Multiple origins of outbreak populations of a native insect pest in an agro-ecosystem

Abstract

Native insects can become epidemic pests in agro-ecosystems. A population genetics approach was applied to analyze the emergence and spread of outbreak populations of native insect species. Outbreaks of the mirid bug, Stenotus rubrovittatus, have rapidly expanded over Japan within the last two decades. To characterize the outbreak dynamics of this species, the genetic structure of local populations was assessed using polymorphisms of the mtDNA COI gene and six microsatellite loci. Results of the population genetic analysis suggested that S. rubrovittatus populations throughout Japan were genetically isolated by geographic distance and separated into three genetic clusters occupying spatially segregated regions. Phylogeographic analysis indicated that the genetic structure of S. rubrovittatus reflected post-glacial colonization. Early outbreaks of S. rubrovittatus in the 1980s occurred independently of genetically isolated populations. The genetic structure of the populations did not fit the pattern of an outbreak expansion, and therefore the data did not support the hypothesis that extensive outbreaks were caused by the dispersal of specific pestiferous populations. Rather, the historical genetic structure prior to the outbreaks was maintained throughout the increase in abundance of the mirid bug. Our study indicated that changes in the agro-environment induced multiple outbreaks of native pest populations. This implies that, given suitable environmental conditions, local populations may have the potential to outbreak even without invasion of populations from other environmentally degraded areas.

Genetic isolation of the sorghum plant bug Stenotus rubrovittatus (Hemiptera: Miridae) in Fukushima and Ibaraki prefectures

“…The boundary location was consistent with our previous report of a large-scale survey, in which populations of S. rubrovittatus along the pacific coast were divided into groups around Fukushima and Ibaraki prefectures (Kobayashi et al 2011). However, our current study with fine-scale sampling identified the location and direction of the border in more detail.…”

“…AB518887-AB518925), and all of the haplotypes were divided into two remote lineages (A or B) whose DNA sequences had diverged by 1.7% from each other (Kobayashi et al 2011). The distributions of these two mtDNA lineages were different on a countrywide scale, such that lineage A was distributed only in northern Japan whereas lineage B was ubiquitous throughout Japan (Kobayashi et al 2011). In this study, only the lineage of mtDNA was determined for each individual, instead of sequencing the COI gene.…”

“…2). The two mitochondrial lineages in S. rubrovittatus (A and B) with large nucleotide differentiation were thought to be caused by segmentation of the refuges during the Pleistocene glaciation (Kobayashi et al 2011). The mixture of two lineages in the northern populations indicates that populations from two different refuges were mixed postglacially in the northern area whereas the southern population was from a single refuge.…”

“…Damage by S. rubrovittatus has rapidly increased since around 2000 and the bug is now widespread over most agricultural areas in Japan (Watanabe and Higuchi 2006;Higuchi 2010). The genetic structure of Japanese S. rubrovittatus consists of three genetic clusters that have distinct geographic distributions: Northern Tohoku, Kanto, and other areas (Kobayashi et al 2011). This population structure suggests the existence of effective barriers to gene T. Kobayashi National Agricultural Research Center for Tohoku Region (NARCT), Yotsuya, Daisen, Akita 014-0102, Japan flow among geographical populations.…”

Genetic Diversity of Brazilian Aedes aegypti: Patterns following an Eradication Program

“…Other loci had null allele frequencies predicted as well (in four populations for AG2, three populations for AC1, two populations for B3 and one population for AC4, AG1 and AC2), although none with frequencies >0.14 (Table S2). Null alleles at microsatellite loci are commonly found in insects [50]–[52] and have been demonstrated to be especially common in species with large population sizes [35], which is likely the case for Ae. aegypti populations.…”