Mitochondrial DNA analysis of field populations of Helicoverpa armigera (Lepidoptera: Noctuidae) and of its relationship to H. zea

Abstract

Background: Helicoverpa armigera and H. zea are amongst the most significant polyphagous pest lepidopteran species in the Old and New Worlds respectively. Separation of H. armigera and H. zea is difficult and is usually only achieved through morphological differences in the genitalia. They are capable of interbreeding to produce fertile offspring. The single species status of H. armigera has been doubted, due to its wide distribution and plant host range across the Old World. This study explores the global genetic diversity of H. armigera and its evolutionary relationship to H zea.

High nucleotide diversity and limited linkage disequilibrium in Helicoverpa armigera facilitates the detection of a selective sweep

“…The Australian H. armigera data set consisted of 16 females from Dalmore, Victoria (38º11′S, 145º25′E) and 10 females from Orbost, Victoria (37º42′S, 148º27′E), both of which come from samples from the work by Behere et al (2007) and a new collection of 112 females from MacIntyre Valley, Queensland (28º32′S, 150º18′E). The three collection sites are all temperate agricultural regions.…”

“…We initially characterized five loci for which Z-linkage was determined by pedigree analyses (Apt, Cyp303a1, Period, Phc and Tpi) in two Victorian population samples described by Behere et al (2007 Table S3), which suggested that LD analyses could be conducted on alleles pooled from all three populations (see below). Levels of nucleotide diversity across all loci and the three Australian collection sites were high (694 single-nucleotide polymorphisms in o6 kb of sequence) and did not differ substantially between collection sites for any locus (Table 1).…”

“…A total of 199 H. armigera (26 Australian and 173 non-Australian), 5 H. assulta and 20 H. punctigera DNA samples were obtained from G Behere; data on the collection of these samples is outlined in Behere et al (2007). The Australian H. armigera data set consisted of 16 females from Dalmore, Victoria (38º11′S, 145º25′E) and 10 females from Orbost, Victoria (37º42′S, 148º27′E), both of which come from samples from the work by Behere et al (2007) and a new collection of 112 females from MacIntyre Valley, Queensland (28º32′S, 150º18′E).…”

“…H. armigera and its New World counterpart, H. zea were once thought to constitute one cosmopolitan species but Hardwick (1965) placed them into separate species groups when he distinguished five species groups on the basis of penis structure: armigera, gelotopoeon, hawaiiensis, punctigera, and zea. Subsequent data from immunological assays and mitochondrial DNA sequence analyses suggested that H. zea is more closely related to H. armigera than some other species within the zea group such as H. assulta (Mitter et al, 1993;Behere et al, 2007). Hybridization between H. armigera and H. assulta and between H. armigera and H. zea is possible in the laboratory (Laster and Hardee, 1995;Wang and Dong, 2001).…”

“…An allozyme study of 12 H. armigera populations dispersed throughout Australia suggested limited population structure (FST = 0.01; Daly and Gregg, 1985). Similarly, analysis of mitochondrial sequences reveals minimal differentiation among global samples with most of the variation distributed throughout the species range (Behere et al, 2007). A survey of eight microsatellite loci revealed that FST among Australian populations was 0.003 after the high frequency of null alleles (410%) was taken into account (Endersby et al, 2007).…”