Optimization of natural management methods against fall armyworm (Spodoptera Frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in maize crops in Morogoro, Tanzania
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Date
2023
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Publisher
Sokoine University of Agriculture
Abstract
Fall armyworm (FAW), Spodoptera frugiperda (J.E Smith) is a notorious pestiferous
insect with wide host range, high dispersal ability and high fecundity that make it one of
the most severe economic pests. It has been restricted to America and in 2016 was
reported from various countries in Africa including Tanzania.
Objectives of this study were (i) Evaluation of natural management methods against FAW
for improved maize productivity. (ii) To evaluate the effectiveness of biopesticides-
enhenced push-pull systems against FAW in selected maize cropping systems (iii) To
determine the influence of cropping systems and biopesticides on parasitism rate and
abundance of Parasitoids of S.frugiperda. A completely randomized design (CRD) with
four replications was adopted to determine developmental biology of the FAW using bio
pesticides B. thuringiensis (Bt), M. anisopliae and neem seed extract with lower dose of 2
mls, 2mls and (30g) per one litre of water respectively, tested against FAW in the
laboratory. Results showed that developmental duration of FAW growth stages differed
significantly among treatments. Egg incubation, larval duration, pupa stage duration and
the total developmental duration were significantly longer on the biopesticides treated
colony compared to untreated groups (p < 0.001). The shortest developmental duration of
FAW stages were observed on control colonies at 2.1 ± 0.18, 14.88 ± 0.18, and 27.7 ±
0.34 days for egg, larva and pupa stages respectively. The longest developmental duration
was observed in colonies under B. thuringiensis treatment (3.5 ± 0.37 SE, 22.03 ± 0.59
SE, 12.68 ± 0.23 SE and 37.7± 0.54 SE) days for egg, larva and pupa stages respectively.
The effectiveness of biopesticides-enhenced push-pull systems against FAW in selected
maize cropping systems was evaluated.
A factorial experiment with treatment
combination of 5 × 2 was used. Factor A included biopesticides with five levels. Factor B
cropping system with two levels. Results showed significant (p ˂ 0.001) effects of
cropping system and biopesticide application on FAW egg masses, abundance of FAW
larvae per plant , percent damaged plant and grain yield of maize crop. However,
interaction of biopesticides × sampled weeks and between cropping system ×
biopesticides × sampled week did not significantly influence egg masses. A total of 777
larval and 2241 egg-larval parasitoid species were collected during the 2020 – 2021
period of this study. To determine the influence of cropping systems and biopesticides on
parasitism rate and abundance of Parasitoids of S.frugiperda, factor A included
biopesticides with five levels (B. thuringiensis, M.anispoliae, neem seed extract,
flubendiamide 480 Sc (positive control) and Maize sole crop (negative control). Factor B
cropping system with two levels (Push pull technology and maize sole crop.
The results showed significant effect on relative abundance of Cotesia sp (p ˂ 0.001) on
plots treated with biopesticides. Results also showed significant effect of parasitism rate
and relative abundance of one egg-larval parasitoid specie (C. bifoveolatus) and two
larval-parasitoids species (C. luteum and Cotesia sp) (P < 0.05) on cropping system.
The results also showed significant effect (P < 0.05) on parasitism rate and percentage
relative abundance of one egg-larval parasitoid specie (C. bifoveolatus) and two larval-
parasitoids species (C. luteum and Cotesia sp) on interaction between cropping system
and biopesticides. The highest mean C. bifoveolatus was observed on maize sole crop
cropping system treated with neem seed extract biopesticides and the lowest was
observed on maize sole crop cropping system with no any biopesticides application, Also
the highest mean of Cotesia sp was observed on Push pull technology (PPT) treated with
Bacillus thurigiensis biopesticides and the lowest was observed on PPT treated with
Metarhizium anisopliae. Then the highest mean of C. luteum was observed on Push pull
technology treated with Bacillus thurigiensis biopesticides and the lowest was observed
on PPT treated with flubendamide as negative control. The results also showed significant
effects of parasitism rate for Chelonus bifoveolatus and Cotesia sp on interaction between
cropping system and biopesticides application, biopesticides and sampling week.
The highest mean parasitism rate of C. bifoveolatus was observed on maize sole crop
cropping system treated with neem seed extract biopesticides and the lowest was
observed on maize sole crop cropping system with no any biopesticides application. The
highest mean of Cotesia sp was observed on Push pull technology treated with Bacillus
thurigiensis biopesticides and the lowest was observed on PPT treated with Metarhizium
anisopliae. No emerged parasitoid species from eggs sampled from plots treated with
Flubendiamide. Overall, both biopesticides and push pull technology demonstrated
potential natural control methods for the invasive fall armyworm in maize fields in
Morogoro Tanzania
Description
Masters Dissertations
Keywords
armyworm, pests, management methods, insect, natural management