Side effects of deltamethrin and thiacloprid on demographic parameters of the aphid parasitoid, Lysiphlebus fabarum Marshall (Hymenoptera: Aphidiidae)
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The black bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae) is one of the most important pests of several cultivated crops worldwide. Lysiphlebus fabarum Marshall (Hymenoptera:
Aphidiidae) is one of the main endoparasitoid of A. fabae in many agro-ecosystems. In this study, the sub-lethal effects of field recommended doses of deltamethrin and thiacloprid (250 ml a.i/ha and 200 ml a.i/ha, respectively) were studied on demographic parameters of L. fabarum adult. Experiments were conducted in a growth chamber at 21±1°C, 60±5% RH and a 16:8 h (L: D) photoperiod. Forty newly emerged females were exposed to insecticides using residual glass plate method for 24 h. Distilled water was used in the control treatment. The females surviving in each treatment were placed individually in ventilated plastic cylinders containing twenty, third instar nymphs of Aphis fabae fed on potted broad bean plants daily for oviposition in new cages until death of the females. The survival of each female parasitoid and its fecundity were recorded daily. Stable population growth parameters were calculated by the jackknife method using the TWOSEXMSChart program (Chi 2005). Gross (GRR) and net reproductive (R0) rates in the control, deltamethrin and thiacloprid were 56.50±3.60 offspring and 37.61±2.30 offspring/individual; 23.89±2.35 offspring and 14.62±1.27 offspring/individual; 17.36±1.14 offspring and 12.15±0.82 offspring/individual, respectively. Mean generation time (T) in the control and insecticidal treatments were 15.87± 0.14 day; 14.73±0.16 day; 14.60±0.15 day, respectively. Intrinsic rate of increase (rm) and finite rate of increase (λ) were estimated 0.23±0.004 day-1 and 1.26±0.007 day-1; 0.18±0.006 day-1 and 1.20±0.007 day-1; 0.17±0.005 day-1 and 1.19±0.006 day-1, respectively. Both insecticides negatively affected five of the estimated demographic parameters. In sum, our results suggest that deltamethrin and thiacloprid is not compatible for simultaneous application with L. fabarum in IPM programs and should not be used in situations where release of L. fabarum adults is undertaken. Further studies needed to be done under more realistic semi-field and field conditions to assess the potential impact of these insecticides on L. fabarum, more precisely.
Aphidiidae) is one of the main endoparasitoid of A. fabae in many agro-ecosystems. In this study, the sub-lethal effects of field recommended doses of deltamethrin and thiacloprid (250 ml a.i/ha and 200 ml a.i/ha, respectively) were studied on demographic parameters of L. fabarum adult. Experiments were conducted in a growth chamber at 21±1°C, 60±5% RH and a 16:8 h (L: D) photoperiod. Forty newly emerged females were exposed to insecticides using residual glass plate method for 24 h. Distilled water was used in the control treatment. The females surviving in each treatment were placed individually in ventilated plastic cylinders containing twenty, third instar nymphs of Aphis fabae fed on potted broad bean plants daily for oviposition in new cages until death of the females. The survival of each female parasitoid and its fecundity were recorded daily. Stable population growth parameters were calculated by the jackknife method using the TWOSEXMSChart program (Chi 2005). Gross (GRR) and net reproductive (R0) rates in the control, deltamethrin and thiacloprid were 56.50±3.60 offspring and 37.61±2.30 offspring/individual; 23.89±2.35 offspring and 14.62±1.27 offspring/individual; 17.36±1.14 offspring and 12.15±0.82 offspring/individual, respectively. Mean generation time (T) in the control and insecticidal treatments were 15.87± 0.14 day; 14.73±0.16 day; 14.60±0.15 day, respectively. Intrinsic rate of increase (rm) and finite rate of increase (λ) were estimated 0.23±0.004 day-1 and 1.26±0.007 day-1; 0.18±0.006 day-1 and 1.20±0.007 day-1; 0.17±0.005 day-1 and 1.19±0.006 day-1, respectively. Both insecticides negatively affected five of the estimated demographic parameters. In sum, our results suggest that deltamethrin and thiacloprid is not compatible for simultaneous application with L. fabarum in IPM programs and should not be used in situations where release of L. fabarum adults is undertaken. Further studies needed to be done under more realistic semi-field and field conditions to assess the potential impact of these insecticides on L. fabarum, more precisely.
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