bric a brac controls sex pheromone choice by male European corn borer moths

The sex pheromone system of similar to 160,000 moth species acts as a powerful form of assortative mating whereby females attract conspecific males with a species-specific blend of volatile compounds. Understanding how female pheromone production and male preference coevolve to produce this diversity requires knowledge of the genes underlying change in both traits. In the European corn borer moth, pheromone blend variation is controlled by two alleles of an autosomal fatty-acyl reductase gene expressed in the female pheromone gland (pgFAR). Here we show that asymmetric male preference is controlled by cis-acting variation in a sex-linked transcription factor expressed in the developing male antenna, bric a brac (bab). A genome-wide association study of preference using pheromone-trapped males implicates variation in the 293kb bab intron 1, rather than the coding sequence. Linkage disequilibrium between bab intron 1 and pgFAR further validates bab as the preference locus, and demonstrates that the two genes interact to contribute to assortative mating. Thus, lack of physical linkage is not a constraint for coevolutionary divergence of female pheromone production and male behavioral response genes, in contrast to what is often predicted by evolutionary theory

Geographic Variation in Sexual Attraction of Spodoptera frugiperda Corn- and Rice-Strain Males to Pheromone Lures

The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina). In dose-response experiments with the critical secondary sex pheromone component (Z)-7-dodecenyl acetate (Z7-12:OAc), we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z)-11-hexadecenyl acetate (Z11-16:OAc) did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E)-7-dodecenyl acetate, to the major pheromone component (Z)-9-tetradecenyl acetate (Z9-14:OAc), we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause geographic differentiation between populations.Fil: Unbehend, Melanie. Instituto Max Planck Institut Fur Chemische Okologie; AlemaniaFil: Hänniger, Sabine. Instituto Max Planck Institut Fur Chemische Okologie; AlemaniaFil: Vasquez, Gissella M.. University Of North Carolina; Estados UnidosFil: Juárez, María Laura. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Reisig, Dominic. University Of North Carolina; Estados UnidosFil: Mcneil, Jeremy N.. University of Western Ontario. Department of Biology; CanadáFil: Meagher, Robert L.. United States Department Of Agriculture; Estados UnidosFil: Jenkins, David A.. United States Department of Agriculture; ArgentinaFil: Heckel, David G.. Instituto Max Planck Institut Fur Chemische Okologie; AlemaniaFil: Groot, Astrid T.. University Of Amsterdam; Países Bajos. Instituto Max Planck Institut Fur Chemische Okologie; Alemani

bric à brac controls sex pheromone choice by male European corn borer moths

International audienceThe sex pheromone system of ~160,000 moth species acts as a powerful form of assortative mating whereby females attract conspecific males with a species-specific blend of volatile compounds. Understanding how female pheromone production and male preference coevolve to produce this diversity requires knowledge of the genes underlying change in both traits. In the European corn borer moth, pheromone blend variation is controlled by two alleles of an autosomal fatty-acyl reductase gene expressed in the female pheromone gland (pgFAR). Here we show that asymmetric male preference is controlled by cis-acting variation in a sex-linked transcription factor expressed in the developing male antenna, bric à brac (bab). A genome-wide association study of preference using pheromone-trapped males implicates variation in the 293 kb bab intron 1, rather than the coding sequence. Linkage disequilibrium between bab intron 1 and pgFAR further validates bab as the preference locus, and demonstrates that the two genes interact to contribute to assortative mating. Thus, lack of physical linkage is not a constraint for coevolutionary divergence of female pheromone production and male behavioral response genes, in contrast to what is often predicted by evolutionary theory

Additional file 7: of Genetic basis of allochronic differentiation in the fall armyworm

Details of BLAST hits of Sf BC contigs to scaffolds of Sf genome and of BLAST hits of Sf genome scaffolds to Bm genome. (PDF 57 kb

Additional file 5: of Genetic basis of allochronic differentiation in the fall armyworm

Coverage of RAD sequences. (PDF 224 kb

Composition of pheromone lures used to attract <i>Spodoptera frugiperda</i> males in the field.

1<p>Compound concentrations were as follows: 100% = 300 µg, 18% = 54 µg, 13% = 39 µg, 10% = 30 µg, 8% = 24 µg, 4% = 12 µg, 2% = 6 µg, 1% = 3 µg.</p>2<p>Blend 1 and Blend 2 were based on the pheromone gland composition of Florida corn- and rice-strain females, respectively <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089255#pone.0089255-Unbehend1" target="_blank">[52]</a>.</p

Attraction of corn-strain (A) and rice-strain (B) males to different doses of Z11-16:OAc.

<p>Bars represent the mean percentage of males caught per trap (0%, 8%, 13%, or 18% Z11-16:OAc +100% Z9-14:OAc +2% Z7-12:OAc) and per biological replicate (n = 3). Error bars show the variation between biological replicates (n = 3). Numbers in the bars represent the total number of males caught. n.s. = not significant. Data from Florida are adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089255#pone.0089255-Unbehend1" target="_blank">[52]</a>.</p

Test statistics on the <i>Spodoptera frugiperda</i> male trap catches of different experiments.

<p>Experiments A (Test of two 4-component blends: Blend 1 and Blend 2) and B (Z7-12:OAc dose-response experiment) were analyzed individually using square root transformed data in a MANOVA and a Wilks’ Lambda test. Bold P-values show a significant effect of geographic region, strain-identity of males, and/or the field crop, influencing the attraction of fall armyworm males to synthetic pheromone blends. Mean values and standard errors are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089255#pone-0089255-g001" target="_blank">Figure 1</a> (Exp. A) and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089255#pone-0089255-g002" target="_blank">Figure 2</a> (Exp. B).</p

<i>Spodoptera frugiperda</i> male trapping experiments conducted in North America, the Caribbean and South America.

1<p>Experiments: A) Test of two 4-component blends (Blend 1 and Blend 2), B) Z7-12:OAc dose-response, C) Z11-16:OAc dose-response, D) Importance of E7-12:OAc.</p>2<p>Data adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089255#pone.0089255-Unbehend1" target="_blank">[52]</a>.</p

Attraction of corn-strain (A) and rice-strain (B) males to different doses of Z7-12:OAc.

<p>Bars represent the mean percentage of males caught per trap (0%, 2%, 4%, or 10% Z7-12:OAc +100% Z9-14:OAc) and per biological replicate (n = 3). Different letters above the bars indicate significant differences. Error bars show the variation between biological replicates (n = 3). Numbers in brackets/bars represent the total number of males caught. Data from Florida are adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089255#pone.0089255-Unbehend1" target="_blank">[52]</a>.</p