The role of 2,6-dichlorophenol as sex pheromone of the tropical horse tick Anocentor nitens (Acari: Ixodidae)

The objective of this study was to evaluate the role of2,6-dichlorophenol (2,6-DCP) as sex pheromone of Anocentornitens. Sex pheromones were extracted by submerging 150 females fed for 6 days in hexane (3 ml) for two hours and sonicating them for15 min. The extract was analyzed by GC-MS employing the Single Ion Monitoring (SIM) method. Identification of 2,6-DCP was based on the comparison of mass spectra with a computer search using the NIST library and by matching the mass spectrum of the peak at the retention time of 2,6-DCP from extract sand the synthetic product. In an olfactometer, males were released at 2.5cm from females, control rubber septa and impregnated rubber septa with increasing concentrations of 2,6-DCP (50, 500 and 5000 ng). A higher percentage of orientation and higher frequencies of angles between 0° and 10° were observed for males tested with females than with controls. Attraction of males to dummies impregnated with 2,6-DCP was observed with highest response (100%) at 50 ng. There was a gradual decrease of responsiveness of males with increasing concentration of 2,6-DCP (70 to 75%).This compound stimulated a behavior of mounting and ventral positioning ofA. nitens males at the lowest 2,6-DCP concentration where as dummies impregnated with 2,6-DCP higher than 50 ng concentration inhibited these behaviors. Therefore, we can conclude that 2,6-DCP can elicit the complete behavior sequence of orientation, location, mounting and ventral positioning behaviors and plays a role as an attractant and, as a mounting sex pheromone in A. nitens. This revised version was published online in July 2006 with corrections to the Cover Date.     

Two body fluids containing bovine estrous pheromone(s)

Bovine females produce an estrous pheromone(s). Because onlyother cattle are reliable detectors of the pheromone(s), weevaluated various body fluids (cervico-vaginal mucus, serumand vulval skin gland secretion) with a bull behavioral assayin the absence of a female. It specified 15 behaviors involvingattraction to the body fluids, detection of the stimulus, andsubseqeunt sexual preparation responses. These behaviors werestereotypical and occurred in a specific sequence. We discoveredthat serum (10–15 ml) taken at estrus was behaviorallypositive, as well as vulval skin glands secretion (<1 mlon a swab, dissolved in 5 ml distilled water). We postulatethat vulval skin glands may be a specialized site for the productionor concentration of the pheromone or that the blood transportsthe pheromone(s) either from vulval skin glands or another source.     

Response to host plant odors and aggregation pheromone by larvae of the Colorado potato beetle on a servosphere

Using a servosphere (locomotion compensator), locomotory behavior of Colorado potato beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) larvae was measured in detail in response to pulsed and non-pulsed odors of hostplant and conspecific pheromone. Second instars showed decreased straightness of movement, and all larvae showed decreased speed, in response to potato odor. Change in straightness by 2nd instars was also significantly affected by the interaction of pheromone and pulsing treatments. Fourth instars showed increased positive anemotaxis in response to the combined hostplant and pheromone odors. To our knowledge, this is the first demonstration of larval behavioral responses to adult pheromone in a holometabolous insect.     

Study of the genetics of female sex pheromone production and male behavioral response in a moth, Ostrinia orientalis

Inheritance patterns of female sex pheromone production and male behavioral response were studied in Ostrinia orientalis. Results showed that the production of the female sex pheromone in O. orientalis was mainly controlled by a single autosomal factor, while the male behavioral response was controlled by a sex‐linked major gene.     

棉铃虫成虫对高浓度性信息素的行为反应

室内行为实验表明,在高浓度性信息素环境中棉铃虫Helicoverpa armigera (Hübner) 雌蛾更加活跃、觅偶行为更加积极主动、求偶时间显著延长,而雄蛾主动求偶时间显著缩短、静止时间显著延长。高浓度性信息素并未引起成虫在取食活动和产卵行为的明显改变,也未能有效阻断其交配行为,而是推迟了它们的交配日期、夜间初始交配时间,缩短了交配蛾的交配持续时间。因此,高浓度性信息素主要影响其交配质量,而不是交配率。     

Sex pheromone components of female Cornutiplusia circumflexa

Capillary gas chromatography indicated the presence of (Z)-7-dodecenyl alcohol and (Z)-7-dodecenyl acetate in the abdominal tip extracts of female Cornutiplusia circumflexa (L.) (Lepidoptera: Noctuidae: Plusiinae) moths. Gas chromatography combined with mass spectrometry and dimethyl disulfide derivatization confirmed the structure of these two principal pheromone components. In a flight-tunnel bioassay, a 5:1 blend of alcohol and acetate elicited the complete courtship sequence by males. The response was comparable to that evoked by a live virgin female, but males spent significantly longer time at calling females than at the synthetic source. The 5:1 blend was also attractive to male C. circumflexa in the field, as indicated by catches in traps baited with this mixture. (Z)-7-dodecenyl alcohol alone was slightly attractive whereas (Z)-7-dodecenyl acetate alone was completely inactive. C. circumflexa is the first reported Plusiinae species which utilizes (Z)-7-dodecenyl alcohol as the major pheromone component.     

