Effects of Artifical Substrate on Rearing of Macrobrachium Rosenbergii Post-larvae in Pond Net Cage

Two experiments were carried out to evaluate the effects of addition of net piece substrates in cages for nursery rearing of freshwater prawn, Macrobrachium rosenbergii post-larvae. In the first experiment, net piece substrates were added with an arrangement to increase the surface area of nursery cages to 50% and 75% and compared with cages without any substrate (control). In the second experiment, maintaining surface area increment at 75% in all cages, the net piece substrates were arranged in three different orientations of horizontal, vertical, and 45o angle sloping. Experiments were conducted in a pond of Faculty of Fisheries, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh for a period of 45 days in June –August of 2015 and 2016. A completely randomized design was followed to assign the treatments with three replications. The 75% area increment group showed significantly higher (P < 0.05) growth (1.02 ± 0.09 g) and survival rate (79.43 ± 1.63%), compared to 50% area increment (0.96 ± 0.05 g and 75.03 ± 2.45%) and control group (0.79 ± 0.06 g and 66.66 ± 3.57%). The vertically oriented substrate group showed significantly lower growth 0.95 ± 0.04 g) and survival (76.33 ± 1.15%), compared to the horizontal (1.06 ± 0.05 g and 77.12 ± 1.20%) and sloping (1.16 ± 0.10 g and 79.33 ± 0.57 %) substrate group. However, there were no differences between horizontal and sloping substrate groups regarding final length, final weight, specific growth rate (SGR), and survival rate except food conversion ratio (FCR). The overall results suggested that modification of net cage nursery structure of M. rosenbergii might have significant effects on growth and survival of post-larvae by the manipulation of their behaviour in culture system. Ann. Bangladesh Agric. (2020) 24(2) : 95-106

Raw and Composted Paper Mill Sludges and Municipal Compost in Nursery Substrates

Silverleaf dogwood (Cornus alba L. `Argenteo-marginata'), forsythia (Forsythia × intermedia Zab. `Lynwood Gold'), and weigela (Weigela florida Bunge A.DC. `Red Prince') were grown in #2 (6-L) containers filled with 100% bark or bark mixed with 20%, 40%, or 60% (by vol.) each of raw paper mill sludge (RB group), composted paper mill sludge (CB group), a proprietory paper mill sludge-derived compost (PB group), and municipal compost (MB group). A fifth substrate group (MH) consisted of 100% hemp chips or hemp chips mixed with the same rates of municipal compost. The containers were trickle-irrigated and fertilized with a controlled-release fertilizer. Among the bark-amended groups, growth was highest for dogwood and forsythia with PB, increasing dramatically and peaking at ca. 40% rate (68 and 94 g/plant top dry weight, respectively). Growth of these species was intermediate with MB and CB and least with RB, increasing to rates ≥ 50% in these groups, except for a nonsignificant response of dogwood to RB. Growth of weigela increased equally with PB and MB substrates up to ca. 40% (117 g/plant), but was unresponsive to rates of RB and CB. With the hemp-amended MH group, growth of all three species increased to rates ≥ 50% (62, 93, and 116 g/plant for dogwood, forsythia, and weigela, respectively). Growth of the three species over most rates of all substrate groups was similar to, or exceeded, that in 80% bark: 15% peat: 5% topsoil, a proven nursery mix. Top dry weight of all three species was positively correlated with soluble salts concentrations in the substrates at planting after first irrigation (0.23-1.72 dS·m-1, range over all substrates) and at various intervals during the season.

Rearing the Cannibalistic Larvae of Calosoma sycophanta (Coleoptera: Carabidae) in Groups

Cannibalistic immatures of the gypsy moth (Lymantria dispar L. [Lepidoptera: Lymantriidae]) predator Calosoma sycophanta L. (Coleoptera: Carabidae) must usually be reared individually. This paper describes a method of rearing C. sycophanta larvae in groups by placing them in plastic containers having 3 cm of moist peat moss in the bottom. Larvae are fed gypsy moth pupae placed on top of the peat moss. Under these conditions, larval mortality is about 50%. By varying the number of prey, it was found that larval mortality increased if less than 0.5 pupae/day/larvae were provided. However, when not starved, at least 40 C. sycophanta larvae can be reared per container with no increase in mortality. Larvae were seen to burrow through the peat moss extensively, which may reduce cannibalism. Higher larval mortality occurred when using paper towelling (wet or dry) as the substrate. Group rearing will make it easier to supply beetles for augmentative releases against the gyspy moth.

A comprehensive study of genic variation in natural populations of Drosophila melanogaster. V. Structural–functional constraints on protein molecules and enzymes and the levels and patterns of variation among genes

Ever since isozyme–allozyme polymorphisms were detected there has been an incessant effort to relate the amount of observed protein variation to various aspects of molecular structure and function. Structural–functional constraints can limit the amount of overall genie variation, and the observed variation can be due to neutral mutation and random genetic drift, mutation–selection balance, or balancing selection. The present analysis of structural–functional constraints on gene–enzyme variation in natural populations of Drosophila melanogaster shows that while both subunit size and substrate group show significant effects on number of alleles and mean heterozygosity, only substrate group affects population structure significantly. Subunit structure (monomer vs. multimer), IUB enzyme class (e.g., tranferase, lyase), and tolerance of null alleles showed no significant effect on level or pattern of variation. While partly interdependent these results suggest that efforts should be made to distinguish between constraints arising from molecular structure and physiological function.Key words: structural–functional constraints, subunit size, gene-enzyme variation, selection, neutrality.