Monitoring Resistance to Spinosad in the Melon Fly (Bactrocera cucurbitae) in Hawaii and Taiwan
Table 2
Susceptibility and resistance to spinosad by topical application in Bactrocera cucurbitae flies (collected during August 2008) from wild populations and laboratory strains after 24, 48, and 72 h.
Collection
Regression parameters
RR1
Slope ± SE
LD50 (ng/fly) (95% FL)2
24 h
Laboratory
5.00 (4.02–6.07) c
3.80
280
Kunia
9.10 (7.56–11.04) e
3.40
219
1.82
Kahuku
9.40 (6.89–13.5) e
4.77
260
1.88
Ewa
20.5 (16.9–24.9) f
1.26
240
4.10
Puna
3.96 (3.38–4.59) bc
0.87
249
0.79
48 h
Laboratory
3.16 (2.07–4.31) ab
4.52*
280
Kunia
6.44 (4.64–8.9) de
4.99*
219
2.04
Kahuku
5.57 (4.64–6.67) d
2.63
260
1.82
Ewa
16.7 (13.6–20.4) f
3.99
240
5.28
Puna
2.60 (2.01–3.29) ab
0.53
249
0.82
72 h
Laboratory
3.07 (2.42–3.76) ab
3.10
280
Kunia
5.22 (4.28–6.32) c
2.81
219
1.70
Kahuku
4.62 (3.15–6.28) bc
4.89
260
1.50
Ewa
12.9 (7.80–19.5) ef
8.00*
240
4.19
Puna
1.86 (1.17–2.43) a
2.46
249
0.61
*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 LD50 of wild population/LD50 of laboratory strain to spinosad for the indicated post treatment time points. 2Within the LD column, different letters after the parentheses indicate significantly different LD50 values, as 95% FL did not overlap.
