Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Front Zool. 2014 Jan 17;11(1):4. doi: 10.1186/1742-9994-11-4.
Female spiders are fine-tuned to detect and quickly respond to prey vibrations, presenting a challenge to courting males who must attract a female's attention but not be mistaken for prey. This is likely particularly important at the onset of courtship when a male enters a female's web. In web-dwelling spiders, little is known about how males solve this conundrum, or about their courtship signals. Here we used laser Doppler vibrometry to study the vibrations produced by males and prey (house flies and crickets) on tangle webs of the western black widow Latrodectus hesperus and on sheet webs of the hobo spider Tegenaria agrestis. We recorded the vibrations at the location typically occupied by a hunting female spider. We compared the vibrations produced by males and prey in terms of their waveform, dominant frequency, frequency bandwidth, amplitude and duration. We also played back recorded male and prey vibrations through the webs of female L. hesperus to determine the vibratory parameters that trigger a predatory response in females.
We found overlap in waveform between male and prey vibrations in both L. hesperus and T. agrestis. In both species, male vibrations were continuous, of long duration (on average 6.35 s for T. agrestis and 9.31 s for L. hesperus), and lacked complex temporal patterning such as repeated motifs or syllables. Prey vibrations were shorter (1.38 - 2.59 s), sporadic and often percussive. Based on the parameters measured, courtship signals of male L. hesperus differed more markedly from prey cues than did those of T. agrestis. Courtship vibrations of L. hesperus males differed from prey vibrations in terms of dominant frequency, amplitude and duration. Vibrations of T. agrestis males differed from prey in terms of duration only. During a playback experiment, L. hesperus females did not respond aggressively to low-amplitude vibrations irrespective of whether the playback recording was from a prey or a male.
Unlike courtship signals of other spider species, the courtship signals of L. hesperus and T. agrestis males do not have complex temporal patterning. The low-amplitude 'whispers' of L. hesperus males at the onset of courtship are less likely to trigger a predatory response in females than the high-amplitude vibrations of struggling prey.
雌性蜘蛛能够精确地探测和快速响应猎物的振动，这对求爱雄性来说是一个挑战，因为它们必须吸引雌性的注意，但又不能被误认为是猎物。当雄性进入雌性的蛛网时，这一点尤其重要，因为这是求爱开始的时候。在居住在蛛网中的蜘蛛中，对于雄性如何解决这个难题，以及它们的求爱信号，我们知之甚少。在这里，我们使用激光多普勒测振仪研究了西方黑寡妇 Latrodectus hesperus 的缠绕蛛网和流浪汉蜘蛛 Tegenaria agrestis 的片状蛛网中雄性和猎物（家蝇和蟋蟀）产生的振动。我们在通常由狩猎雌性蜘蛛占据的位置记录振动。我们比较了雄性和猎物在波形、主频、频带宽度、振幅和持续时间方面产生的振动。我们还通过雌性 L. hesperus 的蛛网回放记录的雄性和猎物振动，以确定触发雌性捕食反应的振动参数。
我们发现 L. hesperus 和 T. agrestis 中雄性和猎物振动的波形有重叠。在这两个物种中，雄性振动都是连续的，持续时间长（T. agrestis 平均为 6.35 秒，L. hesperus 为 9.31 秒），并且缺乏复杂的时间模式，例如重复的主题或音节。猎物振动持续时间较短（1.38-2.59 秒），间歇性且通常是冲击性的。根据测量的参数，L. hesperus 雄性的求爱信号与猎物线索的差异比 T. agrestis 雄性的求爱信号更为显著。L. hesperus 雄性的求爱振动在主频、振幅和持续时间方面与猎物振动不同。T. agrestis 雄性的振动仅在持续时间上与猎物不同。在回放实验中，L. hesperus 雌性对低振幅振动没有做出攻击性反应，无论回放录音是来自猎物还是雄性。
与其他蜘蛛物种的求爱信号不同，L. hesperus 和 T. agrestis 雄性的求爱信号没有复杂的时间模式。L. hesperus 雄性在求爱开始时发出的低振幅“耳语”不太可能引发雌性的捕食反应，而挣扎中的猎物的高振幅振动则更有可能引发捕食反应。
