Susceptibility of cotton jassid, jacobiasca lybica (de burg) (homoptera, cicadellidae) to common used insecticides

Susceptibility of the cotton jassid, Jacobiasca lybica, (de burg), (Homoptera, Cicadellidae) to three common used insecticides: Endosulfan® (endosulfan) 50% EC, Dimethoate® (dimethoate) 32% EC and Avaunt® (indoxacarb) 15% SC, from organochlorine, organophosphate and oxadiazine chemical groups respectively, was studied in laboratory conditions in to Agricultural Research Corporation (ARC), Wad Medani, Sudan. The experiments were conducted during 2005 - 2007. The study investigated the susceptibility of this pest towards the tested insecticides as a representative of the Gezira Research State Farm cotton jassid population using a leaf - dipping method. The objectives of the study were to evaluate the efficacy of tested insecticides when used singlely; through the determination of lethal doses and persistence of tested insecticides on sprayed cotton leaves. The obtained results showed that the cotton jassid exhibited suitable ranges of susceptibility to both Endosulfan and Dimethoate, and the tested population showed to be homogenous to the two insecticides. The LC50, LC90 and LC99 of Endosulfan after 24 h exposure were 270.7 ppm, 822.2 ppm and 2034.2 ppm respectively, the slope was 2.7, the LC90/LC50 was 3 and the Field Recommended Dose (FRD) FRD/LC50, LC90 and Dose (FRD) FRD/LC50, L90 and LC99 were 19, 6 and 2 respectively, whereas the LC50, LC90 and LC99 of Endosulfan after 48 h exposure were 190.5 ppm, 588 ppm and 1473.7 ppm respectively, the slope was 2.6 the LC90/LC50 was 3 and the FRD/LC50, LC90 and LC99 were 26, 9 and 3 respectively. The LC50, LC90 and LC99 of Dimethoate after 24 h exposure were 43.8 ppm, 105.5 ppm and 215.8 ppm respectively, the slope was 3.4, the LC9C/LCs50 was 2.4 and FRD/LC50, LC90 and LC99 were 58, 24 and 12 respectlvely, whereas the LC50, LC90 and LC99 after 48 h exposure were 28.7 ppm, 68 ppm and 137.4 ppm respectively, the slope was 3.4, the LC90/LC50 was 2.3 and the FRD/LC50, LC90 and LC99 were 89, 38 and 19 respectively. Generally, the pest was still sensitive to Endosulfan and Dimethoate. The results obtained from Avaunt experiments showed that the treated population showed heterogeneity towards this chemical as the slope was 0.8 and 0.7 after 24 h and 48 h exposure, consequently. After 24 h the LC50, LC90 and LC99 were 44 ppm, 1828.6 ppm and 38176.4 ppm and LC90/LC50, was 41.6 whereas the FRD/LC50, LC90 and LC99 were 5, 0.1 and 0.01 respectively. After 48 h the LC50, LC90 and LC99 were 2.7 ppm, 193.5 ppm and 6326.8 ppm and LC90/LC50 was 71.7 whereas the FRO/LC50, LC90 and LC99 were 84, 1 and 0.04 respectively. The FRD of the three tested chemicals Endosulfan, Dimethoate and Avaunlt gave 50% mortality up to 3, 4 and 15 days respectively