Encapsulation of Eucalyptus largiflorens Essential Oil by Mesoporous Silicates for Effective Control of the Cowpea Weevil, Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

Abstract

Although the use of synthetic chemicals is the principal method for insect pest management, their widespread application has led to numerous side effects, including environmental pollution and threats to human and animal health. Plant essential oils have been introduced as promising natural substitutes for synthetic insecticides. However, high volatility and/or low durability are the main limiting factors for essential oil application for control of insect pests. Accordingly, along with an evaluation of the fumigant toxicity of Eucalyptus largiflorens essential oil against the cowpea weevil, Callosobruchus maculatus, essential oil was nanoencapsulated by two mesoporous silicates, MCM-41 and zeolite 3A, to enhance fumigant persistence and toxicity. The chemical profile of essential oil was also analyzed through gas chromatographic-mass spectrometry. E. largiflorens essential oil showed significant concentration-dependent toxicity against insect pests; a concentration of 5.16 μL/L resulted in 100% mortality after 48 h. The toxicity of essential oil could be attributed to the presence of various insecticidal terpenes, such as spathulenol (15.6%), cryptone (7.0%), and 1,8-cineole (5.8%). Fumigant persistence was increased from 6 days to 19 and 17 days for pure and capsulated essential oil with MCM-41 and Zeolite 3A, respectively. The insect mortality also increased from 99 insects in pure essential oil to 178 and 180 insects in MCM-41 and Zeolite 3A encapsulated formulations, respectively. Therefore, the encapsulation of E. largiflorens essential oil by MCM- 41 and Zeolite 3A is a beneficial method for enhancing its persistence and toxicity against C. maculatus.

Nanoencapsulation of Acetamiprid by Sodium Alginate and Polyethylene Glycol Enhanced Its Insecticidal Efficiency

“…The Tukey–Kramer test at a 5% significance level was used to compare means using SAS statistical software (SAS Institute, Cary, NC, USA). Encapsulation efficiency and loading percentages were evaluated according to the following formula [ 40 ]: …”

Enhancing Food Grains Storage Systems through Insect Pest Detection and Control Measures for Maize and Beans: Ensuring Food Security Post-COVID-19 Tanzania

“…Ref. [85] tested the toxicity of nanoencapsulated Eucalyptus largiflorens on the cowpea weevil, C. maculatus, and observed persistent and toxic. Mint and rosemary essential oils were found to affect the mating fitness of C. maculatus [86].…”

Essential Oils Encapsulated in Zeolite Structures as Delivery Systems (EODS): An Overview

“…Nonetheless, all the formulations prevented infection and disease development [ 116 ]. Ebadollahi’s work [ 117 ] also evaluated the pest-controlling activity of Eucalyptus largiflorens EO against Callosobruchus maculatus. A higher encapsulation efficiency and loading percentage, as well as a greater efficiency with respect to fumigant toxicity, were observed in this EO encapsulated in zeolite 3A when compared with the mesoporous material MCM-41 and pure EO.…”