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1.
BMC Genomics ; 23(1): 426, 2022 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-35672676

RESUMEN

BACKGROUND: An optimal starting point for relating genome function to organismal biology is a high-quality nuclear genome assembly, and long-read sequencing is revolutionizing the production of this genomic resource in insects. Despite this, nuclear genome assemblies have been under-represented for agricultural insect pests, particularly from the order Coleoptera. Here we present a de novo genome assembly and structural annotation for the coconut rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae), based on Oxford Nanopore Technologies (ONT) long-read data generated from a wild-caught female, as well as the assembly process that also led to the recovery of the complete circular genome assemblies of the beetle's mitochondrial genome and that of the biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). As an invasive pest of palm trees, O. rhinoceros is undergoing an expansion in its range across the Pacific Islands, requiring new approaches to management that may include strategies facilitated by genome assembly and annotation. RESULTS: High-quality DNA isolated from an adult female was used to create four ONT libraries that were sequenced using four MinION flow cells, producing a total of 27.2 Gb of high-quality long-read sequences. We employed an iterative assembly process and polishing with one lane of high-accuracy Illumina reads, obtaining a final size of the assembly of 377.36 Mb that had high contiguity (fragment N50 length = 12 Mb) and accuracy, as evidenced by the exceptionally high completeness of the benchmarked set of conserved single-copy orthologous genes (BUSCO completeness = 99.1%). These quality metrics place our assembly ahead of the published Coleopteran genomes, including that of an insect model, the red flour beetle (Tribolium castaneum). The structural annotation of the nuclear genome assembly contained a highly-accurate set of 16,371 protein-coding genes, with only 2.8% missing BUSCOs, and the expected number of non-coding RNAs. The number and structure of paralogous genes in a gene family like Sigma GST is lower than in another scarab beetle (Onthophagus taurus), but higher than in the red flour beetle (Tribolium castaneum), which suggests expansion of this GST class in Scarabaeidae. The quality of our gene models was also confirmed with the correct placement of O. rhinoceros among other members of the rhinoceros beetles (subfamily Dynastinae) in a phylogeny based on the sequences of 95 protein-coding genes in 373 beetle species from all major lineages of Coleoptera. Finally, we provide a list of 30 candidate dsRNA targets whose orthologs have been experimentally validated as highly effective targets for RNAi-based control of several beetles. CONCLUSIONS: The genomic resources produced in this study form a foundation for further functional genetic research and management programs that may inform the control and surveillance of O. rhinoceros populations, and we demonstrate the efficacy of de novo genome assembly using long-read ONT data from a single field-caught insect.


Asunto(s)
Escarabajos , Secuenciación de Nanoporos , Nudiviridae , Animales , Escarabajos/genética , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Perisodáctilos/genética , Filogenia
2.
J Econ Entomol ; 109(1): 375-84, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26487744

RESUMEN

The wheat aphid, Sitobion miscanthi Takahashi, a serious wheat pest, was previously considered to be highly migratory and anholocyclic in China. We recorded 69 alleles and 346 multilocus genotypes among 708 aphid individuals from 12 populations in China using 5 microsatellite loci. This genotypic diversity indicates that at least some holocyclic lineages exist. Bayesian clustering analysis revealed that there are two differentiated genetic groups of S. misanthi, one northern and one southern, in China. Principal coordinates analysis of population genetic distance, pairwise F(ST)'s, and network analysis of individual minimum spanning distance also supported the division. Low levels of migration were detected between the northern and southern sampling sites, but the high genetic differentiation does not support the hypothesis S. miscanthi overwinters in the south and migrates to the north in the spring annually.


Asunto(s)
Distribución Animal , Áfidos/fisiología , Variación Genética , Partenogénesis , Migración Animal , Animales , Áfidos/genética , China , Análisis por Conglomerados , Genotipo , Estaciones del Año
3.
Am Nat ; 184(6): 777-86, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25438177

RESUMEN

We provide the first evidence for interspecific warfare in bees, a spectacular natural phenomenon that involves a series of aerial battles and leads to thousands of fatalities from both attacking and defending colonies. Molecular analysis of fights at a hive of the Australian stingless bee Tetragonula carbonaria revealed that the attack was launched by a related species, Tetragonula hockingsi, which has only recently extended its habitat into southeastern Queensland. Following a succession of attacks by the same T. hockingsi colony over a 4-month period, the defending T. carbonaria colony was defeated and the hive usurped, with the invading colony installing a new queen. We complemented our direct observations with a 5-year study of more than 260 Tetragonula hives and found interspecific hive changes, which were likely to be usurpation events, occurring in 46 hives over this period. We discuss how fighting swarms and hive usurpation fit with theoretical predictions on the evolution of fatal fighting and highlight the many unexplained features of these battles that warrant further study.


