Blood-sucking insects have bio-active substances in the salivary glands. These substances have activities on host blood coagulation system, hemostasis and blood vessel. Recently many of those molecules were isolated and characterized, and some of their genes have been cloned. We extracted and purified multiple hemoproteins from the salivary glands of reduviid bug, Rhodnius prolixus, and the cDNA of these proteins were cloned. We clarified that one of these proteins with a molecular weight of approximately 20,000 (designated as Prolixin-S) is not only an anticoagulant that inhibits an intrinsic coagulation factor (IX/IXa), but also a relaxant of vascular smooth muscle. We found that Prolixin-S binds with the smooth muscle relaxant nitric oxide NO that is synthesized in the salivary glands, and is injected into host during blood sucking, then release NO and relaxes the host blood vessel. That is, Prolixin-S reversibly binds with NO and function as a NO carrier.

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During blood feeding, the protein contents of the salivary glands of Anopheles stephensi are greatly reduced. To observe the changes in salivary proteins, we analyzed the salivary glands of An. stephensi at different stages of the blood-feeding process; before probing, during probing, during feeding, and after feeding. We also investigated the midgut contents and prediuresis fluid of An. stephensi. Proteins in the salivary glands were reduced not only at the probing phase but also at the blood-feeding phase. In the midgut contents after a full blood meal, we found some proteins reacted with rabbit anti-salivary gland serum, which did not react with the midgut contents of mosquitoes before feeding. This suggests that these proteins come from the salivary glands. After feeding, we also found sporozoites in the prediuresis fluid of An. stephensi, which had been infected with Plasmodium berghei. These sporozoites may come from the salivary glands, because the density of sporozoites in the prediuresis fluid correlated with the number of sporozoites in the salivary glands. These results indicate that An. stephensi mosquitoes draw back their own saliva into their midguts when they feed blood.

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Two new species of the genus Helina Robineau-Desvoidy are described from Japan and their ♂ genitalia are illustrated. These are H. aguii sp. nov. and H. japonica sp. nov.

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Ovicidal effects of the juvenile hormone analogue, pyriproxyfen, against the cat flea, Ctenocephalides felis, were evaluated by laboratory test. Flea eggs aged for <2,4-6,10-12,22-24,or 46-48hrs after oviposition were exposed to pyriproxyfen on filter paper disks for 24hrs at 26℃ and 60%RH. The ovicidal effects were observed when flea eggs aged within 2hrs were exposed to pyriproxyfen, showing that the IC_<50> was 0.021μg/(cm)^2. Higher hatch inhibition tended to occur with younger aged groups of flea eggs. However, hatching of the eggs older than 46hrs was not inhibited. In the experiment on the influence of pyriproxyfen against flea eggs exposed for some fixed time duration, higher inhibition of hatching tended to occur with longer exposure times for any aged group of the flea eggs. Adult males exposed to the pyriproxyfen-treated glass surface (25,10,1μg/(cm)^2 as active ingredient) and females untreated, or vice versa, were infested on a mouse to investigate the ovicidal inhibition effect on flea eggs. The hatchability of eggs laid by females decreased with the increase of dosage. The sexual transmission of sterility by pyriproxyfen-treated males was also observed. However, the influence of pyriproxyfen wore off with time as the fleas aged after exposure.

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In a study of whether black flies transmit pathogens from deer to livestock, black flies were collected with a light trap at a deer shed in Morioka, Iwate Prefecture, Japan, and examined for natural infection with filariae. A total of 970 black flies belonging to the following five species were captured : Simulium bidentatum, S. iwatense, S. aokii, S. nikkoense, and S. daisense. All but S. daisense sucked blood from deer. S. bidentatum, S. iwatense, and S. nikkoense had sucked blood from both cattle and deer. S. bidentatum was naturally infected with first-stage filarial larvae in the pectoral muscle. The black flies may carry pathogens between deer and cattle.

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Three of four men felt severe itchiness on their hips, groin and knees when they stayed in the Jumonji hut (2,030m) in Saitama Prefecture on May 23,1999. Two days after this incident, a total of six fleas were captured from the pants of the three victims. Two of the 6 fleas were brought to the laboratory and were identified as Ceratophyllus garei. Meanwhile, 4 males and 1 female C. garei were collected from the nest of a Japanese wren, Troglodytes troglodytes, on April 4,1977 on Mt. Buko of Saitama Prefecture. These data complement the collection records of C. garei in Japan.

