Successful parasitoid control of Aonidiella orientalis (Newstead) (Hemiptera: Diaspididae) on Carica papaya L

Abstract

The role of three parasitoids in controlling oriental scale, Aonidiella orientalis, in papaya in coastal areas of central and northern Queensland was assessed during 1989–1995. Comperiella lemniscata Compere and Annecke (Hymenoptera: Encyrtidae) was introduced from Hainan Island in China and from the Torres Strait in northern Queensland, and reared and released in 1991 at the rate of 2000 per property. Within 12 months, parasitisation mainly of the third-instar scales rose to as high as 80% and rejection of fruit for the market dropped from 20–30% to 1–2%. Aphytis melinusDeBach (Hymenoptera: Aphelinidae) was augmentatively released in papaya plantations in central and northern Queensland at a rate of 25 000 per ha. Parasitisation mainly of the third-instar scales was boosted by these releases from 0% to between 10 and 30%, but these levels persisted for only a few months and the parasitoid had to be continually re-released. Encarsia citrina (Craw) (Hymenoptera: Aphelinidae) occurred naturally at parasitisation levels of up to 80% in mainly the second-instar scales and was important in the biological control of the scale.