Interchangeability of floral volatiles in ternary lure combinations for catching three cetoniin chafers (Coleoptera, Scarabaeidae)

In behavioural field experiments we aimed to study the interchangeability of molecular structures, which only differ by a single hydrogen, hydroxyl- or methyl-group from components of a known attractant blend of the flower damaging <em>Epicometis hirta</em> (Coleoptera, Scarabaeidae), and two other cetoniin occasional pests <em>Cetonia aurata aurata</em> and <em>Potosia cuprea</em>, typical to the fauna of Central and Southern Europe. 1-Phenethyl alcohol or 3-methyl eugenol (of the known attractant blend of 1-phenethyl alcohol, <em>(E)</em>-anethol and 3-methyl eugenol) were replaced with structurally similar floral compounds widespread among plant families in general. All baited treatments caught significantly more of the three species compared to the unbaited control. The ternary blend containing 2-phenethyl alcohol caught numerically the most of the three species, and gave significant increase compared to the basic blend with 1-phenethyl alcohol for <em>C. a. aurata</em> and <em>E. hirta</em>. Benzyl alcohol performed similarly well to 2-phenethyl alcohol in catching <em>C. a. aurata</em> and <em>P. cuprea</em>, and it was superior over the blend with phenylacetaldehyde. On the contrary, for <em>E. hirta</em> the treatment containing phenylacetaldehyde was better than the combination with benzyl alcohol, resulting in a similar effect to the blend with 2-phenethyl alcohol. In another experiment, the known ternary blend including 3-methyl eugenol performed numerically the best in attracting <em>E. hirta</em> compared to the blends with eugenol or isoeugenol, which results are congruent with the earlier findings on <em>C. a. aurata </em>and <em>P. cuprea</em>. Our work resulted in a single optimized attractant combination for all three cetoniin species, that includes 2-phenethyl alcohol, 3-methyl eugenol and (<em>E</em>)-anethol.