Diversidade genética e estrutura populacional de Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) nas culturas do arroz (Oryza sativa L.) e cana-de-açucar (Saccharum officinarum L.)
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2015-03-25
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Universidade Federal de Goiás
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The change in composition of the host-plants in the agricultural landscape can
generate enough divergent natural selection to allow ecological adaptation that leads to
specialization and subsequently to speciation in species of insect. The objective of this
study was to determine the diversity of genetic and population structures of Diatraea
saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae), which was collected in two hostplants
using microsatellite markers. Samples of larvae of this stem borer were collected on
rice and sugarcane in different fields during the harvest of 2012/2013 in the states of
Tocantins, Goiás, Mato Grosso, Mato Grosso do Sul, and Rio Grande do Sul. A total of
127 alleles were found distributed among the eight loci in seventeen populations, with a
total of 426 individuals. The loci were highly polymorphic, with average of 15,87 alleles.
The expected heterozygosity (HE) and observed (HO) were 0,579 and 0,350, respectively.
A lower total number of alleles (35) was found in population of Morrinhos, as opposed to
Formoso do Araguaia which has the largest (62). The same way, the smallest and the
largest average number of alleles per locus (Am) were observed in these populations (4,38
and 7,75). The population from the Formoso do Araguaia showed the highest value for the
allelic richness (6,82). In all populations, the observed heterozygosity (HO) was lower than
expected (HE). The average polymorphic information content (PIC) in populations of D.
saccharalis was 0,530. The intrapopulational fixation indexes (f) estimated for each
population showed positive values and significantly different from zero with a average
value of 0,403. The coefficient of inbreeding species was 0,399. The estimates FIT and FST
(θ) values were 0,437 and 0,062 respectively. These global estimates indicated that there is
genetic structure among these populations. Despite global estimates had indicated genetic
structure, the structuring (θ) among of populations of the sugarcane was not significant; in
contrast with the populations of the rice which showed θ values significant. There was a
significant correlation between genetic and geographic distances estimated using the
Mantel’s test (r=0,76; p= 0,0033), in which there is an increase in pattern of genetic
distance with the increase of geographic distance in cluster analysis and population
structures observed with the formation of the two groups of populations. The first was
formed by populations from the state of Goiás and the second was composed of
populations of Mato Grosso, Mato Grosso do Sul and Rio Grande do Sul. The population
of Formoso do Araguaia sampled in rice showed in an intermediate position to the two
groups formed. These results indicate that the genetic diversity of D. saccharalis is
structured in space and the plant-host, in this study, did not have a key role in the process
of genetic divergence populations.
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NASCIMENTO, J. B. Diversidade genética e estrutura populacional de Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) nas culturas do arroz (Oryza sativa L.) e cana-de-açucar (Saccharum officinarum L.). 2015. 77 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2015.