Activity of aqueous extract of cassava on mortality and reproduction of the cabbage aphid

Abstract

The objective was to evaluate the action of cassava wastewater (‘manipueira’) in different proportions on mortality and reproduction of the cabbage aphid. Tests were conducted with eleven treatments: ‘manipueira’ pure (1:0), ‘manipueira’: water in proportions 1:1; 1:2; 1:3; 1:5; 1:10; 1:15; 1:20; 1:25; 1:30 and control 1:0 (pure distilled water). Each experimental unit consisted of cabbage leaf infested with ten adult insects. Solutions were sprayed evenly and counts of living individuals performed 24 and 48 h after application. The proportions more efficient were subjected to dose/response test. For the reproduction test extreme doses were used. For analysis of variance and for the mean test ASSITAT program was used while for efficiency (%) formula of Abbott (1925). In solutions 1:0 up to 1:5 efficiency of 100% was obtained, followed by 1:10 and 1:15 with 82.05%, the other solutions presented efficiency
of less than 50%. In case of dose/response test, treatment 1:5 was lethal to 100% insects only 5 h after exposure, while 1:15 caused the death of 80% of the population after 12 h. There was 83% reduction of nymphs generated after application of 1:30 solution. ‘Manipueira’ extract is effective both for reducing generated nymphs and mortality of adult aphid of cabbage.