József Vuts

Optimization of a Phenylacetaldehyde-Based Attractant for Common Green Lacewings (Chrysoperla carnea s.l.)

In field trapping tests, the catch of Chrysoperla carnea sensu lato (Neuroptera: Chrysopidae) increased when acetic acid was added to lures with phenylacetaldehyde. The addition of methyl salicylate to the binary mixture of phenylacetaldehyde plus acetic acid increased catches even further. The ternary blend proved to be more attractive than β-caryophyllene, 2-phenylethanol, or 3-methyl eugenol (compounds previously described as attractants for chrysopids) on their own, and no influence on catches was recorded when these compounds were added as fourth components to the ternary blend. There were minimal changes in activity when (E)-cinnamaldehyde or methyl anthranylate (both evoking large responses from female or male antennae of C. carnea in this study) were added, although both compounds showed significant attraction on their own when compared to unbaited traps. In subtractive field bioassays with the ternary mixture, it appeared that the presence of either phenylacetaldehyde or methyl salicylate was important, whereas acetic acid was less so in the ternary mixture. The ternary blend attracted both female and male lacewings at sites in southern, central, and northern Europe. Possible applications of a synthetic attractant for lacewings are discussed.

New Sex Attractant Composition for the Click Beetle Agriotes proximus: Similarity to the Pheromone of Agriotes lineatus

While testing traps baited with a blend of geranyl octanoate and geranyl butanoate (pheromone components previously identified for Agriotes lineatus, Coleoptera, Elateridae) in Portugal and Bulgaria, large numbers of the closely related Agriotes proximus were captured. In the literature, two different compounds, (E,E)-farnesyl acetate and neryl isovalerate had previously been identified as pheromone components of A. proximus. Subsequent field tests, conducted in several European countries, revealed that A. proximus was weakly attracted to geranyl butanoate on its own, while A. lineatus was weakly attracted to geranyl octanoate on its own. However, the largest catches for both species were observed with a blend of both compounds. No A. proximus was caught in traps baited with the blend of (E,E)-farnesyl acetate and neryl isovalerate at any of the test sites. In electroantennographic studies, antennae of male A. proximus and A. lineatus both gave greater responses to geranyl butanoate than to geranyl octanoate, suggesting that the perception of these two compounds was similar for both species. A 1:1 blend of geranyl octanoate and geranyl butanoate can be used as a bait in traps for the detection and monitoring of both A. lineatus and A. proximus in many European countries.

Improving the floral attractant to lure Epicometis hirta Poda (Coleoptera: Scarabaeidae, Cetoniinae)

In order to improve the efficiency of the known floral attractant of Epicometis hirta [(E)-anethol and (E)-cinnamyl alcohol in a ratio of 1:1], candidate synergist compounds for field tests were selected through electroantennographic tests using the antennae of female and male E. hirta adult beetles. Among synthetic floral compounds 4-methoxyphenethyl alcohol and methyl salicylate evoked high responses from the antennae and were chosen for further field studies. In trapping tests in Bulgaria, the addition of 4-methoxyphenethyl alcohol to the E. hirta bait in the ratio of 1:1:1, in Hungary in ratios of 1:1:0.3 and 1:1:1 significantly increased catches. The addition of methyl salicylate was without effect in both countries. A high-capacity trap supplied with this ternary attractant could be more efficient for mass trapping purposes of E. hirta in environment-friendly plant protection.

New co-attractants synergizing attraction of Cetonia aurata aurata and Potosia cuprea to the known floral attractant

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, (±)‐lavandulol and ß‐ionone, were chosen for field experiments. In field trapping tests in Hungary the addition of (±)‐lavandulol to the known attractant resulted in significantly 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 (±)‐lavandulol did not increase catches of C. a. aurata and P. cuprea. The improved bait consisting of 3‐methyl eugenol/1‐phenylethanol/(E)‐anethol/(±)‐lavandulol described in this study is recommended for use in trapping of C. a. aurata and P. cuprea for agricultural purposes.

Attraction of Lygus rugulipennis and Adelphocoris lineolatus to synthetic floral odour compounds in field experiments in Hungary

Field experiments were carried out to ascertain whether synthetic floral odour compounds were attractive for two pest bug species. The European tarnished plant bug (Lygus rugulipennis Poppius) has been reported to damage various crops (e.g. strawberry, sugarbeet, alfalfa, cucumber), and the alfalfa plant bug (Adelphocoris lineolatus (Goeze)) is considered as a pest of alfalfa and Bt-cotton. In our field tests, traps baited with phenylacetaldehyde caught significantly more L. rugulipennis than unbaited traps. In addition, A. lineolatus was also attracted to phenylacetaldehyde-baited traps. When testing other, EAG active compounds, (E)-cinnamaldehyde attracted A. lineolatus as well. This compound was also attractive for L. rugulipennis, however, to a lesser extent than phenylacetaldehyde. When the two compounds were presented in combination, no synergistic or inhibitory effect was detected in either species. By attracting both sexes of both species, these new attractants may prove to be useful and provide the basis for further development of new lures for agricultural use.

