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Mito-shi, Japan

Sung I.-H.,Miaoli District Agricultural Research and Extension Station | Yamane S.,Lbaraki University | Lu S.-S.,Taiwan Forestry Research Institute | Ho K.-K.,National Taiwan University
Sociobiology | Year: 2011

The flight activities of the stingless bee Lepidotrigona hoozana and honeybee Apis cerana were studied diurnally and periodically to examine temporal and climactic foraging niche differentiation in Taiwan. Statistical analyses showed that the level of flight was correlated with the temperature and light intensity in both species. Both species could fly under dry and moderately wet conditions. We conducted a principle components analysis (PCA) to tease apart the effects of different environmental variables. The first PCA factor for L. hoozana was temperature limits on flights and foraging. For A. cerana, the PCA revealed that light intensity was the most important limiting factor. In most cases, A. cerana foragers had more departure flights per unit time and spent more time flying than foragers of L. hoozana. The minimum flight temperatures for L. hoozana ranged from 11°C to 16 °C, and were higher than the minimum flight temperatures of 8 °C to 10 °C for A. cerana. Thus, A. cerana colonies exhibited greater flight activity during cooler times of the year than L. hoozana. This was more of a benefit in A. cerana than L. hoozana because of the physiological predominance.

Amano K.,Joetsu University of Education | Ando H.,Lbaraki University
Nautilus | Year: 2011

Specimens of Acharax yokostikensis recently collected from the upper lower Miocene Kokozura Formation of the Takaku Group in I baraki Prefecture, central Japan, served as the basis for a re-description of the species. These specimens include a valve of the largest specimen of this genus known worldwide, exceeding 295.7 mm in length. The occurrences of the giant Acharax species in Japan are confined to lower to lower middle Miocene sediments deposited in tropical shallow and deep environments.

Polybia spinifex Richards (Hymenoptera: Vespidae) constructs mud nests characterized by a long slit-like entrance. The ventilation and thermal characteristics of the P. spinifex nest were investigated to determine whether the nest microclimate is automatically maintained due to the size of the entrance. In order to examine this hypothesis, a numerical simulation was employed to predict the effects of the entrance length. The calculations were performed with 3D-virtual models that simulated the P. spinifex nest conditions, and the reliability of the simulations was experimentally examined by using gypsum-model nests and a P. spinifex nest. The ventilation effect was determined by blowing air through the nest at 13 m/s (airflow conditions); the airspeed was found to be higher in models with a longer entrance. The ventilation rate was also higher in models with longer entrances, suggesting that the P. spinifex nest is automatically ventilated by natural winds. Next, the thermal effect was calculated under condition of direct sunlight. Under a calm condition (airflow, 0 m/s), thermal convection and a small temperature drop were observed in the case of models with a long entrance, whereas the ventilation and thermoregulation effects seemed small. Under airflow conditions, the temperature at the mid combs steeply dropped due to the convective airflow through the entrance at 12 m/s, and at 3 m/s, most of the heat was eliminated due to high thermal conductivity of the mud envelope, rather than convection.

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