In field screening tests conducted on selected pest scarabaeids in Hungary, Epicometis (Tropinota) hirta (subfamily Cetoniinae) was attracted to traps baited with either cinnamyl alcohol or trans-anethol. In some tests attraction was also detected to phenethyl alcohol or cinnamyl acetate. In other tests, adults of Cetonia aurata aurata and Oxythyrea funesta (subfamily Cetoniinae) also were attracted to trans-anethol, while the ternary mixture of phenethyl propionate, eugenol and geraniol attracted Potosia cuprea (subfamily Cetoniinae). Some attraction of Valgus hemipterus (subfamily Valginae) to cinnamyl alcohol also was observed. All of the above species are pests of more or less economic importance in Hungary. The attractant chemicals discovered in the present study will form a starting point for the development of effective attractants for the respective pest scarab species.
Several synthetic floral lures have been described for the cetoniin scarabs Cetonia aurata aurata L. and Potosia cuprea Fabr. (Coleoptera, Scarabaeidae), exploiting their olfaction-guided behavioural preference for a wide range of flower volatiles.
A ternary mixture of 3-methyl eugenol, 1-phenylethanol and (E)-anethol has previously been described as a powerful synthetic floral attractant for both C. a. aurata and P. cuprea. The first objective of the present research was to test whether isoeugenol and eugenol, with a very similar molecular structure to 3-methyl eugenol, can substitute 3-methyl eugenol in the ternary blend. All baited traps caught significantly more of both species than unbaited control traps, however, traps containing 3-methyl eugenol caught significantly more than those with either isoeugenol or eugenol. This indicates a fine tuning in behavioural response to 3-methyl eugenol.
The second objective was to devise simpler attractant combinations for C. a. aurata and P. cuprea, based on previous field studies with synthetic floral compounds. Both C. a. aurata and P. cuprea showed strong attraction to the combination of 2-phenylethanol and 4-methoxyphenethyl alcohol, while the combination of 2-phenylethanol and 1,2,4-trimethoxybenzene resulted in medium-size catches, however, mostly catching P. cuprea. This level of selectivity may lead to the development of more selective lures for P. cuprea, and provide a better understanding of the feeding-related olfactory ecology of the two important pest chafer species.
Western corn rootworm (WCR) (
Diabrotica v. virgifera
Le Conte) (Coleoptera, Chrysomelidae) adults were attracted only during daytime hours and showed a bimodal diel activity pattern when responding to the synthetic floral bait in the field. On the other hand, to the synthetic pheromone bait, good responses were recorded apart from daytime hours also well into the night. The present results suggest that in WCR the pheromonal communication channel and the channel connected with feeding (= floral lure) are separated.
Trap designs baited with the synthetic sex pheromone have been optimized for trapping of the western corn rootworm Diabrotica v. virgifera LeConte (Coleoptera: Chrysomelidae) (WCR), which has recently been introduced into Europe. The best trap design proved to be the sticky “cloak” trap (code name “PAL”), which catches only males, and is being used in many countries of Europe for detection and monitoring the spread of the new pest. Preliminarily the range of attraction (as defined by Wall and Perry, 1987) of the pheromone traps was estimated to be <10 m. The performance of yellow sticky plates (used by others for monitoring of the pest) was insignificant as compared to the activity of the pheromone baited traps, and yellow colour had no discernible effect on catches in pheromone traps. The known floral lure of WCR containing 4-methoxy-cinnamaldehyde and indole proved to be active also towards the population in Europe, attracting both females and males. Yellow colour slightly increased catches by the floral lure, hence a yellow sticky “cloak” trap has been developed (code name PALs). Pheromone baited PAL traps caught a total of about 4 times more beetles than the floral baited PALs, which latter however appeared to be preferentially active for females. When placed into the same trap, the pheromonal and floral lures did not interfere with each other's activity.
When applied in funnel traps, the known three-component floral lure of Cetonia a. aurata and Potosia cuprea attracts large numbers of beetles. Further increasing the attractive power of these traps offers the opportunity to develop a more potent mass-trapping tool that directly reduces local scarab populations and, hence, fruit damage. The current study was initiated by the observation of adult beetles aggregating and feeding in large numbers on ripening fruit, accompanied by the presence of fermentation volatiles detectable by the human nose. Addition of apple pieces to the ternary C. aurata aurata / P. cuprea lure resulted in increased catches, but only in traps where the apple fermented as a result of beetle feeding. Volatile extracts collected from fermenting apple were subjected to GC-EAG, and bioactive peaks were identified as 1-hexanol, acetic acid, n-butyric acid, isovaleric acid, hexanoic acid and 3-methylphenol by GC-MS and GC peak enhancement. In preliminary field trials, a synthetic mixture of all identified compounds reduced activity of the ternary lure, indicating that some were inhibitory. As certain individual compounds or their particular combinations enhanced activity of the ternary lure only numerically, further experiments are discussed to optimize a synergistic blend of fruit fermentation and/or beetle-derived volatiles.
The performance of a semisynthetic bisexual lure (SBL, containing isoamyl alcohol, acetic acid and red wine) previously found attractive for a number of noctuids was compared with that of the respective synthetic sex attractants of Orthosia cerasi (=stabilis), O. cruda, O. gothica, O. incerta, Anorthoa munda and Conistra vaccini. The respective sex attractants performed significantly better in the Orthosia spp. than the SBL lure, which, although regularly catching low numbers of both females and males, did not differ significantly from zero catch in unbaited control traps. On the other hand, the SBL lure performed as well as the sex attractant in C. vaccini. Sizeable catches of C. rubiginea, C. rubiginosa and C. erythrocephala were also recorded in traps with the SBL lure. The SBL lure can prove to be a useful tool in ecological and faunistical studies of Conistra and related hibernating Xylenini species.