Asunto(s)
Agresión , Abejas/fisiología , Conducta Animal , Animales , Secuencia de Bases , Repeticiones de Microsatélite , Datos de Secuencia Molecular , Comportamiento de Nidificación , Queensland , Conducta Social
5.
Bull Entomol Res ; 103(5): 611-8, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23702301

RESUMEN

Following the global uptake of transgenic cotton several Hemipteran pests have emerged as primary targets for pesticide control. Previous research on one such emergent pest: the green mirid, Creontiades dilutus, indicated differential use of two crop hosts, cotton (Gossypium hirsutum, Malvaceae) and lucerne (alfalfa) (Medicago sativa, Fabaceae). We tested the hypothesis that this apparent demographic independence of lucerne and cotton inhabiting mirids is the result of cryptic species being associated with these two crops. We assessed gene flow using microsatellite markers across adjacent cotton and lucerne crops at three geographically separated sites (up to 900 km apart). We also analysed the recent feeding behaviour of these insects by amplifying chloroplast markers from their gut contents. We find high gene flow between these two crops (mean pair wise F ST between host plants=0.0141 within localities), and no evidence of cryptic species. Furthermore, the gut analyses revealed evidence of substantial recent movement between these two crops. We discuss the implications of these results for interpreting multiple host use in this species and setting future research priorities for this economically important pest.


Asunto(s)
ADN de Cloroplastos/análisis , Flujo Génico , Hemípteros/genética , Animales , Gossypium , Medicago sativa , Repeticiones de Microsatélite
6.
Pest Manag Sci ; 79(9): 3200-3210, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37029476

RESUMEN

BACKGROUND: Annual sowthistle is a weed that is difficult to control in lentil crops in southern Australia due to a lack of herbicide options, widespread herbicide resistance and prolific production of highly mobile seed. This study investigates herbicide resistance in annual sowthistle in the Mid-North (MN) and Yorke Peninsula (YP) regions of South Australia, identifies and characterizes the mechanisms of acetolactate-synthase (ALS)-inhibitor resistance in this amphidiploid species, and combines this with analyses of population structure and gene flow. RESULTS: ALS-inhibitor-resistant annual sowthistle is widespread across the YP and MN of South Australia and is associated with a variety of Proline-197 mutations of the ALS gene, including leucine, alanine, arginine, serine, threonine and histidine. These mutations were found in different combinations on either of the two copies of the ALS gene. An additional 200 tissue samples were collected from across a single field on the YP and the ALS gene was sequenced for all these individuals. Different ALS-inhibitor resistance profiles were evident between mutation combinations and within mutation combinations, possibly mediated by differing subgenome assortment of the mutations, or altered gene experession of the two ALS homeologs. Population genetics analysis showed evidence of long-distance dispersal, resulting in highly mobile resistance genes, and multiple instances of resistance mutation evolution. CONCLUSIONS: Continuing selection of Sonchus oleraceus populations with ALS-inhibiting herbicides has resulted in the accumulation of additional mutations within the ALS gene. New practices to control herbicide-resistant S. oleraceus should be examined, and control should focus on reducing seed set and dispersal to prevent the spread of emerging cases of resistance. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Asunto(s)
Acetolactato Sintasa , Herbicidas , Sonchus , Humanos , Acetolactato Sintasa/genética , Herbicidas/farmacología , Australia del Sur , Mutación , Resistencia a los Herbicidas/genética , Inhibidores Enzimáticos/farmacología
7.
Pest Manag Sci ; 79(12): 5333-5340, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37615238

