none Ostrinia nubilalis; FOOD-PLANTS; Hymenopteran parasite response to odours from plants utilized by host; HYMENOPTERAN-PARASITES; Macrocentrus grandii; Parasitoid response to odours from food plants utilized by host Macrocentrus grandii; TAXIS-; Parasitoid response to odours from food plants used by lepidopteran host; LEPIDOPTERAN-HOSTS; Ostrinia nubilalis; Parasitoid response to odours from food plants utilized by host. The specialist parasitoid Macrocentrus grandii Goidanich (Hymenoptera: Braconidae) appears to parasitize its polyphagous host, European corn borer (Ostrinia nubilalis (Huebner)) (Lepidoptera: Pyralidae), in only certain habitats. To determine whether it differed in its olfactory response to host-habitat odours, volatiles from four plants were isolated using Tenax. Wind tunnel bioassays of the extracts revealed that, besides corn which was tested in an earlier study, olfactory stimuli for attraction of M. grandii females were present in potato and snap bean but not in pepper or soybean. To further characterize the response to pepper and soybean, these extracts were bioassayed in combination with an attractive extract. The results indicated that pepper volatiles evoked a neutral response in M. grandii while response to soybean volatiles appeared to be neutral or slightly negative. These results support the idea that plant odour may be a factor determining the range of plants on which M. grandii parasitizes its host. The study indicates the occurrence of associative learning of plant-related volatiles during oviposition in M. grandii, and suggests the involvement of diverse plant compounds in the learning process.