Population fluctuation of Phyllocnistis citrella and its parasi-toids in two citrus species in Western Crete (Greece)

Population fluctuation, percentage of parasitism and parasitoid species composition of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) were studied in a citrus orchard with orange and mandarin trees in Chania (Greece), in 1999, three years after the release of the in-troduced parasitoids Citrostichus phyllocnistoides (Narayanan), Quadrastichus sp., Semielacher petiolatus (Girault), Cirrospilus quadristriatus (Subba Rao and Ramamani) and Ageniaspis citricola Logvinovskaya. Results showed that significantly more P. citrella individuals per leaf were recorded on orange than on mandarin trees. Regarding the parasitoid complex composition, the exotic species C. phyllocnistoides, S. petiolatus and Quadrastichus sp., as well as the natives Pnigalio pectinicornis L. and Neochrysocharis formosa (Westwood) were recorded. Among them, C. phyllocnistoides was the most abundant, followed by S. petiolatus. The average percentage of parasitism reached 17% and 22% on orange and mandarin, respectively.

Evaluation of biological control of the oak leaf-miner Phyllonorycter messaniella (Zell.) (Lep., Gracillariidae) in New Zealand

To evaluate the effectiveness of the introduced Hymenopterous parasites Apanteles circumscriptus (Nees) and Enaysma splendens Delucchi in the control of Phyllonorycter messaniella (Zell.) samples of leaves were taken from infested oaks during 1969–70. In Christchurch there were three generations of P. messaniella per year with spring, summer, and autumn emergence periods. Infestation on deciduous oaks was negligible in some areas but was 6.3 mines/leaf in the lower crown of oaks close to evergreen oaks on which P. messaniella overwinters. On deciduous oaks total parasitism ranged from 30% to 80%. Apanteles was the most abundant parasite but Enaysma assumed almost equal importance on oaks with low infestations. Pnigalio pectinicornis (L.), a self-introduced parasite, has been almost completely displaced by the other two parasites since their introduction in 1957. The infestation intensity recorded in Nelson (2.3 mines/leaf) was much lower than the level reported before the release of the parasites (40+ mines/leaf), but still much higher than levels in Europe.