RESUMEN

BACKGROUND: Control of prickly lettuce has become increasingly difficult for lentil growers in southern Australia because of widespread resistance to common herbicides, a lack of alternative herbicide options and the prolific production of highly mobile seed. This study aimed to quantify acetolactate synthase (ALS)-inhibiting herbicide resistance in the Mid North (MN) and Yorke Peninsula (YP) of South Australia, characterize the resistance mutations present and investigate population structure and gene flow in this species. RESULTS: Resistance was identified in all populations tested, with average survival of 92% to chlorsulfuron and 95% to imazamox + imazapyr. Five different amino acid substitutions were identified at proline 197 of the ALS gene. There was no significant difference in the median lethal dose (LD50 ) between plants with these five different substitutions when treated with metsulfuron-methyl; however, the imidazolinone resistance level was higher in plants with a phenylalanine substitution and lower in plants with a serine. Population structure based on 701 single nucleotide polymorphisms and 271 individuals provided evidence for both independent evolution of the same mutation in different populations, as well as frequent short- to medium-distance dispersal accompanied by occasional long-distance dispersal events. The overall inbreeding coefficient (FIS ) was calculated at 0.5174, indicating an intermediate level of outcrossing despite the cross-pollination experiment showing only low outcrossing. In the structure analyses, most individuals from YP were assigned to a single cluster, whereas most individuals from MN were assigned 50% to each of two clusters, indicating some genetic differences between these two regions, but also evidence for dispersal between them. CONCLUSIONS: Use of imidazolinone herbicides has selected for mutations conferring higher levels of resistance, such as the Pro-197-Phe mutation, and resulted in further spread of resistance in this species. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Asunto(s)
Acetolactato Sintasa , Herbicidas , Humanos , Mutación Puntual , Acetolactato Sintasa/genética , Acetolactato Sintasa/metabolismo , Herbicidas/farmacología , Mutación , Resistencia a los Herbicidas/genética , Fenilalanina/genética , Australia , Prolina/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
8.
Neotrop Entomol ; 52(3): 380-406, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36251214

RESUMEN

We provide the identification and species delineation of this biocontrol agent as Stomphastis thraustica (Meyrick in Trans Ent Soc Lond 80(1):107-120, 1908) belonging to the family Gracillariidae. We clarify the distribution pattern of S. thraustica, its host plant preferences, and present taxonomic and molecular diagnoses based on original morphological and genetic data as well as data retrieved from historic literature and genetic databases. Following our own collecting efforts in three continents Africa, South America, and Australia as well as our study of historic museum collection material, we present many new distribution records of S. thraustica for countries and territories in the world including the new discovery of this species in the Neotropical region and we report its introduction in Australia as a biocontrol agent. Using mitogenomic and COI gene data, we clarified that the closest relative of S. thraustica is Stomphastis sp. that occurs in Madagascar and Australia and feeds on the same host plant as S. thraustica - Jatropha gossypiifolia L. (Euphorbiaceae). The molecular sequence divergence in the mitochondrial DNA barcode fragment between these two closely related species S. thraustica and Stomphastis sp. is over 5.7% supporting that they are different species.


Asunto(s)
Euphorbiaceae , Jatropha , Lepidópteros , Mariposas Nocturnas , Animales , Plantas , Australia
9.
iScience ; 25(7): 104521, 2022 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-35754720

RESUMEN

We investigate the genetic basis of anthropophily (human host use) in a non-model mosquito species group, the Anopheles farauti complex from the southwest Pacific. This complex has experienced multiple transitions from anthropophily to zoophily, contrasting with well-studied systems (the global species Aedes aegypti and the African Anopheles gambiae complex) that have evolved to be specialist anthropophiles. By performing tests of selection and assessing evolutionary patterns for >200 olfactory genes from nine genomes, we identify several candidate genes associated with differences in anthropophily in this complex. Based on evolutionary patterns (phylogenetic relationships, fixed amino acid differences, and structural differences) as well as results from selection analyses, we identify numerous genes that are likely to play an important role in mosquitoes' ability to detect humans as hosts. Our findings contribute to the understanding of the evolution of insect olfactory gene families and mosquito host preference as well as having potential applied outcomes.

