A review： chemical ecology of Ips typographus （Coleoptera, Scolytidae）

Chemical ecology of the spruce bark beetle lps typographus （L.） was reviewed. The outbreak of 1.typographus in central Europe triggered extensive research on chemical ecology, Males initiate host location and produce semiochemicals which attract both males and females, A successful mass attack must first overcome the resistance of the host tree. Pioneer I. typographus evolved to use the resin flow of host trees as kairomones in host location, and synthesized semiochemicals initially to detoxify the resin. If small bark beetle populations infest healthy trees, mass attack is prevented by host resistance, Nine monoterpene alcohols were found in male hind-guts, including cis-verbenol （cV） and 2-methyl-3-buten-2-ol （MB） which are regarded as primary aggregation pheromones, and a low proportion of lpsdienol （ld） which increases attractiveness of cV and MB, Verbenone （Vn） and Ipsenol （le） are anti-aggregation pheromones, that play important roles in adjusting attack density and insect density under the bark. Non-host volatiles are repellent to L typographus, so that beetles do not waste energy boring into non-host trees. The relationship between host resistance, pheromone compounds and behavior, non-host volatiles, bioassays and mass trapping are reviewed, Results of field bioassays stressed that traps baited with specific pheromones could be used as a reasonable protection measure.

Field responses of the Asian larch bark beetle, Ips subelongatus, to potential aggregation pheromone components＂ disparity between two populations in northeastern China

Behavioral responses of the Asian larch bark beetle, lps subelongatus Motsch. to three potential aggregation pheromone components, ipsenol （racemic or [-]- enantiomer）, ipsdienol （racemic or [＋]-enantiomer） and 3-methyl-3-buten- l-ol, were tested using partial or full factorial experimental designs in two provinces （Inner Mongolia and Jilin） of northeastern China. Our field bioassays in Inner Mongolia （Larix principis- rupprechtii Mayr. plantation） clearly showed that ipsenol, either racemic or 97%-（-）- enantiomer, was the only compound that significantly attracted both sexes of 1. subelongatus, while all other compounds （singly or in combinations） were unattractive. There were no two- or three-way synergistic interactions. However, in Jilin Province （L. gmelini [Rupr.] Rupr. Plantation）, all the individual compounds tested were inactive, except a very weak activity by 97%-（-）-ipsenol in 2004 when the beetle population was very high. While a combination of ipsenol and ipsdienol （racemates or enantiomerically pure natural enantiomers） showed a significant attraction for both sexes of I. subelongatus, indicat- ing a two-way synergistic interaction between these two major components, addition of 3-methyl-3-buten-l-ol to these active binary blend（s） did not have any effects on trap catches, suggesting that ipsenol and ipsdienol are the synergistic aggregation pheromone components of I. subelongatus in Jilin Province. It seems that 97%-（-）-ipsenol in Inner Mongolia or the binary blend of 97%-（-）-ipsenol and 97%-（＋）-ipsdienol in Jilin Province are superior to their corresponding racemates, which might be due either to weak inhibitory effects of the antipode enantiomers or to reduced release rates of the active natural enan- tiomer（s） in the racemate（s）. Our current bioassay results suggest that there is a strong geographical variation in aggregation pheromone response of L subelongatus in northeastern China. Future research on the pheromone production and response of 1. subelongatus from different regions in Northeast Asia will surely improve our understanding of the dynamic aggregation pheromone system of this economically important forest pest insect.

