Identification of the female-produced sex pheromone of Tischeria ekebladella, an oak leafmining moth.

The native leafmining moth Tischeria ekebladella (Lepidoptera: Tischeriidae) feeds on oaks and recently has become a pest of silviculture and urban green areas in central Europe. The behavioral responses of male moths to hexane extracts of whole bodies of calling females or males were tested under laboratory conditions. Only extracts of females elicited responses from males. Analysis of extracts by coupled gas chromatography/electroantennographic detection revealed the presence of two electroantennogram-active peaks. Structure elucidation of these compounds, by gas-chromatography/mass spectrometry and independent synthesis revealed them to be (3Z,6Z,9Z)-tricosa-3,6,9-triene and (3Z,6Z,9Z,19Z)-tricosa-3,6,9,19-tetraene. While the triene was present in both sexes, the tetraene was female-specific. The latter is a new structure for a pheromone component of Lepidoptera and a novel natural product. Field trapping tests, carried out in a mixed oak forest near Budapest (Hungary), using synthetic compounds applied to rubber dispensers, showed that the tetraene per se elicited catches of males in large numbers. When the triene was added to the tetraene in a ratio of 1:1, there was no increase in trap catch; the triene alone did not elicit catches of males. For monitoring this insect, the tetraene, applied to rubber dispensers at a dose of 300 µg, is a potent sex attractant.

Species spectrum of flea beetles (Phyllotreta spp., Coleoptera, Chrysomelidae) attracted to allyl isothiocyanate-baited traps.

In field tests in Hungary, Slovenia and Bulgaria, in allyl isothiocyanate-baited traps significantly more beetles of Phyllotreta cruciferae, Ph. vittula, Ph. undulata, Ph. nigripes, Ph. nodicornis, Ph. balcanica, Ph. atra, Ph. procera, Ph. ochripes, Ph. diademata and Psylliodes chrysocephalus (Coleoptera, Chrysomelidae, Halticinae) were captured than in unbaited control traps. With the exception of Ph. cruciferae, this is the first report on significant field attraction by allyl isothiocyanate for these species. The species spectrum captured included six important agricultural pests. At all sites a great portion of the catch (ranging from ca 30 to 98%) was Ph. cruciferae, irrespective of the plant culture. The second most abundant species present at most sites was Ph. vittula. The present results are very promising from the point of view of applicability of allyl isothiocyanate in Europe as a bait in cabbage flea beetle traps for detection and monitoring.

Female sex pheromone of Cameraria ohridella Desch. and Dim. (Lepidoptera: Gracillariidae): structure confirmation, synthesis and biological activity of (8E,10Z)-8,10-tetradecadienal and some analogues.

Mass spectrometric investigations confirmed the structure of the female produced sex pheromone of the horse-chestnut leafminer Cameraria ohridella Desch. and Dim. to be (8E,IOZ)-8,10-tetradecadienal. Pure samples, prepared in a straightforward synthesis, were highly attractive in field tests and proved to be suitable for monitoring of flight activities and population dynamics. In mixtures with the synthetic pheromone, analogues like 9-tridecynal and 7-dodecynyl formate were shown to reduce trap catches. In electroantennographic experiments, pheromone analogues were less active than the pheromone. 9-Tridecynal was the most EAG active analogue tested, followed by 7-dodecyn-1-yl formate and 7-undecyn-1-yl formate.

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.

A sex attractant for the scarab beetle Anomala solida Er.

(R, Z)-5-(-)-(Oct-1-enyl)oxacyclopentan-2-one (R-buibuilactone) attracted male Anomala solida Er. (Coleoptera: Scarabaeidae, Rutelinae), a vineyard and orchard pest in Southeastern Europe. The presence of the corresponding (S) enantiomer or of 2-(E)-nonen-1-ol (a frequently found pheromone component in other Anomala spp.) in the bait did not influence catches. Traps baited with (R, Z)-5-(-)-(oct-1-enyl)oxacyclopentan-2-one were successfully used for monitoring the flight of A. solida, and may have practical applications for detection, monitoring, and mass trapping of the pest.

Sex pheromone biosynthetic pathway for disparlure in the gypsy moth, Lymantria dispar.

The pheromone biosynthetic pathway for production of the sex pheromone disparlure, 2-methyl-7R,8S-epoxy-octadecane, was determined for the gypsy moth. Each step in the pathway was followed by using deuterium-labeled compounds that could be identified by using GCMS. This approach provides unequivocal determination of specific reactions in the pathway. It was shown that the alkene precursor, 2-methyl-Z7-octadecene, is most likely made in oenocyte cells associated with abdominal epidermal cells. The pathway begins with valine contributing carbons for chain initiation, including the methyl-branched carbon, followed by chain elongation to 19 carbons. The double bond is introduced with an unusual Delta12 desaturase that utilizes a methyl-branched substrate. The resulting 18-methyl-Z12-nonadecenoate is decarboxylated to the hydrocarbon, 2-methyl-Z7-octadecene. The alkene is then transported to the pheromone gland through the hemolymph, most probably by lipophorin. At the pheromone gland, the alkene is unloaded and transformed into the epoxide disparlure for release into the environment. A chiral HPLC column was used to demonstrate that the (R,S)-stereoisomer of the epoxide, (+)-disparlure is found in pheromone glands.

Sex pheromone of the leaf-miner Phyllonorycter platani: (Z10)-tetradecenyl acetate.

A female produced sex pheromone of the leaf-miner pest Phyllonorycter platani (Staudinger) (Lepidoptera: Gracillariidae) was identified as (Z10)-tetradecenyl acetate. Field trapping trials confirmed activity of this compound. The presence of the geometrical isomer (E10)-tetradecenyl acetate, a pheromone component of other Phyllonorycter species, reduced trap efficacy.

Identification of sex pheromone composition of click beetle Agriotes brevis candeze.

Geranyl butyrate (GB) and (E, E)-farnesyl butyrate (FB) were identified in the pheromone gland extract of females of the click beetle, Agriotes brevis (Candeze) (Coleoptera: Elateridae) as the major sex pheromone components. Polyethylene vial dispensers containing 20-200 mg of a 1:1 mixture caught high numbers of beetles. Captures did not decrease even after 73 days of field exposure of dispensers. At sites where both Agriotes sputator L. and A. brevis were present, the above baits were selectively catching only A. brevis, despite the fact that GB is also the main pheromone component of A. sputator, suggesting that FB has a role in reproductive isolation. In the early part of the season, traps into which the insects could both crawl and fly captured more A. brevis than designs where the insects could only fly in. Trap design was not important later in the season. This indicates the need for future development of a trap suitable for use throughout the whole season.