Habituation versus sensory adaptation as the cause of reduced attraction following pulsed and constant sex pheromone pre-exposure in Trichoplusia ni

Trichoplusia ni males receiving a pulsed regime of sex pheromone pre-exposure later, in a wind tunnel, exhibited reduced upwind flight and close approach to a sex pheromone source compared to males receiving continuous pre-exposure. Electroantennogram (EAG) amplitudes from either pulsed or continuously pre-exposed males were significantly reduced from controls only during exposure. EAG amplitudes returned within one minute after exposure to levels not significantly different from controls, indicating that habituation, not sensory adaptation was probably the cause of reduced flights under the pulsed regime. Additionally, activity levels of males during each pulsed pre-exposure remained high compared to constant or no pre-exposure males, implying that pulsing was better at achieving central nervous system habituation because it avoided adapting the receptors.     

BEHAVIOURAL EFFECT OF VARIOUS BINARY AND TERNARY SEX PHEROMONE BLENDS ON THE ASIAN CORN BORER (OSTRINZA FURNACALZS)

Abstract The response of individual male Asian corn borer moth was observed in a wind tunnel to various binary and ternary blends and dosages of synthetic sex pheromones, tetradecyl acetate. (E)-12-te-tradecenyl acetate and (Z)-12-tetradecenyl acetate. Lures containing two components (Z+E) blends elicit the highest behavioral responses at ratios in the scope of 37. 5% E to 62. 5% E and there was no significant difference in this scope according to source contact step. The highest responses to the lures of three components are observed at ratio 1 ^: 5 ^: 4 (14 ^: Ac/Z/E), which have no significant difference to the best lures of two components. But dose-response shows that the ternary blend has a wider response scope than the binary blend. The ternary blend can elicit behavioral response at dosage even as low as Ing, but the binary blend can not at the same dosage. The highest response scope is 100 to 1 000 ng for the binary blend and 100 to 10 000 ng for the ternary blend.     

Pheromone-blend discrimination by European corn borer moths with inter-race and inter-sex antennal transplants

Transplantation of larval antennal imaginal disks between the pheromone races of the European corn borer moth produced males and females of one race with male antennal phenotypes of the race using the opposite pheromone blend. All of the adults with transplanted antennal disks that exhibited a pheromone-mediated response in the flight tunnel did so with the pheromone blend of the recipient's race, even though the respective males and females possessed male antennae of the opposite race. Our results support the conclusion that male antennal response type is not a determining factor in pheromone-blend discrimination in male moths. Accepted: 13 November 1998     

Ovarian hormones modulate 'compulsive' lever-pressing in female rats

Life events related to the female hormonal cycle may trigger the onset of obsessive-compulsive disorder (OCD) or exacerbate symptoms in women already suffering from it. These observations suggest a possible role for ovarian hormones in the course of this disorder. Yet, the mechanisms that may subserve the modulatory effect of ovarian hormones are currently unknown. The aim of the present study was therefore to test the role of ovarian hormones in the signal attenuation rat model of OCD. Experiment 1 compared the behavior of pre-pubertal and adult male and female rats in the model, and found no age and sex differences in compulsive responding. Experiment 2 found that compulsive responding fluctuates along the estrous cycle, being highest during late diestrous and lowest during estrous. Acute administration of estradiol to pre-pubertal female rats was found to attenuate compulsive behavior (Experiment 3), and withdrawal from chronic administration of estradiol was shown to increase this behavior (Experiment 4). These findings extend the use of the signal attenuation model of OCD to female rats, and by demonstrating that the model is sensitive to the levels of ovarian hormones, provide the basis for using the model to study the role of ovarian hormones in OCD. In addition, the present findings support the hypothesis that the increased risk of onset and exacerbation of OCD in women post-partum may be a result of the decrease in the level of estradiol, which was elevated during pregnancy.     

Electrophysiological and behavioural evidence for a fourth sex pheromone component in the turnip moth, Agrotis segetum

Abstract. In addition to the pheromone components (Z)-5-decenyl, (Z)-7-dodecenyl and (Z)-9-tetradecenyl acetate (Z5-10:OAc, Z7-12:OAc and Z9-14:OAc), it has previously been shown that the sex pheromone gland of the turnip moth, Agrotis segetum (Lepidoptera: Noctuidae Schiff) contains 10:OAc, 12:OAc, Z5-12:OAc, Z9-12:OAc, 11–12:OAc, Z5-14:OAc, Z7-14:OAc and Z11-16:OAc. To find out whether any of these additional compounds is involved in the sex pheromone communication in A. segetum, a comprehensive electro-physiological and behavioural investigation was conducted. Single-sensillum recordings on male antennae revealed three subtypes of sensilla among the previously so-called Z5-10:OAc sensilla. One subtype was identified having one receptor neurone (A) that responded to Z5-10:OAc with a large spike amplitude and another neurone (B) that responded to (Z)-5-decenol (Z5-10:OH) with a small spike amplitude. In another subtype the B neurone responded to Z5-12:OAc and sometimes also to 27-12:OAc and 10:OAc, in addition to responding to Z5-10:OH. In a third subtype the A neurone responded to all acetates identified from the female pheromone gland, whereas the small spike amplitude neurone was tuned to Z5-10:OH. A flight tunnel assay showed that blends composed of nine, eight or seven compounds were equivalent to the previously identified three-component pheromone blend in eliciting male behavioural responses. In field trapping tests, blends of eleven, nine or seven compounds did, however, catch significantly more moths than the three-component blend. Further assays showed that only 25- 12:OAc could significantly increase the catch numbers when added to the three-component blend, and thus qualified as a fourth pheromone component in A. segerum. The behavioural significance of additional female-produced acetates — for which males possess antennal receptors — is suggested, but may be impossible to confirm because of ‘diminishing returns’ when trying to refine a multicomponent pheromone further.     

