves damaged and improved okra yields. Performance of the treatments is rated in the following order: Lambda cyhalothrin > B. coccineus > C. schweinfurthii > C. procera, with B. coccineus and C. schweinfurthii having similar treatment means in all the parameters evaluated. In light of the foregoing, crude extracts of B. coccineus and C. schweinfurthii could be utilized as suitable alternative to synthetic insecticide in sustainable okra production