While extensive surveys of the chironomid midges breeding in and around the Tama River were carried out by the senior author, two new species were collected on the Tama Hills along middle reaches of the river, Paratendipes tamafuscus sp. nov. and Tokyobrillia tamamegaseta gen. et sp. nov., as described in the text.

View full abstract

Catecholamine and polyamine as well as serotonin and histamine contained in spider venom glands of nine typical Japanese species were quantified. Spider venoms generally appeared poor in either catecholamine and serotonin but rich in polyamine. However, only Chiracanthium japonicum was distinguishable since large amounts of norepinephrine, epinephrine and serotonin were contained. We also examined chromatographic elution patterns of the venomous substances by using high performance liquid chromatography with a reversed-phase column, and found that a venom fraction from the spiders belonging to genus Agelena blocked lobster neuromuscular synapse in an irreversible manner.

View full abstract

Fluctuation of fly fauna in livestock and poultry farms was studied at two sites in Ibaraki Prefecture from March to December 1989. A total of 116,042 flies (ca. 15 spp.) were collected with bait-traps. Four species of Muscidae accounted for 86.8% of the total flies collected; these were 28.7% Muscina stabulans Fallen, 24.1% Fannia sp., 23.4% F. canicularis L. and 10.6% Musca domestica L. At the Wakamiya site consisting of an oxenshed, a poultry farm, a cowshed, a swine farm and a house, M. stabulans occurred predominantly and showed a bimodal fluctuation that reached a high density in June and November. The density of M. domestica was relatively low, also showing peaks in June and November. On the other hand, at the Kibe site consisting of an oxenshed, a poultry farm and a house, Fannia sp. and F. canicularis predominated, and their densities reached peaks in June and July, followed by an abrupt decline in August. The number of flies collected showed a large variation among traps. This variation seemed to relate to the farm environment where flies are likely to prefer folds with poor ventilation or places where treacly feedingstuffs and powdered milk were stocked or handled. Furthermore, higher percentages of M. domestica were trapped in sunny and bright places, while higher percentages of M. stabulans and Fannia spp. occupied obscure and dim places.

View full abstract

To elucidate the ecological role of prolonged quiescence (diapause) in proto- and/or pharate tritonymphs of the house dust mite, Dermatophagoides farinae, five groups of nymphs which became quiescent at different periods in May, June, July 1988 and September 1989,were placed in a house room from November of the each year until June 1990. They were incubated over saturated sodium choride solution in a tightly fitted plastic box. Most of the nymphs in each group overwintered and terminated quiescence almost synchronously during the period from April to June (mainly, May) of the following year, irrespective of the time when they entered into quiescence. A few nymphs continued quiescence for over 1 year, and most of them overwintered again and also moulted in April. These results suggest that the prolonged quiescent nymphs have a key role in regulating the population dynamics of the mites with their ability to overwinter and to provide breeding stocks for the population growth in spring through summer.

View full abstract

Warfarin-resistant roof rats, Rattus rattus, were trapped from known resistant population infestations in the Shinjuku district of Tokyo and reared on flour-type baits containing 0.025% (w/w) warfarin. Results of active ingredient intake and median lethal days were 3,703.8mg/kg and 145 days, respectively. On the other hand, active ingredient intake and median lethal days in a colony of warfarin-susceptible roof rats trapped in Amami-Oshima reared on the same toxic baits described above were 107.0mg/kg and 7.3 days, respectively. Moreover, all rats of the Amami-Oshima colony died within 2 weeks. The roof rats of the Shinjuku colony survived for 1 year or more, and their active ingredient amount ingested was about 36 times as much as that of the Amami-Oshima colony. In comparison of median lethal days, the Shinjuku colony was about 20 times as long as that of the Amami-Oshima colony.

View full abstract

Adults of Cx. tritaeniorhynchus were collected by light traps at a pigsty in Hijima-cho, Kochi City, from March to September for 12 years (1968 to 1973,1984 to 1989). The field population showed shortening of the wing length every summer. The average weekly temperature during the sampling period was a major environmental factor which affects seasonal fluctuation of the wing length. A highly negative correlation was also obtained between the wing length and the average number of adult females collected during June and September. Similar results were obtained from laboratory experiments to determine effects of temperature and larval density on the wing length of adults. The number of ovarioles in laboratory populations decreased under extremely high larval densities, and that in field populations varied in accordance with the wing length.

View full abstract

Collections of adult chironomid midges were carried out at two localities in Nagano Prefecture, at Asama-Onsen in the suburbs of Matsumoto City on May 17,and at Kamikochi on May 18 and 19,1990. Most of the midges were collected with sucking tubes at night while they were attracted to the fluorescent lamps of vending machines at both localities. A large number of males of Micropsectra yunoprima Sasa, 1984,swarming at the side of Lake Myojin and Lake Taisho were collected also with insect net during daytime at Kamikochi. All the adult males among them were dissected and mounted on slides, and a total of 9 species (including a new genus and 4 new species) were identified from the collections at Kamikochi, and also 17 species (including 6 new species) from those of Asama-Onsen.

View full abstract

Surveys were undertaken to reveal the population dynamics of house dust mites, Dermatophagoides spp., in floor dusts collected from living rooms and bedrooms of 10 homes in and around Nagoya City, at about 3 month intervals from September 1983 to June 1985. All homes were more or less infested with both species of D. farinae (D. f.) and D. pteronyssinus (D. p.). Mean population density of D. f. exhibited seasonal fluctuation with the highest number in September or June and the lowest in March in most of these homes, irrespective of room types and floor materials. The population structure of D. f. changed by season; relative increase of nymphs in winter populations was characteristic, suggesting the appearance of some desiccation-tolerant nymphs. On the contrary, seasonal fluctuation of D. p. populations varied from home to home according to the types of rooms and floor materials. Relatively large numbers of D. p. were found in December or March in some homes. No marked difference was seen in the population structure of D. p. between summer and winter populations. It was noted that the population density and structure of D. p. were almost constant in bedrooms with tatami floors. D. p. had a tendency to dominate in homes with fewer rooms to the family size. From these results, it was concluded that the population dynamics of D. f. and D. p. differed to some degree, although they have similar ecological niche. The difference seemed to be due mainly to the appearance of diapause nymphs in winter populations of D. f., but not in D. p. populations.

View full abstract

The effects of Plasmodium infection upon the behaviour of vector mosquitoes were examined by the cage-test method. Anopheles stephensi parasitized with Plasmodium yoelii nigeriensis had reduced ability to pass the wide-mesh net barrier. The reduction was particularly remarkable when there was no air-flow in the test cages. It is suspected that in some of these mosquitoes the receptor for chemicals from a blood source may malfunction under a windless condition.

View full abstract

The tiny, spiny-legged rove beetle, Anotylus latiusculus (Kraatz) emerged from house fly puparium collected from a vegetable farm in the Cameron Highlands, Pahang. This beetle parasitoid, and microhymenopteran Spalangia are natural enemies of flies. Spalangia spp. play important roles in regulating the fly population in Malaysia. However, this role is doubtful for the spinylegged rove beetle due to its scarcity.

View full abstract

Sixty third instar larvae of a green bottle fly were found in the purulent pleurisy on the left chest of a 76-year-old man, who lives in Tonami City, Toyama Prefecture. These larvae, about 8mm in length, were reared until emerging into adults and identified as Phaenicia sericata (Meigen). This is the fourth report on human myiasis in Japan by this species.

View full abstract