Monitoring Resistance to Spinosad in the Melon Fly (Bactrocera cucurbitae) in Hawaii and Taiwan
Table 4
Susceptibility and resistance to spinosad by feeding application in Bactrocera cucurbitae flies (collected during August 2008 in Hawaii and from July to September 2007 in Taiwan) from wild populations and laboratory strains after 24, 48, and 72 h.
Collection
Regression parameters
RR1
Slope ± SE
LC50 (μg/mL) (95% FL)2
24 h
Laboratory
3.00 (2.38–3.78) b
1.77
200
Kahuku
9.84 (5.93–16.9) c
8.29
240
3.28
Ewa
21.8 (17.0–31.99) d
2.82
240
7.27
Puna
4.68 (2.75–9.03) bc
11.27*
220
1.56
Changhwa
3.07(2.36–3.80) b
2.34
200
1.32
Pingtung
9.94(8.14–12.2) c
2.65
240
3.31
48 h
Laboratory
0.78 (0.46–1.07) a
1.23
200
Kahuku
2.53 (1.58–3.50) b
1.98
240
3.24
Ewa
11.6 (9.39–15.0) c
3.70
240
14.9
Puna
3.02 (2.05–4.35) b
4.35*
220
3.87
Changhwa
2.78(2.19–3.37) b
0.82
200
3.56
Pingtung
9.02(7.46–10.9) c
3.21
240
11.6
72 h
Laboratory
0.65 (0.26–1.03) a
2.65
200
Kahuku
2.14 (1.24–3.07) b
1.30
240
3.29
Ewa
10.09 (6.36–19.4) cd
9.49*
240
15.5
Puna
2.09 (1.12–3.57) b
8.20*
220
3.22
Changhwa
2.59 (2.04–3.14) b
2.00
200
3.98
Pingtung
8.67 (7.20–10.4) c
2.64
240
13.3
*The asterisk (*) indicates a significant difference at (χ² test) comparing the responses actually observed in the bioassay to the regression line from the probit analysis. 1The RR is given as the values of LC50 of wild population/LC50 of laboratory strain to spinosad for the indicated treatment time points. 2Within the LD column, different letters after the parentheses indicate significantly different LD50 values, as 95% FL did not overlap.
