The blood-meals of two major Simulium species of Hokkaido, Japan were examined immunologically by means of enzyme-linked immunosorbent assay (ELISA) in order to determine the blood source animals of the blackflies. The sources of blood-meals were determined in 59 individuals out of 740 S. japonicum and 44 individuals out of 161 S. rufibasis. The blood-meals of S. japonicum reacted with anti-human, -bovine, -horse, -sheep and -sika deer sera and those of S. rufibasis showed positive reaction to anti-bovine, -horse and -human sera. None of the blood-meals reacted with anti-birds serum. The two blackfly species have S-type tarsal claws and flies belonging to this group are generally considered to be mammalophilic blood suckers. The results obtained in this study provide solid support for this theory.

View full abstract

The seasonal appearance of immatures of Aedes togoi (Theobald) was monitored from January 1979 to January 1980 at their breeding sites of rock holes along the Gushikami coast, Okinawa Prefecture. Large numbers of the immatures were observed from May to June at expanded breeding sites. The density of the immatures was very low from July to December, but even in winter all the immatures were present. It was found that the number of immatures was closely related to climatic conditions such as rainfall, temperature and attack of typhoons.

View full abstract

A revised list of Japanese blackflies (Diptera : Simuliidae) is provided covering 62 species and 2 subspecies. They are placed into 4 genera : Twinnia (3spp.), Prosimulium (9spp.), Cnephia (2spp.) and Simulium (48spp. and 2 subspp.).

View full abstract

New analogs of venom peptides such as waspkinin, mastoparan and chemotactic peptide were isolated from the venom sacs of the paper wasp, Parapolybia indica by reversed phase HPLC. Their amino acid sequences were determined as follows : pGlu-Glx-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-Lys, Ile-Asn-Trp-Lys-Lys-Met-Ala-Ala-Thr-Ala-Leu-Lys-Met-Ile-NH_2,HCO-Ile-Leu-Gly-Leu-Leu-Lys-Gly-Ile-Ser-Ala-Leu-Leu-Ser-NH_2.

View full abstract

Studies on control effect of the permethrin-impregnated mosquito net against Anopheles farauti, the malaria vector species in the Western Pacific countries were carried out in Solomon Islands in 1985,using the experimental hut attached with the exit window traps. Average mortality rate of the mosquitoes entering the hut was 88.2% for a net treated with 0.5g/m^2 and 84.0% for a net treated with 0.2g/m^2 of permethrin. Mortality rate when the mosquito net was hung with a gap at the bottom was slightly higher than when the net was completely closed, showing 90.2% and 85.1%, respectively. Sixty-nine point nine percent and 71.9% of all mosquitoes that entered the 0.5g/m^2-net hut and the 0.2g/m^2-net hut, respectively were caught in the exit window traps, and mortality rates after 24hr were 84.1% and 79%. In case of the control (untreated mosquito net), 98.4% of the mosquitoes was collected at the exit window traps. The permethrin-impregnated mosquito net did not show any repellent effect, because there was no reduction in the number of the mosquitoes entering the treated hut compared to the control hut (76.5 females/night in the 0.5g/m^2-net hut, 69.5 females/night in the 0.2g/m^2-net hut and 61 females/night in the control hut). It was found that permethrin has the fumigation effect, showing that the mortality rate of the caged An. maculatus females which were hung 30-40cm apart from the permethrin-impregnated mosquito net was 89.9%, 90.0%, 94.9% and 100% at 1.5hr, 3hr, 6hr and 12hr of exposure, respectively.

View full abstract

To further improve the efficiency of sound traps, 4 different types of traps were tested on Culex tritaeniorhynchus in a paddy and Aedes albopictus in a woods. A black-painted, board speaker trap, 53×73×1cm, which was set vertically and emitted a 400-Hz sound, caught as many males of Cx. tritaeniorhynchus as a large cup trap and a previous, standard cylinder trap did. However, a board trap caught more unfed and gravid females than others when all were set near a pigpen. The board speaker trap also caught significantly larger numbers of Ae. albopictus females than other traps. This higher attractancy was attributed to its features of sound being emitted from the entire speaker surface, and its visibility to flying mosquitoes. Continuous 8-day trapping of Ae. albopictus with 5 traps of 3 types on each day almost decimated the male population in the woods of 15×100m.