Agriotes proximus and A. lineatus (Coleoptera: Elateridae): a comparative study on the pheromone composition and cytochrome c oxidase subunit I gene sequence

The presence of geranyl octanoate, previously found in pheromone gland extracts of Agriotes lineatus females, was also demonstrated in gland extracts of A. proximus females. Similar to A. lineatus, geranyl butanoate was present only in trace amounts in A. proximus female gland extracts. In air entrainment samples of female A. lineatus and A. proximus beetles, the relative ratio of geranyl butanoate and geranyl octanoate was higher than that in gland extracts. In addition, comparison of a segment of the mitochondrial cytochrome c oxidase subunit I gene of feral specimens of A. lineatus and A. proximus showed >99% similarity. Both pheromone profile and nucleotide sequence analysis delineate close relationship between the investigated taxa and postulate taxonomic revision. Further studies on sympatric populations of A. lineatus and A. proximus are underway to investigate and better understand possible processes of species diversification.

Semiochemistry of the Scarabaeoidea

The superfamily Scarabaeoidea comprises a large and diverse monophyletic group. Members share ancestral characteristics, but often exhibit considerable differences in their ecology, physiology, or mating strategies. A large number of species are regarded as pests of crop or amenity plants, while others are beneficial to humans and even may be extremely rare as a result of anthropogenic activities. A significant number of chemical ecology-based studies have been conducted with the Scarabaeoidea in order to characterize semiochemicals influencing their behavior, such as pheromones and plant-derived allelochemicals. These may be used either to control or preserve populations of the beetles, depending upon pest or beneficial status. This paper is a review of the role and identity of the semiochemicals of the Scarabaeoidea, with comments on possible future research and applied opportunities in the field of chemical ecology.

Development of an attractant-baited trap for Oxythyrea funesta poda (Coleoptera: Scarabaeidae, Cetoniinae)

In electroantennographic tests isosafrol, methyl salicylate, (±)-lavandulol, geraniol, (E)-anethol, and β-ionone evoked the largest responses from antennae of female or male Oxythyrea funesta (Coleoptera: Scarabaeidae, Cetoniinae) adult beetles. In field trapping tests in Hungary the 1: 1 blend of (±)-lavandulol and 2-phenylethanol attracted significantly more adult O. funesta than the single compounds. The addition of (E)-anethol, a previously described attractant for the species, was without effect. There was no difference in the responses of male or female beetles. The binary 2-phenylethanol/(±)-lavandulol bait described in this study is recommended for the use in traps of O. funesta for agricultural purposes.

Electrophysiological responses and field attraction of the grey corn weevil, Tanymecus (Episomecus) dilaticollis Gyllenhal (Coleoptera: Curculionidae) to synthetic plant volatiles

The grey corn weevil, Tanymecus (Episomecus) dilaticollis, is an economically important polyphagous pest in Eastern and Central Europe. The present research is the first published electrophysiological study of olfactory sensitivity of adult T. dilaticollis to plant volatiles. The electrophysiological responses of male and female antennae were recorded to 20 synthetic volatile organic compounds (VOCs), previously identified to be released from the preferred host plants, maize and sunflower. Antennae of both sexes responded to a wide range of volatiles from different chemical classes: fatty acid derivatives, aromatic compounds and terpenoids. Two green leaf volatiles, (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol, and one terpenoid, (±)-linalool, elicited the strongest electrophysiological responses by male and female antennae. Relatively high electrophysiological activity by T. dilaticollis antennae was also recorded to benzaldehyde, eugenol and caryophyllene. In the field, (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol, when presented individually, caught significantly more male and female T. dilaticollis than unbaited controls. These compounds could be developed into an attractive trap for the detection and monitoring of T. dilaticollis.

Preliminary study of female‐targeted semiochemical baits for the western corn rootworm in Europe

Abstract:  In recent years emphasis of semiochemical research on the western corn rootworm (WCR) (Diabrotica v. virgifera LeConte, Coleoptera, Chrysomelidae) shifted towards the development of more female‐specific lures. Through identifying volatile compounds from maize silk, Hammack (J. Chem. Ecol., 27, 2001,1373) claimed that some combinations of the newly identified compounds were more powerful in attracting females than the conventional floral baits (based on 4‐methoxycinnamaldehyde). Earlier we found that the newly developed ‘hat’ trap design (KLP) when baited with the floral bait was especially suitable for the capture of female WCR. Encouraged by this we set out to compare efficiency of female‐targeted Diabrotica baits. None of the treatments tested captured females in higher percentage than the conventional WCR floral bait (4‐methoxycinnamaldehyde + indole). The combination of β‐ionone + methyl salicylate + β‐caryophyllene (attractant found to be more female‐specific in the USA previously) was not more attractive for females than unbaited controls. No other treatment produced significantly higher female percentages than the conventional floral bait. However, the conventional bait caught far more beetles than any of the other treatments. Electroantennographic responses from male or female antennae were very similar, suggesting that all 27 floral compounds tested were perceived similarly by the two sexes. The only exception was β‐ionone, to which females were slightly more responsive. It seemed that among the other compounds none showed potential for the development of a more female‐specific lure. In conclusion, so far the most efficient female‐targeted trap‐bait combination for WCR in Europe is the conventional floral attractant applied in KLP traps.