The side-effects of plant extracts and metabolites of Reynoutria sachalinensis (F. Schmidt) Nakai and conventional fungicides on the beneficial organism Trichogramma cacoeciae Marchal (Hym., Trichogrammatidae)

The aim of this study was to investigate the side-effects of plant extracts (plant strengthener with resistance inducing properties) and conventional fungicides on the egg parasitoid Trichogramma cacoeciae Marchal. Two plant extracts and one metabolite from Reynoutria sachalinensis (F. Schmidt) Naka i (crude water extract (Rey-crude(R)), which is used for the control of pow dery mildew and other diseases, a methanolic fraction of this extract (Rey- meth(R)) and the anthraquinone plant constituent (Physcion(R)), as well as four fungicides (Thiram(R), Dithane(R) M45, Euparen M(R) and Kumulus(R)) we re tested. Adults of T. cacoeciae of uniform age were exposed to fresh dry film of the compounds and the percentage reduction in parasitism compared w ith water-treated controls was calculated. The results of experiments using the highest recommended concentrations sprayed on glass plates showed that the preparations greatly differed in their effect on the parasitoid. All o f the conventional fungicides tested were found to be harmful. In contrast, Rey-crude and Physcion were harmless to T. cacoeciae, whereas the fraction Rey-meth was slightly harmful. In further experiments the side-effects of the plant protection agents on T. cacoeciae were compared when sprayed at d ifferent concentrations either on glass plates or on vine leaves. The resul ts confirmed the findings of the first trials but showed that side-effects of the compounds Dithane M45 and Euparen M were less toxic when applied to vine leaves.