To evaluate bird damage to lotus roots, Nelumbo nucifera Gaertn. （Proteales: Nelumbonaceae）, we collected 170 damaged roots from eight flooded lotus fields around Lake Kasumigaura. There were 258 samples of feeding marks, so-called “duck damage,” and 41 samples of disease damage. The shapes of the feeding marks were categorized into seven types: touch, sharp-peck, shallow-scoop, deep-scoop, boat, cross-section, and eat-up. We experimentally placed the lotus roots in a post-harvest lotus field and confirmed six types, excluding shallow-scoop, from our observation of the leftovers eaten by Eurasian Coots, Fulica atra L. （Gruiformes: Rallidae）, and Mallards, Anas platyrhynchos L. （Anseriformes: Anatidae）. To compare the shape of the damage with bill size, we tested on crows in captivity. While scars caused by numerous pecks impeded the identification of the suspect species, the width of a single sharp-peck by Eurasian Coots or Large-billed Crows, Corvus macrorhynchos Wagler （Passeriformes: Corvidae）, matched their bill width. In the mud of the lotus fields, the color around the feeding marks changed to purple-black after a couple of days, but the shapes did not change and differed from disease damage. Therefore, damaged roots claimed as “duck damage” were caused by ducks and coots’ feeding, and a single sharp-peck can be identified as being caused by coots’ pecking action.

In this study, we examined the effect of light intensity on colony development regulation in Lasius japonicus Santschi. Queens were collected soon after their nuptial flight in Okayama, Japan. They were reared under 16L-8D（16 h light, 8 h dark）and 12L-12D at 25°C with four light intensity conditions: 50, 200, 800, and 3000 lux. The queens started oviposition soon after collection. Thereafter, the larvae, pupae, and workers emerged under the 50–800 lux conditions； however, the hatching and larval development were suppressed under 3000 lux conditions, especially under the long-day photoperiod. Light intensity was also measured under the shelters where queens were found soon after their nuptial flight. Under the shelters, the median light intensities were between 2.4 lux and 1070.5 lux, which was low enough for the queens to develop colonies. These results suggest that queens start colony founding at places with low light intensity. The queens also likely control the rate of colony development by responding to the light intensity of the surrounding environment.

Liothrips wasabiae Haga and Okajima（Thysanoptera: Phlaeothripidae）was previously found only on field-cultivated wasabi（Eutrema japonicum）in the Chugoku region（west Honshu, Japan）. However, it was found on water-cultivated wasabi in Shizuoka Prefecture（central Honshu, Japan）in 2016, where wasabi is cultivated in terraced fields with high humidity saturated by mountain streams. Unlike field-cultivated wasabi, sprayed insecticide on water-cultivated wasabi is susceptible to dilution due to the high humidity and mist. Therefore, we conducted an experiment to determine the lethal effects of three neonicotinoid insecticides on adult and larval L. wasabiae at concentrations below the normal dilution, since both the adult and larval insects usually occur concurrently. The three neonicotinoid insecticides registered to the insect are dinotefuran, nitenpyram, and imidacloprid. The results revealed that dinotefuran and nitenpyram demonstrated greater insecticidal activities against both the adult and larval L. wasabiae than imidacloprid; however, all three insecticides, when used in lower concentrations than normal, proved less effective. This indicates that dinotefuran and nitenpyram may be used when sprayed insecticide is likely to be diluted, such as in water wasabi fields, even when both adult and larval insects occur simultaneously, taking into consideration the reduced insecticidal effect.