Factors affecting the infestation status of African sugarcane stalk borer (Eldana saccharina Walker) (Lepidoptera: Pyralidae) in Tanzania

Abstract

Sugarcane is an important crop that contributes substantially to sugar production globally and across Sub-Saharan Africa. However, its productivity is constrained by stem borer infestations, particularly Eldana saccharina. The pest reduces sugarcane yield by up to 30% and about 18% of sucrose content is compromised. Nonetheless, the influence of ecological parameters on its pest status in Tanzania remains poorly understood. This study evaluated the influence of season, altitude, crop age, and sugarcane variety on E. saccharina infestation in Tanzania. A stratified multistage cross-sectional survey was conducted across three altitudes representing low, medium, and high altitudes. In total, 711 blocks were surveyed, and infestation was assessed from 50 randomly sampled stalks per block. The infestation was quantified as the total number of E. saccharina larvae recovered per 50 stalks alongside other damage parameters. Data were analyzed using generalized linear mixed models in R, with likelihood ratio tests and Type III Wald x2 tests. Infestation was highest at high altitude in both seasons and was significantly influenced by season x altitude x crop-age interaction ( X2=9.58, P<0.0083). Internal stalk-tissue- damage was significantly greater at high-altitude during the rainy season (P = 0.04). Boring intensity was significantly higher at medium and high-altitudes during the rainy season (P =0.013;P = 0.004, respectively), with the bottom stalk part most affected (P = 0.001). Higher infestation was observed in mixed-variety blocks and in cultivars N41 and N49. These findings show that altitude, season, and crop-age are determinants of E. saccharina infestation in Tanzania and should guide pest management strategies.