n-hexane fraction of Zingiber officinale and Moringa oleifera interferes with biological parameters of Callosobruchus chinensis (L.) (Coleoptera: Bruchidae)

Abstract

The development of insecticide resistance, high cost, misuse, dearth of technical expertise, and restrictive legislation associated with synthetic insecticides have necessitated the development of alternatives. Lessons from plant-insect interactions demonstrate that plant terpenes are worthy probes for insecticidal exploration. Hence, this study screened n-hexane fractions of Zingiber officinale and Moringa oleifera oils as protectant against Callosobruchus chinensis and revealed their chemical profiles using Gas Chromatography - Mass Spectrometry (GC-MS). M. oleifera (LC50; 0.007 {micro}l) was found to be more toxic than Z. officinale oil (LC50; 0.055 {micro}l) to C. chinensis. The oils showed a positive correlation with concentration at 24 h (r = 0.959), 48 h (r = 0.977), 72 h (r = 0.915) and 96 h (r = 0.924). GC-MS revealed 21 and 15 volatile compounds in Z. officinale and M. oleifera oils, respectively. The most domimant were 5-(1, 5-dimethyl-4-hexenyl)-2-methyl-1,3-Cyclohexadiene (13.64 %) and 8-Octadecenoic acid, methyl ester (34.52 %) in Z. officinale and M. oleifera oils, respectively. The plant fractions reduced the oviposition potential, egg hatching rate, and adult emergence of C. chinensis. Taken together, the results demonstrate possible developmental and inhibitory effects of the oils against C. chinensis and points to its possible inclusion in Integrated Pest Management (IPM) practices for C. chinensis. Highlights[tpltrtarr] n-hexane fractions from Moringa oleifera seeds are more potent against Callosobruchus chinensis than that from Zingiber officinale rhizome. [tpltrtarr]Both oils can disrupt biological parameters and induce mortality of C. chinensis. [tpltrtarr]M. oleifera can be useful as grain protectant as it is ubiquitous in sub-saharan Africa, including Nigeria, and has been documented to improve grains protein quality in storage.