Kyeung Sik Han

Response of The Lacewing Chrysopa cognata to Pheromones of its Aphid Prey

The lacewing Chrysopa cognata, one of the principal predators of aphids in Korea, was tested for responses to the aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol and the aphid alarm pheromone (E)-β-farnesene. Electroantennogram responses were obtained to the sex pheromone components but not to (E)-β-farnesene. The sex pheromone components were attractive in a Y-tube olfactometer assay and in field trials with water traps, but no attraction was observed to (E)-β-farnesene.

Pheromone biosynthetic pathways in the moths Helicoverpa zea and Helicoverpa assulta

Sex pheromones of many Lepidopteran species have relatively simple structures consisting of a hydrocarbon chain with a functional group and usually one to several double bonds. The sex pheromones are usually derived from fatty acids through a specific biosynthetic pathway. We investigated the incorporation of deuterium-labeled palmitic and stearic acid precursors into pheromone components of Helicoverpa zea and Helicoverpa assulta. The major pheromone component for H. zea is (Z)11-hexadecenal (Z11-16:Ald) while H. assulta utilizes (Z)9-hexadecenal (Z9-16:Ald). We found that H. zea uses palmitic acid to form Z11-16:Ald via delta 11 desaturation and reduction, but also requires stearic acid to biosynthesize the minor pheromone components Z9-16:Ald and Z7-16:Ald. The Z9-16:Ald is produced by delta 11 desaturation of stearic acid followed by one round of chain-shortening and reduction to the aldehyde. The Z7-16:Ald is produced by delta 9 desaturation of stearic acid followed by one round of chain-shortening and reduction to the aldehyde. H. assulta uses palmitic acid as a substrate to form Z9-16:Ald, Z11-16:Ald and 16:Ald. The amount of labeling indicated that the delta 9 desaturase is the major desaturase present in the pheromone gland cells of H. assulta; whereas, the delta 11 desaturase is the major desaturase in pheromone glands of H. zea. It also appears that H. assulta lacks chain-shortening enzymes since stearic acid did not label any of the 16-carbon aldehydes.

Control of the Oriental Fruit Moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) by Mating Disruption with Sex Pheromone in Pear Orchards

Abstract The effect of dispensers containing a 93: 6 : 1 blend of Z8-12: Ac, E8-12: Ac, and Z8–12: OH for mating disruption of Grapholita molesta (Busck) was tested from 1998 to 2000 in pear orchards in Naju, Korea. The permeation of the atmosphere with synthetic sex pheromone significantly reduced the ability of male moths to locate pheromone-baited traps, and reduction of male moths to locate pheromone-baited traps was not significantly different among different pheromone doses. Success in suppression of infestations by pheromone permeation was achieved under the dose rate of 50 g/ha, and increasing pheromone concentration above this dose did not significantly reduce the fruit damage. The efficacy of pheromone treatment could not be predicted using captures of males in traps baited with synthetic pheromone. Apparently, a much lower titer of pheromone was required to reduce trap catch than to reduce damage. The trap catch was influenced by trap position in pheromone plots; significantly more moths were caught at the outer areas than at the inner areas. Also, fruit damage levels in pheromone plots were significantly heavier in the trees located in the outer area. However, the lowered efficacy in the outer areas was partly improved by the application of a high number of dispensers at these areas compared with the inner areas. Assessment of trap catch and damage level over a three-year period showed that the effectiveness of the disruption technique for G. molesta was enhanced through sequential suppression year after year at the same site.

