INFLUENCE OF CONE PESTS ON THE DEVELOPMENT OF SLASH PINE CONE

Investigations in some seed orchards in Zhejiang province showed that the cone insects damaging slash pine cones include Petrova cristata Walsingham, Dioryctria rubella Hampson and Shirahoshizo sp., among which P. cristata and D. rubella are of more importance. The bionomics of these two species and the characteristics between healthy and affected cones are reported. The average thousand-seed weight of affected cones and that of healthy ones are 29.13g and 42.90g respectively, the average germination percentage of the two are 12.8% and 45.0%. It is suggested that the principal indices of cone damage caused by cone pests could be the average thousand-seed weight and the average germination percentage.