Feeding behaviour of the first-instar Choristoneura fumiferana and Choristoneura pinus pinus (Lepidoptera: Tortricidae)

We have discovered that, contrary to the long-held belief, 1st-instar spruce budworm, Choristoneura fumiferana Clemens, do feed. They display red alimentary tracts if they are provided with diet containing the red dye amaranth. They graze on the surface of balsam fir needles sprayed with rhodamine and ingest the fluorescent material, which can be detected in the frass pellets deposited inside the hibernacula. When emerging 1st instars were allowed to crawl on the inside surface of a glass tube coated with the polyhedral inclusion bodies of a recombinant C. fumiferana virus containing the gene for the green fluorescent protein, the larvae showed the characteristic green fluorescence, indicating that not only had they ingested the occlusion bodies but also the virus had replicated and infected different tissues. Similar results were obtained with the jack pine budworm, Choristoneura pinus pinus Freeman, which has an identical life history. The advantages of early-instar intervention to minimize defoliation by using control agents such as the ecdysteroid agonist, tebufenozide (RH-5992, Mimic® formulation), are discussed.