Discovery of the aggregation pheromone of the brown marmorated stink bug (Halyomorpha halys) through the creation of stereoisomeric libraries of 1-bisabolen-3-ols.

We describe a novel and straightforward route to all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol via the rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones 1 and 2. The detailed stereoisomeric structures of many natural sesquiterpenes with the bisabolane skeleton were previously unknown because of the absence of stereoselective syntheses of individual stereoisomers. Several of the bisabolenols are pheromones of economically important pentatomid bug species. Single-crystal X-ray crystallography of underivatized triol 13 provided unequivocal proof of the relative and absolute configurations. Two of the epoxides, (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (3) and (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (4), were identified as the main components of a male-produced aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys, using GC analyses on enantioselective columns. Both compounds attracted female, male, and nymphal H. halys in field trials. Moreover, mixtures of stereoisomers containing epoxides 3 and 4 were also attractive to H. halys, signifying that the presence of additional stereoisomers did not hinder attraction of H. halys and relatively inexpensive mixtures can be used in monitoring, as well as control strategies. H. halys is a polyphagous invasive species in the U.S. and Europe that causes severe injury to fruit, vegetables, and field crops and is also a serious nuisance pest.

Identification of the major sex pheromone component of the scale insect, Aulacaspis murrayae Takahashi.

(R)-Solanone was identified as a female-specific compound from aerations of virgin females of the scale insect, Aulacaspis murrayae Takahashi. The stereochemistry of the insect-produced solanone was confirmed to be (R) by comparison with synthesized racemic and chiral standards on a chiral stationary phase GC column. In bioassays, males were strongly attracted to a synthesized sample of (R)-solanone, demonstrating that this compound is a sex pheromone component for this species.

Chirality and bioactivity of the sex pheromone of Madeira mealybug (Hemiptera: Pseudococcidae).

Two compounds (trans-1R,3R-chrysanthemyl R-2-methylbutanoate and R-lavandulyl R-2-methylbutanoate) identified from aeration extracts of virgin female Madeira mealybug, Phenacoccus madeirensis Green (Hemiptera: Pseudococcidae), were synthesized and tested in field bioassays in northern Taiwan over a 1-mo period. In total, 1,492 male P. madeirensis were captured in sticky traps. Our results showed that 1 microg of synthetic trans-1R,3R-chrysanthemyl R-2-methylbutanoate released from a plastic tube dispenser was attractive to the mealybugs. Different stereoisomers of chrysanthemyl 2-methylbutanoate also were tested. The insect-produced stereoisomer was the most attractive of all the isomers tested, and the stereochemistry of the acid moiety proved to be more critical than that of the alcohol moiety. The minor component found in extracts, R-lavandulyl R-2-methylbutanoate, alone was not attractive to male Madeira mealybugs nor did it act synergistically or additively with the main component.

Glyfoline induces mitotic catastrophe and apoptosis in cancer cells.

Glyfoline exhibits cytotoxic activity in vitro and antitumor activity in mice bearing murine or human solid tumors, but the underlying mechanisms are unknown. In our study, we found that glyfoline inhibited cell growth and induced accumulation of mitotic cells in human cancer cell lines. Glyfoline induced the appearance of spindle abnormalities, chromosome mis-segregation, multipolar cell division and multiple nuclei, all of which are indicative of mitotic catastrophe. However, glyfoline did not bind to DNA and did not inhibit or stabilize tubulin polymerization, but slightly increased the resistance of mitotic spindles to nocodazole-induced disassembly. In addition, microtubule aster formation was significantly enhanced in the extract prepared from glyfoline-arrested mitotic cells compared to that from synchronized mitotic cells. When Eg5, a mitotic kinesin that plays an essential role in establishing mitotic spindle bipolarity, was inhibited using S-trityl-cysteine in glyfoline-treated cells, formation of spindle multipolarity, multipolar cell division, and multinuclei was significantly reduced. After glyfoline-mediated arrest of cells at mitosis, considerable poly(ADP-ribose) polymerase degradation was induced and the number of annexin V-positive cells significantly increased, indicating that glyfoline ultimately induces apoptosis. Small interfering RNA-mediated silencing of the spindle checkpoint proteins BUBR1 and MAD2 markedly reduced induction of mitotic cell accumulation, but did not affect glyfoline-induced mitotic catastrophe and apoptosis. Thus, glyfoline induces mitotic catastrophe probably by enhancing microtubule aster formation and subsequent apoptosis in cancer cells independently of spindle checkpoint function.

