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New Zealand Plant Protection 63 (2010): 282

Detection and identification of a self-introduced parasitoid of the Acacia tortoise beetle

T.J. Murray and T.M. Withers

ABSTRACT

Dicranosterna semipunctata (Coleoptera: Chrysomelidae) was detected in New Zealand in 1996. This Australian tortoise beetle has no specific natural enemies in New Zealand and has become a moderate pest of blackwood (Acacia melanoxylon). Although a number of potential biological control agents have been identified in Australia, none has been intentionally introduced. In January 2009, parasitised eggs of D. semipunctata were found in Rotorua. Comparison of the emergent parasitoids to hymenoptera held in the NZIC and ANIC confirm that the wasp is from the genus Neopolycystus. The taxonomy of this genus is poorly resolved but there were three species of particular interest to which to compare the new specimens. The first, Neopolycystus sp. nr insectifurax, was introduced from Perth against Paropsis charybdis in 1989 but did not establish. The second, Neopolycystus sp., was reared from D. semipunctata eggs in NSW but was never imported into New Zealand as a biocontrol agent for D. semipunctata. The third, N. insectifurax Girault, is self-introduced since 2001 and is well established in New Zealand, contributing significantly to the control of P. charybdis. The parasitoids reared from D. semipunctata eggs in Rotorua were not analogous to any of these. This new species, Neopolycystus sp., from Rotorua has since been recorded in the Northland, Auckland, Waikato and Bay of Plenty regions.

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