Flowers are good sources of food for many animals, and are especially frequently visited by many insects. This means that they are good places for predators to hunt, as there are lots of possible prey. One group that are specialists at this are the crab spiders (or flower spiders, Thomisidae). They have enlarged front legs, hence their name, which enables them to wrap their legs around a bee before injecting venom. Since they are quite common, bees have behaviours to attempt to avoid them.
We studied the behaviour of both crab spiders and bees in patches of lavender (Lavandula stoechas) and rockrose (Cistus ladanifer and Cistus salvifolius). Spiders usually attacked bees that landed on their flowers, but where only successful in capturing the bees about 8% of the time. Honeybees seemed to be quite good, but not perfect, at spotting spiders because they were half as likely to land on flowers that they looked at if there was a spider. Solitary bees on the other hand didn’t seem to respond to spiders. On rockrose, honeybees seemed to be able to detect where spiders had been and didn’t land. They were also less likely to visit flowers that had a dead bee stuck to them.
Spiders tend to hunt on the flowers with the highest number of prey. That is, the best quality flowers. So, bees avoidance of flowers with spiders may help to spread their pollination effort around less high quality flowers. This ensure a mixture of flower qualities all get to pass on their genes to the next generation.
Posted by: Andrew Higginson Posted Tue Aug 29 2017
Posted by: AndrewDHigginson Posted Fri Oct 27 2017