Contemporary evolution of host plant range expansion in an introduced herbivorous beetle Ophraella communa

Abstract

Host range expansion of herbivorous insects is a key event in ecological speciation and insect pest management. However, the mechanistic processes are relatively unknown because it is difficult to observe the ongoing host range expansion in natural population. In this study, we focused on the ongoing host range expansion in introduced populations of the ragweed leaf beetle, Ophraella communa, to estimate the evolutionary process of host plant range expansion of a herbivorous insect. In the native range of North America, O. communa does not utilize Ambrosia trifida, as a host plant, but this plant is extensively utilized in the beetle's introduced range. Larval performance and adult preference experiments demonstrated that native O. communa beetles show better survival on host plant individuals from introduced plant populations than those from native plant populations and they also oviposit on the introduced plant, but not on the native plant. Introduced O. communa beetles showed significantly higher performance on and preference for both introduced and native A. trifida plants, when compared with native O. communa. These results indicate the contemporary evolution of host plant range expansion of introduced O. communa and suggest that the evolutionary change of both the host plant and the herbivorous insect involved in the host range expansion.

Parallel environmental factors drive variation in insect density and plant resistance in the native and invaded ranges

“…For instance, the parsnip specialist webworm, Depressaria pastinacella, has evolved a higher furanocoumarin detoxification rate in the invaded range because of the absence of other host plants with lower furanocoumarin content (Berenbaum and Zangerl 2006). A ragweed specialist leaf beetle, Zygoramma suturalis, evolved an expanded host plant range in its invaded range because the ragweed, Ambrosia trifida, had reduced resistance in the invaded range (Fukano et al 2016). Because generalist and specialist herbivorous insects differ in their response to plant defenses (Ali and Agrawal 2012), the fact that the lace bug is a generalist herbivorous insect feeding on several other Asteraceae plants in Japan (Kato and Ohbayashi 2009, Y. Sakata personal observation) may be one of the reasons why lace bugs have not been adapted to the variation of resistance of S. altissima within and between ranges.…”

Invasions and extinctions through the looking glass of evolutionary ecology

“…For example, nonnative populations of the beetle Ophraella communa in Japan have evolved to use Ambrosia trifida as a host, even though this plant is not used by O. communa in its native range. This host shift is partly explained by relaxed herbivore defences in non-native populations of A. trifida, after having escaped natural enemies for approximately 50 generations [154]. However, the contribution of relaxed selection to niche expansion and the role of genetic constraints are still unresolved.…”

A solanum beetle on a fabaceous weed: Host plant generalization and specialization are two sides of the same coin

“…However, only several instances have been studied in detail so far (e.g. Carroll & Boyd ; Singer et al ; Filchak et al ; García‐Robledo & Horvitz ; Fukano et al ), and this rarity of empirical studies is an obstacle to our understanding of the evolutionary process of divergent host plant specificity. Documentation of the “ongoing” evolutionary change of host specificity, especially of that in the very initial phase, is usually difficult mainly due to the following two points: (i) when the novel insect‐host plant associations are found, it usually means that the association is rather conspicuous or even common in the wild, at such timing, some dynamic and important changes in the host specificity might have ceased and the insects have already more or less adapted to the novel host plants, and additionally, the host‐use pattern observed in the wild does not necessarily fully reflect the ability of insects to utilize the host plants (Fox & Morrow ); and (ii) the degree of adaptation to respective host plants is rarely easy to evaluate and can be examined only at a particular moment, except for the cases in which the evaluation through measurement of external morphological features is possible, such as, for example, beak length of the soapberry bug Jedera haematoloma (Herrich‐Schäffer) (Hemiptera: Rhopalidae) (Carroll & Boyd ).…”