Parallel evolution of behaviour during independent host‐shifts following maize introduction into Asia and Europe

Abstract

Maize was introduced into opposite sides of Eurasia 500 years ago, in Western Europe and in Asia. This caused two host‐shifts in the phytophagous genus Ostrinia; O. nubilalis (the European corn borer; ECB) and O. furnacalis (the Asian corn borer; ACB) are now major pests of maize worldwide. They originated independently from Dicot‐feeding ancestors, similar to O. scapulalis (the Adzuki bean borer; ABB). Unlike other host‐plants, maize is yearly harvested, and harvesting practices impose severe mortality on larvae found above the cut‐off line. Positive geotaxis in the ECB has been proposed as a behavioural adaptation to harvesting practices, allowing larvae to move below the cut‐off line and thus escape harvest mortality. Here, we test whether the same behavioural adaptation evolved independently in Europe and in Asia. We sampled eight genetically differentiated ECB, ACB and ABB populations in France and China and monitored geotaxis through the entire larval development in artificial stacks mimicking maize stems. We find that all ECB and ACB populations show a similar tendency to move down during the latest larval stages, a behaviour not observed in any European or Asian ABB population. The behaviour is robustly expressed regardless of larval density, development mode or environmental conditions. Our results indicate that maize introduction triggered parallel behavioural adaptations in Europe and Asia, harvest selection presumably being the main driver.

Partial reuse of circadian clock genes along parallel clines of diapause in two moth species

“…The formation of the clines on the continents had been rapid. ACB and ECB made the host shift to maize independently around 500 years ago (Alexandre et al, 2013; Calcagno et al, 2017).…”

“…The formation of the clines on the continents had been rapid. ACB and ECB made the host shift to maize independently around 500 years ago (Alexandre et al, 2013;Calcagno et al, 2017). The ECB cline in North America formed within 100 years since its introduction around 1920 (Showers et al, 1975;Sparks & Young, 1971).…”

Revisiting the evolution of Ostrinia moths with phylogenomics (Pyraloidea: Crambidae: Pyraustinae)

“…However, a few species, such as the two major polyphagous pests (European corn borer and Asian corn borer) shifted their primary host plants to monocots (e.g., Poaceae; Figs S2, S3). This result implies that these two morphologically indistinguishable species likely diverged recently in complete allopatry and shifted their host preference to maize, supporting the hypothesis that this may have occurred when its cultivation spread 500 years ago in Europe and East Asia (Gay, 1999; Coates et al ., 2005; Malausa et al ., 2007; Calcagno et al ., 2017). According to Léger et al .…”

De novo genome and transcriptome resources of the Adzuki bean borer Ostrinia scapulalis (Lepidoptera: Crambidae)

“…In Europe, it partly co-occurs with its sibling species, the European corn borer, Ostrinia nubilalis , which is a major pest of maize ( Zea mays ). Previous studies demonstrated that O. scapulalis and O. nubilalis are specialized to their respective host plants [2] , [3] , [4] , [5] , [6] , [7] and that their genetic divergence is rather low so that they can be considered as sibling species [8] . Yet, a few genomic sequences and rearrangements are much more divergent than the rest of the genomic background [1] , [9] , [10] , [11] .…”