Data from: An easy method to sample headspace pheromones in the field

Signal evolution is complex as it is subject to multiple, often
antagonistic selection pressures, and the result is expected to be a
compromise between getting the signal to the desired recipient at minimal
costs and avoiding or at least minimizing reception by an unwanted
audience. In comparison to other modalities, we know very little about
chemical signals, even though they are particularly widespread across many
taxa, including spiders. Spiders use volatile chemicals to attract prey
and mating partners, but are predominantly studied in the laboratory. This
leaves a gap in our knowledge concerning the natural context and
environment for signalling in this large arthropod group. The chemical
nature of the sex-pheromone is known for 12 spider species, including the
wasp-spider Argiope bruennichi. Recent laboratory experiments with this
species have shown that pheromone production is condition-dependent and
that females invest strategically in signalling. One consistent result
from the lab was that freshly matured females do not emit pheromones for
at least 3 days. However, in the field, many freshly matured females have
one or more guarding males in their webs, putting our laboratory results
into question. To solve this incongruity, a method for sampling under
field conditions was required. Here, we present a simple method that we
developed to sample the pheromone emission of an orb-web spider in the
field. We verify the validity of the method by comparing pheromone amounts
in the headspace with body extracts using females in different
developmental stages.