Innate preference hierarchies coupled with adult experience, rather than larval imprinting or transgenerational acclimation, determine host plant use in Pieris rapae.

Hampus Petrén,Gabriele Gloder,Diana Posledovich,Magne Friberg,Christer Wiklund

doi:10.1002/ece3.7018

Hampus Petrén, Gabriele Gloder + Show 3 more

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https://doi.org/10.1002/ece3.7018

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Abstract

The evolution of host range drives diversification in phytophagous insects, and understanding the female oviposition choices is pivotal for understanding host specialization. One controversial mechanism for female host choice is Hopkins’ host selection principle, where females are predicted to increase their preference for the host species they were feeding upon as larvae. A recent hypothesis posits that such larval imprinting is especially adaptive in combination with anticipatory transgenerational acclimation, so that females both allocate and adapt their offspring to their future host. We study the butterfly Pieris rapae, for which previous evidence suggests that females prefer to oviposit on host individuals of similar nitrogen content as the plant they were feeding upon as larvae, and where the offspring show higher performance on the mother's host type. We test the hypothesis that larval experience and anticipatory transgenerational effects influence female host plant acceptance (no‐choice) and preference (choice) of two host plant species (Barbarea vulgaris and Berteroa incana) of varying nitrogen content. We then test the offspring performance on these hosts. We found no evidence of larval imprinting affecting female decision‐making during oviposition, but that an adult female experience of egg laying in no‐choice trials on the less‐preferred host Be. incana slightly increased the P. rapae propensity to oviposit on Be. incana in subsequent choice trials. We found no transgenerational effects on female host acceptance or preference, but negative transgenerational effects on larval performance, because the offspring of P. rapae females that had developed on Be. incana as larvae grew slower on both hosts, and especially on Be. incana. Our results suggest that among host species, preferences are guided by hard‐wired preference hierarchies linked to species‐specific host traits and less affected by larval experience or transgenerational effects, which may be more important for females evaluating different host individuals of the same species.

Highlights

The evolution of diet breadth is pivotal for the organization of diversity, both through niche partitioning (Schoener 1974) and through ecologically driven diversification (Nosil, 2012)
The first major conclusion drawn from our results is that adult experience has a small effect on female host preference in P. rapae butterflies (Table 1), whereas there is no support for either larval experience (HHSP) or anticipatory transgenerational acclimation to affect the female propensity to oviposit on a certain host plant species (Figure 1)
Our results do not lend support to the hypothesis that larval experience (HHSP) coupled to transgenerational acclimation to host plant nitrogen levels impact female choice and preadapt larvae to different host plant species

Summary

| INTRODUCTION

The evolution of diet breadth is pivotal for the organization of diversity, both through niche partitioning (Schoener 1974) and through ecologically driven diversification (Nosil, 2012). A more controversial aspect of learning is the idea that a female's experience from the larval stage should influence her oviposition preference as an adult (Hopkins, 1917) This “Hopkins' Host Selection Principle” (HHSP) states that an ovipositing female should show a preference for the same type of plant that she consumed as a larva (Barron, 2001), since her successful development into adulthood is evidence for the suitability of that particular host under the local ecological circumstances. We test whether the P. rapae host utilization is influenced by larval experience and anticipatory transgenerational acclimation when females are choosing between host plant species that show natural differences in nitrogen content, as well as in other physiological traits, in a series of larval rearing and adult host plant preference experiments. Thereafter, we attempt to disentangle effects of adult learning, larval experience, and transgenerational acclimation on the host plant preference of P. rapae when choosing between host plant species of different nitrogen content. Plant nitrogen content was analyzed using a Carbon-Hydrogen-Nitrogen (CHN) analyzer (Costech ECS (Elemental Combustion System) 4,010)

| METHODS

Findings

| DISCUSSION