Moringa oleifera and Ruta angustifolia fixed oils and a prospective method to obstruct pupal development in cotton leafworm

Abstract

The cotton leafworm, Spodoptera littoralis, is a polyphagous pest that attacks various economic crops. Integrated Pest Management (IPM) uses different techniques to combat this pest unfortunately chemical control is the predominant. However, it does not target the pupal stage of the insect. Therefore, a safe and cost-effective technique must be developed to address this issue.

This technique integrates using plant-based agents; M. oleifera and R. angustifolia seed oils as pupaicids. Various concentrations (1%, 2%, and 4%) of both oils were employed by means of the dipping method of pre-pupae. The study delved into the biological, and biochemical aspects of pupal development to adult emergence. Analysis of the fatty acids along with the hydrocarbons and sterols was conducted through GLC analysis for oils composition.

Our research has shown that Moringa oleifera and Ruta angustifolia oils at a concentration of 4 % have a significant impact on pre-pupal mortality (42.57& 61.9 %) and pupation of survival pre-pupa (57.42&38.09 %) However, emerged adults were reduced to 83.33 % and 60 %, respectively. Chitinase recording significantly disturbance after 1 day for Ruta (6.21 µg/min/g) and Moringa oil (2.12 µg/min/g). Also, Phosphatase enzyme showed a significant disturbance after 4 and 7 days of treatments. GLC data of fatty acids showed that oleic acid (74.42 %) was the major fatty acid in M. oleifera oil, while linolenic, linoleic, and oleic acids represented 31.39 %, 22.70 %, and 21.95 %, respectively, in R. angustifolia oil. Sterols in M. oleifera oil were β-sitosterol and stigmasterol, while Ruta oil contained additional amounts of cholesterol and campesterol,

Briefly, the suggested technique was effective in disturbing pupal development and reducing emerged adults. Ruta was more effective than Moringa oil due to its contents of sterols and hydrocarbons that may affect ecdysis.