A comparative study of pheromone perception in two species of Noctuid moths

The electrical activity of single olfactory receptor neurons in male soybean looper (SBL) Pseudoplusia includens(Walker) and cabbage looper (CL) Trihoplusia ni(Hübner) moths was evaluated in response to stimulation with fixed amounts of the individual components of their respective pheromone blends. In common with earlier observations in the CL, there are at least two classes of morphologically distinct pheromone sensitive sensilla on the antenna of male SBL, each of which contains two olfactory receptor neurons. In both species, one class of sensilla contains an olfactory receptor neuron sensitive to (Z)-7-dodecen-1-ol acetate (Z-7, 12:AC), the major component in each insect's blend, and a companion receptor neuron which is sensitive to (Z)-7-dodecen-1-ol (Z7,12: OH). In both species the second class of sensilla contains an olfactory receptor neuron which is sensitive to one of the minor components of the pheromone blend. (Z)-5-dodecen-1-ol acetate (Z-5,12:AC) is an effective stimulus in SBL, whereas (Z)-7-tetradecen-1-ol acetate (Z-7,14:AC) is an effective stimulus in CL. However, these two stimulatory compounds have been identified only in the female CL gland; neither has been found in the SBL gland. Thus, in contrast to the CL, which has receptor neurons which are responsive exclusively to conspecific pheromone components, the SBL has a class of receptor neurons which is responsive to a minor component of another species' pheromone blend. Field-trapping assays in which Z-5,12:AC is added to the SBL blend suggest that this single CL component is a powerful inhibitor of male SBL behavioral responses to conspecific pheromone blends. The difference observed in the specificity of the receptor neurons in this second class of sensilla are thus believed to play an integral role in the isolation processes that are maintained between these two species and may well account for the observed behavioral differences in their responses to heterospecific pheromone blends.     

Orientation of male gypsy moths,Lymantria Dispar (L.), to pheromone sources: The role of olfactory and visual cues

The role of olfaction and vision in the close-ranging flying and walking orientation of male gypsy moths, Lymantria dispar(L.), to females was studied in the forest and in the laboratory. In the forest, feral males found an isolated pheromone source as readily as one supplemented with female visual cues; dead, acetonerinsed females deployed without pheromone received virtually no visitations. In flight tunnel choice experiments using cylinders as surrogate trees and pheromone in different spatial configurations, visual attributes of the female did not influence either the males' choice of landing site or the efficiency with which they located the female. Rather, the presence of pheromone on the cylinder was necessary to elicit orientation as well as landing and walking on the cylinder. When a female visual model was placed in various positions around a pheromone source, walking males oriented primarily to the chemical stimulus. There were, however, indications that males would alter their walking paths in response to female visual cues over short distances (<5 cm), but only if they continued to receive pheromone stimulation. When visual and chemical cues were abruptly uncoupled by altering the trajectory of the pheromone plume, most males responded to the loss of the odor cue rather than to visual cues from the female. Temporal pheromone stimulation patterns affected male walking orientation. When stimulated by pheromone, males oriented toward the source; loss of the odor cue prompted an arearestricted local search characterized by primarily vertical and oblique movements with frequent reversals in direction. Presumably these maneuvers enhance the likelihood of recontacting the plume or serendipitously encountering the female. The apparent lack of visual response to the female is discussed in light of morphological and behavioral evidence suggesting that gypsy moths were formerly nocturnal.     