Population divergence of aggregation pheromone responses in Ips subelongatus in northeastern China

The Asian larch bark beetle, Ips subelongatus, is considered to be the major pest of larch within its natural range. We investigated the electrophysiological and behavioral characteristics as well as mitochondrial DNA cytochrome oxidase subunit I sequences of L subelongatus from 13 geographic populations throughout northeastern China in order to explore population divergence of aggregation pheromone responses and the extent of potential genetic divergence. Electrophysiological analyses showed that antennae of I. sube-longatus from all the six tested populations responded strongly to （S）-（-）-ipsenol （100% detection; 0.35-0.73 mV） in gas chromatography （GC）-electroantennographic detection （EAD） analyses, while its antipode, （R）-（＋）-ipsenol was antennally inactive. I. subelon- gatus populations varied in their responses to （R）-（-）- and （S）-（＋）-ipsdienol in GC-EAD analyses. Behavioral bioassays demonstrated that （S）-（-）-ipsenol alone was significantly attractive at all the tested sites, supporting its status as a key pheromone component of L subelongatus, whereas （S）-（＋）-ipsdienol was inactive alone. Adding （S）-（＋）-ipsdienol to （S）-（-）-ipsenol did not have any effect on the trap catches from some populations in Inner Mongolia. However, （S）-（＋）-ipsdienol showed a strong synergistic effect on （S）-（-）- ipsenol from several populations in Jilin and Liaoning Provinces, and a weak synergistic effect from some transition populations in Heilongjiang Province. Furthermore, 27 mito- chondrial haplotypes were found among the 13 populations （intraspecific nucleotide di- vergence, 0.1%-1.1%）. Analyses of molecular variance and haplotype networks indicated that different geographic populations have developed some genetic variation but did not form completely independent groups. From an applied point of view, a universal synthetic binary blend ofracemic ipsenol and （S）-（＋）-ipsdienol might have a potential for monitoring or even mass-trapping of I. subelongatus across northeastern China, even though some populations only use （S）-（-）-ipsenol alone as their active pheromone component.

Fecal volatile components elicit aggregation in the oriental migratory locust, Locusta.migratoria manilensis （Orthoptera： Acrididae）

The aggregation components from fecal volatiles of the oriental mi- gratory locust, Locusta migratoria manilensis were identified with gas chromatographic/electroantennographic detector （GC-EAD）, GC-MS （mass spectrometry） analyses and behavioral bioassays. Both last instar nymphs and adults of the oriental migratory locust have similar aggregation pheromones in their volatiles. A total of 11 electrophysiologically active compounds, namely, hexanal, cyclohexanol, heptanal, phenol, 2,5-dimethyl- pyrazine, benzyl alcohol, benzaldehyde, guaiacol, nonanal, 2,6,6-trimethyl-2-cyclohexene- 1,4-dione and decyl aldehyde were identified in the fecal volatiles of 2-day-old immature adult male locusts. Only hexanal, nonanal, benzaldehyde, cyclohexanol and 2,5-dimethyl- pyrazine elicited significant aggregation responses in immature 2-day-old adult males. However, adult males had significantly lower behavioral responses to synthetics of five single compounds than the blend of cyclohexanol, 2,5-dimethyl-pyrazine, benzaldehyde, nonanal, hexanal in ratios of 100 ： 100 ： 2 ： 60 ： 30 in the range of 30 60 μg/mL. We propose that it is the blend of these five compounds that plays a key role in eliciting and sustaining aggregation in gregarious oriental migratory locusts. These results also showed that the aggregation pheromones of the oriental migratory locust are significantly different from those found in the desert locust.

Synthesis of Tribolure,the Common Aggregation Pheromone of Four Tribolium Flour Beetles

Herein we report a synthesis of the natural tribolure,an aggregation pheromone which consists of(4R,8S)-,(4R,8R)-,(4S,8S)-,and(4S,8R)-4,8-dimethyldecanals in a ratio of 4/4/1/1,from(R)-4-methyl-δ-valerolactone,a by-product of the degradation of steroidal sapogenins.Merging the stereoisomers of the same ratios into one synthetic target and using the same chiron for the construction of the C4 stereocenters are notable features of this synthesis.

Synthesis of(Z)-3-dodecenolide,the main aggregation pheromone from the flat grain beetle,Crvptolestes Pusillus Sch(?)nerr

The main aggregation pheromone component(1)of stored grain pest,Cryptolestes Pusillus, was synthesized with organosilicon and organolithium reagents in an overall yield of 18% from 1,7- heptanediol.