Sex‐linked control of sex pheromone behavioral responses in European corn‐borer moths (Ostrinia nubilalis) confirmed with TPI marker gene

Abstract

AbstractIn two races of European corn‐borer moths (ECB), the E‐race females emit and males respond to 99:1 sex pheromone blend of (E)/(Z)‐11‐tetradecenyl acetates, whereas the Z‐race females and males produce and respond to the opposite 3:97 pheromone blend of (E)/(Z)‐11‐tetradecenyl acetates, respectively. We previously have shown that female production of the final blend ratio is under control of a major autosomal locus but that the sequence of male upwind flight responses to the blend is controlled by a sex‐linked (Z‐linked) locus. This sex‐linked control of behavioral responses in crosses of E and Z ECB now is confirmed by use of sex‐linked TPI (triose phosphate isomerase) allozyme phenotypes to determine the origin of the sex chromosomes in F2 populations.F1 males from reciprocal E × Z crosses generate similar behavioral‐response profiles in wind‐tunnel studies, with moderate numbers responding to the Z pheromone and intermediate blends (35%–65% Z), but very few responding to the E pheromone. The F2 behavioral‐response profiles indicate that they are composed of 1:1 mixtures of hybrids and paternal profiles. Analysis of TPI allozyme differences allowed us to separate male F2 populations into individuals whose Z chromosomes both originated from their grandfathers, and individuals who had one Z chromosome originating from each grandparent. With these partitioned F2s, the TPI homozygotes exhibited behavioral‐response profiles very much like their grandfathers, whereas the TPI hybrids produced response profiles similar to their heterozygous F1 fathers. These results demonstrate incontrovertibly that the response to sex pheromone in male ECB is controlled by a sex‐linked gene that is tightly linked to the TPI locus and therefore is independent of the locus controlling pheromone blend production in females.