This study explores the use of essential oils from cardamom (Elettaria cardamomum (L.) Maton) and galangal (Alpinia galanga (L.) Willd) as alternatives to synthetic insecticides for controlling the red flour beetle, Tribolium castaneum (Herbst). The chemical compositions of these oils were analyzed using GC-MS, and their fumigation effects were tested in a vapor-phase bioassay. The experiment followed a factorial design with four types of essential oils, namely, those manually extracted from cardamom leaves (MCL) and galangal leaves (MGL) and those commercially produced from cardamom seeds (CCS) and galangal rhizomes (CGR), at seven concentrations (0, 50, 100, 150, 200, 250, and 300 µL/L air). The manually extracted oils yielded 0.6% from cardamom leaves and 0.25% from galangal leaves. MCL contained 28 components, with eucalyptol (25.2%) being the most abundant, while CCS had 34 components, primarily α-terpinyl acetate (46.1%) and eucalyptol (31.2%). MGL included 25 components, mainly caryophyllene (28.7%) and aciphyllene (18.3%), whereas CGR comprised 27 components, with methyl cis-cinnamate (47.3%) and safrole (19.8%) as the major constituents. The fumigation bioassay results revealed that CGR was the most effective, demonstrating the highest mortality rates of T. castaneum across all the tested periods and concentrations, achieving up to 96% mortality at 168 h with a concentration of 300 µL/L air. Statistical analyses showed significant differences in mortality based on the type and concentration of essential oil, particularly after 96 h. These findings highlight the potential of CGR, with its advantages and differences in chemical composition, as an effective biopesticide against T. castaneum, with increasing efficacy over time and at higher concentrations.

The use of essential oils from certain herbal plants offers a promising alternative to synthetic insecticides for controlling the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Dryophthoridae), a major pest that causes significant damage to stored grains. Essential oils, particularly from aromatic herbs in the Apiaceae family, are widely used in medicinal, cosmetic, and food industries and provided insecticidal properties to mitigate the environmental and health hazards associated with synthetic insecticides. This research aimed to investigate the insecticidal and repellent effects of Apium graveolens L. (celery) seed essential oil against S. zeamais. Chemical analysis of the commercially produced essential oil from A. graveolens seeds was conducted using a gas chromatograph–mass spectrometer (GC-MS), and the biological activity of the essential oil was determined by ingestion, contact, fumigation, and repellent tests. The analysis identified D-limonene (64.21%) and α-humulene (17.46%) as primary components of the oil. Toxicity assays revealed an observable contact toxicity, with higher concentrations and prolonged exposure increasing its effectiveness. The contact toxicity assays reported an LC₅₀ of 19.83 nL/adult after 72 h. Additionally, the essential oil displayed repellent effects, effectively deterring weevils at concentrations above 16 µL/L air, but its feeding deterrence was weak. The essential oil’s strong insecticidal and repellent properties, which were concentration- and time-dependent, highlighted its potential as a sustainable alternative to synthetic pesticides for integrated pest management.

Vigna radiata (L.) R. Wilczek, commonly known as mungbean

The prevention of destruction caused by red flour beetle, Tribolium castaneum (Herbst), using essential oils derived from certain herbal plants presents an interesting alternative to synthetic insecticides, known for their harm to both consumers and the environment. The research aimed to investigate the chemical compositions and fumigating effects of essential oils derived from cardamom (Elettaria cardamomum (L.) Maton) and galangal (Alpinia galanga (L.) Willd) against T. castaneum. Chemical compositions were analyzed using GC-MS, while fumigation bioassay was conducted via a vapor-phase test. Experimental setup followed factorial design in CRD with 5 replications. Factor A encompassed 4 types of essential oils: the manually extracted essential oils from cardamom leaves (MCL) and galangal leaves (MGL), the commercially produced essential oils from cardamom seeds (CCS) and galangal rhizomes (CGR). Factor B consisted of 7 concentrations: 0, 50, 100, 150, 200, 250, and 300 µL/L air. Results indicated that MCL contained eucalyptol, trans-calamenene, and isospathulenol as its main compounds. Similarly, CCS was characterized by camphene and eucalyptol. MGL exhibited caryophyllene, aciphyllene, and α-bisanolene. Lastly, CGR was composed of methyl cis-cinnamate, safrole, and p-vinylphenyl isothiocyanate. Study noted that 250 µL/L air over 168 hours of CGR, demonstrated 94% fumigation efficiency against adult T. castaneum. These results suggest the potential of galangal rhizome derived essential oil as an insecticide for managing T. castaneum populations in agricultural product storage.