11.
PeerJ ; 9: e10552, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33520439

RESUMEN

BACKGROUND: The coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is a severe and invasive pest of coconut and other palms throughout Asia and the Pacific. The biocontrol agent, Oryctes rhinoceros nudivirus (OrNV), has successfully suppressed O. rhinoceros populations for decades but new CRB invasions started appearing after 2007. A single-SNP variant within the mitochondrial cox1 gene is used to distinguish the recently-invading CRB-G lineage from other haplotypes, but the lack of mitogenome sequence for this species hinders further development of a molecular toolset for biosecurity and management programmes against CRB. Here we report the complete circular sequence and annotation for CRB mitogenome, generated to support such efforts. METHODS: Sequencing data were generated using long-read Nanopore technology from genomic DNA isolated from a CRB-G female. The mitogenome was assembled with Flye v.2.5, using the short-read Illumina sequences to remove homopolymers with Pilon, and annotated with MITOS. Independently-generated transcriptome data were used to assess the O. rhinoceros mitogenome annotation and transcription. The aligned sequences of 13 protein-coding genes (PCGs) (with degenerate third codon position) from O. rhinoceros, 13 other Scarabaeidae taxa and two outgroup taxa were used for the phylogenetic reconstruction with the Maximum likelihood (ML) approach in IQ-TREE and Bayesian (BI) approach in MrBayes. RESULTS: The complete circular mitogenome of O. rhinoceros is 20,898 bp in length, with a gene content canonical for insects (13 PCGs, two rRNA genes, and 22 tRNA genes), as well as one structural variation (rearrangement of trnQ and trnI) and a long control region (6,204 bp). Transcription was detected across all 37 genes, and interestingly, within three domains in the control region. ML and BI phylogenies had the same topology, correctly grouping O. rhinoceros with one other Dynastinae taxon, and recovering the previously reported relationship among lineages in the Scarabaeidae. In silico PCR-RFLP analysis recovered the correct fragment set that is diagnostic for the CRB-G haplogroup. These results validate the high-quality of the O. rhinoceros mitogenome sequence and annotation.

12.
Curr Res Insect Sci ; 1: 100015, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-36003604

RESUMEN

Recently, incursions of the Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, have been detected in south Pacific countries that were previously free of the pest. It has been suggested that this range expansion is related to an O. rhinoceros haplotype that is reported to show reduced susceptibility to the well-established classical biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). We investigated O. rhinoceros population genetics and the OrNV status of specimens collected in Fiji, New Caledonia, Papua New Guinea (PNG), Samoa, Solomon Islands, Tonga, Vanuatu and the Philippines. Based on the sequence of the mitochondrial CoxI gene, we found three major mitochondrial haplotype groups (CRB-G, CRB-PNG and CRB-S) across the region. Haplotype diversity varied between and within countries and a high incidence of OrNV infection was detected in all haplotypes wherever they occurred. The O. rhinoceros population in some countries was monotypic and all individuals tested belonged to a single haplotype group. However, in Samoa we detected CRB-S and CRB-PNG and in Solomon Islands we detected all three haplotype groups. Genotyping-by-Sequencing (GBS) showed genetic differentiation in the O. rhinoceros nuclear genome across populations on different islands and provided evidence for gene flow, resulting in a well-mixed population, despite the presence of different CoxI haplotypes in Solomon Islands. Evidence of admixture was also detected on both islands of Samoa. The current CoxI based method is not a reliable diagnostic marker for phenotypic traits, especially in countries such as Solomon Islands where the mitochondrial haplotypes have come back into sympatry and are mixed. To identify possible mechanisms of resistance to OrNV, further molecular analyses O. rhinoceros in response to virus infection is required. To improve biological control of O. rhinoceros, such analyses will need to be combined with an improved understanding of the population genetics of the pest and the evolutionary history of OrNV in the region.

13.
Theor Biol Forum ; 113(1-2): 67-70, 2020 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-33929006

RESUMEN

1. Introduction. 2. The Specific-mate Recognition System (SMRS). 3. The Genetic Change As sociated with Speciation.


Asunto(s)
Preferencia en el Apareamiento Animal , Animales , Especiación Genética
14.
Evol Appl ; 13(8): 2113-2129, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32908608

