Reconsideration of the role of yeasts associated with Chrysoperla green lacewings

As larvae, lacewings in the genus Chrysoperla (Neuroptera: Chrysopidae: Chrysopinae: Chrysopini) are predators of aphids and other soft-bodied insects. Adult Chrysoperla, however, are not predacious and feed on pollen, nectar, and honeydew. Earlier studies observed that Chrysoperla adults house yeasts in their crops, and based on the results of a sorbic acid yeast suppression experiment, concluded that the yeasts may supplement amino acids missing in the largely carbohydrate diet. In the current study, attempts to cure adult Chrysoperla comanche (Banks) and Chrysoperla carnea (Stephens) of yeasts using Hagen et al.'s [Bull. Lab. Entomol. Agric. Fil Silv. 28 (1970) 113] protocol, as well as several other fungicides and heat treatment, were unsuccessful, thus calling into question earlier conclusions about the yeasts. Based on our findings, we suggest possible methods for producing yeast-free lacewings so that future studies might determine how yeasts contribute to lacewing fitness. The earlier research also suggested that lacewings eclose without their yeast symbionts and must obtain them from the environment. Our data suggest that yeast may be transmitted vertically, from mother to offspring.