The use of Leptomastix dactylopii Howard (Hymenoptera: Encyrtidae) to control Planococcus citri (Risso) (Hemiptera: Pseudococcidae) in Queensland citrus orchards.
Studies on the efficacy of the coccinellid Cryptolaemus montrouzieri and the encyrtid Leptomastidea abnormis for the control of pseudococcid Planococcus citri on citrus and custard apple (Anonna spp.) in Queensland before 1980 are reported. Following its introduction in 1980-81, the encyrtid Leptomastix dactylopii became the most common natural enemy of P. citri throughout southeast Queensland. Parasitoid numbers were lowest during winter and spring, indicating that augmentative spring and early summer releases may increase its effect. This was confirmed by widespread releases of 5 000 to 10 000 parasitoids/ha during November-January 1984-87. Releasing increased the parasitoid's activity by 6 weeks and by late March, an average 50% of infested fruit had L. dactylopii present. Pest infestations averaging 38% of fruit in early December were reduced to within an acceptable 5% level by harvest in April. When methidathion (at 0.5 g/litre) was applied in November, an augmentative release in December of 10 000 parasitoids/ha was also beneficial and resulted in acceptable pest levels at harvest in contrast to sprayed areas receiving no releases. Without augmentative releases, parasitism by L. dactylopii increased naturally from late summer but usually too late to reduce the mealybug infestation to 5% or less at harvest.