雌蚊翅振音及其在蚊虫防治中的应用

蚊虫飞翔时 ,翅上下拍打会形成连续的翅振音。雌蚊翅振音频率会随蚊种、蚊体长和日龄及环境温度而变化 ,一般在 3 0 0～ 5 0 0Hz之间。同种个体间翅振音频率变化较小 ,常在平均频率± 5 0Hz范围内。雄蚊只对基本频率的雌蚊翅振音起反应 ,雌蚊翅振音的偶然变化不会降低其对雄蚊的引诱力。雄蚊对雌蚊翅振音具有敏感反应的主要原因是其听觉器官对雌蚊翅振音形成了良好的适应性。因此 ,许多蚊虫研究者希望利用雌蚊翅振音来防治蚊虫。因该方法对环境安全 ,在今后蚊虫防治中其重要性将会日益显现。     

A test of the Acoustic Adaptation Hypothesis in three types of tropical forest: degradation of male and female Rufous-and-white Wren songs

Many animals produce complex vocalizations that show pronounced variation between populations. The Acoustic Adaptation Hypothesis helps to explain this variation, suggesting that acoustic signals are optimized for transmission through different environments. Little is known about the transmission properties of female vocalizations because most studies of the Acoustic Adaptation Hypothesis have focused on male vocalizations of organisms living at temperate latitudes. We explored the relationship between environmental variation and the transmission properties of songs of Rufous-and-white Wrens, resident Neotropical songbirds where both sexes sing. Using playback, we broadcast and re-recorded elements of male and female songs from three populations of wrens living in three different forest habitats in Costa Rica. We measured four variables of the re-recorded sounds: signal-to-noise ratio, excess attenuation, tail-to-signal ratio and blur ratio. Our results show a significant difference between transmission characteristics of both male and female song elements across the three habitats, indicating that sounds transmit differently through different types of tropical forest. The population from which the broadcast sounds were recorded (source population) had little effect on sound transmission, however, suggesting that acoustic differences between these populations may not arise through acoustic adaptation to these habitats. Male and female elements showed similar transmission properties overall, although signal-to-noise ratio of male elements was influenced by source population, whereas blur ratio and excess attenuation of female elements were influenced by source population. Our study highlights the differences in transmission characteristics of animal sounds through different habitats, and reveals some sex differences in transmission properties.     

Experimental demonstration of possible cryptic female choice on male tsetse fly genitalia

A possible explanation for one of the most general trends in animal evolution - rapid divergent evolution of animal genitalia - is that male genitalia are used as courtship devices that influence cryptic female choice. But experimental demonstrations of stimulatory effects of male genitalia on female reproductive processes have generally been lacking. Previous studies of female reproductive physiology in the tsetse fly Glossina morsitans suggested that stimulation during copulation triggers ovulation and resistance to remating. In this study we altered the form of two male genital structures that squeeze the female's abdomen rhythmically in G. morsitans centralis and induced, as predicted, cryptic female choice against the male: sperm storage decreased, while female remating increased. Further experiments in which we altered the female sensory abilities at the site contacted by these male structures during copulation, and severely altered or eliminated the stimuli the male received from this portion of his genitalia, suggested that the effects of genital alteration on sperm storage were due to changes in tactile stimuli received by the female, rather than altered male behavior. These data support the hypothesis that sexual selection by cryptic female choice has been responsible for the rapid divergent evolution of male genitalia in Glossina; limitations of this support are discussed. It appears that a complex combination of stimuli trigger female ovulation, sperm storage, and remating, and different stimuli affect different processes in G. morsitans, and that the same processes are controlled differently in G. pallidipes. This puzzling diversity in female triggering mechanisms may be due to the action of sexual selection.     