Identification and synthesis of the sex pheromone of the Madeira mealybug, Phenacoccus madeirensis Green.

Two components were identified from aeration extracts of the virgin female Madeira mealybug, Phenacoccus madeirensis as trans-(1R,3R)-chrysanthemyl (R)-2-methylbutanoate and (R)-lavandulyl (R)-2-methylbutanoate (with a ratio of 3:1) by a combination of gas chromatography retention time matches, mass spectrometry, and microchemical tests. The structures and chirality of the compounds were confirmed by comparing with synthetic compounds. The synthetic trans-(1R,3R)-chrysanthemyl (R)-2-methylbutanoate was highly attractive to males in laboratory bioassays; the synthetic (R)-lavandulyl (R)-2-methylbutanoate was weakly attractive. No synergistic effect was observed when the mixture of the two compounds was tested.

Suppression pheromone and cockroach rank formation.

Although agonistic behaviors in the male lobster cockroach (Nauphoeta cinerea) are well known, the formation of an unstable hierarchy has long been a puzzle. In this study, we investigate how the unstable dominance hierarchy in N. cinerea is maintained via a pheromone signaling system. In agonistic interactions, aggressive posture (AP) is an important behavioral index of aggression. This study showed that, during the formation of a governing hierarchy, thousands of nanograms of 3-hydroxy-2-butanone (3H-2B) were released by the AP-adopting dominant in the first encounter fight, then during the early domination period and that this release of 3H-2B was related to rank maintenance, but not to rank establishment. For rank maintenance, 3H-2B functioned as a suppression pheromone, which suppressed the fighting capability of rivals and kept them in a submissive state. During the period of rank maintenance, as the dominant male gradually decreased his 3H-2B release, the fighting ability of the subordinate gradually developed, as shown by the increasing odds of a subordinate adopting an AP (OSAP). The OSAP was negatively correlated with the amount of 3H-2B released by the dominant and positively correlated with the number of domination days. The same OSAP could be achieved earlier by reducing the amount of 3H-2B released by the dominant indicates that whether the subordinate adopts an offensive strategy depends on what the dominant is doing.

Identification and synthesis of the sex pheromone of the passionvine mealybug, Planococcus minor (Maskell).

The sex pheromone of the mealybug, Planococcus minor was isolated by fractionation of crude pheromone extract obtained by aeration of virgin females. The pheromone was identified as the irregular terpenoid, 2-isopropyl-5-methyl-2,4-hexadienyl acetate, by mass spectrometry, microchemical tests, and (1)H NMR spectroscopy. The stereochemistry of the pheromone was assigned as (E) by comparison with synthetic standards of known geometry. The compound was highly attractive to males in laboratory bioassays, whereas the (Z)-isomer appeared to antagonize attraction.

Strategic 3-hydroxy-2-butanone release in the dominant male lobster cockroach, Nauphoeta cinerea.

