SUSCEPTIBILITY OF CHORISTONEURA ROSACEANA (HARRIS) (LEPIDOPTERA: TORTRICIDAE) TO THE MICROSPORIDIUM NOSEMA FUMIFERANAE (THOMSON) (MICROSPORIDA: NOSEMATIDAE)

Abstract

AbstractPathogenicity of the microsporidium Nosema fumiferanae (Thomson) in the obliquebanded leafroller, Choristoneura rosaceana (Harris), was evaluated in laboratory bio-assays. When consumed by first-, fourth-, or fifth-instar obliquebanded leafroller larvae, Nosema spores primarily infected the gut and Malpighian tubules. When 2000 spores per square millimetre diet surface were consumed by neonate, fourth-, or fifth-instar larvae, the N. fumiferanae caused 91, 24, and 5% mortality, respectively. Infection by N. fumiferanae had a delayed impact on the older larvae. Large numbers of spores were retained to the adult stage by obliquebanded leafrollers treated as fourth- or fifth-instar larvae.