The influence of vibratory courtship on female mating behaviour in orb-web spiders (Argiope keyserlingi, Karsch 1878)

Abstract

Web-building spiders are important models for sexual selection. While our understanding of post-copulatory mechanisms including sperm competition and cryptic female choice is considerable, our knowledge of courtship and how it influences male and female mating decisions is still extremely poor. Here, we provide the first comprehensive description of male courtship behaviour and vibrations generated in the web by the orb-web spider, Argiope keyserlingi - a recognised model species. We identified three main elements of male courtship: shudders, abdominal wags and mating thread dances (including both plucks and bounces). The vibrations generated by these behaviours are described in detail. Male shuddering behaviour appears to have a strong influence on female latency to mate acceptance, with males that shudder at high rates without compromising shudder duration being preferred. Shuddering behaviour may also mediate female aggressive behaviour, with males that generate long shudders less likely to be cannibalised after copulation. Male abdominal wagging behaviour, however, appears to have only limited influence on female mating decisions. This study provides avenues for future work that synthesises pre- and post-copulatory mechanisms in web-building spiders to generate an all-encompassing model of how sexual selection operates.

Figure 1. Sequence of male A. keyserlingi courtship.

Proportions of males making transitions between each behaviour are shown beside flow arrows. Mean duration (s) (± sd) of phases 2–4 are shown.

Figure 2. Shudder courtship vibrations of A. keyserlingi.

(a) Waveform of a bout of shuddering by male Argiope keyserlingi. The apparent amplitude difference between the two shudders is due to the male approaching the female (and hence also approaching the laser vibrometer focal point), rather than a difference in courtship effort; (b) detail waveform of a single shudder from waveform (a). Shudders are performed from first contact with female silk, to commencement of courtship on the mating thread.

Figure 3. Abdominal wagging vibrations of A. keyserlingi.

(a) Waveform of a bout of abdominal wagging by male Argiope keyserlingi; (b) detail waveform of a single abdominal wag from waveform (a). Abdominal wags are performed intermittently throughout courtship and immediately prior to a copulation attempt.

Figure 4. Mating thread dance vibrations of A. keyserlingi.

(a) Waveform of the mating thread dance by male Argiope keyserlingi; (b) detail waveform showing several plucks from waveform (a). Some bouncing occurs simultaneously during these plucks; (c) detail waveform showing bouncing from waveform (a), including simultaneous plucks. Plucks in the waveform are indicated by arrows.