Synergism in Two-Component Insecticides with Dillapiole against Fall Armyworm

Abstract

The fall armyworm (Spodoptera frugiperda), a polyphagous insect pest, is a major threat to food production, rapidly spreading through all the tropical areas in the world. Resistance has developed to the control protocols used so far (pyrethroids, organophosphorus, and genetically modified plants), and alternative strategies must be found. The bioactivity in essential oils is usually associated with the major constituents, but synergistic interactions among the constituents (even minor ones) can improve the levels of activity considerably. Herein, we tested the insecticidal activity of several constituents of the essential oil from Piper aduncum, an Amazonian Piperaceae, both separately and as binary mixtures, through their application on the dorsal side of the larva pronotum. Dillapiole proved to be, isolated, the most active compound in this oil (LD50 = 0.35 ppm). In binary mixtures, a strong synergistic effect was observed for the pairs of dillapiole with β-caryophyllene (LD50 = 0.03 ppm), methyl eugenol (LD50 = 0.05 ppm), and α-humulene (LD50 = 0.05 ppm). In some cases, however, antagonism was recorded, as for dillapiole + β-pinene (LD50 = 0.44 ppm). The use of binary mixtures of essential oil constituents as low-environmental-toxicity insecticides allows a fine tuning of the insecticidal activity, and the exploitation of synergy effects.

The Repellent Capacity against Sitophilus zeamais (Coleoptera: Curculionidae) and In Vitro Inhibition of the Acetylcholinesterase Enzyme of 11 Essential Oils from Six Plants of the Caribbean Region of Colombia

“…Furthermore, some EOs containing dillapiole as the main component showed a low/moderate repellent effect [98], which would be consistent with this report in that the three EOs were not wholly effective (lower %repellency-20-48%) against S. zeamais compared to C + . According to Fazolin et al [111], the most potent synergistic effect of dillapiole could be verified when it was mixed with β-caryophyllene, methyl eugenol, or α-humulene; however, none of the EOs under study presented any of the mixtures of constituents mentioned above. Of course, the degree of repellency of these EOs was dillapiole-content-dependent, as seen in Figure 6, i.e., the higher the dillapiole content, the higher the degree of repellency (including EO 1bL*), which would follow what was reported by Fazolin et al [115], who stated that the higher the dillapiole content in the EO, the higher the insecticidal effect via residual or topical contact (e.g., on Spodoptera frugiperda).…”

“…Taking into consideration the other less active EOs from P. haugtii (3bL), P. holtonii (1aL), and P. holtonii (1bL**), they contained dillapiole as the main constituent (ca. 48-78%), which is a powerful insecticidal agent (alone or as a co-adjuvant/synergist) or a suitable repellent/fumigant compound (against Plodia interpunctella and S. zeamais, respectively) [111][112][113][114]; however, in the reviewed literature, any report on the repellent capacity of dillapiole on S. zeamais was not found. Furthermore, some EOs containing dillapiole as the main component showed a low/moderate repellent effect [98], which would be consistent with this report in that the three EOs were not wholly effective (lower %repellency-20-48%) against S. zeamais compared to C + .…”

Characterization of the Phytotoxic Potential of Seven Copaifera spp. Essential Oils: Analyzing Active Compounds through Gas Chromatography–Mass Spectrometry Molecular Networking

“…Isolated compounds may do not fully reflect these synergistic or antagonistic interactions, as they are evaluated individually under controlled conditions. 27 This can result in differences in the observed biological effects compared to oils.…”

Mentha spp. essential oils: Toxicity to Alphitobius diaperinus, activity against poultry pathogenic bacteria, and Beauveria bassiana compatibility

“…These ndings are consistent with previous studies, which have identi ed menthol as the primary component in M. When assessing the insecticidal activity of most compounds and EOs, we observed that EOs exhibited higher toxicity compared to the pure compounds. This phenomenon can be attributed to potential synergistic or additive effects resulting from the combination of various substances present in the EOs (Feng et al 2020;Fazolin et al 2023), e.g., the heightened toxicity of compound mixtures is a relatively common occurrence compared to individual pure substances. This is primarily because EOs consist of complex mixtures of various compounds, and these compounds can act on different sites within the insect's body, leading to additive or synergistic interactions.…”