Dear fellow ecologists, I am working at the Department of Entomology at UMass on a project to stem the spread of winter moth throughout the northeast. We are attempting to insert the tachinid fly, Cyzenis albicans, into the populations of winter moth found in eastern Massachusetts. The fly lays its eggs on leaves eaten by winter moth, which are in turn eaten by the caterpillars. The eggs then hatch inside. We have been rearing winter moth caterpillars on diet so that we can infect them in the lab. To infect the caterpillars, we place an individual into a centrifuge tube with a small piece of leaf with 1 to 5 Cyzenis eggs on them. (We have cages full of flies set up to lay eggs on our trees. So far, we have attempted to use beech plum, cherry, maple and oak trees.) Afterwards, we inspect each tube to see if the leaf has been eaten or not, then raise the ones that have eaten until they pupate.
The main problem weve been having this year is that we cannot seem to coerce the caterpillars to eat the leaf. Last year, on average, 70% of the caterpillars had eaten the leaf. However, this year, weve found percentages as low as 30%. The caterpillars seem to prefer the beech plum and cherry, but not by a significant amount. Weve hypothesized that since theyve been raised on diet and have never seen a leaf, they may be having problems recognizing that leaves are food. Does anybody have any ideas on how to make the leaf more enticing towards the caterpillars? Should we try to place the fly egg on diet? Would putting some sugar on the leaf help? Thank you very much, Noel Hahn Departmental Assistant University of Massachusetts Department of Entomology
