Effects of larval age at inoculation, and dosage of microsporidan (Nosema fumiferanae) spores, on mortality of spruce budworm (Choristoneura fumiferana)

Abstract

There is an increase in larval mortality of Choristoneura fumiferana as the insect is fed an increasing dose of Nosema fumiferanae spores. However, there is a decrease in susceptibility to the pathogen with an increase in host age. High concentration (108–109 spores/ml) fed to last-instar larvae will result in 100% infection in the adults. It takes from 14 to 20 days for the pathogen to cause 50% mortality in the larvae.