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Open AccessArticle

Terpenoid Mixtures as Repellents Against the American Cockroach: Their Synergy and Low Toxicity Against Non-Target Species

by Hataichanok Passara, Tanapoom Moungthipmalai, Chamroon Laosinwattana, Sirawut Sittichok, Kouhei Murata and Mayura Soonwera

Insects 2026, 17(1), 65; https://doi.org/10.3390/insects17010065 - 5 Jan 2026

Viewed by 1134

Abstract

The repellent activities (Periplaneta americana) of lone and binary mixtures of terpenoids—geranial, trans-anethole, and trans-cinnamaldehyde—against adult American cockroaches were evaluated in this study. The respective efficacies of these mixtures were compared with that of 12% (w/w) DEET. Safety bioassays for all formulations on non-target species, namely, earthworms (Eudrilus eugeniae) and guppy fish (Poecilia reticulata), were conducted to identify natural compounds with repellent efficacy equal to or surpassing that of DEET while ensuring ecological safety for non-target organisms such as fish and earthworms. All mixtures (RC₅₀ of 0.3 to 1.6 µL/cm³) were more effective than all lone terpenoids (RC₅₀ of 6.2 to 9.1 µL/cm³) and DEET (RC₅₀ of 3.0 µL/cm³), demonstrating strong synergy, with an increased repellent value (IV) of 79 to 96%. The strongest repellency, 98.0% at 72 h and an RC₅₀ of 0.3 µL/cm³, was achieved using geranial + trans-cinnamaldehyde (1:1). This mixture was 5.9 to 10 times more effective as a repellent than DEET. The toxicity of every lone terpenoid and terpenoid mixture to non-target species was low; hence, these mixtures can be considered safe, whereas DEET was highly toxic to non-target species (100% mortality). The terpenoid mixture geranial + trans-cinnamaldehyde showed strong repellency against P. americana. Full article

(This article belongs to the Special Issue Urban Entomology and One Health)

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11 pages, 299 KB

Open AccessArticle

Insecticidal Activity of Some Major Essential Oil Components against Metopolophium dirhodum and Its Predators

by Roman Pavela and Matěj Novák

Plants 2024, 13(13), 1863; https://doi.org/10.3390/plants13131863 - 5 Jul 2024

Cited by 12 | Viewed by 3074

Abstract

Essential oils (EOs) are plant metabolites with important insecticidal effects. Nevertheless, information on the efficacy of the major substances on aphids and their natural enemies is still missing. The objective of this paper is, therefore, to identify the efficacy of selected EO majority substances—β-citronellol, carvacrol, isoeugenol, and linalool, including their binary mixtures—on the mortality and fertility of the aphid Metopolophium dirhodum, an important cereal pest. The best efficacy was proven for the binary mixture of β-citronellol and linalool (1:1 ratio), for which the estimated LC₅₀₍₉₀₎ is 0.56(1.58) mL L⁻¹. This binary mixture applied in sublethal concentrations significantly reduced aphid fertility. It was found that the phenomenon can be attributed to β-citronellol, as the females treated with LC₃₀ laid 45.9% fewer nymphs, on average, compared to the control. Although β-citronellol and linalool, including their 1:1 mixture, showed very good efficacy on aphid mortality, they were, on the other hand, very friendly to the larvae of Aphidoletes aphidimyza and Chrysoperla carnea, which are important aphid predators. Based on our results, the newly discovered synergically acting binary mixture β-citronellol/linalool can be recommended as an efficient substance suitable for the further development of botanical insecticides used against aphids. Full article

(This article belongs to the Special Issue Green Insect Control: The Potential Impact of Plant Essential Oils)

12 pages, 1859 KB

Open AccessArticle

Phenolics Profile, Antioxidant Activity and Flavor Volatiles of Pear Juice: Influence of Lactic Acid Fermentation Using Three Lactobacillus Strains in Monoculture and Binary Mixture

by Leyu Wang, Hexin Zhang and Hongjie Lei

Foods 2022, 11(1), 11; https://doi.org/10.3390/foods11010011 - 21 Dec 2021

Cited by 65 | Viewed by 5568

Abstract

The aim of this study was to evaluate the effects of lactic acid fermentation using three Lactobacillus strains (Lactiplantibacillus plantarum 90, Lactobacillus helveticus 76, and Lacticaseibacillus casei 37) in monoculture and binary mixture on phenolics profile, antioxidant activity and flavor volatiles in pear juice. Results showed that the colony counts of binary mixture were higher than monoculture in fermented pear juice. The total content of phenols was increased, while that of flavonoids was decreased significantly during fermentation (p < 0.05). Antioxidant activities in fermented peer juice including DPPH and ABTS radical scavenging abilities and ferric reducing antioxidant power (FRAP) were significantly improved (p < 0.05). Binary mixture of Lactiplantibacillus plantarum 90 and Lacticaseibacillus casei 37 fermentation exhibited strong DPPH radical scavenging ability, due to the increase in vanillic acid and arbutin contents. Furthermore, lactic acid fermentation improved the formation of alcohols, esters, acids and terpenoids, and reduced the contents of aldehydes and ketones. Thirty new compounds including 15 alcohols, seven esters, five acids, and three terpenoids were observed in fermented pear juice. Hierarchical cluster revealed that flavor volatiles in pear juice were improved dramatically by Lactobacillus strains fermentation, and there were dramatic differences between monoculture and binary mixture. Full article

(This article belongs to the Special Issue Probiotics, Prebiotics, Synbiotics, Postbiotics and Paraprobiotics—New Perspective for Functional Foods and Nutraceuticals)

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