Host‐plant associated genetic divergence of two <i>Diatraea</i> spp. (Lepidoptera: Crambidae) stemborers on novel crop plants

Abstract

<i>Diatraea lineolata</i> and <i>Diatraea saccharalis</i> (Lepidoptera: Crambidae) are moths with stemboring larvae that feed and develop on economically important grasses. This study investigated whether these moths have diverged from a native host plant, corn, onto introduced crop plants including sorghum, sugarcane, and rice. <i>Diatraea</i> larvae were collected from these four host plants throughout the year in El Salvador and were reared on artificial diet until moths or parasitoids emerged. Adult moths were subsequently identified to species. Amplified fragment length polymorphisms (AFLPs) and mitochondrial DNA cytochrome oxidase I (COI) were used to examine whether or not there was genetic divergence of <i>D. lineolata</i> or <i>D. saccharalis</i> populations on the four host plants. Percent parasitism was also determined for each moth on its host plants. <i>D. lineolata</i> was collected from corn in the rainy season and sorghum in the dry season. <i>D. saccharalis</i> was most abundant on sugarcane in the rainy season and sorghum in the dry season. The AFLP analysis found two genetically divergent populations of both <i>D. lineolata</i> and <i>D. saccharalis</i>. Both moths had high levels of parasitism on their dominant host plant in the rainy season, yet had low levels of parasitism on sorghum in the dry season. The presence of two genotypes of both <i>Diatraea</i> spp. on sorghum suggest that host-associated differentiation is occurring on this novel introduced crop plant.