This week we shall look at a very special group of spiders- Bolas Spiders! Bolas spiders hunt in a very unique manner- they don't create a traditional web, rather they stay on a single strand of silk spread across two points. They then use another strand of silk with a sticky 'globule' at the end. Bolas spiders mimic the pheromones of female moths in order to attract the males of that species close enough so that they may be caught with the bolas, which is swung around by the spider. The Spiders detect prey by eyesight as well as the sound of wings in flight. They will attempt to catch anything that flies close enough even if it is not their targeted pheromone species. Research by Haynes et al (2002) Found that the American bolas spider is able to mimic the pheromones of two moth species- the smoky tetanolita:
Tetanolita mynesalis and the bristly cutworm:
Lacinipolia renigera. These two species are active at different times of the evening and the spider is able to alter the pheromones it omits to target each species at these different time periods. Cutworms are actively hunted till approximately 10:30 pm. Tetanolita generally become active from 11 pm and Haynes et al (2002) found that the bolas spider switches the pheromones it produces throughout the night in order too target each species individually.
Image: Haynes, K and Yeargen, K.
If you wish too see a Bolas Spider in action follow this link: https://www.youtube.com/watch?v=EWec266Lo3Q.
References:
Haynes, K Gemeno, C Yeargan, K Millar, J Johnson, K 2002, 'Aggressive chemical mimicry of moth pheromones by a bolas spider: how does this specialist predator attract more than one species of prey?',
Chemoecology, vol. 12, pp. 99-105.
Haynes, K Yeargen K, 'Bolas Spider'
, Photo, Real Monstrosities, viewed 04 May 2014, <http://www.realmonstrosities.com/2012/08/bolas-spider.html>
That’s pretty amazing! Is there any mention of how these spiders are able to alter their production of the different pheromone types? Are there other species of bolus spiders that specialise on different species of prey? How accurate are they during hunting? Cool post.
ReplyDeleteHi Tasmin,
DeleteMost Bolas spiders specialize on one species of prey, however some are able to attract multiple species like the American Bolas Spider. In the case of American Bolas spiders they will produce the mixture of both pheromones at the beginning of the evening as the Cutworm is not put off by the mixed scents but as the evening wears on the level of cutworm pheromone decreases as tetanolita do not like the mix- they prefer a purer scent. As to how this is achieved as far as I'm aware the mechanism behind it is still undiscovered! One study found that spiders attracted a moth approximately every six minutes but they did not always come in range of attack. On average they consume 2.2 moths per evening- a rate that compares well with traditional web builders.