Abstract: In this work we report on the toxicity in the laboratory of some modern pesticides onthe most protected life stage of the tinny parasitic wasp Eretmocerus mundus by evaluating adultemergence as well as sublethal effects on its reproductive performance. Parasitized Bemisiatabaci pupae were placed on glass surfaces and directly sprayed with the maximum fieldrecommended concentrations of the pesticides. Three modern pesticides used in horticulturalcrops in Spain, with different modes of action and included in annex I of EU Council directive91/414/EEC were studied: the naturalyte abamectin (18mg a.i./l), the moulting acceleratormethoxyfenozide (90.8mg a.i./l) and the pyrethroid deltamethrin (12.5mg a.i./l). The naturalytespinosad was used as toxic standard (120mg a.i./l). According to the results obtained,methoxyfenozide was classified as harmless (IOBC toxicity rating 1), abamectin and deltamethrinas slightly harmful (2) (effects on reproduction) and spinosad as harmful (4) (high mortality). Weconclude that more selective pesticides are needed for this beneficial wasp.