Physiologically Dependent Appearance of a Low Density Region That Corresponds to the Tunnel through the 50S Part of the 70S Ribosome

Ribosomes have different conformations in cells that are starved for a required amino acid (giving aminoacyl.tRNA starvation), or treated with kirromycin (blocking EF-Tu.GDP release), or are in exponential growth. A tunnel spans the 50S ribosome from a location facing the 70S ribosomal intersubunit space to the back side of the subunit inEscherichia colicells. Here we have analyzed the internal low density region that corresponds to this tunnel in ribosomesin vivo.The data suggest that the tunnel is opened in connection with spatial separation of the subunits in ribosomes that have an empty A-site due to starvation for aminoacyl.tRNA. A region that corresponds to this tunnel can be found in the more compact structure of ribosomes in kirromycin-treated cells only after a substantial removal of low density material. This region is even less prominent in ribosomes in undefined working modes in growing bacteria. The data suggest that appearance of the tunnel through the 50S ribosomal subunit is working-mode dependent and it is not a characteristic feature of the major fraction of the ribosomal population in growing cells.     

甜菜夜蛾对性信息素的行为反应及其田间诱捕效果

人工合成的甜菜夜蛾性信息素两组分（顺,反）-9,12-十四碳二烯醇醋酸酯（Z9,E12-14：Ac）和（顺）-9-十四碳烯醇（Z9-14：OH）按不同配比制成诱芯,在风洞中均能引起雄蛾搜索气迹、定向飞行及接近诱芯的行为反应.不同配比和剂量的诱芯诱虫效果差异显著（p＜0.05）.Z9,E12-14：Ac和Z9-14：OH按7：3配比,诱虫活性最高,表现在风洞中,搜索气迹、定向飞行和接近诱芯的蛾数最高,与处女蛾的引诱效果相当.以此配比制成的性诱剂在田间诱捕的虫量最多,与风洞的试验结果基本一致.诱芯剂量在0.05～0.5mg范围内均有显著的诱虫效果,但剂量过低或过高均导致诱捕率下降.同一配比诱芯在风洞中引起雄蛾接近诱芯的蛾量与田间诱蛾量呈显著相关（R1=0.968,R2=0.961）.并对这些结果在甜菜夜蛾田间性诱剂防治应用的前景进行了讨论.     

粘虫成虫在气流场中飞行行为的观察研究

通过改进悬吊测飞技术、室内风洞和野外雷达相结合的观测方法,研究了粘虫在气流场中的飞行行为特征及其与气流的关系。直筒风洞自由飞行观测的结果表明,粘虫蛾对气流有明显行为反应,表现为头部迎风起飞和迎风飞行的特性;在3.0～5.5 m/s风速下,有92%～94% 的个体可一次逆风飞行通过2 m长的风洞;当风速≥6.0 m/s时,有71.9%的蛾子沿螺旋状的飞行轨迹逆风通过风洞。环形风洞悬吊飞行测试的结果表明,粘虫可逆风飞行的最大风速为7.2 m/s;在风速≤4 m/s条件下,90%以上个体头部迎风飞行或头部朝向与风向成一定的夹角,侧逆风飞行。 雷达观测发现粘虫在空中迁飞过程中具有成层现象,并有较强的秋季回迁定向行为,其头部总是朝向西南;迁飞的最终位移与风向及风速大小有关,迁飞位移速度是飞行速度与风速的矢量和。     

Effects of prohydrojasmon‐treated corn plants on attractiveness to parasitoids and the performance of their hosts

We investigated the effect of prohydrojasmon [propyl (1RS,2RS)‐(3‐oxo‐ 2‐pentylcyclopentyl) acetate] (PDJ) treatment of intact corn plants, on their attractiveness to the specialist endoparasitoid, Cotesia kariyai Watanabe (Hymenoptera: Braconidae), and on the performance of the common armyworm, Mythimna separata (Walker) (Lepidoptera: Noctuidae) under laboratory conditions. Attractiveness of C. kariyai to PDJ‐treated plants was studied in a wind tunnel, whereas performance of M. separata larvae was tested in plastic cages. The attractiveness of the treated plants increased with concentrations of PDJ increasing to 2 mm , which was equivalent to the attractiveness of host‐infested plants. PDJ‐treated corn plants emitted 16 volatile compounds (α‐pinene, β‐myrcene, (Z)‐3‐hexenyl acetate, limonene, (E)‐β‐ocimene, linalool, (E)‐4,8‐dimethyl‐1,3,7‐nonatriene, (+)‐cyclosativene, ylangene, (E)‐β‐farnesene, (E, E)‐4,8,12‐trimethyl‐1,3,7,11‐tridecatetraene, α‐bergamotene, γ‐cadinene, δ‐cadinene, α‐muulolene and nerolidol), most of which were observed in the headspace of host‐infested corn plants with some quantitative and qualitative differences. We also tested the effects of PDJ treatment on the performance of M. separata larvae. The survival rates of the larval and pupal stages were significantly lower at 2 mm level of PDJ. A significant decrease in weight at 6th stadium larvae was observed only at 2 mm level of PDJ. In contrast, PDJ treatment at all PDJ concentration levels caused significant reduction in weight of pupal stage as compared to control. These data suggested that PDJ, originally developed as a plant growth regulator, especially to induce coloring of fruits, has the potential to induce direct and indirect defenses in corn plants against common armyworm, M. separata.