The circadian rhythm of flight activity of Spodoptera exigua males in response to sex pheromone

In many moths, male attraction to the blend of synthetic sex pheromone releasing continuously in the field shows an apparent circadian rhythm similar to that of locomotion activity. In this study, the daily rhythms of electroantennography (EAG) and behavioral responses to sex pheromone, and the daily rhythms of locomotion activity were measured in male beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). The peaks of males trapped by light and sex pheromone were all during the latter part of the night in the field. However, there was no significant variation among time intervals in the EAG responses of male antennae to sex pheromone stimuli. The principal period of locomotion activity under L15:D9 (LD) continued to occur during the scotophase and the subjective scotophase in the day of constant darkness (DD1) and the second of two consecutive days of constant darkness (DD2). The majority of males contacted the sex pheromone source in a wind tunnel during the latter part of the scotophase under LD and the subjective scotophase for DD1 and DD2. There were significant associations between the rhythm of the behavioral response to sex pheromone and locomotion activity. These results suggested that the male's behavioral response to sex pheromone in the beet armyworm could be observed only until locomotion activity of the male occurred at the end of the dark period, despite sex pheromone being released continuously from synthetic pheromone‐baited traps in the field.     

Realized heritability of behavioral responsiveness to an oviposition deterring pheromone in the azuki bean weevil Callosobruchus chinensis

Artificial selection was conducted to reduce the behavioral responsiveness of female bruchid beetles, Callosobruchus chinensis, to the oviposition deterring pheromone excreted by conspecific females. Significant responses to selection were observed after two generations of selection. Realized heritability was estimated as 0.052 ± 0.017 from cumulative responses regressed on cumulative selection differentials. These results indicate that this pheromone communication system has significant additive genetic variance needed for its evolution.     

Analysis of the mating behavior and some possible causes of male copulatory success in Dryas iulia alcionea (Lepidoptera, Nymphalidae, Heliconiinae)

In this study we examined the mating behavior of Dryas iulia and the acceptance and rejection mechanisms of females during courtship activity. An ethogram of mating behavior was organized on the basis of 100 h of observation in an insectarium. Several different behaviors were catalogued and separated into two behavioral repertoires (pre-coupling, post-coupling). The behavioral sequence of mating behavior was also analyzed using a total of 53 pairs of D. iulia. The courtship activities involved interactions between the sexes in three sequential phases—the aerial, air-ground, and ground phases. In 49% of observations the courtship activities led to copulation. The mean time to the occurrence of the first interaction between males and females did not differ between interactions with and without copulation. The behavior of females and males in the two groups were analyzed and differences were found between behavioral activities of both sexes. The results indicate that males’ insistence on courtship does not affect their copulatory success, and that females play a decisive role in copulation occurrence. Analysis of behavioral transitions showed there are many alternative behavioral routines in interactions with and without copulation. The number of behavioral transitions recorded was smaller in the group in which copulation occurred, indicating that males with copulatory success modified their behavior less frequently. Successful males recorded more transitions with a probability of occurrence greater than 0.4, and their behavioral activity was also less reticulated. Analysis using the stereotyping index showed that situations in which copulations occurred were more stereotyped than those in which it did not.     

Reduction of the response to sex pheromone in the oriental fruit moth,Grapholita molesta (Lepidoptera: Tortricidae) following successive pheromonal exposures

The effects of prior pheromonal experience upon the pheromone- mediated upwind flight response was examined in the oriental fruit moth, Grapholita molesta(Busck) (Lepidoptera: Tortricidae). Adult male G. molestawere subjected to a parallel series of staggered and repeated pheromonal exposures in a sustained-flight wind tunnel. Levels of response to pheromone in male G. molestasignificantly decreased in a (a) rectilinear function with increased ages of individuals, (b) logarithmic function of successive trials, and (c) steeper logarithmic function of successive trials with increased dosage of sex pheromone. The baseline levels of responding were not affected by either the (a) dosage of sex pheromone, (b) posteclosion ages of individuals for their initial exposures once the main effect of age itself was estimated, (c) elapsed time in hours between trials, or (d) discrete days of testing as integral intervals, disregarding hours within days.     

Effect of Serotonin on Dynamics of Changes of the Shadow Reflex in Lymnaea stagnalis at a Rhythmic Stimulation

The dynamics of the Lymnaea stagnalis defensive response to the shadow stimulation and its changes under the effect of serotonin solution injections were studied. The consecutive shadow stimuli led to development of habituation in the form of decreased summarized responses in groups of the studied molluscs. The diagram of distribution of probabilities of transitions between the mollusc states and the definite types of their responses had characteristic peaks. An injection of serotonin at doses corresponding to 0.5–2 µg/g body weight increased responses of molluscs to the shadow stimuli with a rise of the probability of their appearance. Serotonin (4 µg/g) reduced the mollusc response to the shadow stimulation by decreasing the response probability. The serotonin-induced behavioral changes were observed for about 0.5 h after the injection. This was accompanied by a redistribution of probabilities of the states and types of the responses, which in turn led to a partial shift of the peaks in the diagrams obtained.     

