Ecologia da mosca-branca, Bemisia tabaci (Gennadius) e de seus parasitóides em soja
Nenhuma Miniatura disponível
Data
2017-03-22
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
The patterns of parasitism and the influence of the edges between native
vegetation and soybean crop on the population dynamics of whitefly were evaluated in
twenty fields in the center-west of Brazil. Monitoring was carried out in two crop seasons,
2013/2014 and 2014/2015. The samplings were biweekly, in two field sites, one on the
edge, 20 meters away from the native vegetation and another in the interior of the field, at
least 400 meters from the edge. Adult populations of whitefly were monitored using yellow
stick traps and whitefly nymphs and parasitized nymphs where counted in 30 soybean
leaflets in the lower third of the plant per sampling point. Four species of whitefly
parasitoids in soybean, Encarsia lutea, E. porteri, E. nigricephala and Eretmocerus
mundus were identified. The species of greatest abundance was E.lutea, which was found
in approximately 60% of parasitized nymphs. The rate of parasitism ranged from 6.2% to
46.5% in 2013/14 and from 3.6 to 50% in the next season. Whitefly parasitism is strongly
correlated with host density and air temperature, being the first responsible for 98.6% of
the explanation for the variability of whitefly parasitism in soybean. The population of the
parasitoid increases with increasing host density, indicating a positive dense-dependent
response. It was also observed that the population dynamics of the whitefly is affected by
edge, period, the season and the field. Higher density of adult and whitefly nymphs was
observed at the edge adjacent to natural vegetation, when compared to the interior of
soybean crops. On average, 133.3 adults/traps and 6.6 whitefly nymphs/leaflets were
observed at the edge adjacent to the native vegetation within the fields. However, it was
not observed higher density of the parasitism at the edge adjacent to the native vegetation
than inside the soybean field, pointing out that the current conditions of native vegetation
remnants do not contribute as reservoir of parasitoids. Thus, the border adjacent to the
native vegetation has not contributed to the establishment of the natural control of the pest.
The differential effects of the border on the population density of the pest and its
parasitoids indicate that the edges should be prioritized in the monitoring of the whitefly
and that to increase the rates of parasitism of the pest, fragments of natural vegetation need
to be conserved and restored.
Descrição
Palavras-chave
Citação
SANTOS, J. B. Ecologia da mosca-branca, Bemisia tabaci (Gennadius) e de seus parasitóides em soja. 2017. 91 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2017.