| Abstrakt: |
Background: Given the perplexity in the maize pest complex which has been exacerbated by the addition of the invasive fall armyworm to the preexisting stem borers, this study was aimed at assessing the damage effects caused by a complex of lepidopterous maize pests under subsistence maize cultivation techniques in order to facilitate appropriate farm-level implementation of effective sustainable control measures of lepidopterous maize pests and improve productivity. Methods: This study was carried out in eighteen subsistence maize farmer's fields, each measuring 50 × 50 m (2500 m2) in Buea and Tiko in Cameroon's South West Region. All selected fields used a zero-tillage system, with planting done over 3 years (2020, 2021 and 2022) with 2 cropping seasons per year on the 20 March for the first season and the 25 August for the second season. Data were collected on the incidence (%) of damaged plants per plot, severity of leaf damage (1–9 scale) and degree of damage to stems, tassels and ears. Maize grain yield was recorded, and all data were analyzed with Stat soft version 2022. Results: Throughout the study period, fall armyworm had the highest percentage of damage incidence of 34.8, which was significantly different from 27.4 for stem borers (p < 0.001), while stem borers had the highest damage severity (mean 4.5), significantly different from the mean of 3.2 for fall armyworm (p < 0.001). Maize grain yields varied significantly between seasons and years (p < 0.001). The fall armyworm damage incidence varied considerably between seasons (p < 0.001). In contrast to damage incidence, damage severity caused by fall armyworm on maize decreased significantly from 2020 to 2022; the greatest damage severity of 3.2 was observed in 2020, followed by 2.4 in 2021 and 1.8 in 2022. The pattern for stem borers was different, with no significant difference in damage severity (p < 0.001) across the years of research, with the lowest mean damage severity observed in 2021 (4.1), followed by 2020 (4.4) and 2022 (4.5). This study found that damage caused by fall armyworm decreased over time, while damage caused by maize stem borers remained nearly constant. Meanwhile, the overall tunnel length in meters and exit holes were significantly greater in the second seasons of the research period than in the first seasons. Conclusion and recommendation: Maize stem borers are the most damaging lepidopterous pests of maize in the study area, drastically reducing maize grain yield during the study period. The high incidence of fall armyworm damage without a corresponding increase in damage severity and maize grain yield reductions throughout the study period clearly demonstrates the pest's low impact on yields when compared to maize stem borers, which feed on maize stems, making them fragile and significantly impeding nutrient uptake and thus plant growth and yields. Due to the severity of injuries caused by the species complex of fall armyworm and stem borers with significant yield reduction, we recommend the use of integrated pest management (IPM) tactics that takes into consideration the control of fall armyworm and stem borers simultaneously. [ABSTRACT FROM AUTHOR] |
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