CONICET | Buscador de Institutos y Recursos Humanos

Sugarcane borer (Diatraea saccharalis) is the most damaging sugarcane pest in Tucumán, Argentina. Older larvae bore into the stalks, disrupting the physiological integrity of the plant, facilitating colonization by fungi which indirectly reduce yield and quality of sugars. The aim of the present work was to optimize an infestation method under controlled conditions in order to evaluate different strategies to manage the pest. D. saccharalis larvae were obtained from a stock colony originated from field-collected adults, reared on artificial diet. Sugarcane plants of different stages were fertilized one week before inoculation assays with nitrogen source. In seedling plants (two-month-old) of TUC95-10, TUC03-12 and LCP85-384 varieties, different numbers of neonate larvae were placed in the whorl. On single plants of six-month-old (TUC95-10 variety) 10 larvae of several instars were added to the ligule of the second and third fully expanded leaves. Trials were conducted under controlled conditions (28-30ºC; 50-70% RH) with five to ten replicates per treatment; each assay was repeated twice and plants without inoculation were maintained as controls.On six-month-old plants several parameters were evaluated: alive and death recovered larvae and instar stage, number of fully development leaves, damaged leaves, internodes, bored internodes, perforations and total length of stalks, length of each tunnel, cumulative tunnel length, and death heart, whereas on seedlings only the last parameter was measured. Although all treatments were successful on six-month-old plants, since damaged leaves, perforations and tunnels were observed; differences were found among them and compared to the control. Death heart symptoms were observed at the two stages of plants. Result suggested that diverse methods could be used to screen different strategies for sugarcane borer management; however inoculation with neonate larvae seems to be more representative of field conditions since they completed their live cycle on the sugarcane plant without artificial diet.

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