Nematode‐induced galls in Miconia albicans: effect of host plant density and correlations with performance

Abstract

The study of nematodes parasitizing native plants plays a crucial role in understanding plant-pathogen interactions. In the present study we describe the patterns of attack by an undescribed species of Ditylenchus occurring in Miconia albicans (Melastomataceae), a widespread, native shrub from the Brazilian cerrado. We also tested the hypothesis that nematode-induced leaf galls negatively correlate to host plant performance and that gall density is a function of host plant density. We collected paired healthy and attacked shoots from 28 individuals of M. albicans and estimated the leaf area lost to nematodeinduced galls in up to 10 leaves per shoot. We analyzed the relationships between leaf area lost to nematode galls and reproductive traits. Nematode attack levels were also compared to the spatial distribution of the host plant. Inflorescence length and fruit production were significantly reduced in attacked shoots compared with healthy shoots. Seeds from attacked shoots showed no significant reduction in germinability or germination time when compared with seeds collected from healthy shoots. Gall density was positively correlated with host density. Despite being seldom studied in tropical ecosystems, nematodes may play an important role in plant fitness and in structuring tropical communities.

Does plant architectural complexity increase with increasing habitat complexity? A test with a pioneer shrub in the Brazilian Cerrado

“…In contrast to insect galls, few ecological studies have addressed incidence of nematode galls in native species in the Neotropics. Although it seems premature to conclude that nematode-induced galls pose significant losses to plant performance, a consensus is emerging that nematode attack negatively affects plant performance (Seixas et al, 2004a, b;Santos et al, 2012;Viana et al, 2013). However, we still lack unequivocal quantitative data of the impact of nematode galls on plant performance.…”

“…Miconia albicans is the host of galls induced by Ditylenchus gallaeformans (Oliveira et al 2013) (Nematoda). These nematode-induced galls occur in both leaves and reproductive structures, which potentially reduce plant productivity (Viana et al, 2013).…”

“…Because nematode-induced galls potentially decrease plant performance (Viana et al 2013), fruits destroyed by Ditylenchus galls were also recorded. Each infructescence was classified into three categories: healthy (H), partially damaged (PD), and totally damaged (TD).…”

First report of Ditylenchus gallaeformans in Miconia albicans from the Brazilian Cerrado, State of Goiás

“…The symptoms and the density of the galls that were observed on M. albicans inflorescences indicate that D. gallaeformans can quite effectively control pest plants in the family Melastomataceae. Viana et al (2013) verified that M. albicans infected with Ditylenchus sp. has not only significantly shorter inflorescences and less fruit production than specimens not infected with the nematode but also severely reduced seed viability.…”

“…Viana et al (2013) and Silveira and Oliveira (2013) reported symptoms caused by Ditylenchus sp. ; however, the identification of the species of this nematode was not performed.…”