naa a22 4500 510737897 CHVBK 20180411083017.0 cr unu---uuuuu 180411e20130901xx s 000 0 eng 10.1007/s11284-013-1074-5 doi (NATIONALLICENCE)springer-10.1007/s11284-013-1074-5 Why do ants shift their foraging from extrafloral nectar to aphid honeydew? [Elektronische Daten] [Noboru Katayama, David Hembry, Masaru Hojo, Nobuhiko Suzuki] When aphids parasitize plants with extrafloral nectaries (EFNs) and aphid colony size is small, ants frequently use EFNs but hardly tend aphids. However, as the aphid colony size increases, ants stop using EFNs and strengthen their associations with aphids. Although the shift in ant behavior is important for determining the dynamics of the ant-plant-aphid interaction, it is not known why this shift occurs. Here, we test two hypotheses to explain the mechanism responsible for this behavioral shift: (1) Extrafloral nectar secretion changes in response to aphid herbivory, or (2) plants do not change extrafloral nectar secretion, but the total reward to ants from aphids will exceed that from EFNs above a certain aphid colony size. To judge which mechanism is plausible, we investigated secretion patterns of extrafloral nectar produced by plants with and without aphids, compared the amount of sugar supplied by EFNs and aphids, and examined whether extrafloral nectar or honeydew was more attractive to ants. Our results show that there was no inducible extrafloral secretion in response to aphid herbivory, but the sugar concentration in extrafloral nectar was higher than in honeydew, and more ant workers were attracted to an artificial extrafloral nectar solution than to an artificial aphid honeydew solution. These results indicate that extrafloral nectar is a more attractive reward than aphid honeydew per unit volume. However, even an aphid colony containing only two individuals can supply a greater reward to ants than EFNs. This suggests that the ant behavioral shift may be explained by the second hypothesis. The Ecological Society of Japan, 2013 HPLC nationallicence Indirect interaction nationallicence Mutualism nationallicence Plant-animal interaction nationallicence Sugar nationallicence Katayama Noboru Center for Ecological Research, Kyoto University, 3-509 Hirano 2-chome, 520-2113, Otsu, Shiga, Japan aut Hembry David Center for Ecological Research, Kyoto University, 3-509 Hirano 2-chome, 520-2113, Otsu, Shiga, Japan aut Hojo Masaru Department of Environmental Sciences and Technology, Faculty of Agriculture, University of the Ryukyus, Senbaru 1 Nishihara, 903-0213, Okinawa, Japan aut Suzuki Nobuhiko Department of Applied Biological Sciences, Faculty of Agriculture, Saga University, Honjo 1, 840-8502, Saga, Japan aut Ecological Research Springer Japan 28/5(2013-09-01), 919-926 0912-3814 28:5<919 2013 28 11284 https://doi.org/10.1007/s11284-013-1074-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11284-013-1074-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Katayama Noboru Center for Ecological Research, Kyoto University, 3-509 Hirano 2-chome, 520-2113, Otsu, Shiga, Japan aut NATIONALLICENCE 700 1- Hembry David Center for Ecological Research, Kyoto University, 3-509 Hirano 2-chome, 520-2113, Otsu, Shiga, Japan aut NATIONALLICENCE 700 1- Hojo Masaru Department of Environmental Sciences and Technology, Faculty of Agriculture, University of the Ryukyus, Senbaru 1 Nishihara, 903-0213, Okinawa, Japan aut NATIONALLICENCE 700 1- Suzuki Nobuhiko Department of Applied Biological Sciences, Faculty of Agriculture, Saga University, Honjo 1, 840-8502, Saga, Japan aut NATIONALLICENCE 773 0- Ecological Research Springer Japan 28/5(2013-09-01), 919-926 0912-3814 28:5<919 2013 28 11284 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer