The phlaeothripid fauna of Okinawa Prefecture, Japan was investigated in and around cultivated fields during 2009–2018. A total of 295 individuals representing four species belonging to the genus Haplothrips were collected from weeds comprising a wide range of plant taxa. The collected specimens included Haplothrips chinensis（87.5%）as well as H. aculeatus, H. ganglbaueri, and H. gowdeyi. Haplothrips brevitubus, which is commercially available in Japan, was not found. Almost all the phlaeothripid individuals collected from the crop fields were identified as H. chinensis. The most common phlaeothripid thrips in our surveys, H. chinensis, was often collected with thripid thrips. We first evaluated the predatory potential of H. chinensis and H. gowdeyi for Thrips palmi in the laboratory. Our results demonstrated that H. chinensis could consume as many larvae of T. palmi as was observed for H. brevitubus. The mean developmental periods of the three species were also examined at 25, 20, and 15°C under long-day（16L:8D）and short-day（10L:14D）conditions. The results of the laboratory tests and field surveys indicated that H. chinensis may have a high potential as one of the key indigenous natural enemies of thripid thrips in subtropical areas.
The developmental times and reproduction of the burdock-infesting aphid, Uroleucon gobonis（Matsumura）, were determined at different temperatures. The developmental zero, effective cumulative temperature, and intrinsic optimum temperature for the development of this aphid were estimated to be 5.27°C, 141.71 degree-days, and 19.22°C, respectively. This species had growth retardation at 27°C, and no nymphs reached the adult stage at 32°C. Like other aphids, it was found to be strong against low temperatures and weak against high temperatures. The intrinsic rate of natural increase of U. gobonis was 0.26 at 12°C, followed by 0.29 at 17°C, and 0.51 at 22°C suggesting that U. gobonis has a higher reproductive ability at low temperatures than other reported aphid species. Assessment of insecticide susceptibility using the leaf and body dipping methods showed that U. gobonis was highly susceptible to the recommended field rates of the 10 insecticides tested. Clothianidin granules（6 kg/10 a）applied to depths of 2 or 5 cm in the soil significantly suppressed aphid densities compared to surface treatment and the nontreated control. Acetamiprid granules（6 kg/10 a）also showed the same effect as clothianidin granules（6 kg/10 a）on the aphid density, and halving the dose showed no reduction in effectiveness.
The mulberry tiger moth, Lemyra imparilis（Butler）（Lepidoptera: Erebidae）, is a univoltine species that is widely distributed across Japan. Patterns in its population fluctuations and mortality caused by parasitoids and pathogens acting on the post-overwintering larvae were investigated in three areas of Japan. In the Kinki region, where the population follows a seven-year cycle, mortality caused by the parasitoid complex（mainly Hyposoter vierecki［Ichneumonidae］and Carcelia rasa［Tachinidae］）decreased with the L. imparilis population density, while mortality caused by pathogens（mainly Nucleopolyhedrovirus［NPV］）increased with the population density. The southern Nagano Prefecture population was stable, with a low density, and mortality caused by C. rasa and NPV tended to increase with the population density of L. imparilis. On Hachijo Island the population was stable with a high density, and the parasitoid fauna was poor compared to that of Honshu Island. Mortality caused by pathogens, mainly NPV, increased with the population density, and the rate of the population increase decreased linearly with the mortality. This study indicated that the mode of action of parasitoids and pathogens affected the patterns in L. imparilis population fluctuations.
We evaluated the effectiveness of using an indigenous generalist predatory mite, Neoseiulus barkeri（Hughes）（Acari: Phytoseiidae）, to control Thrips palmi Karny（Thysanoptera: Thripidae）in greenhouse melons. In a growth chamber experiment, the density of T. palmi was lower on plants exposed to 20 N. barkeri per plant than on plants grown without a biological control. In a greenhouse experiment, the density of T. palmi was lower in the N. barkeri release plots than in the no-release plots. These results suggest that N. barkeri is an effective biological control agent against T. palmi.
In recent years, damage caused by flower thrips, Frankliniella intonsa（Trybom）（Thysanoptera: Thripidae）, has spread in strawberry fields throughout Japan. Furthermore, cases of F. intonsa developing resistance to existing insecticides have been reported. In this study, to investigate the presence of symbiotic bacterial infections, F. intonsa samples were collected from strawberry fields in Oyama City, Tochigi Prefecture. Symbiotic bacteria are known to affect the survival, reproduction, sex ratio, and insecticide susceptibility of their hosts. Diagnostic polymerase chain reaction and sequencing analysis showed that a portion of the surveyed population of F. intonsa（30.8%）were infected with the symbiotic bacterium Wolbachia. Notably, the Wolbachia infection rate of larvae rapidly increased from 17.4 to 44.8% within just 1 month. These results suggest that Wolbachia infection may have benefitted the host. This is the first report of Wolbachia infection in a population of Japanese F. intonsa. Future studies investigating the function of Wolbachia may facilitate the development of novel methods for controlling thrips using symbiotic bacteria.