The influence of age on insecticide susceptibility of Anopheles arabiensis during dry and rainy seasons in rice irrigation schemes of Northern Tanzania

Table 4 Knock-down time and mortality rates of Anopheles arabiensis exposed to Permethrin for a period of 60 min in dry and rainy seasons

Age (days)	Season	Number tested	24 h mortality	95% CI	KDT₅₀	95% CI	KDT₉₅	95% CI	KDT₅₀ ratio (RR)
2	Dry	800	30.8	25.7–35.8	51.7	49.5–54.1	144.9	135.9–155.3	4.1
2	Rain	800	55.3	52.9–57.6	48.2	46.6–49.9	122	116.4–128.5	3.8
3	Dry	800	43.7	38.7–48.8	37.7	36.1–39.3	105.5	99.6–112.3	3.0
3	Rain	800	88.8	86.3–91.2	25.5	24.6–26.4	64.5	61.7–67.6	2.0
5	Dry	800	43.8	38.8–48.8	37.3	35.8–38.9	104.6	98.6–111.3	3.0
5	Rain	800	93.0	91.6–94.4	16.0	15.4–16.6	40.6	38.8–42.5	1.3
10	Dry	800	64.8	59.1–70.4	22.2	21.2–33.3	62.36	58.8–66.3	1.8
10	Rain	800	97.5	95.6–99.4	24.5	23.7–25.3	62.0	59.4–64.9	1.9
Control^a	Dry	800	100	–	12.5	–	25.1	–	–
Control^a	Rain	800	100	–	12.6	–	24.9	–	–

ISSN: 1475-2875