Sex Pheromones and Reproductive Isolation of Three Species in Genus Adoxophyes

We tested differences in female pheromone production and male response in three species of the genus Adoxophyes in Korea. Females of all three species produced mixtures of (Z)-9-tetradecenyl acetate (Z9–14:OAc) and (Z)-11-tetradecenyl acetate (Z11–14:OAc) as major components but in quite different ratios. The ratio of Z9–14:OAc and Z11–14:OAc in pheromone gland extracts was estimated to be ca. 100:200 for Adoxophyes honmai, 100:25 for Adoxophyes orana, and 100:4,000 for Adoxophyes sp. Field tests showed that males of each species were preferentially attracted to the two-component blends of Z9–14:OAc and Z11–14:OAc mimicking the blends found in pheromone gland extracts of conspecific females. The effects of minor components identified in gland extracts on trap catches varied with species. Addition of 10-methyldodecyl acetate (10me-12:OAc) or (E)-11-tetradecenyl acetate (E11–14:OAc) to the binary blend of Z9–14:OAc and Z11–14:OAc significantly increased captures of A. honmai males, whereas E11–14:OAc exhibited a strongly antagonistic effect on catches of Adoxophyes sp. males. Moreover, (Z)-9-tetradecen-1-ol (Z9–14:OH) or (Z)-11-tetradecen-1-ol (Z11–14:OH) added to the binary blends increased attraction of male A. orana but not A. honmai and Adoxophyes sp. males, suggesting that these minor components, in addition to the relative ratios of the two major components, play an important role in reproductive isolation between Adoxophyes species in the southern and midwestern Korea where these species occur sympatrically.

Sex Pheromone Composition and Monitoring of the Oriental Fruit Moth, Grapholita molesta (Lepidoptera: Tortricidae) in Naju Pear Orchards

Abstract The sex pheromone blend of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) from pear orchards of Naju, Korea, has been identified. Four candidate sex pheromone components in abdominal tip extracts of G. molesta female were detected by gas chromatography (GC). GC analysis indicated that it included (Z)-8-dodecenyl acetate (Z8-12: Ac), ( E )-8-dodecenyl acetate ( E 8-12: Ac), (Z)-8-dodecenol (Z8-12: OH), and dodecanol (12: OH) in a ratio of 100:6.8:19.1:5.4. In the field trappings, Z8-12: Ac alone was not attractive to G. molesta male, and more males were caught by traps baited with Z8-12: Ac containing 4, 5 or 6 % E isomer than by traps baited with other Z : E mixtures. Addition of Z8-12: OH to the two acetates increased significantly catch of G. molesta males. Although a significant amount of Z8-12: OH was detected in the female abdominal tip extracts, addition of Z8-12: OH at the 1 % level of the total acetates was sufficient to enhance the trap catch. Traps baited with 95: 5: 1 blend of Z8-12: Ac, E 8-12: Ac, and Z8-12: OH were successfully used to monitor G. molesta males flights. Analysis of seasonal trap catches over three years summarizes that the moth has four main generation peaks over at least seven months per year in Naju.

Sex Pheromone Composition and Male Trapping of The Oriental Fruit Moth, Grapholita molesta (Lepidoptera: Tortricidae) in Korea

Abstract Sex pheromone composition was analyzed for the oriental fruit moth ( Grapholita molesta ), and field trapping studies were also conducted to develop monitoring system with its sex pheromone in Korea. The calling and mating behavior of G. molesta were seen maximally 2 to 1 hr before lights-off and these behavior ceased after lights-off. Analysis of abdominal tip extracts from virgin females of G. molesta revealed 4 compounds, Z8-dodecenyl acetate ( Z 8-12: Ac), E 8-dodecenyl acetate ( E 8–12: Ac), Z 8-dodecenol ( Z 8–12: OH) and dodecanol (12: OH). In the field trappings, the best capturing activity for G. molesta was observed with the 95:5:1 blend of Z 8–12: Ac, E 8–12: Ac and Z 8–12: OH but 12: OH showed no synergic effect. The most effective amount of sex pheromone blend was 0.5 mg for a lure.

