A new formula for estimating insecticide efficacy against bollworms under Egyptian conditions

Bollworms [ pink bollworm, Pectinophora gossypiella ( Saud.) and spiny bollworm , Earis Insulana ( Boisd) ] are the main cotton insect pests in Egypt. Too many insecticides from different insecticide groups are applied against it. The protocol of estimating insecticide efficacy against it and against many other insect pests depends on the formula of Handerson and Tilliton ( 1955 ), which needs to have a control area ( untreated area ) equals to the area of one insecticide treatment , which is four cotton feddans, to calculate the reduction percentages in bollworms infestation percent after applying each insecticide treatment. Because of this condition is impossible and is not applicable( because the financial costs of the losses of these untreated area is about 40 thousands Egyptian bounds), it's recommended to apply Albeltagy ( 2012 ) formula, which derived from experimental data and it does not depend on the presence of untreated area, but it depends on the initial bollworms infestation percentages before applying the insecticide treated program, to calculate the reduction percentages in bollworms infestation percent.

The application of Albeltagy ( 2012 ) formula solves a lot of insecticide application problems in the estimating insecticide efficacy protocol and gives an acceptable and logic data which could be benefit when its results applied in the cotton fields .