Habitat preference of an herbivore shapes the habitat distribution of its host plant

Abstract

Plant distributions can be limited by habitat-biased herbivory, but the proximate causes of such biases are rarely known. Distinguishing plant-centric from herbivore-centric mechanisms driving differential herbivory between habitats is difficult without experimental manipulation of both plants and herbivores. Here we tested alternative hypotheses driving habitat-biased herbivory in bittercress (Cardamine cordifolia), which is more abundant under shade of shrubs and trees (shade) than in nearby meadows (sun) where herbivory is intense from the specialist fly Scaptomyza nigrita. This system has served as a textbook example of habitat-biased herbivory driving a plant’s distribution across an ecotone, but the proximate mechanisms underlying differential herbivory are still unclear. First, we found that higher S. nigrita herbivory in sun habitats contrasts sharply with their preference to attack plants from shade habitats in laboratory choice experiments. Second, S. nigrita strongly preferred leaves in simulated sun over simulated shade habitats, regardless of plant source habitat. Thus, herbivore preference for brighter, warmer habitats overrides their preference for more palatable shade plants. This promotes the sun-biased herbivore pressure that drives the distribution of bittercress into shade habitats.

A chromosome‐scale Gastrodia elata genome and large‐scale comparative genomic analysis indicate convergent evolution by gene loss in mycoheterotrophic and parasitic plants

“…Previous studies on the plastomes of various parasitic plants indicated strong contraction in the plastomes of parasitic plants (Feng et al., 2016). Gene family contraction has also been found to be one of the major events of nuclear genome evolution of parasitic plants (Alexandre et al., 2018; Cai et al., 2021; Ohigashi et al., 2019; Sun et al., 2018). We found strong signals of gene family contraction in the orchids: Approximately 75% of the conserved gene families in almost all orchids showed contraction and G. elata exhibited the largest extent of gene family contraction (Figure 2).…”

Towards understanding Cameraria ohridella (Lepidoptera: Gracillariidae) development: effects of microhabitat variability in naturally growing horse-chestnut tree canopy

“…Hence, our developed model should confirm its predictive potential also when applied to seminatural conditions like greenhouse experiments (see Jagiełło et al 2019). Some studies suggest that leaf-miners and leaf-gallers prefer sun-exposed leaves over those growing in the shade (Dai et al 2013;Alexandre et al 2018), but Horváth and Benedek (2009) pointed out that the preference of C. ohridella for shaded vs sun-exposed leaves likely results from seasonal r slope and a intercept of regression, R correlation coefficient, E and SE error and standard error of estimation, n number of corresponding observations. Values of equation parameters are calculated for days, and accumulated degree-days (sum of effective temperatures, SET), K upper asymptote of equation (maximal value of relative mine surface), and corresponding parameter in Verhulst equation assumed as K = 1 variation of leaf microclimate and/or nutritional value of the leaf tissue.…”

“…Some studies suggest that leaf-miners and leaf-gallers prefer sun-exposed leaves over those growing in the shade (Dai et al 2013 ; Alexandre et al 2018 ), but Horváth and Benedek ( 2009 ) pointed out that the preference of C. ohridella for shaded vs sun-exposed leaves likely results from seasonal variation of leaf microclimate and/or nutritional value of the leaf tissue. The role of microclimate variability on insect development was analysed by Rebaudo et al ( 2016 ), who concluded ‘…that the model implemented with microclimatic data best predicted observed pest abundances for [their] study sites, but was less accurate than the global dataset model when performed at larger scales’.…”

Insect herbivory reshapes a native leaf microbiome

“…However, the statistical signature of these treatment effects was not clear enough to confidently conclude that our field trials substantially altered natural patterns of herbivory by this specialist, given the high degree of stochastic or unexplained variation in herbivore damage we observed across plant patches ( figure S9, table S5). Discovering the biotic and abiotic factors structuring herbivory patterns in natural host populations thus remains a challenge in this system (48) as well as many others (46), and we have not attempted to solve this problem in the present study.…”