The effects of age, egg development, and mating on calling behavior of the bertha armyworm, Mamestra configurata Walker, were studied at 20°C, 60% RH, and a 16-h L: 8-h D photoperiod. Most virgin females called and copulated for the first time during the second or third scotophase after emergence. The first copulation was 17.0 ± 0.2 h (mean±SE) long and was terminated within 1 h after lights off in the scotophase following the initiation of copulation. The ovaries contained the first chorionated eggs before the beginning of the second scotophase after emergence. The first egg laying occurred during the same scotophase in which the first copulation was terminated, i.e. scotophase three or four. Almost 75% of the eggs were laid by the end of the seventh scotophase after emergence. Mated females resumed calling after a refractory period of about 2 days. Once calling was resumed after copulation, most females laid eggs and called nightly, with egg laying occurring during the first 5–6 h and calling during the last 2–3 h of the scotophase. Mated females called for a shorter period during each scotophase than virgin females of the same age (1–3 h vs. 4–6 h). In virgin females, the diel periodicity of calling was advanced and the length of the daily calling period was increased with age until the seventh scotophase after emergence; thereafter, both remained relatively unchanged.

The calling posture, diel periodicity of calling, calling pattern, photoperiodic cue of calling, and endogenous circadian rhythm of calling were studied in virgin females of the bertha armyworm, Mamestra configurata Walker, at 20°C, 60% RH, and a 16 h light: 8 h dark photoperiod. The female had a definite calling posture: the ovipositor was extruded and curved downward at an angle of about 45°, the wings were raised above the abdomen in the form of a “V”, the antennae were directed posteriorly and held close to the sides of the thorax, and the abodmen was bent so that the two ends were raised slightly and the middle was lowered. Calling had a discrete diel periodicity, occurring in the last two-thirds of the scotophase. The calling pattern was characteristic of the continuous pattern of calling. The lights-off signal was the photoperiodic cue responsible for setting the timing of the diel periodicity of calling. The circadian rhythm of calling was endogenously based.

No abstract

Effects of five different concentrations of sodium chloride (5 to 25%) treated fish flesh was tested on oviposition, growth and developmental parameters of blowfly, Lucilia cuprina (Wiedemann). The salt worked as an oviposition deterrent in the female flies. The highest amount of eggs (0.247 ± 0.0464 g) was oviposited on lowest salt concentration (5%) and the minimum amount (0.0003 ± 0.0004 g) of eggs was laid on the highest salt concentration (25%). The eggs laid on 20 and 25% salt treated fishes were not hatched. The larval periods were significantly affected by 10 and 15% salt treated fish while the pupal periods were prolonged at 15% of salt treated fish (p < 0.05). Average larval and pupal durations in control were 4.543 ± 0.18 and 4.833 ± 0.753 days, respectively, whereas at 15% salt average larval and pupal durations were 5.937 ± 0.133 and 5.5 ± 0.548 days, respectively. The average weight of the larvae and pupae were also reduced with the high concentrations of salt. Pupation rate also significantly reduced at higher concentrations of salt. These results suggest that application of 15% salt in raw fish can effectively protect sun?drying fish from blowfly infestation. DOI: http://dx.doi.org/10.3329/dujbs.v23i1.19825 Dhaka Univ. J. Biol. Sci. 23(1): 47-51, 2014