Effects of Foliar Endophytic Fungi on the Preference and Performance of the Leaf BeetleChelymorpha alternansin Panama

Abstract

Foliar endophytic fungi live inside healthy plant leaves, and in some cases they confer herbivore resistance to the host. All previous studies of endophyte–herbivore interactions have occurred in temperate areas, and many use correlations rather than experiments. In Panama, Glomerella cingulata is a common endophyte species found in healthy leaves, and Chelymorpha alternans is a common herbivore on Merremia umbellata, a tropical vine. We manipulated the abundance of G. cingulata in the leaves of M. umbellata. We then assessed the effects of high and low endophyte densities on the food choice, development, and reproductive success of the leaf beetle, C. alternans. In ‘choice’ experiments, adult females with a history of feeding on wild plants showed no preference when offered food plants with high and low endophyte densities. Further, in ‘no‐choice’ experiments, C. alternans larvae that were fed high‐ or low‐density endophyte leaves did not differ in development or survivorship. However, when larvae fed on leaves with low endophyte densities became adults, they produced 80 percent more offspring. This suggests high endophyte levels in hosts can have a negative effect on herbivore fecundity. Further experiments are necessary to understand whether the reproductive effects are due to feeding on low‐density endophytes in the larval or adult stages, and whether changes in reproductive success are motivated by the adult's perception of food quality or by physiological constraint due to food quality.

Endophytic fungi reduce leaf-cutting ant damage to seedlings

“…Endophytes produce a broad array of chemicals, some of which have antagonistic activity towards bacteria and other fungi [11]. Moreover, endophytes and the chemicals they produce may be toxic or distasteful to insects [12], pathogenic to insects [13] and/or could decrease insect fitness [6]. Continued research on the impacts of endophytes on leaf-cutting ant colonies and their cultivar may reveal similar effects.…”

“…They are extremely diverse, particularly in the tropics where estimates suggest that a single leaf may contain up to 17 species [4]. Little is known about tropical endophyte ecology, but available evidence indicates that endophytes can reduce plant pathogen damage [5], and negatively affect the fecundity of a herbivorous beetle [6].…”

Two fungal symbioses collide: endophytic fungi are not welcome in leaf-cutting ant gardens

“…Endophyte-derived anti-herbivore defence has been described in some temperate grasses (Clay 1990) and trees (Wilson & Carroll 1994Wilson 1995b;Preszler et al 1996;Wilson & Faeth 2001). By contrast, tropical host-endophyte-herbivore interactions are only beginning to be studied ( Van Bael et al 2009). Endophytes can be extremely diverse in the leaves of tropical plants (Arnold et al 2000), with endophyte communities that conservatively range from 10 to 20 species per host plant and generally exhibit low similarity among hosts ( Van Bael et al 2005;Arnold & Lutzoni 2007).…”

Symbiotic fungi alter plant chemistry that discourages leaf‐cutting ants

“…Reduction in herbivory by plants hosting endophytes can result from directly decreasing survival rates of herbivores to indirectly affecting their developmental time, fecundity or foraging behaviors (Webber, 1981;Clark et al, 1989;McGee, 2002;Jallow et al, 2004;Van Bael et al, 2009b;Bittleston et al, 2011). Production of endophyte-specific toxins is one of the best-known examples of a defense mechanism against herbivores (Clay, 1991;Calhoun et al, 1992).…”