Effect of Pymetrozine on Square Protection and Emergence of Adults of the Boll Weevil, Anthonomus Grandis, in Cotton

The ever increasing quest for alternatives that are both safer and less aggressive to the environment in the control of agricultural pests has brought a significant development of new insecticides, thus contributing towards a safer and more effective pest control management. Within this context, insecticides in the selective feeding blocker group are considered selective with a beneficial toxicological profile. This experiment was installed under field conditions to investigate the effect of pymetrozine (Selective Feeding Blocker) on cotton square protection and boll weevil adult emergence, in order to be used as an alternative to the utilization of older insecticides with higher toxicity, such as organophosphorus compounds and pyrethroids. The experimental design was arranged as random blocks, with 5 treatments and 4 replicates. The treatments and doses (g a.i./ha) consisted of 4 foliar applications (at 5-day intervals between applications) of pymetrozine at 50, 100, and 200 g a.i./ha, endosulfan at 700 g a.i./ha, and a control. Sprays were initiated when the mean percentage of squares attacked by the boll weevil was 1.25%. Evaluations were conducted 5 days after the fourth application, by counting the number of squares damaged by the boll weevil. Fallen squares were collected 12 days after the fourth application, taken to the laboratory, and placed in plastic containers. Counts were obtained daily for the number of boll weevil adults emerged from each container. The data were submitted to analysis of variance and the means were compared by Tukey’s test (5%). At doses of 100 and 200 g a.i/ha, the insecticide pymetrozine was effective to protect squares against boll weevil attack, and reduced the emergence of adult weevils. The insecticide can thus be used as a new option for boll weevil management in cotton.