Are web stabilimenta attractive to praying mantids?

Certain species of orb-weavers add extra silk structures, termed a stabilimentum or web decoration, to their webs. In the genus Argiope stabilimenta are silken structures of densely woven zig-zag ribbons. The adaptive value of these stabilimenta is still unclear and controversially discussed. In the course of time, many functional hypotheses have been proposed for silk stabilimenta. Because of their high visibility they are claimed to act as a visual signal for insects. So most recent hypotheses consider them as prey attractants although also predators (e.g. mantids) have been shown to be attracted by these structures. Bruce et al. (2001) reported that the praying mantid Archimantis latistylus was attracted to decorated webs of Argiope keyserlingi in a Y-maze choice test. In Argiope-species spiders construct different basic shapes of stabilimenta which can be cruciate, linear or discoid. The predator attraction hypothesis was supported by testing cruciate forms of A. keyserlingi. To test these predictions also for linearly shaped stabilimenta, the web decorations of the palearctic wasp spider A. bruennichi were tested in a laboratory experiment, adopting the Y-maze setup of Bruce et al. (2001) to make it comparable. Also a taxonomically similar predator was used for the test, Mantis religiosa (Mantodea: Mantidae). M. religiosa showed no preference for webs with stabilimenta, but only a very small number of individuals reached one of the both maze exits at all, rendering universally valid conclusions difficult. Generally, Mantis showed a scarce locomotor activity in the Y-maze apparatus and no signs of any predatory response, which indicates that the experimental design might be problematic for studying behavioural elements of praying mantids.