Vine mealybug sex pheromone increases citrus mealybug parasitism by Anagyrus sp. near pseudococci (Girault)

The present study was aimed at elucidating the role of lavandulyl senecioate (LS), the sex pheromone of Planococcus ficus, in host selection of the parasitoid Anagyrus sp. near pseudococci. Field trials were carried out in Portugal, Italy and Israel. The effect of LS on the parasitism rate of the wasp was determined by exposing sentinel mealybugs combined with pheromone dispensers impregnated with LS, in comparison with other baits: lavandulyl isovalerate (LI); planococcyl acetate (PAc); and unbaited control traps. In addition, in order to study the host location behavior of A. sp. near pseudococci, pheromone dispensers were placed at three different distances: inside the trap, 30 or 60 cm away from the trap. The number of parasitoid females inside the traps, the number of parasitized mealybugs, and the number of days required for the first parasitoid emergence were recorded. The response of A. sp. near pseudococci females to different doses of LS (25–1350 μg) was also evaluated using sticky plate traps. The rate of mealybug parasitism by A. sp. near pseudococci was significantly increased by LS in the three parasitoid populations. PAc and LI had no significant effect on the wasp parasitism rate in most of the trials. However, the Italian population of the parasitoid responded to PAc, showing apparently a different behavioral pattern. The number of parasitoid females trapped did not significantly differ between tested doses of LS. The use of LS as an arrestant in host location by the A. sp. near pseudococci female is discussed.     

黑翅土白蚁踪迹信息素组分数量的柱层析分离和活性测定分析

本文分析了在活性限浓度进行生物活性测定时,黑翅土白蚁Odontotermes formosanu Shiraki对踪迹信息素的行为反应特点以及使用不同踪迹线载体对踪迹信息素活性的影响。并设计标准生物活性测试方法,测定了采用柱层析方法分离的黑翅土白蚁踪迹信息素各分离馏分的活性,发现黑翅土白蚁踪迹信息素用22%乙酸乙酯/正己烷洗脱液等度洗脱分离后的各馏分中包含两个强活性区段,推测黑翅土白蚁踪迹信息素至少包含2个有轻微极性差异的组分。     

Behavioral and electrophysiological responses of Helicoverpa assulta, H. armigera (Lepidoptera: Noctuidae), their F1 hybrids and backcross progenies to sex pheromone component blends

Two sibling species, Helicoverpa assulta and Helicoverpa armigera both use (Z)-9-hexadecenal and (Z)-11-hexadecenal as their sex pheromone components but in almost reversed ratios, 93:7 and 3:97, respectively. H. assulta and H. armigera males performed upwind flight in response to the H. assulta sex pheromone blend (93:7). H. armigera responded strongly to the H. armigera blend (3:97), whereas H. assulta males remained inactive upon exposure to this blend. Both species gave clear dose-dependent electrophysiological responses to (Z)-11-hexadecenal. However, (Z)-9-hexadecenal evoked strong dose-dependent electrophysiological responses in H. assulta males but not in H. armigera. The two male F₁ hybrids exhibited similar behavioral responses to two sex pheromone blends and electrophysiological responses to two pheromone components as H. armigera males. This indicated that H. armigera genes appear dominant in determining the behavioral response and electrophysiological responses. Behavioral and electrophysiological responses of backcrosses of male F₁ hybrids (H. armigera female × H. assulta male) with female H. assulta and H. armigera were close to that of H. assulta and H. armigera, respectively. However, backcrosses of female F₁ hybrids (H. assulta female × H. armigera male) with male H. assulta and H. armigera showed reduced behavioral responses but normal electrophysiological responses compared to males of the respective parental line.     

Emergence, Mating, and Postmating Behaviors of the Oriental Beetle (Coleoptera: Scarabaeidae)

In a previous field-trapping study of the oriental beetle, Exomala orientalis (Waterhouse), by using synthetic sex pheromone on golf course fairways, numerous males were observed and trapped during the hours of peak mating activity. However, very few beetles were observed in the same areas when synthetic pheromone was absent. To investigate the hypothesis that mating in nature occurs cryptically within vegetation at the soil surface, laboratory studies on female emergence and pheromone release, male emergence and mate-locating, and female and male mating behaviors were conducted. Mate acquisition and copulation occurred on the soil surface near the female emergence site, with both sexes engaging in pheromone-mediated behaviors after having emerged from the soil. A highly stereotyped female pheromone release, or calling, behavior was observed, consisting of insertion of the female's head into the soil and elevation of the tip of her abdomen into the air. Bioassays conducted in a wind tunnel that simulated a turf fairway environment showed that walking and flying were both important in the upwind response of males to females. Mating and copulation occurred without an obvious complex courtship, but observations of postmating behaviors suggested that mate guarding occurs.     