Sex Pheromone Composition and Male Trapping of the Peach Fruit Moth, Carposina sasakii (Matsumura) (Lepidoptera: Carposinidae) in Korea

Abstract Sex pheromone composition, mating behavior, and field trapping were analyzed for the peach fruit moth, Carposina sasakii (Matsumura) to develop a monitoring system with its sex pheromone. The upwind flying response of males to female was the most frequent at 4th to 5th hr after lights-off. The highest mating rate was seen at 5th hr after lights-off. The extract of female abdominal tip was analyzed with gas chromatography and proved to have two compounds, ( Z )-7-eicosen-11-one and ( Z )-7-nonadecen-11-one. In field-trapping, however, a lure containing ( Z )-7-eicosen-11-one only showed the highest attractivity.

Sex Pheromone of Aphis spiraecola (Homoptera: Aphididae): Composition and Circadian Rhythm in Release

Abstract Aphis spiraecola (Patch) virginiparae were reared for 3 generations on the dropwort, Oenathe javanica DC, under low temperature (15°C) and short days (10L:14D) for artificial induction of sexual forms (Hong and Boo, 1998). These oviparae, artificially induced in the third generation in the laboratory, showed a typical behavior of releasing sex pheromone by waving their hind tibiae and abdomen in the air during photophase. The air around these oviparae, individually or in groups, was collected and analyzed by gas chromatography for pheromone components. (+)-(4aS,7S,7aR)-nepetalactone and (-)-(1R,4aS,7S,7aR)- nepetalactol were detected in the ratio of 6:1 ∼ 8:1. For wild oviparae collected from an apple orchard and a spiraea arboretum during Oct. 1995. ∼ Nov. 1996, the ratio between the two components was around 2:1. Oviparae showed a circadian rhythm in release of sex pheromone, with beginning to release nepetalactone at the start of lights-on and stopping with lights-off. This rhythm was also maintained in an all dark condition. The sex pheromone was always detected during the photophase, even when the photoperiod was altered to a longer regime, for example from 10L:14D to 16L:8D.

Right stereoisomers for sex pheromone components of the apple leafminer, Lyonetia prunifoliella, in Korea.

The sex pheromone of the American population of Lyonetia prunifoliella (Lepidoptera: Lyonetiidae) was reported to be composed of three components, 10,14-dimethyloctadec-1-ene (10me14me-1-ene-18Hy), 5,9-dimethyloctadecane (5me9me-18Hy), and 5,9-dimethylheptadecane (5me9me-17Hy). Studies with a Korean population showed that the 10S,14S isomer of the major compound was the major electrophysiologically by active stereoisomer. The 5S,9S isomers of the minar constituents also elicited electrophysiological responses. In field trappings, among the three components, the racemic mixture of 10me14me-1-ene-18Hy attracted L. prunifoliella males strongly, and the binary or tertiary combinations with racemic mixtures of the other two components did not increase trap catches. Among the four stereoisomers of 10me14me-1-ene-18Hy, only the 10S,14S isomer attracted L. prunifoliella males, as suggested by the EAG test, and attraction to the other three isomers was not observed. All stereoisomers of each minor component, as well as their racemic components, did not seem to have any additional effect on male attraction in Korea.

Identification of Volatiles Responsive to the Alder Leaf Beetle (Agelastica coerulea) from its Host Plant, the Japanese Alder (Alnus glutinosa)

Abstract Electroantennography (EAG) and gas chromatography coupled with electroantenno-graphic detection (GC-EAD) were used to identify volatiles from Alnus glutinosa attractive to Agelastica coerulea. Seven compounds (3-cyclohexene-1-methanol, 2-cyclohexen-1-ol, 5-methyl-2-(1-methylethyl)-cyclohexanol, 5-alpha-androstan-17-beta-ol, 3-ethyl-3-hydroxy-androstan-17-one, (Z)-2-(9-octadecenyloxy)-ethanol, and hexadecanoic acid) showed responsiveness to the antenna of A. coerulea. In bioassays, adults and larvae of A. coerulea were attracted to volatiles from A. glutinosa.