Looking for the Pupae of Spotted Wing Drosophila
One of the unsolved mysteries of our work in berries has been what of the pupae of spotted wing drosophila? As anyone who has worked with this fly in the lab knows, many larvae exit the fruit and pupate outside, either on the surface of the fruit or on the floor and walls of the container in which they are being held.
In the field however, it's been very rare to find the pupae. We don't see them on the leaves or fruit hanging on the plant, and one generally doesn't find them on the surface of the soil.
Following the lead of a group of scientists out of Maine on blueberry, my research assistant Monise and I are going to attempt to solve this issue once and for all. We first confirm that a fallen fruit has at least one larvae in it, and then covering each of these with a centrifuge tube with airholes punched in the sides, taking care to push the tube about an inch into the ground (see picture below). Since we are engaged in science and not a quest to confirm our own bias, we accompany these tubes with an equal number of tubes without fruit in them. After about a week, Monise will recover these tubes, separate the fruit from soil and look in both for the pupae.