PREDICTING HOST RANGE EVOLUTION: COLONIZATION OFCORONILLA VARIABYCOLIAS PHILODICE(LEPIDOPTERA: PIERIDAE)

Abstract

Extensive sympatry is currently arising between the common sulfur butterfly, Colias philodice Latreille (Lepidoptera: Pieridae) and a potential leguminous host plant, Coronilla varia (L.). In laboratory trials, larval surviviorship and growth were higher on the primary host, Medicago sativa (L.), than on the nonhost C. varia. However, because females reared from C. varia were on average more fecund than females reared from M. sativa, fitness on C. varia (approximately as survivorship times fecundity) was commensurate with fitness on M. sativa. Thus, it is predicted that selection would favor oviposition on C. varia, if such behavior were to arise. In addition, significant among-family variation exists for several measures of larval performance on both C. varia and M. sativa, indicating that C. philodice can potentially respond to selection for increased performance on each species. Moreover, larval performance was significantly positively correlated across these species, suggesting that selection for increased performance on each species will facilitate, not constrain, evolution of increased performance on the other. It is concluded that behavioral rather than physiological barriers currently account for the absence of C. philodice from C. varia and that, if such barriers are overcome, C. philodice will expand its host plant range to include C. varia.

Host range evolution is not driven by the optimization of larval performance: the case of Lycaeides melissa (Lepidoptera: Lycaenidae) and the colonization of alfalfa

“…The novel host was found to be a suitable and even superior larval resource, relative to the primary host. Karowe (1990) hypothesized that variation for oviposition preference could be favored in the Weld, leading to an expansion of host range which would correspond to our Novel Superiority model.…”

“…The populations diVered in that M. sativa-associated populations showed evidence of larval adaptation to the novel host. Karowe (1990), using the same butterXy, C. philodice, investigated barriers to the colonization of another novel host, Coronilla varia, which the butterXy encounters but is not known to utilize in the Weld. The novel host was found to be a suitable and even superior larval resource, relative to the primary host.…”

Escaping an evolutionary trap: preference and performance of a native insect on an exotic invasive host

“…First, if adults fail to recognize the novel plant as a potential host, there may be no direct impact on the native insect [e.g., Colias philodice on crown vetch (Coronilla varia), Karowe 1990; recognized as a potential host, the exotic plant may interfere with host finding by altering the apparency of the native plant or repelling the insect (reviewed by Hämback and Beckerman 2003).…”

Variation in hostplant preference and performance by the milfoil weevil, Euhrychiopsis lecontei Dietz, exposed to native and exotic watermilfoils

“…The simultaneous decreasing availability of the ancestral host and increasing availability of the exotic host may result in an increased preference for the exotic plant species (Bowers et al 1992). Therefore, the effects of exotic plant invasions may provide scientific opportunity (e.g., Potvin and Tousignant 1996) to study host range expansions by herbivorous insects as they occur, rather than post facto as is usually practiced (Karowe 1990). This approach may offer insight on host range expansion or host shifts by herbivorous insects exposed to novel hostplants, and may also provide information on how insects may be better used to control invasive plants.…”