Cuminum cyminum Methanolic Extract - Fe_3O_4 Nanocomposite: A Novel and Efficient Insecticide against the Potato Tuber Moth (Lepidoptera: Gelechiidae) to Protect Potatoes

摘要

Phthorimaea operculella is a significant insect pest of cultivated potatoes in tropical and subtropical regions such as Iran. Since the potato is one of the most valuable sources of human food, non-chemical control of potato pests is essential. Application of medicinal plant extracts is a low-risk alternative method to synthetic chemical insecticides. Hence, the present study was conducted to investigate a potential strategy to improve the insecticidal activity of plant extracts for efficient management of P. operculella. The insecticidal efficacy of pure methanolic extract (PME) and Fe_3O_4@methanolic extract (FME) of Cuminum cyminum were evaluated against the potato tuber moth under laboratory conditions. The morphological characteristics of Fe_3O_4@Cumin were investigated by scanning electron microscope. Magnetic properties of the samples were determined using a vibration sample magnetometer. XRD was used to prove the crystalline structure of Fe_3O_4@Cumin. SEM，FTIR, XRD, and VSM analyses confirmed that the methanolic extract was loaded on Fe_3O_4. The toxicity of PME and Fe_3O_4@Cumin were evaluated on one-day-old eggs and penetration the first instar larvae of P. operculella into potato tubers and leaves. The LC_(50) values of Cumin extractand Fe_3O_4@Cumin were 961.07 and 601.48 and 496.84 and 268.82 ppm for penetrating neonate larvae to tubers and leaves, and 874.90 and 595.16 ppm for eggs，respectively. Bioassays revealed that Fe_3O_4@Cumin was more toxic than non-formulated Cumin methanolic extract against eggs and neonate larvae of P. operculella. The formulated methanolic extract was significantly more repellent against the pest. Our results suggested that the prepared nanocomposite could be used as a new effective tool for P. operculella management strategies to protect potatoes.