Tropical Forest Community Ecology

Endophytic Fungi 267

0 0.1 0.2 0.3 0.4

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Damaged lamina

Undamaged lamina

0

25

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Abundance of endophytes (%)

Endophyte species

Infection frequency (%)

Figure 15.4 Effects of damage by hesperiid larvae on the endophyte community associated withGustavia superba
at BCI. Endophyte species composition differs markedly between the undamaged lamina and along edges cut by
caterpillars. Inset: Caterpillar damage increases infection of leaf segments in young leaves ofGustavia superba.

and Hymenoptera, disrupts the leaf cuticle,
thereby openin gleaf interiors to ambient fun gi.
Insects with piercin gor suckin gmouthparts
(e.g., Hemiptera) are more frequently associated
with the transmission of viruses than with fungi,
but exceptions do exist. For example, two species
of aphids (Aphis fabaeandUroleucon cirsii) are
capable of transmittin gthe fun gal rust patho gen
Puccinia punctiformis(Kluthet al.2002). More-
over, sugar-rich exudates produced by piercing or
suckin ginsects may increase the prevalence of,
or survival of, fungi on leaf surfaces, increasing
infectionsuccess.Forexample,honeydewprovides
a critical nutrient source for germination and sur-
vival ofSeptoria nodorum,Uromyces vitis-fabae, and
Botrytis fabaeontheirrespectivehostplants,which
facilitates infection (reviewed in Hatcher 1995).
The observation that folivory can increase
endophyte colonization, coupled with the obser-
vation that propagules of endophytic fungi remain
viable followin gpassa ge throu gh the orthopteran
gut (Monk and Samuels 1990), suggests that
some endophytes may benefit from folivory. Such
a benefit would have two components: folivores

would open new substrates by compromisin gleaf

cuticles, and would provide a means by which

endophytes could reproduce (from frass) more

rapidly than if trapped within long-lived leaves.

This incidental mycophagy should be evaluated:

do chemical changes in leaf tissues, or the pres-

ence of fungal tissues, increase attractiveness to

herbivores? Does the presence of fungal amino

acids or other products improve forage quality?

Could compounds generated by endophytes play

a role in protectin gherbivores from parasitoids?

In general, the role of insect-mediated transmis-

sion of endophytes remains little explored in the

tropics, but may be critical for understandin gthe

complex interplay of endophytic and pathogenic

fungi, herbivorous insects, and tropical plants.

SANTA ROSALIA’S FUNGAL

BLESSINGS

A tremendous number of fungal species are capa-

ble of colonizin glivin gplant tissues in tropical

forests. Myriad species coexist within a landscape