Effects of a commercial formulation of a plant resistance elicitor on non-target organisms

Abstract: The toxicity of Fyto11, a plant resistance elicitor commercial formulation used to increase the natural resistance of Cucurbitaceae (cucumber, zucchini and melon) and Solanaceae (tomato and sweet pepper) against powdery mildew under greenhouse conditions, has been assessed on several beneficial arthropods: the honeybee Apis mellifera, the predatory mite Typhlodromus pyri, the aphid parasitic wasp Aphidius rhopalosiphi and the aphid predator Episyrphus balteatus.Tested at 0.5% and 1.0% spray dilution on plants, Fyto11 did not lead to significant corrected mortalities for E. balteatus larvae and adult wasps of A. rhopalosiphi, with a maximum of 5.4% mortality. No effects on reproduction capacity of the parasitic wasps were observed.The exposure of T. pyri protonymphs to Fyto11 on glass plates lead to corrected mortalities of 1.1% and 32.6% at 0.5% and 1.0% and to a reduction of female fertility of 9.0% and 25.4%, compared to the control performance. When assessed on the honeybee by contact and oral exposure, Fyto11 did not lead to significant effects, with LD50 estimated as > 10 μg a.i./bee (oral) and 12.5 μg a.i./bee (contact), leading to HQ ratio < 50 and classifying the product at no or low risk for honeybees.These results showed that the product was harmless for all beneficials at the proposed commercial rate, except for T. pyri at 1.0% on glass plates, where the product was rated as slightly harmful. Even if all the beneficial species’ diversity has not been assessed with this product, negative effects on non-target organisms are not expected in field conditions and Fyto11 can be considered as compatible with IPM programs.