(E)-anethole is a phenylpropanoid that is the main compound found in the essential oils (EOs) of anise and fennel seeds, and either fumigant or direct contact activity of this compound has been demonstrated against aphids and stored product pests. In this work, solid microspheres were prepared by three methods—oil emulsion entrapment, spray-drying, and complexed with β-cyclodextrin. Fumigation activity of each microsphere preparation was tested against the green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), on pepper leaves. The best insecticidal activity was with (E)-anethole encapsulated in oil emulsion beads and introduced to aphids as a vapour over 24 h, with an LC50 of 0.415 μL/L compared to 0.336 μL/L of vapors from free (E)-anethole. Scanning electron microscopy of the beads revealed a compact surface with low porosity that produced a controlled release of the bioactive for more than 21 d, whilst most of the volatile was evaporated within two days if applied unformulated. Spray drying gave spherical particles with the greatest encapsulated yield (73%) of 6.15 g of (E)-anethole incorporated per 100 g of powder. Further work will be done on improving the formulation methods and testing the solid microspheres in all aphid stages scaling up the experimental assay. It is foreseen that nanotechnology will play a role in future developments of low risk plant protection products.
Pheromone-lured funnel traps are widely used for pest monitoring and mass trapping in agricultural fields and stores. DDVP vapona (dichlorvos), the insecticide of choice as a killing agent inside traps, has been banned, and research on new products is being pursued. Essential oils (EO) could be an alternative if properly formulated. To test their potential, beads of encapsulated coriander and basil EO were tested in funnel traps in stores of almonds and pet foods during 2 mo. The number of adult moth ( Plodia interpunctella (Hübner) and Ephestia kuehniella Zeller) dead captures was similar with either coriander or basil EO beads and with vapona tablets while there were more insects alive in the control. These preliminary results indicate a good potential for the development of such natural products as an alternative to synthetic insecticides to include them inside funnel traps.
Myzus persicae (Sulzer) (Hemiptera: Aphididae) is one of the most important aphid crop pests, due to its direct damage and its ability to transmit viral diseases in crops. The objective is to test whether spraying nanoemulsions of botanical products repels winged individuals of M. persicae in a bioassay in culture chambers. The bioactive volatiles were applied on pepper plants at a dose of 0.2% alone or at 0.1% of each component in blends. A treated plant and a control plant were placed at each side of an entomological cage inside a growth chamber. The winged individuals were released between the plants, in a black-painted Petri dish suspended by wires in the upper half of the cage. The most repellent products were farnesol (repellency index, RI = 40.24%), (E)-anethole (RI = 30.85%) and coconut fatty acid methyl ester (coconut FAME) (RI = 28.93%), alone or in the following blends: farnesol + (E)-anethole + distilled lemon oil (RI = 36.55%) or (E)-anethole + distilled lemon oil + coconut FAME (RI = 30.63%). The observed effect of coconut FAME on aphids is the first report of this product having a repellent effect on a crop pest. Repellent substances for viral disease vectors should be further investigated to develop new strategies for plant protection.