Feeding habits of lycosid spiders in field habitats |
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Authors: | Anna-Karin Kuusk Barbara Ekbom |
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Institution: | 1.Department of Ecology,Swedish University of Agricultural Sciences (SLU),Uppsala,Sweden;2.Swedish Board of Agriculture,J?nk?ping,Sweden |
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Abstract: | Generalist arthropod predators are potential drivers of population dynamics in a wide variety of ecosystems but their feeding
habits are often difficult to reveal as they are small, mobile, and live among dense vegetation or in soils. DNA-based gut-content
analysis is a powerful tool that enables studies on arthropod predator–prey interactions. We studied lycosid spiders (Pardosa spp.) in agroecosystems to see if they consumed cereal aphids (Rhopalosiphum padi) and Collembolans at random, i.e., in proportion to their abundance in the field. We also tested if consumption of the target
prey items was affected by the presence of alternative food. Spiders were captured in farmers’ fields and their gut-contents
screened by PCR with R. padi and Collembola primers. On all sampling occasions, concurrent assessments of total prey availability were carried out. Spider
predation rates on R. padi always exceeded 50 %. Spiders also tested positive for Collembola but to a lower and more varying degree. In general, Pardosa did not consume R. padi and Collembolans in relation to their abundance in the field. Aphid predation was much higher than expected whereas consumption
of Collembolans was considerably lower. The presence of alternative prey influenced consumption of the aphid. It was concluded
that prey consumption by Pardosa spiders generally cannot be assumed to simply mirror prey availability. The spatial distribution of the target prey needs
to be considered as well as the abundance, composition, and nutritional content of potential alternative food items. |
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