Yien-Shing Chow

Role of calcium in the stimulation of ecdysteroidogenesis by recombinant prothoracicotropic hormone in the prothoracic glands of the silkworm, Bombyx mori

Abstract The aim of this study was to clarify whether Ca 2+ plays a role in the mechanism by which recombinant prothoracicotropic hormone (PTTH) stimulates ecdysteroidogenesis by the prothoracic glands of the silkworm, Bombyx mori . Omission of Ca 2+ from the incubation medium, or inclusion of a Ca 2+ channel blocker (verapamil or lanthanum) did not affect basal ecdysteroid secretion, but greatly inhibited the stimulation of ecdysteroidogenesis by PTTH. The addition of a Ca 2+ ionophore (ionomycin or A23187) stimulated ecdysteroid secretion in a dose-dependent manner. Furthermore, thapsigargin, a potent Ca 2+ -ATPase inhibitor, enhanced ecdysteroid secretion. In contrast, thimerosal, a thiol-oxidizing reagent, inhibited prothoracic gland activity. The mechanism of Ca 2+ action was examined further in relation to the cAMP effector system. Ca 2+ deprivation greatly suppressed the accumulation of cAMP in prothoracic glands treated with PTTH but had no effect on basal levels. Omission of Ca 2+ from the incubation medium, or inclusion of a Ca 2+ channel blocker (verapamil or lanthanum) did not affect the stimulation of ecdysteroid secretion in response to dibutyryl cAMP or 1-methyl-3-isobutylxanthine. The present study suggests that specific regulatory actions of Ca 2+ in prothoracic gland cells are exerted prior to cAMP generation.

Alarm pheromone of pentatomid bug,Erthesina fullo Thunberg (Hemiptera: Pentatomidae)

In the pentatomid bug,Erthesina fullo Thunberg, the odor of male metathoracic scent gland elicits an alarm response, making the male individuals of the same species alert and disperse; the alarm response of males is more obvious than that of females. Chemical composition of the glandular secretion was identified by gas chromatography and mass spectrometry data in comparison with authentic compounds. No sexual dimorphism exists in the glandular composition in this species. A total of 9 compounds [(E)-2-hexenal, (E)-4-keto-2-hexenal, (E)-2-hexenyl acetate,n-undecane,n-dodecane, (E)-2-decenal,n-tridecane, (E)-2-decenyl acetate, andn-pentadecane] are identified, among whichn-tridecane and (E)-4-keto-2-hexenal comprised nearly 70% of the total secretion in both females and males.

Investigation of sex pheromone components of female asian corn borer,Ostrinia furnacalis (Hübner) (Lepidoptera: Pyralidae) in Taiwan

Abstract(E)-12-Tetradecenyl acetate (E12–14∶OAc), (Z)-12-tetradecenyl acetate (Z12–143nOAc), and tetradecanyl acetate (14∶OAc) were extracted and identified as major chemical components from female tips of the Asian corn borer,Ostrinia furnacalis (Hübner) (Lepidoptera: Pyralidae) in Taiwan, with a combined wash ratio of 48∶37∶15 and an individual female ratio of 45∶39∶16. The average amount ofE12-,Z12–14∶OAc and 14∶OAc in each female gland was 6.6±4.6, 5.8±3.5, and 2.4±1.7 ng/female, respectively. The mixture of these three synthetic chemicals not only gave strong activities in male antennae but also could catch significantly more males than virgin females in field-trapping tests. The field test also showed no significant difference in trapping ability among the three-component Taiwan formulations, the two-component Taiwan formulation (Z12–14∶OAc andZ1214∶OAc, 53∶47), and the Japan formulation (Z12–14∶ OAc andE 12–14∶OAc, 3:2).

Attraction responses of the American cockroach to synthetic periplanone-B.

Synthetic periplanone-B has been shown not only to be a sex excitant to malePeriplaneta americana by bioassay in the laboratory but also an attractant pheromone by field tests in a rice storage house in Taipei. During both summer and winter months, it attracted signincantly more adult males into the traps used in the experiments than adult females. There is a statistically significant increase in the sex ratio (male-female) of the trapped adults with increase in periplanone-B used. An attempt has been made to explain the trapping of females and nymphs in addition to males by the chemicals used in our tests.

Individual variation in sex pheromone of smaller tea tortrix moth,Adoxophyes sp. (Lepidoptera: Tortricidae)

Female smaller tea tortrix mothsAdoxophyes sp. (Lepidoptera: Tortricidae), which initiated calling at 1, 2, or 3 days old, respectively, were analyzed individually for (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (Z)-9-tetradecenyl acetate (Z9–14: OAc) in the pheromone gland via GLC. Among different age groups, broad and similar distributions were found for pheromone quantity (¯X=58.6±52.9 ng/female; range 1.3–219.8 ng/female). The ratio of the two pheromone components averaged 65∶35 but ranged from 84∶16 to 40∶60. The significance of the pheromone blend variation to the attraction of males was tested in a field experiment. The ratio of males trapped by the most attractive blend versus the least attractive one was 2.2.

