Preliminary Study of Damage to Male Cone of Pinus massoniana by Dioryctria yiai

The damage of Dioryctria yiai on young shoots of Pinus massoniana and the influence of this pest insect on development of male cone and pollen were studied. It is demonstrated that the wormhole of D. yiai is harmful to the development of male cone, microsporophyll and pollen in the next year. The length and diameter of male cone and microsporophyll number decreased and accounted for 33.3% and 40.2% of the health plant, respectively. The vertical and transverse diameter of microsporophyll accounted for 62.0% and 71.0% of the health plant, and the fresh and dry weight of microsporophyll accounted for 30.3% and 43.6% of the health plant. It is concluded that D. yiai could seriously damage the young shoot of P. massoniana and cause bad development of male cone shoot and pollen abortion.