Parasitism of single or combined pyralid populations by Venturia canescens and Habrobracon hebetor in laboratory and storeroom conditions

Abstract

Venturia canescens and Habrobracon hebetor are cosmopolitan parasitoids found in large numbers in food processing facilities in northeastern Spain and in many other countries. These parasitoids attack larvae of pyralid moths, which are important pests of stored products and food industries worldwide. In this study, we evaluated the performance of these two parasitoids when offered single or combined populations of Plodia interpunctella and Ephestia kuehniella, since these can occur together in storehouses. We tested the parasitoid’s performance in small cages under laboratory conditions and small experimental storerooms (≈ 30 m3). In the laboratory, the two parasitoids were able to reduce pyralid populations by more than 37% over a 48-h period (40–44% for E. kuehniella, 37–41% of P. interpunctella and 53–55% of both hosts when offered together). Similar results were obtained in small storerooms after 10 days: a > 35% reduction in pyralid populations also was obtained when host species were offered either singly (E. kuehniella or P. interpunctella) or in combination (E. kuehniella + P. interpunctella) (35–57% for E. kuehniella, 40–54% of P. interpunctella and 41–46% of both hosts when offered together). Parasitism was consistently good from June through November (mean temperatures from 18 to 28 °C and 9.5 to 15 h of daylight). Therefore, both parasitoids, single or in combination, can be efficient biological control agents of these two pyralid moths when infesting stored food facilities.