The blue gum psyllid,
Ctenarytaina eucalypti
(Maskell) (Hemiptera: Psyllidae), was detected in
Eucalyptus
sp. shoots in the I Region of Chile in 1999. The successful results obtained in North America and Europe using biological control with
Psyllaephagus pilosus
Noyes (Hym.: Encyrtidae) motivated its application in Chile. After its introduction during 2001, studies showed a rapid establishment and a high dispersion capacity during the first year. To evaluate its permanent establishment and its controlling efficacy on the pest without requiring new releases, population fluctuations of both species were determined in contiguous eucalyptus plantations of 14 and 2 months, with and without release of the parasitoid, respectively. The study was performed in Casablanca (33°26' S lat, 71°29' W long, 320 m.o.s.l.).Two plots of 60 x 40 m with 311 plants were selected. Biweekly were collected shoots, placed directly in glass jars, and all stages of psyllids and parasitoids were identified and counted under a stereoscopic microscope in the laboratory. Results showed that when the highest density of the psyllia, parasitoidism affected over 80% of the developed nymphs, reducing drastically the total density of
C. eucalypti throughout the season. Results also indicated that the parasitoid established definitely and is able to control outbreaks of the psyllids without new releases. In addition to the parasitoid, the physiological state of the plant shoots and the transformation of foliage associated with the plant development also influenced psyllid population fluctuation.
