Biology Reference
In-Depth Information
Competitiveness may also play an important role in the invasion of established associations by
new fungi. Highly competitive fungi may capture and retain host-plant resources (and consequently
hosts) ahead of less competitive established associates. In aggressive beetle systems, many
coevolved associates are nonpathogenic, while more recently associated fungi exhibit varying
degrees of virulence to the host tree. Pathogenicity, by increasing competitiveness, may allow some
fungi to invade established associations because they can grow in and capture still living or recently
killed tree tissues ahead of nonpathogenic associates.
Oligophily is likely to have several important consequences for both the host beetles and the
symbiotic fungi. For any given association, fungal associates vary greatly in their effects on host-
beetle Ýtness and therefore are likely to differ in their inÞuence on host-population dynamics.
Additionally, interactions, including competition for hosts, among multiple fungal associates of a
beetle species may determine the relative abundance of each in a population, which, in turn, may
also inÞuence host-population dynamics. Oligophily may be a less desirable state than monophily
in associations that involve at least one mutualistic fungus. In such associations, for at least some
beetles in a population the mutualist can be displaced by less beneÝcial associates or by detrimental
fungi, resulting in lower overall Ýtness within a population. While cheaters are potentially detri-
mental, beetles may be unable to develop effective means of avoiding cheaters without also
negatively impacting beneÝcial associates.
ACKNOWLEDGMENTS
I extend sincere gratitude to T.D. Paine, A. Adams, and K. Bleiker for their very helpful comments
and suggestions for this chapter.
REFERENCES
Abrahamson, L.P. and Norris, D.M. (1970). Symbiontic interrelationships between microbes and ambrosia
beetles. V. Amino acids as a source of nitrogen to the fungi in the beetle.
Ann. Entomol. Soc. Am.
63:
177Ï180.
Amman, G.D. (1972). Some factors affecting oviposition behavior of the mountain pine beetle.
Environ.
Entomol.
1:
691Ï695.
Anderbrant, O. (1988). Survival of parent and brood adult bark beetles,
Ips typographus
, in relation to size,
lipid content and re-emergence or emergence day.
Physiol. Entomol.
13:
121Ï129.
Atkins, M.D. (1969). Lipid loss with Þight in the Douglas-Ýr beetle.
Can. Entomol.
101:
164Ï165.
Ayres, M.P., Wilkens, R.T., Ruel, J.J., Lombardero, M.J., and Vallery, E. (2000). Nitrogen budgets of phloem-
feeding bark beetles with and without symbiotic fungi (Coleoptera: Scolytidae).
Ecology
81:
2198Ï2210.
Barras, S.J. (1970). Antagonism between
Dendroctonus frontalis
and the fungus
Ceratocystis minor
.
Ann.
Entomol. Soc. Am.
63:
1187Ï1190.
Barras, S.J. (1973). Reduction of progeny and development in the southern pine beetle following removal of
symbiotic fungi.
Can. Entomol.
105:
1295Ï1299.
Barras, S.J. and Hodges, J.D. (1974). Weight, moisture, and lipid changes during the life cycle of the southern
pine beetle. USDA Forest Service Experimental Station Research Note SO-178.
Barras, S.J. and Perry, T. (1971). Gland cells and fungi associated with prothoracic mycangium of
Dendroc-
tonus adjunctus
(Coleoptera: Scolytidae).
Ann. Entomol. Soc. Am.
64:
123Ï126.
Barras, S.J. and Perry, T. (1972). Fungal symbionts in the prothoracic mycangium of
Dendroctonus
frontalis
(Coleoptera: Scolytidae).
Z. Angew. Entomol.
71:
95Ï104.
Batra, L.R. (1963). Ecology of ambrosia fungi and their dissemination by beetles.
Trans. Kansas Acad. Sci.
66:
213Ï236.
Batra, L.R. (1966). Ambrosia fungi: extent of speciÝcity to ambrosia beetles.
Science
153:
193Ï195.
Beaver, R.A. (1986). The taxonomy, mycangia, and biology of
Hypothenemus
curtipennis
(Schedl), the Ýrst
known cryphaline ambrosia beetle (Coleoptera: Scolytidae).
Entomol. Scand.
17:
131Ï135.
