Preliminary results for the eνaluation of the action of Saissetia oleae parasites in Corfu.

Abstract

The action of parasites of Saissetia οleae (OIiv.) (Homoptera-Cοccidae) is studied in Corfu from 1980 in the framework of an ongoing project on the population dynamics of Saissetia οleae. Results obtained during the period 1980-1983 from 17 experimental sites indicate the following: a) the population of S. οleae increased in 1981 but from 1982 it declined to very low levels; following the overall decline of the host population, parasitization rates of third instar larvae (mainly by Μetaphycus helνolus Comp.) were relatively low and ranged from 2.1% to 6.7% for the autumn period and from 14.6% to 29.4% for the spring period; this does not minimize the possibility that Μetaphycus helνolus plays an important role on the regulation οf S. οleae populations; b) a considerable proportion of females of S. οleae is attacked during summer by Μetaphycus lounsburyi How. (an internal parasite on preovipositing females), Μoranila californica How. and Scutellista cyanea Μοtsch. (egg predators), but their significance upon the population system of S. οleae is not expected to be great. The action of Μetaphycus lounsburyi in spring, when the peak of the suitable stage occurs (i.e. fourth instar larvae), appears to be very low, at least for these three years. Its action is delayed and most of the specimens of this parasite emerge from ovipositing females in early summer. Among the species attacking S. οleae females, Μ. californica (recently introduced in Corfu) was the most abundant and it might be worthy to be introduced to other parts of Greece too.