The role of insects in the dynamics of cone production of red pine.

The mortality of red pine cones was studied for several consecutive years using life tables in eight different stands in the northern Great Lakes States. Usually less than 20% of a cohort of female flowers survived to maturity. Insects were the main source of mortality and were primarily responsible for annual fluctuations in the abundance of mature cones. Insects were probably also responsible, along with late summer weather (especially precipitation), for influencing the rate of initiation and differentiation of flower bud primordia, as shown in a model of the flowering-cone production processes. These studies suggest that the devastation of developing cone crops by insects may actually enhance flower primordia production and thus the future abundance of feeding and breeding sites for cone insects.