Measuring the Flight Ability of the Ambrosia Beetle, <em>Platypus Quercivorus</em> (Murayama), Using a Low-Cost, Small, and Easily Constructed Flight Mill

The ambrosia beetle, Platypus quercivorus (Murayama), is the vector of a fungal pathogen that causes mass mortality of Fagaceae trees (Japanese oak wilt). ...

Kyoto University

This study investigated spatio-temporal variation in the leaf area consumed by insect herbivores within a canopy of Fagus crenata, with reference to the light conditions of leaf clusters. There was no clear relationship between photosynthetic photon flux density (PPFD) and consumed leaf area (CLA) in May, immediately after leaf flush, but CLA decreased with an increase in PPFD after June. Leaf mass per area, carbon concentration, C/N ratio, concentration of total phenolics, and condensed tannin concentration were higher in leaves under high light intensity than those of leaves under low light. On the other hand, the nitrogen concentration of leaves decreased as light availability increased. Consequently, within-tree variation in light availability affects the consumption of leaves by insect herbivores through temporal changes in leaf characteristics.

Temporal and spatial variations in leaf herbivory within a canopy of Fagus crenata.

We investigated the biogeographic history of Kalopanax septemlobus, one of the most widespread temperate tree species in East Asia, using a combined phylogeographic and palaeodistribution modelling approach. Range-wide genetic differentiation at nuclear microsatellites (G'(ST) = 0.709; 2205 samples genotyped at five loci) and chloroplast DNA (G(ST) = 0.697; 576 samples sequenced for 2055 bp at three fragments) was high. A major phylogeographic break in Central China corresponded with those of other temperate species and the spatial delineation of the two temperate forest subkingdoms of East Asia, consistent with the forests having been isolated within both East and West China for multiple glacial-interglacial cycles. Evidence for multiple glacial refugia was found in most of its current range in China, South Japan and the southernmost part of the Korean Peninsula. In contrast, lineage admixture and absence of private alleles and haplotypes in Hokkaido and the northern Korean Peninsula support a postglacial origin of northernmost populations. Although palaeodistribution modelling predicted suitable climate across a land-bridge extending from South Japan to East China during the Last Glacial Maximum, the genetic differentiation of regional populations indicated a limited role of the exposed sea floor as a dispersal corridor at that time. Overall, this study provides evidence that differential impacts of Quaternary climate oscillation associated with landscape heterogeneity have shaped the genetic structure of a wide-ranging temperate tree in East Asia.

Climate oscillation during the Quaternary associated with landscape heterogeneity promoted allopatric lineage divergence of a temperate tree Kalopanax septemlobus (Araliaceae) in East Asia.

In Japan, rice paddies play an important role as a substitute habitat for wetland species, and support rich indigenous ecosystems. However, since the 1950s, agricultural modernization has altered the rice paddy environment, and many previously common species are now endangered. It is urgently necessary to evaluate rice paddies as habitats for conservation. Among the species living in rice paddies, frogs are representative and are good indicator species, so we focused on frog species and analyzed the influence of environmental factors on their habitat use. We found four frog species and one subspecies (Hyla japonica, Pelophylax nigromaculatus, Glandirana rugosa, Lithobates catesbeianus, and Pelophylax porosa brevipoda) at our study sites in Shiga prefecture. For all but L. catesbeianus, we analyzed the influence of environmental factors related to rice paddy structure, water management and availability, agrochemical use, connectivity, and land use on breeding and non-breeding habitat use. We constructed generalized additive mixed models with survey date as the smooth term and applied Akaike's information criterion to choose the bestranked model. Because life histories and biological characteristics vary among species, the factors affecting habitat use by frogs are also expected to differ by species. We found that both breeding and non-breeding habitat uses of each studied species were influenced by different combinations of environmental factors and that in most cases, habitat use showed seasonality. For frog conservation in rice paddies, we need to choose favorable rice paddy in relation to surrounding land use and apply suitable management for target species.

Effects of water management, connectivity, and surrounding land use on habitat use by frogs in rice paddies in Japan.

Geographic variation in the traits of a species is shaped by variation in abiotic conditions, biotic interactions, and evolutionary history of its interactions with other species. We studied the geographic variation in the density of the lace bug, Corythucha marmorata, and the resistance of tall goldenrod Solidago altissima to the lace bug herbivory in their native range in the United States and invaded range in Japan. We conducted field surveys and reciprocal transplant experiments to examine what abiotic and biotic factors influence variation in lace bug density, and what ecological and evolutionary factors predict the resistance of the host plant between and within the native and invaded ranges. Lace bug density was higher throughout the invaded range than in the native range, higher in populations with warmer climates, and negatively affected by foliage damage by other insects in both ranges. The higher lace bug density in warmer climates was explained by the shorter developmental time of the lace bugs at higher temperatures. The resistance of S. altissima to lace bugs was higher in populations with lace bugs compared to populations without lace bugs in both native and invaded ranges, indicating that the evolutionary history of the interaction with the lace bugs was responsible for the variation in S. altissima resistance in both ranges. The present study revealed that abiotic and biotic factors, including temperature and other herbivorous insects, can drive the geographic variation in lace bug density, which in turn selects for variation in plant resistance in both in the native and invaded ranges. We conclude that the novel combination of factors such as higher temperature and lower number of other herbivorous insects is responsible for the higher lace bug density in the invaded range than in the native range.

Michimasa Yamasaki

Laboratory of Forest Biology,
Division of Forest and Biomaterials Science,
Graduate School of Agriculture,
Laboratory of Forest Biology, Division of Forest and Biomaterials Science, Graduate School of Agriculture

Kyoto University

Measuring the Flight Ability of the Ambrosia Beetle, Platypus Quercivorus (Murayama), Using a Low-Cost, Small, and Easily Constructed Flight Mill

Michimasa Yamasaki

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Laboratory of Forest Biology,Division of Forest and Biomaterials Science,Graduate School of Agriculture,Laboratory of Forest Biology, Division of Forest and Biomaterials Science, Graduate School of Agriculture

Kyoto University

Measuring the Flight Ability of the Ambrosia Beetle, Platypus Quercivorus (Murayama), Using a Low-Cost, Small, and Easily Constructed Flight Mill

Laboratory of Forest Biology,
Division of Forest and Biomaterials Science,
Graduate School of Agriculture,
Laboratory of Forest Biology, Division of Forest and Biomaterials Science, Graduate School of Agriculture