Insect Damage to Conelets, Second-Year Cones, and Seeds of Ponderosa Pine in Southeastern Nebraska

1988

S. 1681-1690

6 Tab., 36 Lit. Ang.

Unselbständiges Werk

200042617

Rhyacionia spp. and Retinia metallica (Busck) annually conelet losses (Formel), respectively. Absorption and disappearance of conelets caused by Leptoglossus occidentalis Heidemann or physiological dysfunction averaged (Formel) and were reduced by 13% when conelets were protected with screen cages. Survival of conelets averaged (Formel). Of those remaining, (Formel) appeared healthy after the second growing season. Dioryctria spp. annually damaged an average of (Formel) of the second year cones. Mean annual seed potentials ranged from 77.4 to 127.1 seeds per cone, but mean annual seed yields ranged fromonly 0.4 to 8.1 filled seeds per cone. Caging cones to exclude L. occidentalis increased seed yield and efficiency and decreased damaged and empty seed. Feeding by L. occidentalis damaged an estimated 41% of initial ovules in cones harvested in 1985. Thus, insects can significantly reduce cone production and seed yield of ponderosa pine in southeastern Nebraska.