Origin of Pest Lineages of the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

Abstract

Colorado potato beetle (Leptinotarsa decemlineata Say [Coleoptera: Chrysomelidae]) is a pest of potato throughout the Northern Hemisphere, but little is known about the beetle's origins as a pest. We sampled the beetle from uncultivated Solanum host plants in Mexico, and from pest and non-pest populations in the United States and used mitochondrial DNA and nuclear loci to examine three hypotheses on the origin of the pest lineages: 1) the pest beetles originated from Mexican populations, 2) they descended from hybridization between previously divergent populations, or 3) they descended from populations that are native to the Plains states in the United States. Mitochondrial haplotypes of non-pest populations from Mexico and Arizona differed substantially from beetles collected from the southern plains and potato fields in the United States, indicating that beetles from Mexico and Arizona did not contribute to founding the pest lineages. Similar results were observed for AFLP and microsatellite data . In contrast, non-pest populations from the states of Colorado, Kansas, Nebraska, New Mexico, and Texas were genetically similar to U.S. pest populations, indicating that they contributed to the founding of the pest lineages. Most of the pest populations do not show a significant reduction in genetic diversity compared to the plains populations in the United States. We conclude that genetically heterogeneous beetle populations expanded onto potato from native Solanum hosts. This mode of host range expansion may have contributed to the abundant genetic diversity of contemporary populations, perhaps contributing to the rapid evolution of climate tolerance, host range, and insecticide resistance.

Effects of contemporary agricultural land cover on Colorado potato beetle genetic differentiation in the Columbia Basin and Central Sands

“…We focused our sampling on a 12,855 km 2 area in the Columbia Basin, and an 8,736 km 2 area in the Central Sands, collecting CPB from com- sequenced a 544 base-pair fragment of the mitochondrial genome (COI-COII), using the method described in Crossley et al (2017), from 133 beetles in Oregon, and 50 beetles in Washington (and from several other sites in the USA; Tables S1 and S2), and combined these data with existing datasets (Crossley et al, 2017;Grapputo et al, 2005;Izzo, Chen, & Schoville, 2018). Mitochondrial DNA sequence data are available on GenBank (accession no.…”

Silencing chitin deacetylase 2 impairs larval–pupal and pupal–adult molts in Leptinotarsa decemlineata

“…The Colorado potato beetle Leptinotarsa decemlineata (Say) is a notorious defoliator of potato. The beetles often cause serious yield loss to potato production in most major potato-growing areas of the world (Izzo et al, 2018). An overreliance upon chemical control has led to development of resistance of the beetle to over 50 different insecticides of all major classes (Alyokhin et al, 2008).…”

Elevated rates of positive selection drive the evolution of pestiferousness in the Colorado potato beetle (Leptinotarsa decemlineata, Say)

“…One non-pest individual was collected in Kansas on its natal host plant, Buffalo bur, Solanum rostratum Dunal, with no prior exposure to insecticides, and an additional pest specimen was collected in Wisconsin from a beetle population in a conventional potato field known to be resistant to neonicotinoids. Furthermore, beetle populations on Buffalo bur are considered ancestral to the potato-feeding pest populations (Izzo et al 2018). For each individual, genomic DNA was isolated using DNEasy Blood & Tissue Kits (Qiagen, Hilden, Germany), according to the manufacturer’s protocols.…”

“…The consequences of these boom and bust periods on the pest population heterozygosity may or may not be evident (Crossley et al 2017), but standing genetic variation in non-pest individuals should be similar to close relatives. Thus, we examined different CPB individuals (pest and non-pest) to ensure levels of polymorphism in this species are not biased by the invasion history (Izzo et al 2018) or numerous episodes of selection from pesticide exposure.…”