inflated calyx of Physalis angulata: a refuge from parasitism for Heliothis subflexa

Heliothis subflexa and H. virescens are the only known hosts of the parasitoid Cardiochiles nigriceps. H. subflexa, a specialist on plants in the genus Physalis, appears to have a lower parasitism rate compared to the polyphagous H. virescens. Physalis is characterized by producing fruits that are concealed within a paper-like lantern, within which H. subflexa larvae feed. We conducted an experiment to determine whether H. subflexa is protected from parasitism by feeding within the lanterns of Physalis. We compared parasitism rates of wild H. subflexa larvae on normal P. angulata plants to parasitism rates of larvae on plants that had the tips of all the lanterns removed to allow parasitoids access to the larvae. A higher percentage of larvae were parasitized on plants with cut lanterns (48.25%) than uncut lanterns (6.74%). A second experiment was conducted to determine whether volatiles released from cut lanterns influenced the searching of C. nigriceps. This experiment consisted of the two treatments from the previous experiment and a third in which the tips of lanterns were removed and the resulting hole was stapled shut. Cutting plants did not make the plants more attractive to searching parasitoids. We conclude that H. subflexa gains protection from parasitism by feeding within the inflated calyx of Physalis.