Katherine M. Girsch, kgirsch@purdue.edu1, Rick E. Foster, rfoster@purdue.edu1, and Bruce Bordelon, bordelon@purdue.edu2. (1) Purdue University, Department of Entomology, 901 W. State St, West Lafayette, IN, (2) Purdue University, Department of Horticulture & Landscape Architecture, 625 Agricultural Mall Dr, West Lafayette, IN
The multicolored Asian lady beetle (MALB), Harmonia axyridis (Pallas), can aggregate in late-ripening wine grapes and transfer taint aromas into wine during processing. Even though insecticides may kill beetles, treated grapes can still contain above-threshold numbers (1-4 beetles per gallon) as beetles can remain trapped in broken berries. For this study, beetles were left dead for different lengths of time (24, 36, 48, 72, or 96 h) in two conditions (simulated cluster environment and no cluster) before fermenting with the wine. Three additional wine treatments (no beetles, all live beetles, freshly dead beetles) were used for comparison. MALBs were added at a rate of 16 beetles per gallon to ensure there was an above-threshold taint level in the ‘all live beetles’ treatment. Each treatment was evaluated 41 times by a sensory panel using a 9-point category scale representing taint intensity. The live beetle wine was rated higher in taint than all other treatments. Wine receiving beetles that were freshly dead, left in a ‘cluster’ for 24 h, and left in a ‘cluster’ for 96 h were rated higher in taint than the no-beetle wine. All other treatments were not rated significantly different from the no-beetle wine. Chemical analysis of wines will be conducted to see if actual taint levels mirror sensory panel results.
Species 1: Coleoptera Coccinellidae
Harmonia axyridis (multicolored Asian lady beetle)
Keywords: Wine grapes, Sensory evaluation