Evaluation of the biological control of the pink wax scale Ceroplastes rubens Maskell (Hom., Coccidae) with the introduced parasitoid Anicetus beneficus Ishii & Yasumatsu (Hym., Encyrtidae) in the Central province of Papua New Guinea

In order to evaluate the possibility of a classical biological control of the pink wax scale Ceroplastes rubens (Hom., Coccidae) with the parasitoid Anicetus beneficus (Hym., Encyrtidae), endemic parasitoids were collected (2000/2001) in three provinces in Papua New Guinea and parasitization levels were determined. Eight hymenopteran parasitoid species were identified: Aprostocetus sp. (Eulophidae), Coccophagus sp. (Aphelenidae), five Encyrtidae: Cheiloneurus sp., Coccidocnotus sp., Diversinervus sp., Metaphycus sp., Microterys sp. and Moranila sp. (Pteromalidae). Levels of parasitization were low, varying between 1.4 and 2.8%. A. beneficus was imported from Australia and 1100 specimens were released in spring 2002 at two locations with mango infested by C. rubens (Laloki and Tahira) in the Central Province. A. beneficus did establish at both sites. Six months after release, parasitization levels of C. rubens had increased from 2.8 to 5.9% (P = 0.05) at Laloki and from 1.8 to 22.2% (P = 0.01) at Tahira, with A. beneficus being the most frequent parasitoid (69% of all parasitoids). Workers of the ant genus Tapinoma (Dolichoderinae) were frequently collected from infested trees at Laloki, but were not present at Tahira. It is assumed that their presence is at least partly responsible for the lower degree of parasitization and number of A. beneficus at this site. The necessity of further studies is stressed.