Acaricides Application Rates and Residue Levels in Homemade Sprays, Soil and Water from the Southern Ewaso Nyiro River in Kajiado West Sub County, Kajiado County, Kenya

Abstract

Acaricides used in controlling ectoparasites (ticks) is the most preferred and economical sound conventional mode of tick eradication. The study aimed at determining acaricide application rates and residue levels in the homemade cattle sprays, soils within the spraying sites and water from the nearby southern Ewaso Nyiro River. The livestock drink river water which is used for domestic purposes. Acaricide residues levels analyzed were those used by farmers in for homemade cattle sprays. The cattle sprays and soil samples were collected from ten selected homes spraying sites randomly from 138 willing farmers in the May and November representing wet and dry seasons respectively in 2018. The sprays were collected after farmers prepared them in the usual way before spraying their animals. The livestock farmers’ ways of mixing and application of acaricides after normal preparation was assessed. The different acaricides identified were analysed for active ingredient levels after preparation using Gas chromatography-Mass spectrometry. Water samples were collected from six sites adjacent to the homes where the sprays were prepared since some homes were found to share the same water drawing area. Solvents used were triple distilled for samples extractions. The homemade sprays and water samples were extracted using dichloromethane while Soxhlet method for soil in a mixture of acetone and hexane in the ratio of 1:3. Samples were concentrated using a rotary evaporator and the clean-up through aluminium oxide chromatographic glass column. Refrigerator was used for sample storage while a Hewlett-Packard Agilent Gas chromatography system equipped with a mass selective detector was used for quantification of acaricide residues levels. Out of the nine acaricides reported by farmers through the questionnaire, three namely amitraz, cypermethrin and deltamethrin were detected in the homemade cattle sprays and soil samples. Amitraz levels ranged from 884±25.3 to 12,236±14.54 µg/L, Cypermethrin was at 3,834±80.2 to 11,972±74.0 µg/L with Deltamethrin at 3,879±33.2 to 12,298 ±82.1 µg/L in the dry while amitraz was at 5,430±96.10 to 11,634±107.2 µg/, 8,975± 103.7 to 10,383±562 µg/L for Cypermethrin while Deltamethrin was only used by home 3 at concentration of 4,781± 125.8 µg/L in the wet seasons in homemade cattle sprays. In the soil, acaricides were in the range of 3,129±98.7 to 10,641±144.2 µg/kg for amitraz, 3,041±33.15 to 8,654±141.2 µg/kg, Cypermethrin and 1,341±58.06 to 8,167±16.4 µg/kg Deltamethrin in dry and 3,875±97.3 to 7,905±184.2 µg/kg amitraz, 4,832±86.7 to 8,694±146.9 µg/kg Cypermethrin. Deltamethrin was only used by home 3 at a level of 2,367±76.9 µg/kg in the wet season. The analysis revealed that homemade cattle sprays in the sub-county had low levels of amitraz, cypermethrin and deltamethrin than those recommended by the manufacturers of 50,000-400,000 µg/L, indicating that the acaricides were over diluted leading to the observed tick re-occurrence in Kajiado West Sub County.