Isopropyl (Z9)-hexadecenoate as a male attractant pheromone from the sternal gland of the rove beetle Aleochara curtala (Coleoptera: Staphylinidae)

Summary. In the rove beetle Aleochara curtula, a male specific sternal gland is described. Isopropyl (Z9)-hexadecenoate has been identified by GC/MS of surface and sternal gland extracts as a male specific compound. Its emission in the air was demonstrated by closed-loopstripping-analyses. In field experiments, conspecific males and females were attracted by the odor of carrion, caged males from laboratory cultures, and by the synthetic ester. Isopropyl (Z9)-hexadecenoate or live males, combined with fresh carrion attract more beetles than a fresh carcass alone. Isopropyl hexadecanoate as a minor compound was not attractive. The term “aggregation” pheromone and the ecological significance of attracting females to a fresh carcass allowing early copulation and egg-deposition are discussed. Received 20 August 1998; accepted 15 January 1999.     

Anthranilic acid: a free amino‐acid pheromone in the black chafer, <Emphasis Type="Italic">Holotrichia loochooana loochooana</Emphasis>

Summary. Ether extract of the abdominal gland of female black chafers Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae) induced a series of pre-mating behaviors that included short-distance orientation, mounting and abdominal bending toward females in the laboratory. When the extract was chromatographed on a silica gel column, the activity was eluted with 50% ether in hexane and ether fractions. GC-MS analyses revealed that both the active fractions contained anthranilic acid (2-aminobenzoic acid) as a major compound. When partitioned to basic, acidic and amphoteric fractions, pheromonal activity was observed with the latter two fractions and anthranilic acid was detected in these fractions by HPLC analyses. The amount of anthranilic acid in the female extract was estimated to be ca. 1.3 μg/female. Authentic anthranilic acid induced pre-mating behavior in males of at levels equal to that elicited by the compound in the extract. It also attracted male beetles to the traps in the field. Received 29 October 2002; accepted 9 January 2003. R1D=" Correspondence to:Hiroe Yasui, e-mail:yasui@affrc.go.jp     

The olfactory response of the reindeer nose bot fly,Cephenemyia trompe (Oestridae), to components from interdigital pheromone gland and urine from the host reindeer,Rangifer tarandus

Summary The linked gas chromatographical/electroan-tennogram (GC/EAG) technique revealed that the parasitic reindeer nose bot fly is able to specifically sense components produced by the interdigital pheromone gland of reindeer. The head-space extraction technique, with Porapak Q as the collecting polymer, was used to trap pheromone gland and urine components used to assess fly responses. One component from reindeer urine also was a potent stimulus for the sensory neurons of the fly. These components can be important chemical signals to the flies for long distance orientation towards host animals. This is the first report on EAG in Oestridae.     

Chemical recognition of queen cells by honey bee workersApis mellifera (Hymenoptera: Apidae)

Summary Honey bee workers are able to nurse or to destroy and thus to recognize the capped queen cells containing a pupa. Fatty acid esters, especially methyl oleate, methyl palmitate and ethyl oleate were found in significant amounts on the queen pupal cuticle. Methyl oleate, the major component, along with smaller amounts of methyl linoleate and methyl linolenate, were involved in the recognition of queen cells by workers. In natural conditions of the colony, queen cells containing a paraffin pupal lure with methyl oleate were accepted 5.9 days by workers, releasing about 1.8 queen pupa equivalents during that period, when control cells (without ester) were kept only 2.1 days. Although these esters are non specific to honey bees, they are of great importance in social regulation of the honey bee colony.     

Sex pheromone of the large aspen tortrix, Choristoneura conflictana(Lepidoptera: Tortricidae)

Summary. Three components that elicited antennal response from male Choristoneura conflictana were found from female gland extracts analyzed using a coupled gas chromatographic-electroantennographic detector system. The main component in gland extracts was (Z)-11-tetradecenal (Z11-14:Ald). Two minor components also elicited antennal response: (E)11-tetradecenal (E11-14:Ald) and (Z)-11- tetradecen-1-ol (Z11-14:OH). Analysis of effluvia indicated that calling virgin females release mostly Z11-14:Ald and trace amounts of Z11-14:OH. Field and wind tunnel behavioral studies showed that Z11-14:Ald alone attracted male moths in a dose response pattern. Tests comparing male response to blends of components detected in gland extracts showed that addition of 1.8% of E11-14:Ald to Z11-14:Ald did not influence male moths in the wind tunnel, but resulted in significantly lower trap captures in the field. The threecomponent blend [Z11-14:Ald (100), E11-14:Ald (1.8), Z11-14:OH (11)], was less attractive than Z11-14:Ald alone in both field and wind tunnel studies. Traps baited with two virgin female moths were equally attractive to males as traps baited with the three-component synthetic blend but less attractive than traps baited with Z11-14:Ald alone. Field tests of various blends of the two components (Z11-14:Ald, Z11-14:OH) detected in the females’ effluvia showed that the addition of 1–10% Z11-14:OH to Z11-14:Ald did not affect the males’ response to Z11-14:Ald. Our data demonstrate that female C. conflictana release sex pheromone components in a different ratio than they are stored in the pheromone gland. The sex pheromone is comprised of a single component, Z11-14:Ald, that can be used to monitor mated and virgin male C. conflictana throughout their flight period.     

Did certain chemoreceptors for host plant stimuli in the cabbage root fly evolve as pheromone receptors?

