Fungal Phyllosphere Communities are Altered by Indirect Interactions Among Trophic Levels

Abstract

Trophic interactions involving predators, herbivores, and plants have been described in terrestrial systems. However, there is almost no information on the effect of trophic interactions on microbial phyllosphere community abundance, diversity, or structure. In this study, the interaction between a parasitoid, an insect herbivore, and the fungal phyllosphere community is examined. Parasitoid wasps have an indirect negative impact on fungal community diversity. On the citrus phyllosphere, the exotic wasp species, Amitus hesperidum and Encarsia opulenta, may parasitize the citrus blackfly (Aleurocanthus woglumi). If parasitism levels are low, the blackfly may produce significant amounts of honeydew secretions on the surface of the leaf. Honeydew deposition provides a carbon-rich substrate for the development of fungal growth persisting as sooty mold on the leaves. Leaves from sooty mold-infested grapefruit (Citrus paradisi) trees were collected from multiple orchards in south Texas. The effect of different levels of exotic parasite activity, citrus blackfly, and sooty mold infestation on phyllosphere mycobiota community structure and diversity was examined. Our results suggest the presence of the parasitoid may lead to a top-down trophic cascade affecting phyllosphere fungal community diversity and structure. Additionally, persistent sooty mold deposits that have classically been referred to as Capnodium citri (and related asexual morphological forms) actually comprise a myriad of fungal species including many saprophytes and potential fruit and foliar pathogens of citrus.

Caspary's fungi from Baltic amber: historic specimens and new evidence

“…However, sometimes sooty mould colonies can cover leaf surfaces and thus interfere with the host plant's photosynthesis (Perez et al . ). Caspary's Fungites hirtus may have been an active parasite growing mostly inside the host plant's leaf.…”

Diversity of microfungi associated with phyllosphere of endemic Serbian plant Nepeta rtanjensis Diklić & Milojević

“…Due to strong melanization of hyphae and conidia, these fungi are resistant to UV radiation, and are tolerant to a long period of desiccation (Butler and Day 1998). Although phyllosphere can be referred to as relatively ''hostile environment'' (Perez et al 2009), fungal melanin can be a factor facilitating successful colonization of the leaf surface, as well as penetration of leaf tissues. Thus, moniliaceous hyphomycetes, coelomycetes, ascomycetes, and zygomycetes were determined with a lower frequency.…”

Do plant‐ and soil‐mediated legacy effects impact future biotic interactions?

“…Also higher tropic levels, parasitoids, can have indirect, herbivore‐mediated effects on the diversity and structure of fungal communities in the phylllosphere (Perez et al . ). Whether pollinators influence phyllosphere microbial communities is largely unknown.…”

“…Similarly, but looking from the opposite direction, it has been documented that aphids, mediated by their honeydew excretion, and chewing insect larvae can have significant effects on phyllosphere microbial communities (Stadler & M€ uller 1996(Stadler & M€ uller , 2000Stadler et al 2001a;Stadler, Solinger & Michalzik 2001b;Muller et al 2003). Also higher tropic levels, parasitoids, can have indirect, herbivore-mediated effects on the diversity and structure of fungal communities in the phylllosphere (Perez et al 2009). Whether pollinators influence phyllosphere microbial communities is largely unknown.…”