Table 1.

Direct estimates of resistance (R) allele frequency from responses of pink bollworm larvae to Bt toxin Cry1Ac

Strain	3.2 μg of Cry1Ac per ml of diet			10 μg of Cry1Ac per ml of diet			Estimated R allele frequency†
	Live	Total	Survival (%)*	Live	Total	Survival (%)*
APHIS-S	10	170	6.4	0	140	0	0
Coolidge	11	110	15.5	0	40	0	0
Eloy Bt	23	175	19.3	4	50	11.8	0.34
Eloy non-Bt	1	140	1.2	0	70	0	0
Marana	0	95	0.0	0	70	0	0
Mohave Valley	15	100	19.2	7	40	22.4	0.47
Paloma	12	70	22.2	0	70	0	0
Parker Valley	5	106	6.2	0	40	0	0
Safford	12	80	19.4	1	50	2.6	0.16
Solomon	20	105	23.0	2	20	12.0	0.35
Stanfield	7	80	14.0	2	50	6.4	0.25

APHIS-S is a susceptible laboratory strain; the other 10 strains were derived from Arizona cotton fields in 1997. 

^*Larvae that had not reached the fourth instar after 21 days were considered dead. Adjusted survival was calculated as survival on treated diet divided by survival on untreated diet. 

^†Square root of the adjusted frequency of survivors at 10 μg of Cry1Ac per ml of diet.