, ,
Volume 3, Issue 4 (2-2015)
Abstract
In recent years the use of rotifers as live food for rearing fish larvae and crustacean is very important. Growth and density is considered as an important factor in the production of rotifers. In this study, the effect of three different concentrations (1.5×106, 3×106, 4.5×106 cell/ml-1) of green algae, Tetraselmis Suecica, on growth, reproduction, body and egg size of marine rotifer, Brachionus plicatilis were investigated. Rotifers were cultured in standard conditions in 500 ml plastic containers. The initial density of rotifers in different treatments was 30 ind/ml. Based on the results, the highest density (331/67 ± 13/32) were showed in high concentration, which were significantly (P <0/05) higher than the other two treatments. Specific growth rate at concentrations of 3×106 cell/ml-1and 4.5×106 cell/ml-1 were significantly greater than concentrations of 1.5×106 cell/ml-1 of green algae (P<0.05). However, no significant differences were observed between the two treatments, medium and high. The maximum number of eggs and egg-bearing females were observed in the fourth and seventh days. Mean body size (lorica area) and egg size (bio-volume) in rotifers fed with high concentrations (4.5×106cell/ml-1) significantly greater than the mean body size of rotifers fed with medium (3×106 cell/ml-1) and low (1.5×106 cell/ml-1 ) concentrations while no significant differences were observed between low and medium treatments(P>0.05). The present study showed that the concentration of algae Tetraselmis suecica might be used in marine rotifer breeding and changing various concentrations, can produce various sizes of rotifers.
Volume 13, Issue 1 (1-2011)
Abstract
Reproduction parameters for Helicoverpa armigera (Hübner) were determined and compared on 13 soybean varieties (DPX, L17, BP, Clark, JK, 356, M4, M7, M9, Gorgan3, Sahar, Zane and Williams) at 25±1ºC, 65±5% RH over a photoperiod of 16:8 (L:D) hours. Reproduction parameters were estimated for individual newly emerged moths, which had spent their immature stages on different soybean varieties. The highest rate of gross fecundity was on M4 (2,238 eggs female-1), whereas the lowest value of this parameter was on Gorgan3 (467 eggs female-1). The gross fertility rate was the highest on M7 (782 eggs female-1) and lowest on Gorgan3 (149 eggs female-1). The net fecundity rate varied from 192 (BP) to 1,275 eggs (M7). The net fertility rate was the highest on M7 (586 eggs female-1) and lowest on Sahar (56 eggs female-1). The daily number of eggs laid per female ranged from 50 to 282 eggs, the minimum on Gorgan3 and the maximum on M4. Our results demonstrated that M9, Williams, Clark, L17, M7, M4 and Zane varieties were more suitable host plants for reproduction of the studied population of H. armigera. The other varieties examined showed less suitability as host plants for H. armigera reproduction.
