Experience may outweigh cue similarity in maintaining a persistent host‐plant‐based evolutionary trap

Abstract

Rapid environmental change can decouple previously reliable cues from important resources, causing specialized recognition systems to result in maladaptive behaviors. For native herbivorous insects, such evolutionary traps are often imposed by attractive invasive plants that prove harmful to their offspring. Despite the costs of ovipositing on a poor-quality host, evolutionary traps are expected to persist when overlapping cue sets (cue similarity) link decreased preference for the novel, unsuitable plant with decreased preference for the historical or native resource. We evaluated the role of cue similarity in the persistence of maladaptive oviposition by a native butterfly on a lethal, invasive mustard. While the novel plant shares glucosinolate cues with at least one of the native hosts and the most abundant cue is a strong oviposition stimulant, we found that this cue was not a major driver of preference for either plant. Nor was preference for the two plants correlated, meaning decreased preference for the invasive mustard would not cause butterflies to miss potential oviposition opportunities on the superior native host. Instead, butterfly preference was modified by previous experience in a way that suggests that frequent encounters with native hosts in the wild may buffer butterflies against this evolutionary trap.

Host repertoires and changing insect–plant interactions

“…This stands in contrast to other examples where host preference was remarkably inert and virtually unaffected by the local variation in host availability (e.g. Wehling & Thompson, 1997; Bergstrom et al ., 2004; Chandra & Hodge, 2021), sometimes even at a considerable cost, as in the case of the persistent acceptance for the oviposition of the introduced plant Thlaspi arvense , which is lethal to the larvae, by the butterfly Pieris macdunnoughii (Chew, 1977; Steward & Boggs, 2020). Most likely such differences in tempo of host repertoire evolution are caused by differences in the genetic architecture of the traits involved, something that we are only beginning to unravel.…”

Impacts of invasive plants on animal behaviour

“…2013). However, while several studies claim to have revealed an evolutionary trap (Table ), relatively few provide evidence of preference for the lower‐fitness outcome over higher‐fitness alternatives (Keeler & Chew 2008; Rodewald et al 2011; Augustine & Kingsolver 2018; Steward & Boggs 2020; Sun et al . 2020), which is a prerequisite for an evolutionary trap (Robertson et al .…”

“…2019b). For example, constraints imposed by behavioural plasticity on the evolution of host preferences may explain why native Pieris macdunnoughii butterflies continue to oviposit on invasive Thlaspi arvense , even though no larvae laid on T. arvense survive to adulthood (Steward & Boggs 2020).…”

Preference Provides a Plethora of Problems (Don't Panic)

“…Therefore, unless there is evidence that eggs laid at different times are independent events (e.g., 54), analyses should not assume independence. Modern analytical methods can tackle these difficulties (23,72).…”