Summary. The cabbage root fly possesses highly specialised and extremely sensitive receptors for “CIF”, a group of compounds present on cabbage leaves in very small amounts, and the strongest oviposition stimulants known. Here we present evidence that the same receptors are sensitive to a methanol extract of cabbage root fly eggs, which may contain the fly's host marking pheromone. Based on these results, the possible role of CIF in cabbage root fly behaviour and in cabbage plants is discussed. Received 4 April 2001; accepted 24 September 2001.     

Comparative studies on the sex pheromones of Ostrinia spp. in Japan: the burdock borer, Ostrinia zealis

Summary. To gain insight into the evolution of the sex pheromone communication system in Ostrinia (Lepidoptera Pyralidae), the sex pheromone of the burdock borer, O. zealis was analyzed by means of gas chromatography-electroantennographic detection (GC-EAD), GC-mass spectrometry and a series of bioassays. Four EAD-active compounds were detected in the female sex pheromone gland extract, and these were identified as tetradecyl acetate (14:OAc), (Z)-9-tetradecenyl acetate (Z9–14:OAc), (E)-11-tetradecenyl acetate (E11-14:OAc) and (Z)-11-tetradecenyl acetate (Z11-14:OAc). The average amounts (ratio) of the four compounds in single sex pheromone glands were 2.5 ng (13%), 11.6 ng (61%), 4.1 ng (21%) and 0.9 ng (5%), respectively. In a wind-tunnel bioassay, the ternary blend of Z9-, E11- and Z11-14:OAc at a ratio found in the sex pheromone gland elicited the same behavioral responses from the males as did virgin females. 14:OAc did not show any enhancement or inhibition of the males’ behavioral responses when added to the ternary blend. The attractiveness of the 3-component lure to O. zealis males was also confirmed by field trapping experiments. Based on these results, we concluded that the sex pheromone of O. zealis is composed of Z9-14:OAc, E11-14:OAc and Z11-14:OAc at a ratio of 70:24:6. The evolutionary changes of the sex pheromones in Ostrinia are also discussed based on the presently available information on the sex pheromones and phylogenetic relationships of Ostrinia spp. Received 25 September 1998; accepted 2 December 1998.     

The sex pheromone of the grain aphid,Sitobion avenae (Fab.) (Homoptera,Aphididae)

Summary The sex pheromone of the grain aphid,Sitobion avenae (Fab.), is identified as (4aS,7S,7aR)-nepetalactone, for which specific olfactory cells are located in the secondary rhinaria of the male antenna. The related (1R,4aS,7S,7aR)-nepetalactol was not produced by females in significant amounts (ca 10,000-fold less than the nepetalactone), although cells in the male antenna were found that responded specifically to this compound. Behavioural activity in the linear track ol-factometer showed attraction of males to the nepetalactone, but not to the nepetalactol.     

Elevated CO2 reduces the response of Sitobion avenae (Homoptera: Aphididae) to alarm pheromone

The aphid alarm pheromone (E)-β-farnesene (EβF) is an efficient signal that warns aphids of attack by natural enemies. In this field study, eight open-top chambers (OTCs) located in Beijing, China (40°11′N, 116°24′E) with spring wheat Triticum aestivum were used to examine the response of the grain aphid Sitobion avenae to CO₂ (ambient vs. double ambient) and EβF (applied zero, two, or five times each day). We experimentally tested the hypotheses that, depending on frequency of EβF release, elevated CO₂ reduces the response (in terms of population density) of S. avenae to EβF, and that lower activity of acetylcholinesterase (AChE) in S. avenae may be involved in its reduced sensitivity to EβF under elevated CO₂. Numbers of S. avenae declined with increased frequency of EβF application under ambient CO₂ but were unaffected by EβF application under elevated CO₂. Additionally, the mean relative growth rate (MRGR) and the dry material and amino acid content of S. avenae increased with elevated CO₂ but declined when with EβF application. Activities of superoxide dismutase and catalase were higher in S. avenae under elevated vs. ambient CO₂. Under elevated CO₂, however, AChE activity remained low when S. avenae was exposed to the lower EβF frequency, while the highest AChE activity occurred in aphids exposed to the higher EβF frequency. These results indicate that aphids become insensitive to EβF under elevated CO₂, perhaps because of decreased AChE activity.     

How floral odours are learned inside the bumblebee (Bombus terrestris) nest

Recruitment in social insects often involves not only inducing nestmates to leave the nest, but also communicating crucial information about finding profitable food sources. Although bumblebees transmit chemosensory information (floral scent), the transmission mechanism is unknown as mouth-to-mouth fluid transfer (as in honeybees) does not occur. Because recruiting bumblebees release a pheromone in the nest that triggers foraging in previously inactive workers, we tested whether this pheromone helps workers learn currently rewarding floral odours, as found in food social learning in rats. We exposed colonies to artificial recruitment pheromone, paired with anise scent. The pheromone did not facilitate learning of floral scent. However, we found that releasing floral scent in the air of the colony was sufficient to trigger learning and that learning performance was improved when the chemosensory cue was provided in the nectar in honeypots; probably because it guarantees a tighter link between scent and reward, and possibly because gustatory cues are involved in addition to olfaction. Scent learning was maximal when anise-scented nectar was brought into the nest by demonstrator foragers, suggesting that previously unidentified cues provided by successful foragers play an important role in nestmates learning new floral odours.