Hybridization and introgression between Helicoverpa armigera and H. zea: an adaptational bridge

Abstract

Background Invasion of organisms into new ecosystems is increasingly common, due to the global trade in commodities. One of the most complex post-invasion scenarios occurs when an invasive species is related to a native pest, and even more so when they can hybridize and produce fertile progeny. The global pest Helicoverpa armigera was first detected in Brazil in 2013 and generated a wave of speculations about the possibility of hybridization with the native sister taxon Helicoverpa zea. In the present study, we used genome-wide single nucleotide polymorphisms from field-collected individuals to estimate hybridization between H. armigera and H. zea in different Brazilian agricultural landscapes. Results The frequency of hybridization varied from 15 to 30% depending on the statistical analyses. These methods showed more congruence in estimating that hybrids contained approximately 10% mixed ancestry (i.e. introgression) from either species. Hybridization also varied considerably depending on the geographic locations where the sample was collected, forming a ‘mosaic’ hybrid zone where introgression may be facilitated by environmental and landscape variables. Both landscape composition and bioclimatic variables indicated that maize and soybean cropland are the main factors responsible for high levels of introgression in agricultural landscapes. The impact of multiple H. armigera incursions is reflected in the structured and inbred pattern of genetic diversity. Conclusions Our data showed that the landscape composition and bioclimatic variables influence the introgression rate between H. armigera and H. zea in agricultural areas. Continuous monitoring of the hybridization process in the field is necessary, since agricultural expansion, climatic fluctuations, changing composition of crop species and varieties, and dynamic planting seasons are some factors in South America that could cause a sudden alteration in the introgression rate between Helicoverpa species. Introgression between invasive and native pests can dramatically impact the evolution of host ranges and resistance management.

Helicoverpa armigera and Helicoverpa zea hybridization: constraints, heterosis, and implications for pest management

“…The positive results obtained only by using multiple (five) couples per cage suggest that the successful hybridization is consistent with field observations in which hybridization increased under outbreak conditions. 23,70 This indicates that appropriate management actions to maintain natural populations of the two species in balance reduce the chance of interspecific crosses, and may reduce the likelihood of encounters between compatible genes or those associated with fitness in variable environmental conditions, 71,72 variation in host use, 73 and resistance to insecticides. 25,74 Although the data presented here suggest that each hybridization event reduces the reproductive potential of both species, hybridization should be discouraged.…”

Climate Change Increases the Expansion Risk of Helicoverpa zea in China According to Potential Geographical Distribution Estimation

“…To date, studies on H. zea have mainly focused on its morphological features [35] and biological characteristics [33], while few studies have aimed to identify its invasive risk in different areas. In this study, distribution data of H. zea and related environmental data were used to identify the PGDs of H. zea in China based on the MaxEnt model and ArcGIS software, and we aimed to investigate the following issues: (1) the relationship between the PGDs of H. zea and environmental variables; (2) the PGDs of H. zea in China under the current climate; and (3) changes in the PGDs of H. zea in China under climate change, and the shifting trend of PGDs of H. zea.…”

A chromosome-scale genome assembly of aBacillus thuringiensisCry1Ac insecticidal protein resistant strain ofHelicoverpa zea

“…These reductions in H. zea insecticide susceptibility (Yang et al 2020; Santiago González et al 2021) contribute to increased levels of crop damage and lower yields (Reisig and Kurtz 2018; Reay-Jones 2019), presenting a threat to global food security (Coates et al 2015). This has been exacerbated by the introduction and spread of the sister species, H. armigera , into South America and the Caribbean (Czepak et al 2013; Tay et al 2013; Arnemann et al 2015; Murúa et al 2016; Sosa-Gómez et al 2016; Tembrock et al 2019) where introgression of adaptive alleles has led to novel phenotypes that further complicate pest management efforts (Anderson et al 2018; Cordeiro et al 2020; Valencia-Montoya et al 2020; Rios et al 2021).…”