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by
G.A. Bajwa |
Total Records (
2 ) for
G.A. Bajwa |
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F. Abood
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G.A. Bajwa
and
Y.B. Ibrahim
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The tiger moth, Atteva sciodoxa is a serious pest of tongkat Ali, Eurycoma longifolia. The morphology, development times and fecundity aspects were studied at 27± 2°C, 80± 5% relative humidity and 12 h photoperiod. The eggs were yellow and ovoid in shape with a mean length and width of 1.19± 0.02 and 0.86± 0.02 mm, respectively. Width measurements of larval head capsules showed that A. sciodoxa undergoes five larval instar stages. The mean head capsule widths of the first to fifth instar larvae were 0.55± 0.01, 0.89± 0.01, 1.23± 0.02, 1.52± 0.01 and 2.11± 0.02 mm, while the body lengths were 4.71± 0.1, 8.63± 0.1, 12.87± 0.1, 16.29± 0.1 and 21.74± 0.2 mm, respectively. The mean male and female pupal body lengths were 10.36± 0.1 and 11.26± 0.2 mm, respectively. The mean male and female wing span were 21.63± 0.2 and 24.28± 0.2 mm, respectively. The mean pre-oviposition and oviposition periods were 6.2± 0.23 and 8.5± 0.28 days, respectively. A single female laid on average 106.1± 4.85 eggs with maximum production between days 8-15 of adult emergence. The maximum number of eggs laid per female per day was 20.1± 0.5. The mean hatching time was 5.7± 0.1 days with a mean hatchability of 81.1± 0.6%. The mean larval, pupal and adult periods were 20.7± 0.2, 6.2± 0.8 and 13.2± 0.5 days, respectively. The female pupal period and adult lifespan were significantly longer than the male. Atteva sciodoxa completed its life cycle in 46.28± 0.49 days. |
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F. Abood
,
G.A. Bajwa
,
Y.B. Ibrahim
and
A.S. Sajap
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Seven isolates of Beauveria bassiana were screened for pathogenicity and infectivity at a concentration of 5x107 conidia mL-1 against Atteva sciodoxa at 27±2°C and 75±5% relative humidity with 12 h photoperiod. Based on screening results, isolates Bba-Pp and FS-11 were further bioassayed at 1x106, 5x106 and 1x107 conidia mL-1. All the isolates were found to be pathogenic. However, the infectivity varied significantly among the isolates. The earliest mortality was recorded three days after inoculation. The most virulent isolate, Bba-Pp, caused 100% mortality with a median infective time (ET50) of 3.6 days on day seven following inoculation while FS-11 caused 83.3% mortality with an ET50 value of 4.1 days. Bba-Sl3 was the least infective isolate with 24.9% mortality and 15.3 days of median effective time. Mycelia appeared on 24 to 48 h old cadavers. The highest level of sporulation on two-week old cadavers was 150.6x105 Bba-Pp conidia mg-1 cadaver while the lowest was 12.23x105 Bba-Sl3 conidia. The median effective concentration (EC50) of Bba-Pp was 9.89x105 conidia mL-1 while that of FS-11 was 3.85x106 conidia mL-1. The ET50 values for 1x106 and 1x107 conidia mL-1 of Bba-Pp ranged between 7.0 and 4.4 days, respectively, while that of FS-11 were 10.3 and 5.8 days. A strong negative correlation was found between inoculum concentrations and food consumption (R2 = -0.99). The infection by Bba-Pp and FS-11 resulted in 55.8 to 72.5% reduction in food consumption by A. sciodoxa compared to the controls. |
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