Effectiveness of commonly used insecticides in controlling key vegetable pests in peri-urban areas of Dar Es Salaam, Tanzania

Abstract

Vegetable growers in peri-urban centres of Dar es Salaam use various types of insecticides to control vegetable pests.
However, some farmers recently complained of the ineffectiveness of some of the currently traded insecticides such that
worries on possible resistance by target pests or rampancy of counterfeit pesticides in the market had become a growing
concern by scientists. The present study was undertaken to determine the most grown vegetable and the commonly used
insecticides upon which the effectiveness of the later was tested against major pests. Chinese cabbage, Brassica rapa subsp.
pekinensis and eggplant, Solanum melongena were the main vegetable grown hence used for experiments at Malolo Center in
in Dar es Salaam, Tanzania. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three
replications and four treatments applied at three-week interval. The insecticides tested were: Duduba 450EC (Cypermethrin
10% + Chlorpyrifos 35%), Septer (Imidacloprid 200 g/l) and Ninja 5EC (Lambdacyhalothrin 50 g/l) alongside with a control
(unsprayed). The results showed that Duduba 450 EC applied at the rate of 2 ml/l of water, Septer at the rate of 1 ml/l of water,
and Ninja 5EC at the rate of 2.5 ml/l of water, caused significant reduction in larval population of P. xylostella. Equal
protection against hairy caterpillars on leaves of B. rapa and S. melongena was recorded. Obtained yield of Chinese cabbage
was 8.6 t ha-1, 6.7 t ha-1 and 4.6 t ha-1
from plots treated with Duduba 450EC, Septer and Ninja 5EC respectively. The recorded eggplant yield (fruits) was 6.7 t ha-1
, 5.9 t ha-1 and 5.7 t ha-1 in plots treated with Septer, Duduba 450EC and Ninja 5EC
respectively. The study recommended the use of Duduba 450EC and Septer for effective control of P. xylostella on B. rapa
and hairy caterpillar on S. melongena. © 2021 Department of Agricultural Sciences, AIOU