RESUMEN

The presence of distinct evolutionary lineages within herbivorous pest insect taxa requires close attention. Scientific understanding, biosecurity planning and practice, and pest management decision-making each suffer when such situations remain poorly understood. The pest bug Nezara viridula Linnaeus has been recorded from numerous host plants and has two globally distributed mitochondrial (mtDNA) lineages. These mtDNA lineages co-occur in few locations globally, and the consequences of their divergence and recent secondary contact have not been assessed. We present evidence that both mtDNA lineages of N. viridula are present in Australia and their haplotype groups have a mostly separate distribution from one another. The north-western population has only Asian mtDNA haplotypes, and the population with an eastern distribution is characterized mostly by European mtDNA haplotypes. Haplotypes of both lineages were detected together at only one site in the north of eastern Australia, and microsatellite data indicate that this secondary contact has resulted in mating across the lineages. Admixture and the movement of mtDNA haplotypes outside of this limited area of overlap has not, however, been extensive. Some degree of mating incompatibility or differences in the climatic requirements and tolerances of the two lineages, and perhaps a combination of these influences, might limit introgression and the movement of individuals, but this needs to be tested. This work provides the foundation for further ecological investigation of the lineages of N. viridula, particularly the consequences of admixture on the ecology of this widespread pest. We propose that for now, the Asian and European lineages of N. viridula would best be investigated as subspecies, so that "pure" and admixed populations of this bug can each be considered directly with respect to management and research priorities.

15.
Pest Manag Sci ; 76(2): 695-703, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31359582

RESUMEN

BACKGROUND: The rice stem borer, Chilo suppressalis, is a serious pest of rice, but also damages an aquatic vegetable, water oats (Zizania latifolia Turcz.). The time at which mating occurs is different between populations of rice stem borer associated with rice and those associated with water-oats, which suggests that undetected cryptic species may be associated with these plant hosts. If true, this would have significant management implications. This study is the first empirical test of this idea, using population genetic tools from two sampling cohorts. We genotyped 320 rice stem borer individuals from 2014, collected from rice and water-oats across five locations (where they exist in sympatry), using seven microsatellite loci. RESULTS: We found no genetic structuring associated with host plant species. On water oats, some rice stem borers were found that had a similar mating time to the rice population, so in 2016, a second cohort of samples was screened by their timing of mating to get 'pure rice feeders' and 'pure water oats feeders'. These samples were genotyped with microsatellites, mitochondrial DNA (mtDNA) (COI and COII), and a nuclear gene (EF1-α). Our mtDNA data suggest a relatively low amount of population subdivision associated with plant host, but the microsatellite data revealed no such genetic structure, and we were only able to identify one haplotype of EF1-α. CONCLUSIONS: Our results indicate gene flow between rice and water oats populations of rice stem borer, indicating that water oats will likely provide a refuge for resistance management of Bt rice. © 2019 Society of Chemical Industry.


Asunto(s)
Mariposas Nocturnas , Oryza , Animales , Flujo Génico , Haplotipos , Repeticiones de Microsatélite
16.
Evol Appl ; 13(9): 2449-2459, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33005233

RESUMEN

INTRODUCTION: Brown planthoppers (Nilaparvata lugens) are the most serious insect pests of rice, one of the world's most important staple crops. They reproduce year-round in the tropical parts of their distribution, but cannot overwinter in the temperate areas where they occur, and invade seasonally from elsewhere. Decades of research have not revealed their source unambiguously. METHODS AND RESULTS: We sequenced the genomes of brown planthopper populations from across temperate and tropical parts of their distribution and show that the Indochinese peninsula is the major source of migration into temperate China. The Philippines, once considered a key source, is not significant, with little evidence for their migration into China. We find support for immigration from the west of China contributing to these regional dynamics. DISCUSSION: The lack of connectivity between the Philippine population and the mainland Chinese populations explains the different evolution of Imidacloprid resistance in these populations. This study highlights the promise of whole-genome sequence data to understand migration when gene flow is high-a situation that has been difficult to resolve using traditional genetic markers.

