The side-effects of 21 pesticides were tested on the Hymenoptera egg parasitoid Trichogramma cacoeciae, using four different types of laboratory methods. The methods combined: (a) adult parasitoid exposure to fresh pesticide residue on glass plates - initial toxicity worse case to select harmless preparations, (b) direct spray of host eggs enclosing the parasitoid pupae (less susceptible life stage), (c) duration of harmful activity (persistence) on adults - select preparations that are less persistent and (d) dose-response exposures LD50 - to assess the risk margin. The results showed that the preparations (used at the highest recommended dose) greatly differed in their initial toxicity as well as in their persistence. The fungicide Topsin M(R) (thiophanat-methyl) and the herbicides Pyramin(R) (chloridazon), Butisan(R) S (metazachlor) and Banvel(R) 70 WG (dicamba) were harmless to T. cacoeciae. The insecticides Match(R) (lufenuron) and Admiral(R) (pyriproxifen), the fungicides Bavistin(R) (carbendazim), Aliette(R) (fosetyl) and Captan(R) 83 W (captan) as well as the herbicides Duplosan(R) 600 KV (mecoprop-p) and Focus(R) (cycloxydim) were slightly harmful. The fungicide Scala(R) (pyrimethanil) was moderately harmful. Telmion(R) (rape oil), Vertimec(R) (abamectin) and Scala were harmful in the initial toxicity test but only slightly persistent. These less persistent preparations are likely to have less impact on the natural enemy in the field. In the persistence test, Zolone Flow(R) (phosalon), Polo(R) (difenthiuron), Euparen(R) M (tolylfluanid), Dithane(R) M 45 (mancozeb), Kumulus(R) (sulphur) constantly reduced parasitism by between 90 and 100% and were rated as persistent. The direct spray of parasitized host eggs showed that Zolone Flow, Polo, Eupareum M, Dithane M 45, Scala and Touchdown(R); were harmless to the parasitoid pupae within the egg, that Telmion, Thiram(R) 80 WG and Kumulus were slightly harmful and Vertimec was moderately harmful. The dose-response test indicated a risk quotient (dose in g or ml product per ha/LD50 value) of spray drift for off-field parasitoids for the chemicals in the order of increasing risk as follows: Polo (1.33) followed by Thiram (3.62), Touchdown (7.54), Scala (10.39), Dithane M 45 (13.94), Telmion (27.04) and Zolone Flow_(39.34).