In the lobster cockroach Nauphoete cinerea, the dominant-subordinate hierarchy formed via the agonistic interactions is unstable, and changes in rank order are common. Our previous results showed that in the first encounter fight during initial rank formation, microgram levels of 3H-2B are released by the aggressive posture (AP)-adopting dominant male. In the present study, the pattern of daily pheromone (3H-2B) release during the domination period and on the day of rank switch, rank duration, and rank switch frequency were investigated in three-male groups and six-male groups to examine the effect of higher frequency of agonistic encounters. The results showed that, in the three-male groups (50-day observation period), daily 3H-2B release rate was not constant, but fluctuated, the average duration of dominant rank was 16.6 +/- 2.0 days, rank switch occurred in 58.8% of groups, and the frequency of rank switching (average number of rank switches/group/50 days) was 1.4 +/- 0.2. For the six-male groups (30-day observation period), the daily 3H-2B release rate also fluctuated, but the duration of dominant rank was significantly shorter at 4.2 +/- 0.6 days, rank switch occurred in 100% of groups, and the frequency of rank switching (average number of rank switches/group/30 days) was significantly higher at 6.9 +/- 0.6. The results for both sets of male groups showed that as a new rank formed (either on the first encounter day or on the day of rank switching), the dominant status was significantly associated with a higher 3H-2B release rate. In the animal kingdom, fighting usually involves communication or the exchange of signals, and the results of this study indicated that the fluctuating daily 3H-2B release rate adopted by the dominants is a kind of strategic release and the 3H-2B release rate is a signal used to determine dominance.

3-Hydroxy-2-butanone and the first encounter fight in the male lobster cockroach, Nauphoeta cinerea.

Although agonistic behavior in the male lobster cockroach, Nauphoeta cinerea, has been known for more than 40 years, this is the first study to directly collect and quantify the emitted pheromones. In the present study, emitted volatile pheromones were collected from each male pair for 60 min during the first encounter fight and identified and quantified by gas chromatography-mass spectrometry. The major compound collected was 3-hydroxy-2-butanone (3H-2B). The strength of the attack by the dominant male was classified into three categories from weakest (C) to strongest (A). Of the 92 pairs, eight (8.7%) showed no agonistic interactions, and the amount of 3H-2B collected was 121.8+/-37.7 ng/male pair. In the five pairs (5.4%) displaying attack strength C, the amount of 3H-2B collected was 689.6+/-273.7 ng/male pair, and the attack duration was 9.6+/-2.4 min. In the 53 pairs (57.6%) showing attack strength B, the corresponding values were 5396.2+/-449.0 ng/male pair and 22.7+/-1.6 min, while those for the 26 pairs (28.3%) showing attack strength A were 7910.4+/-1120.6 ng/male pair and 24.9+/-2.9 min. For both attack strengths A and B, a linear relationship was found between the amount of 3H-2B collected and attack duration, suggesting that the longer the duration of the attack, the more 3H-2B was emitted. In addition, the rate of 3H-2B emission for attack strength A was significantly higher than that for attack strength B. Using Vaseline-coating, we demonstrated that, in the first encounter fight, the 3H-2B was emitted by the dominant male.

Effect of rearing conditions on production of sternal gland secretion, and identification of minor components in the sternal gland secretion of the predatory stink bug Eocanthecona furcellata.

Production of the male specific compound, 6,10,13-trimethyltetradecyl isovalerate by the predatory stink bug Eocanthecona furcellata (Wolff) was dramatically affected by rearing conditions. Male bugs kept isolated after eclosion produced an average of 1,948 ng of 6,10,13-trimethyltetradecyl isovalerate per bug, whereas male bugs reared in groups of 5-8 bugs produced an average of only 4 ng of 6,10,13-trimethyltetradecyl isovalerate per bug. Same-sex or mixed-sex pairs of bugs produced less than 50 ng per bug. Male bugs kept isolated for 1 wk and then grouped for 1 wk produced 3 ng of 6,10,13-trimethyltetradecyl isovalerate per bug, whereas male bugs grouped first and then isolated produced 135 ng of 6,10,13-trimethyltetradecyl isovalerate. A total of 11 minor components in relative amounts of less than 1% of the major 6,10,13-trimethyltetradecyl isovalerate were found in the sternal gland secretion. These included 6,10,13-trimethyltetradecanol, acetate, propionate, and butyrate esters of 6,10,13-trimethyltetradecanol, and isovalerate or valerate esters of homologs of 6,10,13-trimethyltetradecanol.