New co-attractants synergizing attraction of Cetonia aurata aurata and Potosia cuprea to the known floral attractant J. Vuts 1 , Z. Imrei 2 & M. To ´ th 1 1 Plant Protection Institute, Hungarian Academy of Sciences, Budapest, Hungary 2 Central Agricultural Office Plant Protection, Soil Conservation and Agri- Environment Directorate Registration Subdirectorate, Budapest, Hungary Introduction Adults of Cetonia aurata aurata L. and Potosia cuprea Fabr. (Col., Scarabaeidae, Cetoniinae) damage the reproductive parts of the flowers of several orna- mental plants and orchard trees and later in the sea- son also the ripening fruit. Reports of significant damage in Hungary increased in frequency during recent years (Voigt et al. 2005), indicating that the pest impact of these species is growing. These scarabs are active during daytime; during the night they hide in the soil (Hurpin 1962). Control of these spe- cies is difficult, as most insecticides cannot be applied right before harvest or during flowering without affecting humans or honeybees and other benefi- cials. Mass trapping of adult beetles can be an alter- native control method provided that an efficient trapping system is available. A ternary chemical attractant consisting of 3- methyl eugenol, 1-phenylethanol and (E)-anethol in the ratio of 1 : 1 : 1 has been optimized previously and proved to be attractive for adults of both C. a. aurata and P. cuprea (Imrei 2003; To ´ th et al. 2005). These compounds are common flower scents (Knudsen et al. 1993). Similar to many other flower-feeding insects (Kevan and Baker 1983), C. a. aurata and P. cuprea use visual cues in host location and have a prefer- ence towards blue colour in the presence of the floral attractant. When using both the chemical attractant and the blue colour catches of C. a. aurata and P. cuprea were generally higher than in traps containing the chemical attractant in transparent traps or painted to fluorescent yellow, yellow or white (To ´ th et al. 2005). Blue traps baited with the ternary Cetonia/Potosia floral attractant are in use Keywords electroantennogram, floral attractant, (Æ)-lavandulol Correspondence Jo ´ zsef Vuts (corresponding author), Plant Protection Institute, Hungarian Academy of Sciences, Herman O. u. 15., H-1525 Budapest, Hungary. E-mail: joci2@freemail.hu Received: February 12, 2009; accepted: June 2, 2009. doi: 10.1111/j.1439-0418.2009.01432.x Abstract To improve the efficiency of the known floral attractant of Cetonia aurata aurata and Potosia cuprea [3-methyl eugenol, 1-phenylethanol and (E)- anethol] electroantennographic tests were conducted using the antennae of both species. Among synthetic floral compounds eliciting the highest responses from the antennae, geraniol, (Æ)-lavandulol and ß-ionone, were chosen for field experiments. In field trapping tests in Hungary the addition of (Æ)-lavandulol to the known attractant resulted in signifi- cantly higher catches of both scarabs than the ternary blend alone or the single compounds. Only geraniol resulted in higher catches of P. cuprea when added to the ternary attractant. The addition of ß-ionone to the known attractant decreased catches. In further tests the addition of geraniol in the same single dispenser as the known ternary mixture plus (Æ)-lavandulol did not increase catches of C. a. aurata and P. cuprea. The improved bait consisting of 3-methyl eugenol/1-phenylethanol/ (E)-anethol/(Æ)-lavandulol described in this study is recommended for use in trapping of C. a. aurata and P. cuprea for agricultural purposes. J. Appl. Entomol. J. Appl. Entomol. 134 (2010) 9–15 ª 2009 Blackwell Verlag, GmbH 9