Ambrosia beetle Platypus quercivorus causes a mass mortality of oak trees, Japanese oak wilt, by transporting a pathogenic fungus from trees to trees. Clarifying the ecology of the beetle is essential for the management of this disease in a field. Field studies revealed that clumped thick trees are attacked by the beetle in high probability, and that canopy density of host is one of the factors which increase the beetle attack probability. Analysis of the distribution of attacked trees in a forest suggested that beetles don’t disperse to the close vicinity. Studies using flight mill showed that the beetle can fly nearly 30km in maximum, and that positive phototaxis decrease after the flight, and response to host leaf volatiles increase after flight. Studies using olfactometer revealed that the beetle is attracted by host leaf volatiles, and is repelled by non-host leaf volatiles. Beetle preference was observed for volatiles from fresh leaves, not for volatiles from dried leaves. Laboratory experiments showed that the beetle recognize a crevice structure by its opening angle and bore hole at the bottom of crevice. Process of host selection by the beetle was discussed.

This review summarizes experimental results in the flesh fly Sarcophaga similis as a model insect to determine the impacts of urbanization on insect seasonality. This species enters pupal diapause induced by short-day conditions at the embryonic and larval stages. Under decreasing photoperiod by two min/day, similar to autumn daylengths, at a constant temperature, the diapause incidence increased as the day advanced. Under natural light conditions in autumn in an urban area at the same constant temperature, however, some insects did not enter diapause even in late autumn. From these results we suggest that artificial light at night (ALAN) prevents diapause entry in the urban area. Then we found that in the laboratory, short-day induction of diapause was prevented by nighttime light levels as low as 0.01 lux. To compare the timing of diapause induction between in urban and rural areas, flies were reared on outdoor shelves in these areas. Diapause induction was delayed by approximately four weeks in the urban area compared to that in the rural area. Moreover, almost all flies in the site facing an urban residential area failed to enter diapause, even by late autumn. Although an autumnal low temperature in the urban area would mitigate the negative effect of ALAN, strong light pollution seriously disrupts the flesh fly seasonal adaptation.