Prey preference of Amblyseius swirskii between Tetranychus urticae and Trialeurodes vaporariorum on strawberry
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Amblyseius swirskii (Athias-Henriot) is used as a biocontrol agent against different pests such as two-spotted spider mite (TSSM), Tetranychus urticae Koch and greenhouse whitefly (GHWF), Trialeurodes vaporariorum (Westwood). In this study, the prey preference of A. swirskii was examined between the different stages of TSSM, between the egg and larval stages of GHWF and between the preferred stage of TSSM and preferred stage of GHWF, which was conducted on fresh and full of web leaves. The study was done under laboratory conditions at 25 ± 1° C and 70 ± 5% RH and a photoperiod of 16L: 8D h in 20 replications on strawberry leaf discs. Five-days-old mated females of the predator which were starved for one day used in all the treatments. The number of each prey-stage consumed by the predator was recorded after 24 h. The Chesson’s preference index (α) in choice experiments was calculated and compared with paired t-test and one way ANOVA. When ANOVA was conducted, multiple comparisons were also conducted with Tukey test. The results of first treatment showed that there was significant difference between preference index (F = 453.44, df = 2, 59, P<0.001) (choice) (egg, larval and protonymphal stages α was 1± 0, 0.32± 0.12 and 0.12±0.11, respectively) and mean predation (F = 43.47, df = 2,59, P<0.001) (no-choice) among different TSSM stages. Also, the preference of A. swirskii was significantly different between egg and larval stages of GHWF in choice (t=11.10, df= 20, P<0.001) (egg and larval stages α was 0.99± 0.04, 0.35± 0.25, respectively), and no choice (t=8.06 df = 36, P<0.001) experiments. The results showed that A. swirskii fed on all stages of both pests but had a clear preference for eggs compared to other stages. Furthermore, our findings showed that A. swirskii consumed significantly greater number of TSSM eggs than GHWF eggs on fresh leaf (t=10.11, df=1, 23, P<0.001) (egg stage&#039;s α = 0.97± 0.08 and larval stage&#039;s α = 0.42± 0.23), but clearly had a higher predation on GHWF eggs compared to TSSM eggs on full of web leaves (t= 5.32, df= 21, P<0.001) (egg stage&#039;s α = 0.67± 0.24 and larval stage&#039;s α = 0.97± 0.06). The results showed that the consumption rate and prey preference of A. swirskii reduced and changed significantly in severely infected plants. So choosing the right time to release the predators according to the target pest is very important in pest management.
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