none Pholeastor (Apanteles) glomeratus; LEPIDOPTERAN-HOSTS; Pieris brassicae; Control by plant extract, indirect effects on parasite; DISEASES-AND-DISORDERS; Deformities, plant extract significance; MORTALITY-; Plant extract effect; CHEMICAL-FACTORS; Plant extract as cause of mortality & deformities, lepidopteran host Neem seed extract was applied orally and topically to 4th and 5th instar Pieris brassicae L. larvae which contained larvae of the parasitoid, Pholeastor (Apanteles) glomeratus (L.), and also topically to P. glomeratus cocoons. As well as heavy parasitoid mortality due to premature host death, P. glomeratus suffered increased mortality at all subsequent life stages and deformities in emerged adults. Neem seed extract is capable of having direct negative effects of P. glomeratus populations. It is suggested that care should be taken in the use of such extracts and that assessment of potential impact on parasitoid populations should take place beforehand.