Floral spatial morphological characteristics preferences facilitate mating and predation in flower-visiting spiders

Numerous flower visitors exhibit varying preferences for floral characteristics. As one group of flower visitors, the preferences of spiders for flower colour have garnered attention; however, their preferences for the spatial morphological characteristics of flowers remain largely unexplored. This study investigated the preferences of flower-visiting crab spiders Ebrechtella tricuspidata for flower size, petal density, and symmetry, and explored the underlying reasons from the courtship and predation. The results indicated that male spiders preferred larger flowers, while females favored densely petaled flowers and symmetrical flowers. Additionally, males exhibited a stronger preference for females that sitting on larger flowers than on smaller ones. Furthermore, consistent with spider preferences, the potential prey houseflies and honeybees, also showed a significant preference for larger, densely petaled, and symmetrical flowers in visitation experiments. We propose that prey preferences for floral characteristics may be a primary factor influencing spider preferences. We hypothesize that the flower characteristics influence insect visitation preferences, which may extend to third trophic level predators, thereby determining the preferences of flower-visiting spiders. Overall, our research provided new insights and evidence regarding spider preferences for floral characteristics, emphasizing that these preferences may facilitate both predation and mating in spiders.

Methods
We used E. tricuspidata spiders and odorless artificial L. maximum flowers to conduct all experiments. First, the preferences of E. tricuspidata for floral spatial morphological characteristics were assessed by offering spiders (a) large versus small flowers, (b) densely versus sparsely petaled flowers, and (c) symmetrical versus asymmetrical flowers. Second, the mating preferences of E. tricuspidata were examined by presenting males with females sitting on flowers with different characteristics. Third, we tested the visitation preferences of the potential prey of the spider for flowers with different characteristics.