A Quantitative Analysis of the Courtship Acoustic Behaviour and Sound Patterning in Male Sand Goby, <Emphasis Type="Italic">Pomatoschistus minutus</Emphasis>

Many animal groups use sounds in reproduction in order to court mates or repel rivals. We describe the sounds and behavioural context of courtship sound production in male sand gobies, Pomatoschistus minutus, and examine the variability of acoustic parameters and the fine temporal patterning of sound units. Male sand gobies excavate a nest under a suitable solid substrate and attract females to mate, attaching the eggs to the ceiling of the nest. Before mating a female may repeatedly enter and leave a male's nest. Sounds were not detected during the courtship phase outside the nest, but were recorded when females were in the nest before spawning. Sounds were produced in 44–100% of such nest visits, varying with individual males. The sand goby sound consists of a train of pulses repeated at a rate of 23–29 pulses per second. The frequency spectrum of single pulses was continuous from 20–30Hz to 500Hz and reached a peak around 100Hz. The absolute sound pressure level ranged from 118 to 138dB re 1µPa at 1–3cm. The sand goby emits sound in distinct sound groups (bursts). Sound temporal features (duration, pulse repetition rate) vary systematically over the course of the burst. Within- and between-male variation of acoustic parameters was examined from sounds emitted by the male. Sound amplitude (peak-to-peak, mV) and pulse rate varied significantly among males, despite low individual stereotypy. Furthermore, sound pressure level correlated with body size. The potential informative content of acoustic parameters is discussed in the light of a possible role of the sand goby sound in mate choice.     

Effects of Host Resistance on the Fecundity of Globodera rostochiensis

The fecundity of Globodera rostochiensis (R₁A) females that developed on resistant Rosa and susceptible Katahdin potato cultivars were compared. Cysts collected from each cultivar were bulked, separated into four sizes (> 500 μm, 355-500 μm, 250-355 μm, and < 250 μm), and crushed to determine fecundity as measured by viable egg content (VEC). Fewer and generally smaller cysts developed on Rosa than on Katahdin. Although cyst size significantly (P = 0.01) influenced VEC, cyst age (8 or 13 weeks) had no effect. Regardless of size, cysts produced on Rosa contained significantly fewer viable eggs than did cysts produced on Katahdin. The fecundity of progeny from cysts produced on Rosa was significantly reduced compared with that of progeny from cysts produced on Katahdin. After two generations on Katahdin, the VEC of cysts from a population originating from Rosa was significantly less than that of cysts from a population originating from Katahdin, indicating that in the presence of a pure population of G. rostochiensis R₁A, the females that develop on the resistant cultivar Rosa represent a diminished rather than a superior selected population.     

Mitochondria-responsive signaling between egg and central cell controls their coordinated maturation

Recent studies suggest a complex regulatory network in female gametophyte of angiosperm. The cell-cell communication between female gametes was confirmed during their maturation and functional specialization. The mitochondria-responsive signaling may play a critical role in this process. Here, we briefly summarized the recent discussion on this topic and proposed a two-pathway’s mechanism for regulating coordinated development of the female gamete cells.     

On the gametogenesis and early embryogenesis in some olive tree cultivars

A comparative embryological study on two Spanish cultivars and one growing in Bulgaria of Olea europaea was carried out. The embryo sac develops according to Allium (bisporic)-type. The critical phases during the development of male and female gametophyte that lead to sterility and abortiveness of the embryo sacs and ovules are reported. The embryogenesis follows the Asterad-type. The endosperm passes a free nuclear stage and later on becomes cellular.     

Females prefer to associate with males with longer intromittent organs in mosquitofish

Sexual selection is a major force behind the rapid evolution of male genital morphology among species. Most within-species studies have focused on sexual selection on male genital traits owing to events during or after copulation that increase a male''s share of paternity. Very little attention has been given to whether genitalia are visual signals that cause males to vary in their attractiveness to females and are therefore under pre-copulatory sexual selection. Here we show that, on average, female eastern mosquitofish Gambusia holbrooki spent more time in association with males who received only a slight reduction in the length of the intromittent organ (‘gonopodium’) than males that received a greater reduction. This preference was, however, only expressed when females chose between two large males; for small males, there was no effect of genital size on female association time.