View full abstract

From 1983 to 1987,vertical distribution of trombiculid mites fed on small rodents was surveyed at six sites of different heights on Mt. Hakusan (2,702m above sea level) in Ishikawa Prefecture, which is preserved as a national park. A total of 1,605 mites belonging to four genera and 13 species were found from 21 rodent hosts belonging to four genera and five species. Host animals and mite species were more abundant in the forested habitat below 1,200m than in the higher zones. Mt. Hakusan was regarded as the westernmost distribution of Neotrombicula microti in Japan, which was found at the 2,200m level. The population of N. nagayoi was composed of both the original and variant types. Furthermore, based on present information of the morphological characteristics and geographical distribution throughout central-northern Japan, the so-called Leptotrombidium miyazakii group including three variants may be reasonably represented by the two species, L. owuense and L. miyazakii, as each one was originally described.

View full abstract

Entomogenous nematodes, Steinernema feltiae (ALL and Mexican strains), S. bibionis, S. glaseri, and Heterorhabditis heriothidis were evaluated for their infectivity to larvae of a Japanese species of flesh fly, Boettcherisca peregrina by the contact method with nematode suspension. The 3rd instar larvae of B. peregrina were forced to contact with a suspension of infective larvae of nematodes for 48hr and the mortality of treated insects calculated from adult fly emergence was determined. Both strains (ALL and Mexican) of S. feltiae and S. bibionis were most infective to B. peregrina larvae, followed by H. heriothidis, whereas S. glaseri showed no significant infectivity to larvae of the fly. To investigate the effect of temperature on infectivity of nematodes, the 3rd instar larvae of B. peregrina were incubated with a suspension of nematodes at 5 different temperatures between 15 and 35℃ for 48hr. S. feltiae (ALL and Mexican strains) were most infective at 25 and 30℃, less infective at 30℃, and showed no remarkable activity at 15 and 35℃. Loss of S. feltiae infectivity at 35℃ was due to death or weakening of nematodes at higher temperature. Loss of infectivity at 15℃, on the contrary, was caused by immobility of nematodes at lower temperature. Housefly (SRS strain) larvae were reared in a medium containing S. feltiae (ALL strain) for evaluation of its infectivity. The 2nd instar housefly larvae were placed on standard barley bran media with infective larvae of the nematode and adult fly emergence was subsequently observed. S. feltiae almost completely inhibited house fly emergence at a concentration of (10)^5 per 100g larval medium.

View full abstract

The tabanid fauna of the eastern part of Hokkaido, Japan, was surveyed at 14 sites by collecting adult females with a mosquito-net trap baited with dry ice on August 9-11,1985. A total of 3,567 adult females belonging to 5 genera and 13 species were collected. Haematopota tristis was the most predominant occupying 86.6% of the total catch, then followed by Hybomitra olsoi (4.4%), Tabanus chrysurus (3.8%). T. nipponicus (2.1%), Chrysops suavis (1.2%) and Hy. borealis (0.9%). Hy. takahasii, a very rare species, was collected at Kamioboro and Kiritappu. Mass occurrence of Ha. tristis was observed at the forest areas of Kamioboro, Lake Notoro and Lake Chimikeppu.

View full abstract

[in Japanese]

View full abstract

The blackflies fauna was surveyed at 68 stream sites in Tochigi Prefecture, Japan, in April-May 1983. A total of 2,794 larvae and 993 pupae belonging to 20 species were collected from 61 sites in Tochigi. The predominant species were Simulium uchidai (21% of the total), S. japonicum (21%) and Prosimulium yezoense (11%). The widely distributed species were S. japonicum (56%), S. uchidai (49%), S. subcostatum (45%) and S. suzukii (30%). Six species (S. iwatense, P. yezoense, S. japonicum, S. subcostatum, S. uchidai and P. kiotoense) were collected from the low land (lower than 500m above the sea level) to the high land (higher than 1,000m).

View full abstract

[in Japanese]

View full abstract

A recurrence of tsutsugamushi disease in 1983 in Saga Prefecture, western Kyushu, Japan, led us to survey the vector of the disease and antibodies against Rickettsia tsutsugamushi among wild rodents and inhabitants in the prefecture. In the foothills of four different areas, a total of 185 wild rodents (all Apodemus speciosus, except for 3 individuals of A. argenteus) were captured alive between October 1984 and October 1985. From these rodents, a total of 10,456 trombiculid mites of 11 species were collected. Leptotrombidium scutellare and L. pallidum, known vectors of tsutsugamushi disease in Japan, were confirmed. The former was found from October through March, while the latter was collected from November through May. This seasonality coincided with the occurrence of tsutsugamushi disease from fall through spring in Saga Prefecture. Wild rodents having antibodies against R. tsutsugamushi were present throughout the year. Detection of antibodies from 2.6% of the inhabitants suggests the presence of unreported cases of infection with R. tsutsugamushi in Saga Prefecture.

View full abstract