Abstract
Apanteles glomeratus has been known to be a parasitoid of larvae of a small white butterfly, Pieris rapae crucivora. This paper deals with the response of the parasitoid to closely related species found together in the same habitat as the principal host, P. rapae crucivora.Attacking almost all larvae of P. rapae crucivora, the wasp frequently avoided those of P. napi nesis and P. melete. When she oviposited, she deposited less eggs in P. melete than in P. napi nesis. The eggs deposited in P. napi nesis and P. napi japonica developed as well as in P. rapae crucivora, but were encapsulated by host hemocytes in P. melete. Parasitized larvae of P.melete pupated. Successful parasitization rates were 100, 100, 40 and 0% for P. rapae crucivora, P. napi japonica, P. napi nesis and P.melete, respectively.