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The drop-off rhythms of engorged Ixodes nipponensis larvae and nymphs on albino mice were observed in a 14L-10D photoperiod. The engorged larvae and nymphs on mice exhibited a diurnal drop-off rhythm. The drop-off rhythm on mice was the same as that on the lizard, Takydromus tachydromoides. This suggests that the drop-off rhythms of the engorged larvae and nymphs are not affected by the physiology and daily activity of host animals.

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Invasive phenomenon and incidence of the Musca species in the process of construction and development of human settlements in a tropical forest were observed with bait-traps in the dry season in Sulawesi and Seram, east Indonesia. Flies collected at 7 stations in the Toili district of Central Sulawesi numbered 2,215 comprising 3 families, viz., Muscidae, Calliphoridae and Sarcophagidae. Of them, 47 individuals of 3 species, Musca domestica Linnaeus, M. ventrosa Wiedemann, and M. sorbens Wiedemann, were collected. No Musca species was caught in the uninhabited forest. M. domestica and M. ventrosa were caught in the deforestation area and at the boundary between the natural forest and a new village. M. sorbens, together with M. domestica and M. ventrosa, was caught in a new village, an old village and the Toili town. The proportion of the Musca species in total flies increased with the lapse of time after construction of human settlements. In Manusela village isolated by a tropical forest in Seram, M. sorbens occupied 98.3% of the Musca species collected, while M. domestica were very few.

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Between 1996 and 1998,a total of 550 unfed ticks were collected from vegetation at 11 sites in the central part of Hokkaido, and were examined for spotted fever group rickettsiae. When 261 ticks consisting of Ixodes ovatus, I. persulcatus, I. tanuki, Haemaphysalis douglasi and H. flava were examined by inoculating tick emulsions into L-929 cells, two adults of I. persulcatus from one site (Hobetsu Town) yielded rickettsial isolates. Serotyping showed that the present isolates (IP-1 and IP-2 strains) were of the unclassified IO-1 serotype belonging to the spotted fever group, which was previously designated by us.

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With a view to clarifying the differences in distribution among chironomid species with respect to water velocity and depth in a riffle-pool unit of the river, compositions of adult males were examined which were obtained from larval samples attached to artificial substrates submerged at various points of a site of the Ohta River, Hiroshima Prefecture. As regards water velocity, Tanytarsus tamaduodecimus, Parakiefferiella oyabelurida, Microtendipes britteni, Tanytarsus tamagotoi, Cryptochironomus tamayoroi, Nanocladius quadrivittatus, Parametriocnemus stylatus, Polypedilum asakawaense, Potthastia montium and Tanytarsus arduennensis were distributed only in a range of 0-0.4m/s whereas Nilotanypus dubius, Polypedilum takaoense, Polypedilum tamahosohige and Synorthocladius tamaparvulus were distributed only in a range of 0.4-0.8m/s. On the other hand, Polypedilum hiroshimaense and Cladotanytarsus vanderwurpi were distributed in a wide range of 0-1.2m/s. As regards depth, N. dubius and P. takaoense, P. tamahosohige and S. tamaparvulus were distributed only in a range of 0-30cm whereas T. tamaduodecimus, M. britteni, T. tamagotoi, C. tamayoroi, N. quadrivittatus, P. stylatus, P. asakawaense; and P. montium and T. arduennensis were distributed only in ranges of 30-60 and 60-90cm, respectively. On the other hand, Microtendipes truncatus was distributed in a wide range of 0-90cm. These results suggest that there is a habitat-segregation with respect to water velocity and depth among the species living in a riffle-pool unit in relation to their life styles or foods.

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The fauna and distribution of blackflies in Kagoshima Prefecture were studied based on the collections of larvae and pupae from streams and adults flying around the collectors at 73 sites in spring of 1997. A total of 15,650 blackflies, 14,114 larvae (90.2% in total number), 1,519 pupae (9.7%) and 17 adults (0.1%), were collected at 68 sites. All these blackflies were classified into 16 species of the genus Simulium Latreille. One species, Simulium (Simulium) suzukii was newly recorded from Kagoshima Prefecture. The most abundant species was S. (Gnus) bidentatum (51.3% in total number), followed by S. (S.) arakawae (21.2%) and S. (S.) japonicum (10.2%). The most widely distributed species was S. (Gn.) bidentatum (54 sites), followed by S. (S.) arakawae (46 sites), S. (Nevermannia) uchidai (32 sites), S. (S.) japonicum (19 sites) and S. (S.) quinquestriatum (19 sites).

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