Poblational dynamics and the effect of defoliation in decreasing nymphs Mahanarva andigena in the cultivation of sugar cane

Abstract

The spittlebug (Mahanarva andigena Jacobi) is one of the most important pests in the sugar cane crop (Saccharum officinarum L.) at Pastaza province of Ecuador, insect that has caused big losses at the agricultural and industrial yield. The present study has the objective to determine the population dynamics and the effect of the frequency of manual defoliation over the decrease of nymphs´s population of M. andigena in sugar cane. The assay was carried out in the Tarqui parish, of Pastaza County of Ecuador under an experimental design of complete random blocks, with five treatments and four replications. Defoliation treatments were T1:  without defoliation, T2:  defoliation every 15 days, T3: defoliation every 30 days, T4: defoliation every 45 days and T5:  defoliation every 60 days. Nymphs´s population monitoring was carried out every 15 days. It was selected a random sugar cane stump per bock and quantified the number of nymphs located inside the leaf sheaths and inside the corm´s heart. The analysis was carried out based on the Threshold of Economic Damage (UDE).  At Tarqui parish the amount of nymphs per stalks exceeded the UDE in late February and continued until early October, key aspect to consider in the establishment of preventive control measures like manual defoliation. Defoliation every 15 days of sugar cane stalks was the most effective treatment that kept the nymphs´ number per stalk below to the UDE.