Host odours enhance the responses of adult Rhyzopertha dominica to male-produced aggregation pheromone

The behavioural responses of adult male and female Rhyzopertha dominica (Coleoptera, Bostrichidae) to blends of host volatiles and male-produced aggregation pheromone were observed in a four-arm airflow olfactometer. The odour sources used were five pheromone-releasing males each on a single maize grain (lower maize-volatiles blend), five pheromone-releasing males on 500 g of maize (higher maize-volatiles blend) or the host volatiles emanating from 500g of maize (maize volatiles alone). Multiple-choice tests, in which volatiles from all three odour sources were presented in the exposure chamber at the same time, were used to study odour preferences of the males and females. Both sexes showed strongest attraction to the higher maize volatile blend but there were significant sex differences in response to the odour sources. Males spent significantly more time than females in the zone with only maize volatiles, and females spent significantly more time in the higher maize-volatiles zone. However, when odour sources were offered singly, females gave numerically greater responses than males to all sources although this difference was statistically significant for only the lower maize-volatiles blend. As males are more attracted than females to host odours alone it is suggested that they may be more highly adapted to seek out new hosts while females are more inclined to locate a food source by following the pheromone signals produced by males. However, both sexes responded most strongly to the odour source comprising aggregation pheromone with the higher proportion of maize volatiles.     

Comparative study of courtship in twelve phycitine moths (Lepidoptera: Pyralidae)

The courtship behavior of 12 phycitine moths (Lepidoptera: Pyralidae) was studied using frame-by-frame analysis of video recordings. Behavioral transitions during courtship were quantified for selected species and kinematic diagrams of courtship sequences were constructed. Interspecific similarities in courtship behaviors were measured by calculating Euclidean distances between species based on 12 courtship characters and by clustering species according to UPGMA (unweighted pair-group method using arithmetic averages). The resulting phenogram revealed two major behavioral patterns in courtship: (1) interactive and (2) simple. The former was characterized by a complex sequence in which, typically, a male approached a pheromoneemitting female, engaged in a head- to- head posture with the female, and then brought his abdomen over his head and struck the female on the head and thorax. This action brought male abdominal scent structures into close proximity with the female antennae. The male then attempted copulation from the head- to- head position by a dorsolateral thrust of the abdomen toward the female genitalia. Males of these species possessed scent structures located either on the eighth abdominal segment, or in a costal fold of the forewing, or both. Courtship in the second group was much more prosaic. After locating the female by response to her sex pheromone, the male simply attempted copulation by lateral abdominal thrusts under the female wing, without behavioral embellishments. Males of species exhibiting simple courtship had either no scent structures or structures that appeared vestigial. The grouping of species based on courtship characters was poorly correlated with taxonomic relationships, suggesting that the selective pressures governing the evolution and maintenance of courtship and male pheromones were distinct from those involved in the evolution of other morphological characters. While we argue that the primary force molding the evolution of courtship was an adaptive response to interspecific mating mistakes, we do not believe that isolation is brought about by the sequence of courtship behaviors themselves, due to the striking similarity in the sequence across several diverse species. Rather, these behaviors act to deliver more efficiently the male pheromonal message, which mayhave evolved for reproductive isolation.     

Spring dispersal ofSitona lineatus: The use of aggregation pheromone traps for monitoring

The spring dispersal ofSitona lineatus L. (Coleoptera; Curculionidae) was investigated on a Danish farm.S. lineatus dispersed by flight in the early spring on sunny, calm days with temperatures above ca. 15°C. Two thirds of the population ofS. lineatus dispersed from perennial leguminous crops (clover and lucerne) in the first period of flight activity. The next dispersal did not occur until one month later despite several intermediate flight activity periods. The first period of dispersal occurred before the germination of the spring sown summer host crop,Vicia faba L. The field bean crop was infested in three later invasions during a period of more than three weeks. The aggregation pheromone, 4-methyl-3,5-heptanedione, had a significant effect on captures of both males and females in cone traps placed on the ground. There was no effect of the pheromone on captures in yellow sticky traps placed 1.5 m above ground. The pheromone effect is discussed in relation to behavioural observations. Both types of traps may be used in a survey system for monitoring spring dispersal ofS. lineatus and optimal timing of insecticide spraying. However, the pheromone cone traps were highly specific whereas all kinds of flying insects were caught in the yellow sticky traps, thus making the latter traps less suitable for monitoring.