Mineralogical composition of sediment determines the preference for smooth particles by caddisfly larvae during case construction

1. The mineralogical/petrological composition of the substratum influences aquatic organisms in several ways. However, the actual mechanisms are often unclear. Some caddisfly larvae actively concentrate smooth quartz particles in their portable cases thus producing a smooth inner surface of the case wall. 2. The particle surface‐roughness preference of Perissoneura paradoxa (Odontoceridae) McLachlan inhabiting granite areas in relation to the mineral composition and surface roughness of sediment particles was examined. 3. Field surveys revealed that quartz was consistently smoother than other minerals but that it became rougher in larger size fractions, and the relative abundance of quartz decreased in larger size fractions. Consequently, smooth particles were less abundant in larger size fractions of the sediment. When larval cases were compared with sediment, quartz was actively concentrated in smaller cases of early instar larvae but was gradually less abundant in larger cases of well‐grown larvae. Because larvae use larger particles as they grow, late instar larvae develop an unselective choice of mineral types. 4. Subsequently, we experimentally forced the larvae to choose from a mixture of equal amounts of two artificial particles that had different textures (rough and smooth). The proportion of smooth particles chosen by larvae gradually decreased as they grew larger. 5. These results indicate that the larvae varied in their degree of preference according to particle availability in the surrounding sediment, which is governed by mineral composition and weatherability. We suggest that case‐bearing caddisfly can adapt to the local sediment environments by varying their standard and/or criteria for material choice. In this study, the possible mechanism for the variation is discussed.     

ESTABLISHMENT AND SOME CHARACTERISTICS OF A CONTINUOUS CELL LINE DERIVED FROM FAT BODYS OF THE CABBAGE ARMYWORM (LEPIDOPTERA, NOCTUIDAE)

Fat bodies from fully grown larvae of the cabbage armyworm, Mamestra brassicae , were cultivated in a synthetic medium, MGM–431. Small free cells migrated out and multiplied rapidly. The first cell passage was done after culture for 26 days, and 100 passages were performed in the following 9 months. The established cell line was designated as NIAS–MaBr–85. The cell population is morphologically heterogeneous, but most of the cells are hexaploid with 180 microchromosomes. The cells could be stored for 3 months at 5°C, or for longer when frozen at -80°C in medium containing 10% glycerol. Qualitatively the cell line requires few amino acids: only cystine, histidine, isoleucine, methionine and threonine are essential as determined by omission of individual amino acids. The cells are susceptible to Chilo iridescent virus and Autographa californica nuclear polyhedrosis virus. This cell line can grow in serum-free M-M medium.     

ESTABLISHMENT AND CHARACTERIZATION OF CONTINUOUS CELL LINES FROM PUPAL OVARIES OF THE CABBAGE ARMYWORM, MAMESTRA BRASSICAE (LEPIDOPTERA, NOCTUIDAE)

Continuous cell lines (NIAS-Mb-19, NIAS-Mb-25 and NIAS-Mb-32) were established from the ovaries of pharate adults of the cabbage armyworm, Mamestra brassicae. One-and-a-half year elapsed before the cells multiplied steadily. The continuous cell lines consisted of a heterogeneous cell population, consisting of glass-attached flat cells and spherical free cells. The former varied considerably in shape and size. Most of the cells had finely branched cytoplasmic processes. Morphologically these three lines were not distinguishable from each other. In all the cell lines, diploid cells were predominant. The adhesiveness of cells to glass differed somewhat among the different lines. The patterns of amino acid utilization of these cell lines were characterized by marked consumption of aspartic acid, cystine, glutamine, histidine, isoleucine, leucine, methionine, tryptophan, tyrosine and valine, and by production of α-alanine and proline. These cell lines were susceptible to Chilo iridescent virus, and the infected cultures maintained a carrier state for many passages. The cell lines could be preserved for a long period by freezing or for a short period by placing them in a refrigerator.