Population Genetics of the Western Bean Cutworm (Lepidoptera: Noctuidae) Across the United States

Abstract

The western bean cutworm, Striacosta albicosta (Smith), is a secondary pest of maize (Zea mays L.) and dry beans (Phaseolus vulgaris L.) in the western United States. Recently, this insect has undergone a major territory expansion into the eastern United States and has become a pest throughout much of the Corn Belt. This study was instigated to examine the population genetics of this pest to facilitate control and resistance management, as well as to shed light on the current habitat expansion. S. albicosta individuals were collected from 24 different locations across the traditional and expanded range and amplified fragment length polymorphism analysis was conducted to assess genetic variability. In total, 90 markers were analyzed, encompassing >90% of genetic variation. Gst across all locations was moderately high (Gst = 0.5032). AMOVA analysis revealed that the majority of genetic variation was within locations (54%) and among locations within groups (45%) indicating genetic differentiation of subpopulations. The Mantel test revealed no correlation between geographic and genetic distance (n = 548; r = 0.0045; P = 0.4350). Locations sampled in the eastern United States did not exhibit any reduction in genetic variation in comparison to locations sampled in the western United States, so we conclude that no bottleneck event has occurred with this territory expansion.

What type of Bt corn is suitable for a region with diverse lepidopteran pests: A laboratory evaluation

“…45 However, in the meantime a secondary pest S. albicosta has increased and become a major lepidopteran pest in some areas of the Corn Belt in the US and Canada due to low susceptibility of this species to most transgenic maize expressing Cry1Ab. 13,[46][47][48] In Europe, Bt corn expressing Cry1Ab toxin exhibits high efficacy against two primary lepidopteran borers, S. nonagrioides and O. nubilalis, 10,49 but low efficacy against several secondary pests, such as S. albicosta and M. unipuncta, 50,51 and similarly the latter two species are becoming more common in some European countries. 52 To overcome this phenomenon, stacked Bt corn hybrids targeting multiple species expressing combinations of Cry1Ab, Cry1F, Cry1A.105, Cry2Ab and/or Vip3A became available more recently.…”

Genetic variability of the stable fly assessed on a global scale using amplified fragment length polymorphism

“…AFLP‐PCR was performed using a protocol commonly used in our laboratory (Lindroth et al ., ; Kneeland et al ., , ), modified from Vos et al . (), and included: (i) restriction of the DNA with Mse I and Eco RI restriction enzymes; (ii) adapter ligation with Mse I and Eco RI adapters; (iii) preamplification; and (iv) selective amplification with 4 combinations of Mse I and Eco RI primers (Table ).…”

Amplified Fragment Length Polymorphism Used to Investigate Genetic Variability of the Stable Fly (Diptera: Muscidae) Across North America

“…A few grains of sea sand (Fisher, Pittsburg, PA) were added to facilitate homogenization. DNA extraction then proceeded following a protocol common to our laboratory, described in previous publications (Krumm et al 2008, Tiroesele 2011, Lindroth et al 2012.…”

“…For example, AFLP markers have been used to study the genetic structure of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Martinelli et al 2007), in Brazil and the European corn borer, Ostrinia nubilalis (Hubner), in the midwestern United States (Krumm et al 2008). Recently, Lindroth et al (2012) studied the genetic variation of western bean cutworm, Striacosta albicosta (Smith), across the United States, and Kneeland et al (2012a) evaluated the genetic variation among laboratory populations and Þeld populations of the spined soldier bug, Podisus maculiventris (Say), in Missouri.…”