An aggregation attractant for the sugar-beet weevil, Bothynoderes punctiventris

During our screening studies, attractiveness of a ternary mixture of synthetic Grandlure I [racemic cis-1-methyl-2-(1-methylenethenyl)-cyclobutane ethanol], Grandlure II [(Z)-2-(3,3-dimethyl)cyclohexylidene ethanol], and Grandlure III-IV [(Z)- and (E)-2-ochtodenal; (Z)- and (E )-(3,3-dimethyl)cyclohexylidene acetaldehyde] for the sugar-beet weevil, Bothynoderes punctiventris Germar (Coleoptera: Curculionidae), was observed in field-trapping tests at several sites in Hungary and Serbia. The mixture attracted both males and females. Later tests revealed that of the components in the ternary mixture, only Grandlure III-IV were responsible for attraction, and the addition of Grandlures I or II in varying percentages had no influence on trap captures. Traps baited with 50-50 000 μg of Grandlure III-IV on rubber or polyethylene dispensers yielded high catches of weevils. When testing synthetic samples enriched in the respective geometrical isomer, Grandlure IV had a tendency of catching more weevils, but differences were not significant from lower catches by a 1:1 Z:E blend or Grandlure III. In gas chromatography-flame ionization detection/electroantennographic detection studies, antennae of both female and male weevils were more responsive to the (E)- than to the (Z)-isomer suggesting a more important role for Grandlure IV. Efforts to verify the presence of Grandlure III or IV in volatiles collected from either sex of live sugar-beet weevils or body washings with pentane remained inconclusive. Traps baited with Grandlure III-IV can now be used as sensitive and powerful trapping tools in the control of the sugar-beet weevil.