Effects of biopesticides on demographic parameters of fall armyworm spodoptera frugiperda j.e smith (lepidoptera: noctuidae) in Morogoro Tanzania
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Date
2019
Authors
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Publisher
sokoine university of agriculture
Abstract
Fall armyworm (FAW) Spodoptera frugiperda J.E Smith is a new insect pest in Africa
causing severe damage to maize (Zea mays) at its growth leading to yield loss as between
8.3 to 20.6 million metric tonnes per year (Day et al., 2017). The pest is native to America
with a wide host range of about 80 plant species that makes it difficult to manage
(Prasanna et al., 2018). This study aimed at establishing the population dynamics of FAW
in maize treated with biopesticides. Developmental biology and demographic parameters
of FAW were determined using biopesticides (Beauveria bassiana, Metarhizium
anisopliae and Bacillus thuringiensis) in a commercialized maize variety (DK9089,
Monsanto Company, Nairobi, Kenya). The study was conducted at the entomology
laboratory of Sokoine university of Agriculture in Morogoro, Tanzania. Experiments were
set in a completely randomized design (CRD) and the FAW cohorts were maintained at
26 o C and 75% relative humidity. Results on the developmental biology of FAW showed
significant variations in developmental durations of immature stages of FAW among
treatments. Treated cohorts had significantly longer developmental durations than
untreated cohorts. Likewise, results on demographic parameters of FAW differed
significantly among treatments. In life table parameters, treated cohorts had low
survivorships (p < 0.001), life expectancy (p < 0.001) and high probability of dying (p <
0.001) and mortality rates (p < 0.001) than untreated cohorts. Biopesticides also showed
significant variation on population parameters of FAW between treated and untreated
cohorts. Treated cohorts had low net reproductive rates (p < 0.003), intrinsic rate of
increase (p < 0.001), finite rate of increase (p < 0.001) and long doubling time (p < 0.001)
as well as the mean generation time (p < 0.001) contrary to untreated cohorts. Results
obtained from this study can be used in implementing sustainable management options
against FAW populations in Tanzania and rest of the world.
Description
A Dissertation 2019
Keywords
Biopesticides, Demographic, Lepidoptera, Morogoro, Tanzania