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

We have discovered that, contrary to the long-held belief, Ist-instar spruc e budworm, Choristoneura fumiferana Clemens, do feed. They display red alim entary tracts if they are provided with diet containing the red dye amarant h. They graze on the surface of balsam fir needles sprayed with rhodamine a nd ingest the fluorescent material, which can be detected in the frass pell ets deposited inside the hibernacula. When emerging Ist instars were allowe d 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 gre en fluorescence, indicating that not only had they ingested the oc elusion bodies but also the virus had replicated and infected different tissues. Si milar results were obtained with the jack pine budworm, Choristoneura pinus pinus Freeman, which has an identical life history. The advantages of earl y-instar intervention to minimize defoliation by using control agents such as the ecdysteroid agonist, tebufenozide (RH-5992, Mimic(R) formulation), a re discussed.