Evidence for the Site of Female Sex Pheromone Production in Periplaneta americana

We used bioassays to determine the sex pheromone production site in the female American cockroach (Periplaneta americana). Bioassayed extracts from various body parts aroused sexual responses from unmated males. However, the extract of hindgut (including both colon and rectum) induced strong responses. Colon extract stimulated the strongest sexual response. To compare the sex pheromone contents of atrial glands, pygidium, rectum, and colon, we recorded the EAG responses of male antennae to these extracts. Among the four tissues, colon extract caused the strongest EAG response. From gas chromatographic (GC) analysis, the quantities of periplanone-A (PA) and periplanone-B (PB) (the main sex pheromone components in female American cockroach) were 0.34 and 8.31 ng, respectively, in the colon of a virgin female. The ratio of PA to PB was ca. 1:24. The present results are different from those reported in a previous study, in which it was concluded that atrial glands are the sites of sex pheromone production in P. americana, and from GC analysis the quantity of PB was estimated to be 60 ng/female. There was no difference in sexual behaviors induced by colon and atrial glands of calling virgin females. It is unclear whether the colon is the sole sex pheromone source in the female American cockroach.

Sex pheromone components of female smaller tea tortrix moth, Adoxophyes sp. (Lepidoptera: Tortricidae) in Taiwan

Abstract(Z)-11-Teiradecenyl acetate (Z11-14: Ac) and (Z)-9-tetrade-cenyl acetate (Z9–14: Ac) were isolated as major sex pheromone components from the female tips of the smaller tea tortrix moth,Adoxophyes sp., in Taiwan. The average amount ofZ11- andZ9–14: Ac in each female gland was 24.9 and 14.1 ng, in a ratio of 64∶36, respectively. When compared to a closely related Japanese strain, which used theZ9-14: Ac,Z11-14∶ Ac,E11–14:Ac, 10-Me-12:Ac four-component system (in a ratio of 63∶31∶4∶2), the Taiwan formulation of two components caught significantly more Taiwan males than the Japanese formulation of four components.

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-trimethyltetra- decyl 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.

Voltage-dependent calcium channels in the corpora allata of the adult male loreyi leafworm, Mythimna loreyi

In the corpora allata (CA) of the adult male loreyi leafworm, Mythimna loreyi, juvenile hormone acid (JHA) biosynthesis and release show a dose dependence on extracellular Ca(2+) concentration. Maxima are obtained with Ca(2+) concentrations of 2-10 mM, and synthesis and release are significantly inhibited under a Ca(2+)-free condition. The Ca(2+)-free inhibition of JHA release can be reversed by returning the glands to medium at 5 mM Ca(2+). The cytosolic free Ca(2+) concentration ([Ca(2+)](i)), which was measured with fura-2, in individual CA cells also shows a dose dependence on extracellular Ca(2+) concentration, with significant [Ca(2+)](i) depression being observed in the absence of extracellular Ca(2+). High K(+) significantly increases the JHA release and causes a transient [Ca(2+)](i) increase within seconds in CA cells. High-K(+)-stimulated JHA release is partially inhibited by the benzothiazepine (BTZ)-, dihydropyridine (DHP)- and phenylalkylamine (PAA)-sensitive L-type voltage-dependent calcium channel (VDCC) antagonists diltiazem, nifedipine and verapamil, respectively; by the N- and P/Q-type VDCC antagonist omega-conotoxin (omega-CgTx) MVIIC; and by the T-type VDCC antagonist amiloride. The N-type antagonist omega-CgTx GVIA is the most potent in inhibiting the high-K(+)-stimulated JHA release. No inhibitory effect is shown by the P-type antagonist omega-agatoxin TK (omega-Aga TK). The high-K(+)-induced transient [Ca(2+)](i) increase is largely inhibited by the L-type antagonists (diltiazem, nifedipine, verapamil), by the N- and P/Q-type antagonist omega-CgTx MVIIC and by the T-type antagonist amiloride, and is totally inhibited by the N-type antagonist omega-CgTx GVIA. No inhibitory effect is shown by the P-type antagonist omega-Aga TK. We hypothesize that L-type, N-type and T-type VDCCs may be involved to different degrees in the high-K(+)-stimulated JHA release and transient [Ca(2+)](i) increase in the individual CA cells of the adult male M. loreyi, and that the N-type VDCCs may play important roles in these cellular events.

Evidence for presence and nature of female sex pheromone ofBrithys crini fabricius (Lepidoptera: Noctuidae).

The existence of a female sex pheromone of the noctuid mothBrithys crini Fabricius was confirmed in both laboratory bioassay and field tests. Crude extracts and airborne volatiles from females were analyzed by gas chromatography and mass spectrometry and the data compared with authentic compounds. The primary sex pheromonal compound was Z11-16: Ald. Scanning electron microscopy showed that the external surface of the sex pheromone gland was covered with folds that might increase the sex pheromone evaporation area.