The use of 'Leptomastix dactylopii' Howard (Hymenoptera: Encyrtidae) to control 'Planococcus citri' (Risso) (Hemiptera: Pseudococcidae) in custard apples in Queensland

The parasitoid 'Leptomastix dactylopii' Howard was introduced into Queensland from California in 1980 to control citrus mealybug, 'Planococcus citri' (Risso) in citrus and custard apples. 'L. dactylopii' became a common natural enemy of 'P. citri' in custard apples from April to July each year. To increase its effect, augmentative releases from late December to mid April of a total of 10 000 parasitoids per ha were made in two orchards over three seasons between 1984 and 1989. Releases advanced activity of 'L. dactylopii' by three months with the parasitoid present in 50-80% of mealybug infested fruit by March. The percentage of mealybug infested fruit was usually kept below 25% with less than 5% of fruit infested with populations of 10 or more third instars and/or adult females per fruit. Where there were no releases the corresponding percentages were 40% and 10% and where deltamethrin was used to suppress natural enemies, 80% and 40%. The lacewing 'Oligochrysa lutea' (Walker) and the ladybird 'Cryptolaemus montrouzieri' Mulsant occurred on 20-40% and 10-20% of infested fruit, respectively.