Diorhabda carinulata as a possible food source for Coccinella septempunctata

The first open-field releases of Diorhabda spp., a biological control agent of the invasive shrub, salt cedar, began in 2001. Currently released in fourteen states and recently approved for release in Oklahoma, the beetles have established with mixed success. One of the main reasons thought to be hindering establishment is predation. The ladybeetle Coccinella septempunctata, a prominent natural enemy, has been recorded in salt cedar stands at the Salt Plains National Wildlife Refuge and thought to be a possible predator of the biological control agent. To test the possibility of D. carinulata as a food source for this natural enemy, a C. septempunctata lab colony was established from two field populations (Lahoma and Jet, OK). All four larval instars and the adult stage of the Coccinellid were fed an adequate but not unlimited diet of either Diorhabda carinulata eggs or larvae or a corresponding amount of Acerythosiphon pisum, a known suitable food source. The survival, development times (in days) and elliptical body area (mm²=[∏ x .5(body length) x .5(body width)]) of the larvae were tracked.