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Landscape composition, pond size and prey availability affect web-building spiders and their realized prey around ponds

Zamorano Lido, Mario (2014) BIOM01 20141
Degree Projects in Biology
Popular Abstract
Agricultural intensification and its effect on spiders and their prey

Spiders are abundant predators that can be very useful for biological control, as they eat insects that can damage crops. To study the potential of this group as biocontrol agents it is necessary to understand the trophic relationships and the factors that affect the distribution of both spiders and their prey. For this purpose I examined web building spiders and their prey in non-crop habitats around ponds. The aim was to study how pond size and the area of annually tilled land around the ponds (which reflects agricultural intensification) affect spiders and their prey, with special interest in aphids as a common agricultural pest.

The field work was carried out... (More)
Agricultural intensification and its effect on spiders and their prey

Spiders are abundant predators that can be very useful for biological control, as they eat insects that can damage crops. To study the potential of this group as biocontrol agents it is necessary to understand the trophic relationships and the factors that affect the distribution of both spiders and their prey. For this purpose I examined web building spiders and their prey in non-crop habitats around ponds. The aim was to study how pond size and the area of annually tilled land around the ponds (which reflects agricultural intensification) affect spiders and their prey, with special interest in aphids as a common agricultural pest.

The field work was carried out in summer 2014 in Scania (Sweden). I visited ten ponds for five times, and collected web-building spiders and spider webs with prey remains (actual prey). I also placed sticky traps that simulated spider webs to analyze the availability of potential prey in the area. I identified all spiders to family level, and their actual and potential prey was identified to order level. Then I analyzed the data using distance-based linear models to see which factors explain spider family composition, potential and actual prey and, due to their importance, aphid prey numbers. I also studied the temporal dynamics of aphids and the two most abundant spider families, Araneidae (orb weavers, in the picture) and Linyphiidae (sheet weavers).

The results show that the availability of flying prey explains spider family composition. The results indicate that the area of annually tilled land could affect to a certain degree the spider family composition and the availability of potential aerial prey, although more research would be needed. Actual prey was affected by the abundance of potential Diptera prey, pond size and the number of Araneidae webs at each pond. Aphids were more abundant in habitats surrounded by small areas of agricultural fields (indicating that they choose primarily crop fields to live), and their importance on spider diet increased throughout summer. Results of actual prey highlight the contribution of spiders to biological control, as aphids, dipterans and thysanopterans (three groups that can be agricultural pests) were important in the diet of spiders. The temporal dynamics of spiders depend on the studied family, and a longer study would be needed for a full understanding of the dynamics.

In conclusion, the present study shows the importance of landscape characteristics when studying natural enemies and their prey, and how agricultural intensification affects their interactions. It further highlights the important contribution of spiders to pest control even outside agricultural fields.

Advisor: Klaus Birkhofer
Master´s Degree Project 30 credits in Biology 2014
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Zamorano Lido, Mario
supervisor
organization
course
BIOM01 20141
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
4780378
date added to LUP
2014-11-18 11:22:28
date last changed
2014-11-18 11:22:28
@misc{4780378,
  author       = {{Zamorano Lido, Mario}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Landscape composition, pond size and prey availability affect web-building spiders and their realized prey around ponds}},
  year         = {{2014}},
}