Demographics and Genetic Variability of the New World Bollworm (Helicoverpa zea) and the Old World Bollworm (Helicoverpa armigera) in Brazil

Abstract

Helicoverpa armigera is one of the primary agricultural pests in the Old World, whereas H. zea is predominant in the New World. However, H. armigera was first documented in Brazil in 2013. Therefore, the geographical distribution, range of hosts, invasion source, and dispersal routes for H. armigera are poorly understood or unknown in Brazil. In this study, we used a phylogeographic analysis of natural H. armigera and H. zea populations to (1) assess the occurrence of both species on different hosts; (2) infer the demographic parameters and genetic structure; (3) determine the potential invasion and dispersal routes for H. armigera within the Brazilian territory; and (4) infer the geographical origin of H. armigera. We analyzed partial sequence data from the cytochrome c oxidase subunit I (COI) gene. We determined that H. armigera individuals were most prevalent on dicotyledonous hosts and that H. zea were most prevalent on maize crops, based on the samples collected between May 2012 and April 2013. The populations of both species showed signs of demographic expansion, and no genetic structure. The high genetic diversity and wide distribution of H. armigera in mid-2012 are consistent with an invasion period prior to the first reports of this species in the literature and/or multiple invasion events within the Brazilian territory. It was not possible to infer the invasion and dispersal routes of H. armigera with this dataset. However, joint analyses using sequences from the Old World indicated the presence of Chinese, Indian, and European lineages within the Brazilian populations of H. armigera. These results suggest that sustainable management plans for the control of H. armigera will be challenging considering the high genetic diversity, polyphagous feeding habits, and great potential mobility of this pest on numerous hosts, which favor the adaptation of this insect to diverse environments and control strategies.

Mitochondrial DNA COI characterization of Helicoverpa armigera (Lepidoptera: Noctuidae) from Paraguay and Uruguay

“…Note that KU255537 from Uruguay and KU255542 from Paraguay are identical to the previously published sequences KM275131 (Leite et al, 2014) and KF624850 (Mastrangelo et al, 2014), respectively. A sequence identity search of the NCBI GenBank database confirmed that all suspected moths significantly matched (i.e., 99-100% nucleotide identity) published H. armigera sequences.…”

“…The low π observed for H. armigera is likely due to the small sample size. In Paraguay, the h was similar to that found for the Brazilian population by Leite et al (2014), and higher than those found in populations from India, Pakistan, Burkina Faso, and Uganda (Behere et al, 2007). On the other hand, the π was considerably higher in Paraguay, when compared with H. armigera populations from Brazil, India, Pakistan, Burkina Faso, and Uganda.…”

“…We included sequences of four H. zea (KM275162, KM274998, KM274954, and EU768942), four H. punctigera (HQ951242, HQ951243, KF977797, and EU768941), the two most common haplotypes of H. armigera, identified in Brazil by Mastrangelo et al (2014;KF624850) and Leite et al (2014;KM274936), three sequences from Uruguay (five individuals, three haplotypes, KU255535, KU255536, and KU255537), and six sequences from Paraguay (10 individuals, six haplotypes, KU255538, KU255539, KU255540, KU255541, KU255542, and KU255543). The Chloridea subflexa "C" sequence (KT598689) was used as the out-group (de Souza et al, 2015).…”

“…The pest has since been detected in Puerto Rico and Florida in the United States of America (Animal and Plant Health Inspection Service, 2015). To date, Brazil has been the only country where extensive surveys of population genetic diversity of H. armigera have been carried out (Leite et al, 2014;Mastrangelo et al, 2014), with attempts to better understand host plant usages in different seasons combined with pest genetic diversity across populations from northern and central Brazilian states. Sequence data (i.e., three mtDNA cytochrome oxidase I (COI) haplotypes; KP984522, KP984523, and KP984524) for H. armigera from Argentina was also recently reported by Arneodo et al (2015).…”

Isolamento reprodutivo entre linhagens brasileiras de <i>Helicoverpa zea</i> e <i>Helicoverpa</i> <i>armigera</i> (Lepidoptera: Noctuidae)

“…Estudos filogenéticos, morfológicos e ecológicos têm relacionado estas duas espécies como espécies-irmãs (CHO et al, 2008;POGUE, 2013;LEITE et al, 2014). Tal fato sugere que as populações de H. zea encontradas nas Américas possivelmente se originaram por especiação alopátrica devido a eventos evolutivos como efeito fundador de um pequeno grupo de H. armigera oriundo do velho mundo (BEHERE et al, 2007).…”