The Effects of Natural Insecticides on the Green Peach Aphid <i>Myzus persicae</i> (Sulzer) and Its Natural Enemies <i>Propylea quatuordecimpunctata</i> (L.) and <i>Aphidius colemani</i> Viereck
Francesco Lami,
Giovanni Burgio,
Serena Magagnoli,
Laura Depalo,
Alberto Lanzoni,
Elettra Frassineti,
Ilaria Marotti,
Mattia Alpi,
Dario Mercatante,
Maria Teresa Rodriguez-Estrada,
Giovanni Dinelli,
Antonio Masetti
Affiliations
Francesco Lami
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Giovanni Burgio
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Serena Magagnoli
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Laura Depalo
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Alberto Lanzoni
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Elettra Frassineti
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Ilaria Marotti
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Mattia Alpi
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Dario Mercatante
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Maria Teresa Rodriguez-Estrada
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Giovanni Dinelli
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Antonio Masetti
DISTAL-Department of Agricultural and Food Sciences, University of Bologna, 40127 Bologna, Italy
Botanical insecticides and soaps are frequently proposed as environmentally safer alternatives to synthetic insecticides. However, the efficacy and selectivity of these products are often only partially supported by empirical evidence. Here, we tested the effectiveness of five botanical insecticides, belonging to different categories, on the green peach aphid Myzus persicae (Sulzer) and their selectivity towards two natural enemies, the ladybird beetle Propylea quatuordecimpunctata (L.) and the parasitoid Aphidius colemani (Dalman). White thyme essential oil (EO), sweet orange EO, crude garlic extract and Marseille soap were tested and compared with a pyrethrin-based commercial product. Both direct spray assays and residual contact assays on treated cabbage leaf disks were carried out. The tested products had low efficacy against aphids when compared to pyrethrins but were in general less detrimental to ladybird beetle larvae, meaning that if applied against other pests, they have a lower chance of harming this agent of aphid biocontrol. Some of the products (soap, orange EO) did, however, show direct exposure toxicity toward ladybird larvae, and thyme EO had extensive phytotoxic effects on cabbage leaves, possibly indirectly leading to higher mortality in ladybird adults. These results underline the necessity for case-by-case evaluations of botanical insecticides.