Feeny revisited: condensed tannins as anti‐herbivore defences in leaf‐chewing herbivore communities of Quercus

Abstract

Abstract. 1. Community level oak–tannin–insect patterns have been largely unexplored since Paul Feeny's ground‐breaking research. Two hypotheses were tested for Quercus velutina and Q. alba in the Missouri Ozarks: abundance and richness of leaf‐chewing herbivores are negatively correlated with foliar condensed tannin concentrations and variation in condensed tannin concentrations explains variation in herbivore community structure. 2. In 2001, foliar condensed tannins in the understorey and canopy of these two oak species were quantified simultaneously with censuses of herbivores in May, during leaf expansion, and in June and August, when leaves were fully expanded. Thirty‐eight of the 134 species encountered had densities sufficient to be analysed individually (n = 10). Of those, Acronicta increta (Noctuidae) and Attelabus sp. (Curculionidae), both oak specialists, were negatively correlated with condensed tannins in the canopy of Q. alba. One additional specialist, Chionodes pereyra (Gelechiidae), was marginally negatively correlated with condensed tannins in the understorey of Q. velutina. Understorey species richness of May Q. velutina herbivores was negatively correlated with condensed tannins, as were total canopy insect density and species richness of August herbivores on Q. alba. 3. Principal component analysis (PCA) of insect abundances indicated that understorey and canopy Q. velutina and Q. alba had different communities of leaf‐chewing insects. Furthermore, condensed tannin levels contributed significantly to variation in PCA scores for Q. velutina, explaining 25% of the total variation. 4. Overall, these results indicate that specialists were more likely than generalists both to correlate negatively with condensed tannins and to occur in lower tannin habitats; abundance and richness of both early and late season fauna correlated negatively with tannins; and species were more likely to correlate negatively with condensed tannins when feeding on Q. alba than on Q. velutina and when feeding in the canopy than in the understorey. Future studies of tannin–insect interactions should manipulate leaf quality in combination with manipulations of other factors that likely influence community structure.

Herbivory on bracken (Pteridium spp.) by Bolax palliata Burmeister (Coleoptera: Scarabaeidae), a poliphagous beetle of the Venezuelan Andes

“…tree neighboring our study site. The aforementioned record by Briceño (1989) and this confi rming observation lends additional support to our hypothesis, since some Inga species are known for their high contents in condensed tannins (Koptur 1985, Galindo et al 1989, Myster 2002), a group of compounds commonly known as defensive, due to their alleged antinutritional properties (Balick et al 1978, Tempel 1981, Forkner et al 2004.…”

Phenological asynchrony between herbivorous insects and their hosts: signal of climate change or pre-existing adaptive strategy?

“…Larvae fed on late-gathered leaves encountered the accumulation of host defences as those leaves matured and produced very small pupae that had zero survival to adulthood. Subsequent authors have studied changes of leaf quality over shorter time periods and confirmed that the rapid decline of host quality as leaves mature reduces the pupal weight of late-feeding insects (Wint 1983;Buse et al 1999;Forkner et al 2004;van Asch & Visser 2007). Small pupae pay a clear penalty in terms of fecundity (figure 5).…”

Influence of plant resistance traits in selectiveness and species strength in a tropical plant‐herbivore network

“…Factors infl uencing both food availability and resistance against herbivores such as seasonality ( Shure and Wilson, 1993 ;Coley, 1998 ;Forkner et al, 2004 ;Pearse and Hipp, 2012 ;Scherrer et al, 2016 ), habitat structure (which governs the eff ects of the microclimate or spatial distribution of the host plants) ( Nice and Fordyce, 2006 ;Stoepler and Lill, 2013 ) and the natural history of plants (i.e., life forms) ( Th ompson, 1988 ;Menge, 2003 ), are therefore likely to promote temporal and spatial variation in plant-herbivore network parameters. In this study, we investigated the infl uence of foliar resistance traits and plant cover on species-level parameters of plant-herbivore networks, specifi cally on plant species strength (i.e., how important a plant species is to a set of herbivores) and herbivore selectiveness (herbivore specialization).…”