Faculté des sciences

Does the Land Snail Arianta arbustorum Prefer Sequentially Mixed Over Pure Diets?

Speiser, B. ; Rowell-Rahier, Martine

In: Functional Ecology, 1993, vol. 7, no. 4, p. 403-410

1. Most herbivores have a very restricted host range (the specialists), but some (called generalists) include a large number of different food plants in their diet. Here, we investigate the land snail Arianta arbustorum (Helicidae) to discover whether eating several plant species is more advantageous than eating one plant species only. 2. In the faeces of... Plus

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    Summary
    1. Most herbivores have a very restricted host range (the specialists), but some (called generalists) include a large number of different food plants in their diet. Here, we investigate the land snail Arianta arbustorum (Helicidae) to discover whether eating several plant species is more advantageous than eating one plant species only.
    2. In the faeces of field-collected Arianta arbustorum, the plant species eaten were identified anatomically. Over 89% of the snails had eaten more than one food item within the period of 1-3 days, for which the faeces are representative.
    3. In the laboratory, Arianta arbustorum was presented with two different food plants in sequence and the amounts eaten were measured (sequentially mixed diet group). The controls were fed only one plant species throughout the experiment (pure diet group). When the snails of the sequentially mixed diet group received the food plants Circaea lutetiana (Onagraceae) or Stachys silvatica (Lamiaceae) together with Adenostyles alliariae (Asteraceae) (irrespective of order of presentation) they ate more than the snails from the pure diet group. However, when the snails of the sequentially mixed diet group received Senecio fuchsii (Asteraceae) together with Adenostyles alliariae (irrespective of order of presentation) they ate similar amounts as the snails from the pure diet group.
    4. Adenostyles alliariae and S. fuchsii belong to the same subtribe Senecioneae and contain very similar secondary compounds, while C. lutetiana and S. silvatica belong to different plant families from Adenostyles alliariae and contain completely different secondary compounds. This suggests that secondary compounds may be important in causing snails to eat sequentially mixed diets. However, nutrient complementation and sampling cannot be ruled out as additional factors responsible for the maintenance of sequentially mixed diets.