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The objectives of this study are to clarify the relative importance of sink and related factors of dry matter and water use pre-and post-heading in four millet species under severe water deficit. Panicum miliaceum, Panicum sumatrense, Setaria glauca., and S. italica were used. Water deficit (20% soil water content) was imposed from 25 d after sowing until harvest, with 40% soil water as a control. At the heading, half of the leaf area or all leaves on each plant were removed in both the control and the water deficit treatment (Source manipulation). Water deficit treatment markedly decreased the leaf water potential of all species from −2.02 MPa (S. italica) to −1.72MPa (P. miliaceum). The grain yields of water deficit treatment in S. italica, P. miliaceum, S. glauca and P. sumatrense decreased to 62, 48, 31, and 24% of the control, respectively. Four millet species were divided to dehydration-tolerant millet (S. italica and P. miliaceum) and dehydration-susceptible millet (S. glauca and P. sumatrense) by calculating drought susceptibility index. The interspecific difference in dehydration tolerance was accounted for by the number of grains per panicle and the harvest index. The source operation showed that the sink was more important than the source. In conclusion, under severe soil drying, it was considered that S. italica and P. miliaceum showed strong dehydration tolerance because they maintained the number of grains per panicle and did not reduce dry matter production and the partitioning of dry matter to the panicle after heading. Abbreviations: CLA0: all leaves were removed at heading in the control; CLA0.5: half of the leaf area per plant was removed at heading in the control; DAS: days after sowing; DLA0: all leaves were removed at heading in the dehydration treatment; DLA0.5: half of the leaf area was removed at heading in the dry treatment; DSI: drought susceptibility index; NSC: nonstructural carbohydrate; OA: osmotic adjustment; WUE: water use efficiency. [ABSTRACT FROM AUTHOR]

The accidentally introduced beetle Ophraella communa was first found in 1996 in Japan and has rapidly expanded its distribution range to include regions with substantially different climates. During this range expansion and subsequent establishment in new habitats, the life history traits of O. communa have changed depending on new habitat environmental conditions. In this study, we investigated the photoperiodic response of O. communa controlling its reproductive diapause, an important trait that adjusts the life cycle to local climate and phenology of host-plants. We examined temporal changes and geographical differences in this trait. In the Tsukuba population of O. communa, the diapause incidence under conditions of 12 h light : 12 h dark ( LD 12:12), 13:11 and 14:10 did not consistently increase or decrease during 2005-2012, although it fluctuated yearly. The diapause incidence in this period, however, was lower than that in 1999 reported previously and the critical day-length inducing diapause was shortened by >1 h from 1999 to 2005. These results suggest that the photoperiodic response of O. communa shifted during this period. To examine geographical differences in this trait, we compared the Hirosaki, Morioka, Tsukuba and Koshi lines. The diapause incidence at LD 13:11 was significantly different between the O. communa lines: 86.5% in the Hirosaki line (collected in 2010) , 81.4% in Morioka (collected in 2010), 45.0% in Tsukuba (collected in 2011) and 7.1% in Koshi (collected in 2009), and was positively correlated with the latitude of the origin. These results suggest that this trait shifted, responding to the environmental conditions in the colonized regions. [ABSTRACT FROM AUTHOR]

This study was carried out in the natural herbaceous grassland of Mt. Aso, which had been almost completely grazed, and which is subjected to routine grassland burning every spring (February or March) to conserve Shijimiaeoides divinus asonis ( Matsumura, 1929). We clarify that ants protect the larvae of this butterfly and evaluate the effects of grazing intensity on the attendant ant population. The results obtained are summarized as follows: (i) Five species of attendant ant were identified, with the dominant species being Formica japonica ( Motschulsky, 1866) and Camponotus japonicus ( Mayr, 1866) . (ii) The number of attendant ants decreased at night time; however, only one or two ants attended the larva until the following morning. (iii) Ten species of insect excluding ants and three species of spiders that approached the larva were recorded on the larval host-plant. Formica japonica and C. japonicus fought off most newcomers of other insects including the natural enemies of these butterfly larvae. (iv) The number of ants in this butterfly habitat under regular grazing intensity was significantly higher than during low grazing intensity and non-grazing periods. (v) A positive correlation was found between the number of attendant ants and the number of butterfly larvae on the host-plant. We concluded that the interaction between this butterfly and attendant ants is one of facultative mutualism because the attendant ants protect the butterfly larva. Therefore, the numbers of this butterfly species may decrease if the number of attendant ants decreases due to the cessation of pasturage. [ABSTRACT FROM AUTHOR]