Biology Reference
In-Depth Information
Microbial symbionts may be important in the biology and behavior of these
ants in other ways. For example, cuticular hydrocarbon profiles, used by social
insects to recognize nest mates, are determined by both environmental and
genetic factors.
Richard et al. (2007)
compared the cuticular hydrocarbon pro-
files of 18 colonies of
Acromyrmex
and compared the variability of the 47
compounds. Colony-specific profiles were distinct and significantly different
between two
Acromyrmex
species. Interestingly,
Richard et al. (2007)
showed
that workers previously exposed to and fed with the fungal symbiont of another
colony “are met with less aggression when they are later introduced into that
colony. It appears, therefore, that fungus gardens are an independent and sig-
nificant source of chemical compounds, potentially contributing a richer and
more abundant blend of recognition cues to the colony “gestalt” than the
innate chemical profile of the ants alone.” If adjacent colonies contain different
strains of fungus, it would allow workers to discriminate readily between nest-
mates and nonnestmates.
4.12.6 Southern Pine Beetle Symbionts
Scott et al. (2008)
found that southern pine beetles,
Dendroctonus frontalis
,
have a mutualism somewhat similar to attine ants that involves two fungi
and an actinomycete bacterium. The adult beetles carry a beneficial fungus
(
Entomocorticium
) in a specialized storage compartment called a mycangium.
Females excavate galleries within the inner bark and phloem of pine trees
to oviposit. At the same time, they inoculate the galleries with the beneficial
fungus that provides food for their larvae. However, a fungus that can out-
compete
Entomocorticium
can affect the mutualistic relationship between
Entomocorticium
and the beetle larvae.
Scott et al. (2008)
discovered an actino-
mycete related to a
Streptomyces
bacterium that produces a diffusible product
that inhibits the antagonistic fungus but that only slightly affects the beneficial
fungus. The antifungal molecule was named mycangimycin because the bacte-
ria are found in the mycangia as well as in the galleries.
Scott et al. (2008)
sug-
gested the use of antibiotic-producing actinomycetes could be “a common
method for maintaining beneficial microbes.”
4.12.7 Aphid Symbionts
Aphids not only have a primary endosymbiont that is obligatory, but also can
harbor up to seven secondary (facultative) symbionts that can affect sev-
eral aspects of the biology of their host (
Oliver et al. 2010, Simon et al. 2011
).
Perhaps the best studied is
Buchnera aphidicola
, located in 60-80 very large cells
called bacteriocytes (
Baumann et al. 1997, Douglas 1998, Moran and Baumann
