Host plant or geographic barrier? Reproductive compatibility among Diatraea saccharalis populations from different host plant species and locations in Argentina

Abstract

The sugarcane borer, Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae), is one of the main lepidopteran pests of sugarcane and maize. The association of insects with different environments and/or host plants may occur by adaptation and this can generate host races. Adaptation may produce phenotypic or genotypic variation, which results in the differences in bioecological characteristics such as reproductive compatibility that reduces gene flow among populations. The objective of this study was to determine the reproductive compatibility of three population combinations collected in various geographic locations and from different host plants, thereby determining the influence of geographic distance and/or insect plant association. Interpopulation crosses of D. saccharalis populations from Tucumán (maize and sugarcane) and Jujuy (sugarcane) provided evidence of pre‐zygotic and post‐zygotic incompatibility. The results indicate that gene flow barriers are influenced by the host plant. However, populations from various locations revealed that geographical location is the main factor influencing gene flow among populations of D. saccharalis.

Unraveling the population structure of the sugarcane borer,Diatraea saccharalis, in Argentina

“…In a study of the plant pathogenic fungus Calonectria morganii Crous et al, the genetic diversity among progeny was remarkable when compared to the field isolates, which were much less variable, revealing that sexual reproduction has hardly occurred in the isolated strains (Overmeyer et al, 1996). In the present study, more different haplotypes were detected in field‐collected samples, and those found in the offspring did not add relevant information related to the low fitness previously found (Fogliata et al, 2019).…”

“…DNA was extracted from a total of 288 insects -175 from field collections and 113 from offspring obtained from the cross experiments made by Fogliata et al (2016Fogliata et al ( , 2019 -among individuals of different regions and host plants. Analyses were performed on 102 sequences (35 of insects from five pure populations and 67 from offspring) selected from a total of 288 sequences, considering their length and the quality of the nucleotides.…”

“…In addition, individuals obtained from previous crosses (Fogliata et al, 2016(Fogliata et al, , 2019 among individuals of different regions and host plants, were included for DNA extraction and analysis. The experiment was performed to determine pre-and post-zygotic compatibility between populations, according to the methodologies described by Murúa et al (2008) and Fogliata et al (2016).…”

“…Its genetic divergence occurs throughout its wide distribution. Most of the studies to characterize sugarcane borer populations used molecular tools (Lange et al, 2004;Cadena Goyes, 2008;Cortés et al, 2010;Joyce et al, 2014;Pavinato, 2014;Silva-Brandão et al, 2015), which are supported by morphological, physiological, and behavioral differences between populations (Box, 1951(Box, , 1956Pashley et al, 1990;Fogliata et al, 2016Fogliata et al, , 2019. In a previous study, Fogliata et al (2016) determined the existence of reproductive incompatibilities, both pre-and post-zygotic, as well as a low fitness in the offspring obtained in crosses between Buenos Aires and Tucumán populations from different host plants (sugarcane and corn); however, the genetic base of this incompatibility is still unknown.…”

Fundamental and specialized questions on host race formation and speciation – an introduction

“…Entomologia Experimentalis et Applicata has a long history in publishing studies on host race formation and speciation. The number of articles on this topic exceeds 300 over the period 1968-2021 including seminal reviews by Feder & Filchak (1999) and Matsubayashi et al (2010) as well as several case studies in the last few years (e.g., Saint Jean et al, 2018;Tadeo et al, 2018;Fogliata et al, 2019;Hensen et al, 2020). It becomes clear from these publications that many questions remain concerning host race formation.…”