Impact and control of the cone tortricid Pseudococcyx tessulatana (Staudinger), damaging the cone crop of a selected clone of cypress (Cupressus sempervirens L.) in Italy

The green cypress (Cupressus sempervirens) is of great interest for ornamen tal, reforestation and windbreak use in the whole Mediterranean basin. In I taly, seed material selected for resistance to the fungus Seiridium cardina le is produced in seed orchards by controlled crosses of parent trees. The insect pest showing the highest impact on seed cone production is Pseudococ cyx tessulatana (Lep.; Tortricidae), which attacks cones during the initial growth period as well as full-grown cones. The impact on the seed cone cro p of the tortricid was estimated on a clone patented for its resistance to cypress canker (Agrimed 1). The attack was inversely related to the cone cr op, as it concerned 36.7% of cones in 1999 (high crop year) and the 66% in 2000 (low crop year). In both years, about 90% of the surveyed branches rev ealed cones attacked by P. tessulatana by the 1(st) life-cycle larvae, wher eas only 40% of branches were also attacked by the larvae of the 2(nd) life cycle. The highest attack rate per branch was always observed on branches bearing a low number of cones. The potential of two control methods against P. tessulatana to protect cones which result from crossing a mother tree " Agrimed 1" with selected father trees was also evaluated in 2000. The prote ction given by a sleeve surrounding the branch was almost complete (0.4% co ne mortality), whereas a cone mortality of 24.3% was observed on branches t reated by the insecticide diflubenzuron. Sleeves appear to be useful to pro tect branches on which special crosses were done, but are expensive and tim e-consuming and may favour the attack of the mealybug Planococcus vovae ins ide the sleeve The insecticide application may represent a valid alternativ e, especially when protection should be directed toward a high number of br anches.