Pesticide residue levels in vegetables and surface waters at the Central Rift Valley (CRV) of Ethiopia.

Seven pesticides, profenofos, metalaxyl, λ-cyhalothrin, 4,4'-DDT, 4,4'-DDE, and α- and ß-endosulfan, were determined in vegetables (tomato, onion) from 20 locations and surface waters from 12 locations in the Central Rift Valley (CRV) of Ethiopia. Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) and solid phase extraction (SPE) methods were used for the vegetables and water, respectively. In 2.5% of the tomato samples, profenofos was detected above European maximum residue limits (MRLs), in 12.5% of the samples metalaxyl, and in 2.5% α- and ß-endosulfan. In 5% of the onion samples, profenofos was detected above European MRLs, in 7.5% of the onion samples metalaxyl, and in 5% λ-cyhalothrin. In surface water, profenofos was detected at the highest concentration of 2300 µg/L in the Bulbula River, 890 µg/L near the agricultural land north of Lake Ziway (ANLZ-1), 1700 µg/L in the floriculture effluent (FE-1), and 900 µg/L in tap water at the Batu Drinking Water (BDW) supply. These results show that the levels of pesticides are in several cases substantially elevated, and emphasize the need of regular pesticide monitoring programs for surface waters and vegetables in the Ethiopian CRV.

Bio-efficacy evaluation of nanoformulations of ß-cyfluthrin against Callosobruchus maculatus (Coleoptera: Bruchidae).

In the present investigation, bioefficacy of developed ß-cyfluthrin formulations, utilizing laboratory synthesized poly(ethylene glycols) based amphiphilic copolymers, were evaluated against Callosobruchus maculatus (Coleoptera: Bruchidae). The bioefficacy data indicated that the formulations developed by utilizing polymers having PEG - 1500 (3c) and PEG - 2000 (3d) as the hydrophilic segment showed greater efficacy after 14 days as evident from EC(50) values (2.2 and 1.58 mg L(-1) respectively). Also, release from the commercial SC formulation was faster than developed formulations as the commercial formulation had the lowest EC(50) value on the first day (0.51 mg L(-1)). The mean EC(50) of the commercial formulation against C. maculatus was quite high as compared to those of developed formulations. The results suggest that depending upon the polymer matrix used, the application rate of ß-cyfluthrin can be optimized to achieve insect control at the desired level and period. The results described in this paper are promising and provide a comparison of developed formulations with the commercial one showing an earlier degradation of ß-cyfluthrin in the latter and relatively prolonged activity in the former.