Effect of interaction between diatomaceous earth and cypermethrin in control of stem borer in maize (Zea mays L.)

Abstract

The Lepidopteran stem borers Chilo partellus, Busseola fusca and Sesamia calamistis are the most important pests of maize. One of the most used methods to control stem borer is the use of insecticides, which often creates problems in the environment, beyond the cost of its acquisition. The mixture of insecticides is a technique that has been widely used in pest control programs, reducing application costs, environmental pollution and time of application. Because of the need of finding more effective alternative control method this study was carried out with the objective of assessing the interaction of cypermethrin and diatomaceous earth in the control of stem borers in maize. The study was conducted at the experimental field of the Faculty of Agronomy and Forestry Engineering, Eduardo Mondlane University. The experimental design used was a randomized complete block design with six (6) treatments and three (3) replications. The treatments used were: diatomaceous earth at 5 and 10 g/L, cypermethrin 0.25 ml/L, mixture of diatomaceous earth and cypermethrin, and control. The variables analyzed included: plant height, stem diameter, number of internodes, damaged internodes, tunnel length, cob weight, density and abundance of stem borers. The control had the highest average damage and mixtures of diatomaceous earth 10 g/L + cypermethrin 0.25 ml/L and diatomaceous earth 5 g/L + cypermethrin 0.25 ml/L the best results and did not differ in all variables analyzed. The interaction between cypermethrin 0.25 ml/L and diatomaceous earth at the rates of 5 and 10 g/L was classified as being additive.