Effects of wheat foliar fungicides on the aphid endoparasitoid Aphidius rhopalosiphi DeStefani-Perez (Hym., Aphidiidae) on glass plates and on plants

The side-effects of several fungicides used in wheat to control disease at heading growth stage were assessed on the aphid parasitoid Aphidius rhopalo siphi by tests conducted in the laboratory on glass plates and in the green house on young wheat plants. Very few formulations containing only one acti ve ingredient (carbendazim, cyproconazole or epoxyconazole) or combinations of two (carbendazim + cyproconazole, carbendazim + hexaconazole) were harm less to A. rhopalosiphi in the glass-plate tests. There was no apparent syn ergism between fungicides tested in combinations. The parasitoid mortalitie s in tests carried out on plants were less and chlorothalonil, epoxyconazol e, fenpropidin, fenpropimorph, flusilazole, flutriafol, prochloraz, tebucon azole, tridemorph and a number of combinations (carbendazim + flutriafol, c hlorothalonil + cyproconazole, epoxyconazole + tridemorph, chlorothalonil hexaconazole, chlorothalonil + flutriafol, cyproconazole + prochloraz, epo xyconazole + fenpropimorph, fenpropimorph + propiconazole, propiconazole tridemorph, triadimenol + tridemorph) were harmless or only slightly harmfu l to the aphid parasitoid. Several combinations (carbendazim + epoxyconazol e, carbendazim + fenpropimorph, carbendazim + flusilazole, carbendazim + te buconazole, chlorothalonil + fenpropimorph, chlorothalonil + flusilazole, f enpropimorph + fenpropidin, fenpropimorph + prochloraz, fenpropidin + propi conazole, fenpropidin + tebuco nazole, tebuconazole + triadimenol) were tox ic for wasps on plants. The parasitoid mortalities were less on plants than on glass plates but the wasps spent less time on treated leaves and in som e cases parasitism of aphids was reduced to a large extent. These results s uggest that in addition to study of the direct effects of pesticides on ben eficial insects (mortalities, reduction of fertility) their effects an the behaviour of the insects should also be studied. Products that induced a re pellent effect need further testing in field or semi-field conditions. Howe ver, many fungicide combinations that have little or no effect on A. rhopal osiphi can protect wheat against a wide range of diseases and the results o btained in this study indicate that an appropriate and effective protection of wheat at earing growth stage can be achieved with products that have no effects on aphid parasitoids.