Browsing by Author "Mwatawala, M."

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    Anna Karenina as a promoter of microbial diversity in the cosmopolitan agricultural pest Zeugodacus cucurbitae (Diptera, Tephritidae)
    (Public Library of Science (PLoS), 2024) Mullens, N.; Hendrycks, W.; Bakengesa, J.; Kabota, S.; Tairo, J.; Svardal, H.; Majubwa, R.; Mwatawala, M.; De Meyer, M.; Virgilio, M.; Md. Asaduzzaman Shishir
    Gut microbial communities are critical in determining the evolutive success of fruit fly phytophagous pests (Diptera, Tephritidae), facilitating their adaptation to suboptimal environmental conditions and to plant allelochemical defences. An important source of variation for the microbial diversity of fruit flies is represented by the crop on which larvae are feeding. However, a “crop effect” is not always the main driver of microbial patterns, and it is often observed in combination with other and less obvious processes. In this work, we aim at verifying if environmental stress and, by extension, changing environmental conditions, can promote microbial diversity in Zeugodacus cucurbitae(Coquillett), a cosmopolitan pest of cucurbit crops. With this objective, 16S rRNA metabarcoding was used to test differences in the microbial profiles of wild fly populations in a large experimental setup in Eastern Central Tanzania. The analysis of 2,973 unique ASV, which were assigned to 22 bacterial phyla, 221 families and 590 putative genera, show that microbial diversity (as estimated by Abundance Coverage Estimator, Faith’s Phylogenetic Diversity, Shannon-Weiner and the Inverse Simpson indexes) as well as β microbial diversity (as estimated by Compositional Data analysis of ASVs and of aggregated genera) significantly change as the species gets closer to its altitudinal limits, in farms where pesticides and agrochemicals are used. Most importantly, the multivariate dispersion of microbial patterns is significantly higher in these stressful environmental conditions thus indicating that Anna Karenina effects contribute to the microbial diversity of cucurbita. The crop effect was comparably weaker and detected as non-consistent changes across the experimental sites. We speculate that the impressive adaptive potential of polyphagous fruit flies is, at least in part, related to the Anna Karenina principle, which promotes stochastic changes in the microbial diversity of fly populations exposed to suboptimal environmental conditions.
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    An economic comparison of biological and conventional control strategies for insect pests in cashew and mango plantations in Tanzania
    (Journal of Economics and Sustainable Development, 2013) Mwatawala, M.; Rwegasira, G.; Esbjerg, L.; Hellas, J.; William, J. G.
    This study was undertaken to compare alternative methods of pest control for insect pests in order to determine which methods has the highest efficacy against insect pests and the least detrimental side effects, while maintaining production and profits. The analysis was based on the experimental trials for three treatments: weaver ants, chemical insecticides and control. Data on yields, quantities and prices of inputs and output were collected and analyzed using inferential statistics (t-test), partial budgetary technique and marginal analysis involving dominance analysis. The results of partial budget analysis shows that a change from chemical insecticides treatment to weaver ants returned net benefits greater than zero by Tsh. 692 923 and Tsh.1019665 in cashew and mango plantations respectively. Similarly, positive net benefits was obtained when growers change from control to weaver ants treatment by Tsh. 504 989 and Tsh. 891 297 in cashew and mango plantations. The dominance and MRR analyses shows that if cashew and mango growers change from conventional agricultural practices to weaver ants, they would earn MRR of 1621% which is above minimum acceptable rate of return (MARR) of 100%. The t-test analyses show that weaver ant treatment is superior over conventional agricultural practices. The study concludes that weaver ant treatment was economically feasible and financially undertaking. Further field experimental trials will be repeated in the next two growing seasons to confirm results obtained in 2012.
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    Partial budgeting analysis of different strategies for management of insect pests in cashew and mango orchards in Tanzania
    (Conscientia Beam, 2015) William, J. G.; Hella, J.; Lars, E.; Offenberg, J.; Mwatawala, M.; Rwegasira, G.
    Before changing from one production method to another, farmers need to consider costs and incomes resulting from the change. This study estimated the effects on net benefit of switching from conventional Tanzanian growing practices (spraying of chemical pesticides and non-pest control) to the use of African weaver ants (Oecophylla longinoda) to control pests in cashew and mango. Yield data from one cashew and one mango plantation covering two cropping seasons was used in an economic analysis. The use of chemical pesticides and the use of weaver ants resulted in higher yields compared to the non-control treatment. Lower input costs in weaver ant treatments, though, resulted in higher economic returns than the use of chemical insecticides in both seasons and crops. In all cases weaver ant treatments also produced higher returns than non-control treatments, despite their higher costs. Switching to African weaver ants without feeding was feasible due to positive net change in benefits in both crops. In cashew the average net benefit for the two seasons was 94% higher when using ants compared to non-control and 112% higher than in the chemical treatment. The corresponding values in mango were 117% and 63%, respectively. Marginal Rate of Return (MRR) was highest for African weaver ants without feeding in cashew at 235% in 2012/13 and 405% in 2013/14 seasons. Similarly, MRR was highest for weaver ant without feeding in mango at 509% in 2012/13 and 743% in 2013/14 seasons. In conclusion, the use of African weaver ants without feeding was consistently the most economically feasible management strategy to be used in Tanzanian cashew and mango pest management.