Table 3. The LC₅₀ values of M. incognita measured for three organophosphates.

Organophosphates	Nematode populations	LC50a (μg ml−1)	95% CLb	Slope ( ± SE)	RRc
Fosthiazate	RP	152.18	98.12–217.56	1.98 ± 0.34	2.74
	SP	55.54	38.20–86.57	1.06 ± 0.38	—
Fenamiphos	RP	13.51	8.39–20.58	2.73 ± 0.44	1.08
	SP	12.48	7.41–19.62	2.75 ± 0.39	—
Phonamiphos	RP	43.29	31.12–64.35	3.07 ± 0.31	1.05
	SP	41.26	29.58–61.46	3.12 ± 0.43	—

^aConcentrations of nematicides causing 50% mortality at 72 h post-treatment.

^bConfidence limit.

^cRR (resistance ratio) = LC₅₀ (the resistant population) ÷ LC₅₀ (the susceptible population).