Screening some Common Molecular Markers and a Desaturase Marker, Linked to Sex Pheromone Biosynthesis, in Three Z-Strain and an E-Strain Populations of the European Corn Borer, Ostrinia nubilalis, Occurring in Central Europe

Abstract

The European corn borer moth, (ECB), Ostrinia nubilalis (Lepidoptera: Crambidae, Pyraustinae) is one of the most destructive pests of maize worldwide. ECB has two pheromone-strains, separated by specific ratios of isomers of E- and Z11-tetradecenyl acetates (E11- and Z11-14Ac), but appearing morphologically identical. Accordingly, E- and Z-ECB pheromone traps are available for the respective populations for practical monitoring of the flight, however, traps for Z-strain are unreliable for practical usage in some parts of Central-Europe. E- and Z-ECB populations occur in sympatry in some areas, while in allelopatry in other areas. Determining the strains before the flight of adults, when difference in the composition of their respective pheromones is manifested, would be of practical interest for early warning. In addition to the known fatty-acyl-reductase (FAR) marker, further markers would allow more comprehensive studies. We screened the following common markers for mitochondrial and nuclear DNA regions: partial cytochrome c oxidase I (COI), cytochrome B (CytB), the second spacer of the internal transcribed spacer (ITS2), Elongation factor 1a (EF1a) and actin gene (Act). In addition, a marker of the Δ11-desaturase gene (11desat), linked to biosynthesis of female-produced sex pheromone, was also included, because we reported earlier a differential expression for this site. Three Z-ECB populations locating at distant sites within Hungary, an area where only Z-strain occurs, and an E-ECB population in Slovenia, known as the closest-occurring E-strain, were included into the study. Separate laboratory colonies were established from each population, and F1 generations were sampled to verify the identity of pheromone strains, by analysing the composition of sex pheromone by gas chromatography linked to an electroantennographic detector (GC-EAD). Molecular studies were conducted using specimens taken from the F2 generations. Results of genetic studies showed that there were no differences between the Z and E populations for the common markers. In contrast to this, several nucleic acid changes (11 nt in 4 positions) were found between the three Z-populations (Hungary) and the E-population (Slovenia) in the desaturase marker. Further study is required to reveal whether the differences found in this study are consistent across E-populations, thus making these markers suitable for diagnostic purposes.

Occurrence of Z‐ and E‐strain Ostrinia nubilalis in Sweden shortly after first detection of the Z‐strain

“…(2010) and Király and Szőcs (2009) based on allelic variations in a fatty‐acyl reductase and delta 11 desaturase, respectively, or that of Bozsik et al. (2019) based on sequence variation of common nuclear and mitochondrial markers, the RFLP method of Coates et al. (2013) offers the advantages of high reliability and ease of application.…”

“…The patterns produced by these fragments on a 3% agarose gel allowed identifying the strain of each ECB individual. Although other molecular methods have been successfuly tested for identifying ECB strains, such as those of Lassance et al (2010) and Király and Szőcs (2009) based on allelic variations in a fatty-acyl reductase and delta 11 desaturase, respectively, or that of Bozsik et al (2019) based on sequence variation of common nuclear and mitochondrial markers, the RFLP method of Coates et al (2013) offers the advantages of high reliability and ease of application.…”

Evolution of the Sex Pheromone Communication System in Ostrinia Moths

“…In addition, both species exhibit intraspecific polymorphism in the relative proportion of the components; E11 is the major component in the E-strain while Z11 is dominant in the Z-strain [17][18][19] (Figure 2a). The E and Z strains, sometimes also referred to as races, are indistinguishable based on the morphology or the common barcoding genes such as cytochrome c oxidase I (COI) and cytochrome B (CytB); they are however distinguishable by the pheromone biosynthesis genes (fatty-acyl reductase and ∆11-desaturase genes) [20]. They may have the same or different host plant preference [21][22][23].…”

Alternative evolutionary strategies and tactics used by polyphagous insect to inhabit agricultural environment: Ostrinia nubialis as a case

“…Absolutely the same data on differentiation of mugwort (E-race) and corn (Z-race) populations, except for morphological differences, were obtained in northern France (Calcagno et al, 2010). The recent studies on the host plant specialization and molecular aspects of pheromone biosynthesis of the E-and Z-races of the ECB (Leppik and Frérot, 2012;Bozsik et al, 2019) provide new directions hopefully producing important results. The materials obtained in Germany (Lorenz, 1993) also give us the reason to believe that the situation here is very similar to that observed in the north of France.…”