Persistence of nanoemulsions of bioactive volatiles and their impact on aphid feeding behaviour

Nanoformulations of essential oils (EOs) improve stability of the active ingredient, and thereby its biological activity and persistence. Because compatibility of EOs with natural enemies is not explored sufficiently, we evaluated the impact of nanoformulations of EOs (aniseed, lemon) or pure products (farnesol) on different activities of the generalist predator Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). In dual choice bioassay, chrysopid larvae were significantly attracted to aniseed-treated pepper disks and deterred by farnesol. Larval activities (resting, walking, and preying) on treated leaves infested with Myzus persicae (Sulzer) (Hemiptera: Aphididae) were compared. There were no differences among nanoemulsions, nor aphid consumption varied. We studied the toxicity of nanoformulations to larvae and evaluated their development after contact with treated leaf disks, ingestion of treated artificial diet, and both routes of exposure (application of biopesticides on aphid-infested plants). This is the first evidence of the compatibility of EO nanoformulations with C. carnea by single route of exposure. Whether any effect appeared, it was sublethal. Compounds significantly reduced aphid consumption after 6 h on double route exposure, but this negative short-term effect disappeared as time progressed. Our results showed the optimal biopesticide to apply depends on which biological feature of the natural enemy we targeted. The key element to introduce these nanoemulsions is to match their persistence period on the crop with the release of the appropriate biological stage of C. carnea. This reinforces the fact that the main activities of C. carnea can be substantially maintained in joint application with nanoemulsions of EOs.

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Aphicidal and antifeedant activity of Synandrospadix vermitoxicus extracts against Myzus persicae on potato plants

López-Isasmendi,

Machado-Assefh,

Reyes

et al. 2024

Preprint

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Potato crops are usually kept virus-free through intensive aphid vector control schemes that require multiple treatments with insecticides. The generalist aphid Myzus persicae developed different mechanisms of resistance to insecticides, and there is a need for sources of novel insecticides. Synandrospadix vermitoxicus (Griseb.) Engl., an Araceae family native to the northwestern region of Argentina, Paraguay, and Bolivia has been locally described as having insecticidal properties against insect larvae and could be a potential source of new natural insecticides against aphids. We tested the antifeedant and aphicidal effects of two extracts from the tubers of S. vermitoxicus, ethanolic and hexanic, on M. persicae. First, we treated potato leaves with the extracts to assess their antifeedant effect by measuring host preference changes in M. persicae. Then, we evaluated its aphicidal effect by offering the extracts to aphids through artificial diets and the aphid probing behaviour by electrical penetration graph. We also analysed the extracts for the main classes of secondary metabolites. We found that both extracts have antifeedant effects, with the hexanic being the strongest and accordingly, aphid probing behaviour was affected on leaves treated with hexanic extract. While the ethanolic extract affected the survival of aphids fed on artificial diets, the hexanic extract did not. The analysis of S. vermitoxicus extracts shows an array of flavonoids and triterpenoids compounds. Therefore, our results show that the tubers of this plant could be a source for a novel product with potential use on the control of M. persicae on potato crops.

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Persistence of nanoemulsions of bioactive volatiles and their impact on aphid feeding behaviour

Cited by 4 publications

References 51 publications

Innovative formulation strategies for botanical- and essential oil-based insecticides

Innovative formulation strategies for botanical- and essential oil-based insecticides

Compatibility of Chrysoperla carnea (Neuroptera: Chrysopidae) with nanoformulations of natural active substances

Aphicidal and antifeedant activity of Synandrospadix vermitoxicus extracts against Myzus persicae on potato plants

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