PLOS ONE · 6 authors, 4 centres
This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.
This study found that applying the insecticide chlorpyrifos reduced banana weevil damage by 57%, while high nitrogen (N) fertilization increased damage. In contrast, high rates of potassium (K) and silicon (Si) fertilizers significantly reduced weevil damage—by up to 67% for K at 250 kg/ha/yr and 45% for Si at 300 kg/ha/yr—suggesting that combining these nutrients with insecticide can improve integrated weevil management in East African Highland Bananas.
**Background:** Banana weevil (Cosmopolites sordidus) is a major pest of East African Highland Bananas (EAHBs), causing up to 44% yield loss by the third crop cycle. The influence of crop nutritional status on weevil damage is poorly understood. Previous studies using low, combined NPK rates failed to isolate individual nutrient effects. This study aimed to evaluate the effect of chlorpyrifos insecticide combined with nitrogen (N), phosphorus (P), potassium (K), and silicon (Si) on weevil damage in EAHBs.
**Methods:** Two field experiments were conducted in Uganda. The nutrient omission trial (2004–2009) was established at Ntungamo (southwest) and Kawanda (central Uganda) using a randomized complete block design with four blocks. Ten treatments varied N (0–400 kg/ha/yr), P (0–50 kg/ha/yr), K (0–600 kg/ha/yr), and chlorpyrifos application. The potassium response trial (2018–2021) at Kawanda used three blocks with 16 treatments varying K (0–600 kg/ha/yr), Si (0 or 300 kg/ha/yr), and irrigation (rain-fed vs. drip-irrigated), with all plots receiving chlorpyrifos and 100 kg N/ha/yr. Weevil damage was assessed on freshly harvested corms by estimating the percentage area of tissue consumed in the central cylinder and cortex at two cross-sections. Data were analyzed using generalized linear mixed models with a negative binomial distribution.
**Key Results:** In the nutrient omission trial, chlorpyrifos significantly reduced weevil damage by 57% (p = 0.000). Every 1 kg/ha/yr increase in N was associated with a 0.08% increase in weevil damage (p = 0.003). P, K, and other nutrients had no significant effect when combined with high N rates. In the potassium response trial, applying 300 kg Si/ha/yr reduced weevil damage by 45% (p = 0.002). Compared to 0 kg K/ha/yr, 250 kg K/ha/yr reduced damage by 67% (p = 0.001) and 600 kg K/ha/yr reduced damage by 57% (p = 0.005); these two high K rates did not differ significantly from each other. Irrigation had no significant effect (p = 0.761).
**Clinical Implications:** The findings demonstrate that combining chlorpyrifos with high rates of K and Si fertilizers can substantially reduce weevil damage in EAHBs, particularly on sites with low nutrient availability. This supports integrated pest management strategies that may reduce reliance on insecticides. However, high N application (e.g., 400 kg/ha/yr) increases weevil damage and should be avoided. The optimal N:K ratio for balancing yield and pest suppression remains unknown. Further research is needed to quantify Si's contribution to yield and to validate these results across multiple sites.