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Keywords
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intrinsic rate of natural increase, net reproductive rate, finite rate of increase, generation time, Aphis fabae, Lysiphlebus fabarum
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Abstract
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The black been aphid, Aphis fabae Scopoli (Hemiptera: Aphididae) is one of the most polyphagous aphid species, and Lysiphlebus fabarum (Marshall) (Hymenoptera: Braconidae: Aphidiinae) is a parasitoid of this pest on both crops and weeds. Biocontrol agents can be used in combination with resistant host plants as complementary methods in pest control. In this study, the impact of different broad bean cultivars (G-f-5, G-f-20, G-f-21, G-f-560 and Qaramalek as native cultivar) was investigated on population parameters of A. fabae and L. fabarum at 21±1 ºC, 60±5 % RH, 16:8 h (light: dark) in the germinator by Carey (1993) method. Results showed that the highest and lowest intrinsic rate of natural increase (r) (0.6231±0.01 and 0.1579±0.01 d-1), net reproductive rate (R0) (136.51±6.38 and 6.07±0.7 f/f) finite rate of increase (λ) (1.86±0.03 and 1.17±0.011 d-1) and the lowest and highest generation time (T) (7.88±0.23 and 11.46±0.17 d) of A. fabae were on Qaramalek and G-f-21 respectively. For L. fabarum the highest and lowest r (0.5939±0.013 and 0.4265±0.01 d-1), R0 (135.59±2.05 and 80.72±3.69 f/f) and λ (1.81±0.23 and 1.53±0.01 d-1) and the lowest and highest generation time (T) (8.26±0.5 and 11.85±0.26 days) were on Qaramalek and G-f-21 respectively. There was no significant difference between intrinsic rate of increase and finite rate of increase of L. fabarum on G-f-5, G-f-20 and G-f-560 cultivars. According to the results, although G-f-21 cultivar was not convenient for feeding and reproduction to A. fabae, but it was also unsuitable cultivar for L. fabarum. It seems that the aphids that fed on cultivar G-f-21, due to their low quality, have also reduced the efficiency of L. fabarum.
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