Table 2. Toxicity of permethrin and pirimiphos methyl by topical application to adult Aedes aegypti and the synergistic effects of PBO.

Insecticide	Population or strain	na	Slope ± SE	LD50 (ng/♀)	95% CL	SRb	RRc
Permethrin	SMK	354	7.0 ± 0.64	1.5	1.4–1.6		1.0
	SPS0	480	2.0 ± 0.14	52	37–74		35
	SPS1	440	2.2 ± 0.18	106	92–123		71
	SPS2	199	3.9 ± 0.41	212	157–278		141
	SPS3	200	4.7 ± 0.51	318	212–443		212
	SPS4	280	4.2 ± 0.37	509	461–562		339
	SPS5	400	3.2 ± 0.26	685	610–769		457
	SPS6	280	7.4 ± 0.75	757	684–838		505
	SPS7	360	5.2 ± 0.50	1090	959–1240		727
	SPS8	360	4.7 ± 0.46	1650	1440–1890		1100
	SPS9	280	6.4 ± 0.65	1900	1690–2130		1270
	SPS10 ( = SP)	280	5.0 ± 0.59	2470	2160–2840		1650
	F1(SP♀ × SMK♂)	200	11.8 ± 1.5	14	13–15		9.3
	F1(SMK♀ × SP♂)	240	7.8 ± 0.84	12	11–14		8.0
	BC1(SMK♀x F1(SP♂ × SMK♀)♂)	320	5.8 ± 0.62	3.6	3.2–4.0		2.4
	BC1(F1(SP♀ × SMK♂)♀ × SMK♂)	320	5.9 ± 0.62	4.9	4.4–5.5		3.3
Permethrin +PBOd	SMK	300	6.0 ± 0.55	0.89	0.83–0.95	1.7	1.0
	SPS0	420	2.8 ± 0.22	9.8	7.3–13	5.3	11
	SPS10 ( = SP)	360	5.8 ± 0.57	30	26–34	82	34
	SP♀ × SMK♂	200	9.7 ± 1.4	3.3	3.0–3.6	4.2	3.7
	SMK♀ × SP♂	240	10.5 ± 1.2	2.3	2.1–2.5	5.2	2.6
Pirimiphos methyl	SMK	360	10.5 ± 0.94	7.7	7.0–8.4		1.0
	SPS0	359	6.5 ± 0.56	20	19–21		2.6
	SPS10 ( = SP)	200	16.2 ± 2.2	38	35–41		4.9

^an, number of females tested.

^bSR, synergistic ratio  =  LD₅₀ (without PBO)/LD₅₀ (with PBO).

^cRR, resistance ratio  =  LD₅₀ (each population)/LD₅₀ (SMK).

^dPBO (5 µg/mosquito) was administered 1 h prior to permethrin treatment.