The Guatemala-Japan Cooperative Project on Onchocerciasis Research and Control sponsored by Japan International Cooperation Agency (JICA) was run for 8 years (1975-1983), targeted mainly at the establishment of effective vector control measures of Guatemalan onchocerciasis by applying an insecticide to the streams inhabited by the principal vector, Simulium ochraceum. Following basic studies on taxonomy, biology and transmission of the suspected vector blackflies, extensive and intensive studies were carried out on insecticides, i.e., trough tests to determine the comparative effectiveness of various chemicals, laboratory tests to determine the extent of adsorption of insecticides to soil, and field tests to determine insecticidal carry in various types of streams and the behaviour of insecticides after application in streams. It gradually became clear that the special feature of this vector control lies in infestation of S. ochraceum larvae in streamlets, which accelerates adsorption of insecticides to streambeds, hence accounting for extremely short carry. Together with the information on distribution of the target streams based on geology, geomorphology and geography, the control strategy was established : applying 24g of 5% temephos wdp fortnightly to all the streams with the discharge range of 0.1-50 liter/sec, irrespective of the discharge rate. After the Phase 3 operation commenced in July 1982,the density of S. ochraceum on human bait was suppressed to an extremely low level far below 1.9 flies/man/hr, the critical level theoretically established. The epidemiological evaluation has been made, but final conclusions are not yet drawn.

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Golden Malrin fly bait containing 1% methomyl bait plus Z-9 tricosene (Muscamone) was evaluated against Musca domestica L. population in a chicken farm in Malaysia. Application of methomyl bait at 50mg a.i./m^2 caused an almost sevenfold higher adult mortality rate than that of methomyl application at 10mg a.i./m^2. Methomyl, however, showed poor larvicidal effects on M. domestica. Thus, methomyl as an attractant bait formulation seems to have the potential for adult fly control in the field in Malaysia.

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Cerebrospinal setariosis, or lumbar paralysis, caused by infection with Setaria digitata to sheep and goats results in serious economic loss for stock farmers in Ibaraki Prefecture, Central Japan. Seasonal fluctuations of vector mosquitoes were studied using light traps from May to October during 1989 and 1990. The traps were set in the evening in cattle sheds and sheep sheds. A total of 168,970 female mosquitoes belonging to 9 species were collected by light traps. Culex tritaeniorhynchus was the most abundant species followed by Cx. pipiens pallens and Anopheles sinensis. However, An. sinensis was the most abundant mosquito during the Setaria transmission season of June and July. One out of 408 Cx. tritaeniorhynchus and four out of 312 An. sinensis dissected were found to carry thirdstage larvae of Setaria digitata. It is thus suspected that An. sinensis plays an important role in transmitting the larvae from cattle to sheep or goats in this area.

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Three carboxylesterases (CE's) were separated by PAGE from an organophosphate resistant Culex pipiens quinquefasciatus (Okinawa strain). The first CE was found specifically in the alimentary canal and the second CE distributed throughout the larval body. These CE's were monomeric protein (MW : 60,000) and were categorized as B-type CE. The third CE was a homodimeric protein (MW : ca. 120,000) categorized as A-type CE and detected in all parts except the haemolymph. All CE's showed the characteristic inhibition pattern with organophosphates and carbamates, but their low dissociation constants indicated that the CE's had no hydrolyzing activity against these chemicals. It was supposed from the data presented that the CE's sequestered insecticides and prevented their access to the target, AChE in the central nervous system.

