Plant phenology and absence of sex-biased gall attack on three species of Baccharis

Dioecy represents a source of variation in plant quality to herbivores due to sexual differences in intensity and timing of resource allocation to growth, defense and reproduction. Male plants have higher growth rates and should be more susceptible to herbivores than females, due to a lower investme...

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Bibliographic Details
Published in:PloS one 2012-10, Vol.7 (10), p.e46896-e46896
Main Authors: Espírito-Santo, Mário M, Neves, Frederico S, Fernandes, G Wilson, Silva, Jhonathan O
Format: Article
Language:English
Subjects:
Abundance
Animals
Asteraceae
Baccharis - growth & development
Baccharis - physiology
Biology
Ecological and Environmental Phenomena
Females
Gall
Galling
Gender
Growth rate
Herbivores
Herbivory
Host plants
Insects
Investment
Males
Phenology
Plant growth
Plant phenology
Plant Tumors
Reproduction
Reproduction (biology)
Resource allocation
Seasons
Sex
Sex Characteristics
Sexes
Shoots
Species
Studies
Time Factors
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Summary:Dioecy represents a source of variation in plant quality to herbivores due to sexual differences in intensity and timing of resource allocation to growth, defense and reproduction. Male plants have higher growth rates and should be more susceptible to herbivores than females, due to a lower investment in defense and reproduction. We compared resource investment to growth and reproduction and its consequences to herbivore attack on three Baccharis species along one year (B. dracunculifolia, B. ramosissima, and B. concinna). Phenological patterns presented by the three species of Baccharis were quite different over time, but the number of fourth-level shoots and plant growth rate did not differ between sexes in any studied species. Intersexual difference in reproductive investment was only observed for B. concinna, with female individuals supporting higher inflorescence density than male individuals throughout the year. Gall abundance on the three Baccharis species was not influenced by plant sex. However, all plant traits evaluated here positively influenced the gall abundance on B. concinna, whereas only the number of fourth-level shoots positively influenced gall abundance on B. ramosissima and B. dracunculifolia. The absence of differential reproductive allocation may have contributed to similar growth and shoot production between the sexes, with bottom-up effects resulting in gender similarities in gall abundance patterns. The number of fourth-level shoots, an indicator of meristem availability to herbivores, was the most important driver of the abundance of the galling insects regardless of host plant gender or species. Albeit the absence of intersexual variation in insect gall abundance is uncommon in the literature, the detailed study of the exceptions may bring more light to understand the mechanisms and processes behind such trend.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0046896