A novel biofumigant from Tithonia diversifolia (Hemsl.) A. Gray for control of stored grain insect pests

For the well-being of human health as well as ecological concerns and the development of insect resistance to conventional chemical insecticides, efforts have increased worldwide, to find eco-friendly, effective and safer insect control agents which are of natural origin. A bioactive biofumigant molecule named dihydro-p-coumaric acid was isolated and characterized from the leaves of Tithonia diversifolia Hemsl. A. Gray following laboratory bioassays against the rice weevil, Sitophilus oryzae L (Coleoptera: Curculionidae); the lesser grain borer, Rhyzopertha dominica F (Coleoptera: Bostrichidae) and the rust-red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). The isolated compound acted as a fumigant, toxic to adults of stored grain insect pests with LC₅₀ values of 17.86, and 11.49 μg/L (S. oryzae), 19.80 and 10.29 μg/L (R. dominica) and 24.41 and 17.80 μg/L air (T. casatneum) respectively. Further, in vivo data reveal that the percentage of inhibition of acetyl cholinesterase (AChE) was dose-dependent and in vitro results showed potent AChE inhibitor. The isolated compound acts as an efficient biofumigant against the stored grain insect pests and has no adverse effect on seed germination. From this study, we assume that the isolated biofumigant molecule has the ability for used in IPM programs for stored-grain pests because of its biofumigant activity.