RESUMO
BACKGROUND: Pink bollworm (PBW) adaptation to transgenic Bacillus thuringiensis (Bt) cotton expressing crystal 1Ac (Cry1Ac) (Bt-I) and Cry1Ac + Cry2Ab (Bt-II) was assessed in India during 2010-2017 in 38 districts of the 10 major cotton-growing states. RESULTS: PBW larval incidence on Bt cotton was nil in northern India, wherein the resistance ratios (RRs) to Cry1Ac were 26-262 and those to Cry2Ab were 1-108. In central and southern India, the annual average PBW larval recovery from Bt II cotton was high at 28.85-72.49% during 2014-2017. In central and southern India, the 50% lethal concentration (LC50 ) of Cry1Ac increased from a mean of 0.330 µg mL-1 (range 0.126-0.849 µg mL-1 ) in 2013 to a mean of 6.938 µg mL-1 (range 3.52 to 10.30 µg mL-1 ) in 2017 and the RR increased from a mean of 47.12 (range 18-121) in 2013 to a mean of 1387 (704-2060) in 2017, whereas the LC50 value for Cry2Ab increased from a mean of 0.014 µg mL-1 (range 0.004-0.094 µg mL-1 ) in 2013 to a mean of 12.51 µg mL-1 (range 3.92 to 28.10 µg mL-1 ) in 2017 and the RR increased from a mean of 5.4 (range 1-31) in 2013 to a mean of 4196 (1306-9366) in 2017. CONCLUSION: High PBW larval recovery on Bt-II in conjunction with high LC50 values for Cry1Ac and Cry2Ab in major cotton-growing districts of central and southern India provides evidence of field-evolved resistance in PBW to Bt-I and Bt-II cotton. © 2018 Society of Chemical Industry.
Assuntos
Proteínas de Bactérias/farmacologia , Endotoxinas/farmacologia , Gossypium/genética , Proteínas Hemolisinas/farmacologia , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mariposas/fisiologia , Animais , Bacillus thuringiensis/química , Toxinas de Bacillus thuringiensis , Evolução Molecular , Índia , Larva/genética , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/genética , Mariposas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/genéticaRESUMO
Amrasca biguttula biguttula (Ishida), the cotton leafhopper, is a polyphagous insect pest of Asia and Southeast Asian countries. We sequenced a mitochondrial COI gene fragment from 67 individuals of cotton leafhopper collected from 7 major cotton growing states of North, Central, and South India. Genetic divergence analysis of leaf hopper population across India confirmed the presence of single species. Thirty haplotypes, in total, were determined across different regions of India. While population from North India was dominated by single haplotype, the south and central Indian populations show dispersion of different haplotypes across the region. The neutrality test rejection for the north Indian population also suggests population expansion. The genetic differentiation and gene flow analysis together confirmed the phylogeographic structure of the A. biguttula biguttula Ishida as isolated by distance.
Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/genética , Variação Genética , Hemípteros/classificação , Análise de Sequência de DNA/métodos , Animais , Evolução Molecular , Fluxo Gênico , Genética Populacional , Haplótipos , Hemípteros/genética , Índia , Proteínas de Insetos/genética , FilogeniaRESUMO
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. RESULTS: We obtained partial (511 bp) mitochondrial DNA (mtDNA) Cytochrome Oxidase-I (COI) sequences for 249 individuals of H. armigera sampled from Australia, Burkina Faso, Uganda, China, India and Pakistan which were associated with various host plants. Single nucleotide polymorphisms (SNPs) within the partial COI gene differentiated H. armigera populations into 33 mtDNA haplotypes. Shared haplotypes between continents, low F-statistic values and low nucleotide diversity between countries (0.0017-0.0038) suggests high mobility in this pest. Phylogenetic analysis of four major Helicoverpa pest species indicates that H. punctigera is basal to H. assulta, which is in turn basal to H. armigera and H. zea. Samples from North and South America suggest that H. zea is also a single species across its distribution. Our data reveal short genetic distances between H. armigera and H. zea which seem to have been established via a founder event from H. armigera stock at around 1.5 million years ago. CONCLUSION: Our mitochondrial DNA sequence data supports the single species status of H. armigera across Africa, Asia and Australia. The evidence for inter-continental gene flow observed in this study is consistent with published evidence of the capacity of this species to migrate over long distances. The finding of high genetic similarity between Old World H. armigera and New World H. zea emphasises the need to consider work on both pests when building pest management strategies for either.
