Main nutrient compounds in food bodies of Mexican
<Emphasis Type="Italic">Acacia</Emphasis> ant-plants |
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Authors: | Email author" target="_blank">Martin?HeilEmail author Birgit?Baumann Ralf?Krüger K Eduard?Linsenmair |
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Institution: | (1) Dept. of Bioorganic Chemistry, Max-Planck-Institute of Chemical Ecology, Beutenberg Campus, Hans-Knöll-Str. 8, 07745 Jena, Germany;(2) Zoologie III, Biozentrum, Theodor-Boveri-Institut der Universität Würzburg, Am Hubland, 97074 Würzburg, Germany |
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Abstract: | Summary. Myrmecophytic plants use obligate ant mutualists as a constitutive
indirect defence mechanism. These plants often produce cellular food bodies (FBs) to
nourish their resident ants. Lipids, proteins, and even highly specialised compounds
such as glycogen have been reported from FBs, but detailed chemical analyses of FB
composition have so far been presented only for Southeast Asian Macaranga
and Central American Piper myrmecophytes. Here we
report the chemical composition of FBs of five myrmecophytic Acacia
(Fabaceae) species from Mexico using HPLC (carbohydrates and proteins) and GC-MS
(lipids). Feeding experiments revealed no hints on any use of external food sources
by the inhabiting Pseudomyrmex ants. These ants
obviously rely completely on FBs and extrafloral nectar provided by their hosts.
The total content of nutrients in Acacia FBs was 15-25% of FB
dry mass, being much lower than in Macaranga or
Piper FBs. Proteins were dominating (8-14 % dm)
in Acacia FBs and thus were present in higher amounts than in
Macaranga FBs, yet in lower amounts than in
Piper. Lipids contributed 1-9 %
of dry mass, showing a lower proportion than in FBs of Macaranga
or Piper. Carbohydrates made up 3-11 % dm, reaching
in most Acacia species the same range as observed in
Macaranga and in Piper FBs.
Water content was 18-24 % of FB fresh mass, and structural tissue obviously made up
a much higher proportion in Acacia FBs than in
Macaranga or Piper
FBs. Both characters might represent an adaptation to producing FBs unprotected at
the leaf tips under dry conditions. Acacia FBs
contain all amino acids and all fatty acids that are considered essential for
insects, and their contents of lipids and proteins are higher than in the leaves
from which they are ontogenetically derived. This indicates a putatively adaptive
enrichment of nutritionally valuable compounds in structures functioning as ant-food. |
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Keywords: | Acacia chiapensis Acacia collinsii Acacia cornigera Acacia globulifera Acacia hindsii ant-plant interaction indirect defence mutualism myrmecophytism Pseudomyrmex swollen-thorn-acacias |
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