Host‐habitat location by Apanteles glomeratus and effect of food‐plant exposure on host‐parasitism

. 1. The study investigates differences in the oviposition pattern of a braconid parasitoid, Apanteles glomeratus L., in three Pieris species in Japan in relation to their use of different cruciferous foodplants. 2. A.glomerutus females located various habitats of different crucifers. On field crops and exposed wild crucifers P.rapae crucivora Boisduval and P.napi japonica Shirôzu, which are both physiologically suitable hosts, were attacked at a high rate, although P.n.japonica is rare in such situations, while P.melete Ménétriès, which is a physiologically unsuitable host, was attacked slightly less frequently. 3. When P.n.japonica occurred on crucifers hidden by overshadowing vegetation, as it generally did, it suffered a very low level of parasitism by A.glomeratus , but if the overshadowing vegetation was cleared then a high rate of parasitism ensued. 4. The foodplant concerned, Arubis , was attractive to the parasitoid and not deleterious to its development in P.n. japonica , but it was not used by P.r.crucivora , which usually failed to develop on it under experimental conditions. 5. The parasitoid females could not locate foodplants hidden by overshadowing vegetation. Therefore the most important difference between foodplants in host‐habitat location was the situation in which the foodplant grew.