Overwintering of Bemisia tabaci Q-biotype（Gennadius）, an important agricultural pest, was investigated in Kumamoto. As a result of research from 2007 to 2008, it was found that some of the eggs and nymphs of Q-biotype could overwinter under semi-outdoor conditions: the survival rate was 0.1–1.2%. However, the adult of Q-biotype could not overwinter under the same conditions. Furthermore, during 2008–2009, it was found that some of the eggs and nymphs of Q-biotype could overwinter under natural environmental conditions: the survival rate was 0.7%. All stages of B-biotype, however, could not overwinter under semi-outdoor conditions. These results indicate the possibility of overwintering of Q-biotype under natural environmental conditions, which has not been reported in Japan.
Occurrence of the onion thrips, Thrips tabaci Lindeman, was examined from late December to late May at onion fields with three different cropping types, early, middle, and late seasons, in Kagawa Prefecture, western Japan. In the early season onions, survival of adults, larvae and newly hatched larvae of T. tabaci was observed on onion plants during winter and their occurrence was increased from April. In the middle season onions, T. tabaci of all developmental stages were found from late April. In the late season onions, newly hatched larvae increased from early March in the field where T. tabaci adults had occurred. On the other hand, no such increase of newly hatched larvae was observed in the field where fewer adults had existed. Oviposition of adults on onion seedlings was also examined in the laboratory and field conditions in March. The newly hatched larvae from onion seedlings were found at 10°C and 20°C in the laboratory and in the field.
In this study, we examined the effects of photoperiod and light intensity on the regulation of colony development in Lasius japonicus Santschi. Queens were collected soon after their nuptial flight in Okayama City, Japan and reared in the laboratory. In the first experimental series, insects were reared under 14L10D（14 hours light 10 hours dark）, 13L11D, 12L12D, 11L13D, and 10L14D at 20°C to examine the effects of photoperiod on colony development. In the second experimental series, the insects were maintained under either of the two light intensity conditions, i.e., 3,000 or 30 lx, under 12L12D at 25°C. The eggs, larvae, and pupae were counted daily. No significant differences among photoperiods were detected in the number of eggs, larvae, and pupae, indicating that photoperiod does not play a considerable role in the seasonal regulation of colony development. Under the 3,000 lx condition, larvae and pupae did not emerge in most of the colonies, although queens continued ovipositing throughout the experimental periods. It was considered that queens eat eggs or first-instar larvae.
In July 2015, an unidentified gall midge（Diptera: Cecidomyiidae）infesting new leaves of blueberry, Vaccinium spp. was found in Gunma Prefecture, Japan. Morphological examinations of adults and larvae revealed that the gall midge belongs to the genus Dasineura and is very similar to the blueberry gall midge Dasineura oxycoccana（Johnson）, which is native to North America and associated with blueberry. In order to confirm whether or not the species of Dasineura on cultivated blueberry is identical to D. oxycoccana, a partial region of the mitochondrial DNA cytochrome oxidase subunit I（COI）（676 bp）gene was sequenced for several individuals collected from Gunma. As a result, the sequence was identical to an individual of D. oxycoccana in the database. Based on the morphological examinations and molecular analysis, we identify the gall midge infesting blueberry in Gunma as D. oxycoccana. This is the first report of D. oxycoccana in Japan.
We surveyed the occurrence of Stethorus pusillus（Herbst）and Stethorus japonicus H. Kamiya from Hokkaido to Kyushu districts in Japan. Stethorus pusillus, whose occurrence was recently recorded in Japan again, was abundant and widely distributed from Hokkaido to Kumamoto Prefectures. On the other hand, fewer S. japonicus individuals, which had been regarded as a major species within Hokkaido to Kyushu districts, were collected: they were found in only seven prefectures ranging from Shizuoka to Kumamoto Prefectures.
Prevention or reduction of infection by the neogregarine parasite Farinocystis sp. is indispensable for effective mass-production of the West Indian sweet potato weevil Euscepes postfasciatus（Fairmaire）. The established method of weevil collection, coercively drawing weevils from the larval rearing cage, was suspected to increase the risk of breaking infected individuals, which causes horizontal transmission of the parasite to uninfected individuals. Here, we developed a novel collection method in which the weevils were permitted to spontaneously leave the larval rearing cage. The significant decrease in infection rate and the significant increase in the fecundity of weevils collected by the novel method suggested that this method may improve the mass-production of weevils.