Field releases and recovery of an introduced aphid parasitoid, Lysiphlebus testaceipes (Hym.: Braconidae) in Shaanxi.
Lysiphlebus testaceipes was introduced from Oklahoma to Shaanxi, China, in 1983. Several aphid species, including Schizaphis graminum, Aphis gossypii, A. craccivora, A. rumicis, Rhopalosiphum maidis and R. padi, were found to be hosts of the parasitoid. During 1983-86, a total of 21 307, 11 508, 2933 and 19 562 parasitoids was released on cotton, wheat, wasted weedy lands and 3 greenhouses in Xian Botanical Garden, resp. In 1987, no individuals of L. testaceipes were recovered from 172 parasitized aphids collected from the cotton fields, while one adult emerged from 34 parasitized individuals of S. graminum and one from 314 parasitized individuals of R. padi collected from the wheat fields. Six parasitoids were recovered from 420 parasitized individuals of A. craccivora collected from the weedy lands. The rate of parasitism of aphids on 2 ornamentals, Hibiscus rosa-sinensis and P. hosporumtobira, in the greenhouse was 49.3 and 32.2%, resp., and all the emerged parasitoids were L. testaceipes. Factors influencing the establishment of the introduced parasitoid in Shaanxi are discussed.