17.
J Econ Entomol ; 112(6): 2931-2939, 2019 12 09.
Artículo en Inglés | MEDLINE | ID: mdl-31352482

RESUMEN

Cylas formicarius F. and Euscepes batatae Waterhouse are the most damaging sweet potato insect pests globally. Both weevils are thought to have invaded the Pacific alongside the movement of sweet potato (Ipomoea batatas (L.) Lam. Convolvulaceae), with C. formicarius having originated in India and E. batatae in Central or South America. Here we compare the genetic relationships between populations of the pests, primarily in the Asia-Pacific, to understand better their contemporary population structure and their historical movement relative to that of sweet potato. Cylas formicarius has divergent mitochondrial lineages that indicate a more complex biogeographic and invasive history than is presently assumed for this insect, suggesting it was widespread across the Asia-Pacific before the arrival of sweet potato. Cylas formicarius must have originally fed on Ipomoea species other than I. batatas but the identity of these species is presently unknown. Cylas formicarius was formerly designated as three species or subspecies and the genetic data presented here suggests that these designations should be reinvestigated. Euscepes batatae has very low genetic diversity which is consistent with its historical association with sweet potato and a recent introduction to the Asia-Pacific from the Americas. The distribution of E. batatae may be narrower than that of C. formicarius in the Asia-Pacific because it has relied relatively more on human-assisted movement. Consequently, E. batatae may become more widespread in the future. Investigating the invasion history of both species will help to understand the probability and nature of future invasions.


Asunto(s)
Escarabajos , Ipomoea batatas , Gorgojos , Animales , Asia , India , América del Sur
18.
Mitochondrial DNA B Resour ; 3(2): 521-522, 2018 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-33474225

RESUMEN

Cheilopdipterus quinquelineatus (Apogonidae) is an interesting species for investigating processes driving population divergence in marine system due to its wide distribution and life-history traits. However, to date, there is a limited genetic resource available for this species, or the family Apogonidae as exemplified by the availability of only two mitogenomes. In this study, we assembled the whole mitochondrial genome of this species yielding a 16,537 bp circular assembly composed of the typical vertebrate mitochondrial features. Phylogenetic inference of the supraordinal group of C. quiquelineatus showed monophyly of the major families.

19.
Mitochondrial DNA B Resour ; 3(1): 217-219, 2018 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-33490499

RESUMEN

In this study, we sequenced the full mitochondrial genome of Bathygobius cocosensis, an abundant intertidal fish species, which may provide insights into the evolutionary genetics of chaotic genetic patchiness and range expansion in marine systems. The mitochondrial genome is 16,692 bp, and contains 13 protein-coding genes along with 22 tRNA and 2 rRNA genes and a D-loop region, arranged similarly to other Gobiidae species. A Bayesian phylogeny of Gobiidae species indicates close relationships to the genus Glossogobius. The B. cocosensis mitochondrial genome is now available through GenBank (Accession = MG704838).

20.
Pest Manag Sci ; 74(10): 2363-2375, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29542257

RESUMEN

BACKGROUND: Because herbicide resistance evolves in very large populations over periods of many years, modelling is an important tool for investigating the dynamics of the problem. The Diversity model tracks the simultaneous evolution of resistance to multiple herbicides, using multiple genetic pathways, in several weed species at once. Tracking multiple species and simultaneous resistances is an important development in resistance modelling. We used the Diversity model to test weed management strategies for new cropping cotton varieties with multiple herbicide tolerances ('triple-stacked' varieties), in an Australian context. RESULTS: The diversity required for long-term control of three key weeds in Australian cotton goes beyond using three herbicides, especially where there is already a substantial background of existing resistance to one or more of these herbicides. Assuming some glyphosate resistance is already present, simulations showed that glyphosate-resistant summer grass populations reach 20 000 seeds m-2 within 12 years using the triple-stack herbicides (glyphosate, glufosinate and dicamba) and a minimum of other tactics. Adding three pre-emergent modes of action plus cultivation to the system effectively controls glyphosate-resistant grasses for over 30 years. In conditions where resistance genes are as frequent as 1 in 100, however, highly fecund weeds such as Conyza bonariensis are hard to control beyond 15 years even with very highly diverse management. CONCLUSIONS: Stacked herbicide tolerances in new crop varieties offers potential for increased herbicide diversity, but existing glyphosate-resistant weed populations need substantial extra management beyond what a glyphosate/glufosinate/dicamba resistance stack provides. More diverse systems can provide robust management over 30 years in the absence of very high levels of background resistance to other herbicides. © 2018 Society of Chemical Industry.


Asunto(s)
Producción de Cultivos/métodos , Evolución Molecular , Resistencia a los Herbicidas/genética , Control de Malezas/métodos , Riego Agrícola , Australia , Gossypium/crecimiento & desarrollo , Modelos Genéticos
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