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In order to investigate the influence of housing conditions on the prevalence of house-dust mites in concrete apartment buildings in and around Nagoya City, mite surveys were conducted in living rooms and bedrooms of 20 apartments on the 1st to 10th floors from September 1983 to June 1984 at about 3-month intervals. Allergic children were found in 16 apartments. The mite fauna did not differ much from previous reports : Dermatophagoides farinae (D.f.) and D. pteronyssinus (D.p.) were predominant, constituting about 82% of the totals, followed by Haplochthonius simplex, Euroglyphus maynei, Glycyphagidae, Cheyletidae, Acaridae, Cosmochthonius reticulatus, and Tarsonemidae. A significant negative correlation was found between the percentage compositions of D.f. and D.p. : D.p. had a tendency to predominate over D.f. in apartments with more than 4 members in a family, less than 0.8 of the room ratio (No. of rooms/family size), and on floor levels below the third floor. The numbers of D.p., Glycyphagidae, Tarsonemidae, and C. reticulatus were greater in low-floor apartments (below 3rd) than in high-floor apartments (above 4th). while the numbers of D.f., Acaridae, and Cheyletidae did not greatly vary with the floor levels. These results suggested that household activities and the distance from the ground level were limiting factors for the prevalence of house-dust mites in apartments. The cause of the habitat segregations was considered to be mainly due to the interaction of humidity requirements in mites and the dampness of microhabitats. The mite communities were more complicated in low-floor apartments than in high-floor apartments. The number of allergic children was also greater in low-floor apartments. These data suggested a relationship among the housing conditions, prevalence of mites, and allergic sensitization.

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Atylotus nagatomii n. sp. is described based on male and female materials from Kyushu Island, Japan. This species is related to Atylotus bivittateinus Takahasi, 1962,but can be easily distinguished from it by the dark abdominal tergites with a paler median stripe, which is especially distinct in the male, and by rudimentary middle callus on frons and dense black hairs on maxillary palpi in the female.

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The genetic mode of warfarin resistance in Rattus rattus was studied by crossing experiments of resistant and susceptible colonies. The configuration of the selected colony, [RR]・F_1,was estimated to be [5/10 RR+3/10 RS+2/10 SS] from the plateaux on the log day-probit mortality curve. The log day-probit mortality line of the RR, or homozygous resistants, was estimated from the high mortality portion of the [RR]・F_1 curved line. The [RS]・F_1 colony was obtained by crossing the [RR]・F_1 with the Amami Colony, which is considered to be a homozygous susceptible colony (hereinafter referred to as SS). Theoretically, the [RS]・F_1 colony should be a mixed population of [13/20 RS+7/20 SS]. The theoretical curve thus calculated was similar to the observed curve. Accordingly, the estimated straight line for the RS, or heterozygous hybrids, was established. The [RS]・F_2 colony obtained by crossing [RS]・F_1×[RS]・F_1 should theoretically be a mixed population of [169/1,600 RR+702/1,600 RS+729/1,600 SS]; and the backcross [RRS]・F_1 colony obtained by crossing [RR]・F_1×[RS]・F_1 should theoretically be a mixed population of [169/800 RR+442/800 RS+189/800 SS]. The theoretical curves for the above two were compared with the observed curves. The observed curves were similar to the corresponding theoretical curves, except in respect to the high mortality portions. The reason for the discrepancy at the high mortality portion was not clear. Through these results, warfarin resistance in R. rattus was concluded to follow the mode of monofactorial Mendelian resistance; and from the locality of the RS line, the resistant gene should be incompletely recessive. The discriminating date should preferably be the 28th day, because the survivals on that date should be only the homozygous resistants, thereby enabling easy calculation of the RR ratio in any population concerned.

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Seven colonies of Aedes albopictus larvae collected on 7 islands (Okinawajima, Agunijima, Miyakojima, Ishigakijima, Iriomotejima, Yonagunijima and Minamidaitojima) in Okinawa Prefecture in 1988 were tested for susceptibility levels to 11 insecticides. The (LC)_<50> values of these colonies were 0.057-0.855ppm to p, p'-DDT, 0.046-0.211ppm to malathion, 0.0035-0.0319ppm to fenitrothion, 0.029-0.044ppm to dichlorvos, 0.232-0.516ppm to trichlorfon, 0.163ppm to diazinon, 0.0055ppm to fenthion, 0.011ppm to temefos, 0.019-0.036ppm to bromofos, 2.563-4.922ppm to propoxur and 0.0039-0.0092ppm to permethrin. (LC)_<50>tto p, p'-DDT against the larvae in Iriomotejima was the highest value in Japan, being 50.6 times the lowest value (0.017ppm) obtained in Nagasaki, 1960 (Suzuki and Mizutani, 1962). Against fenitrothion, larvae in Minamidaitojima, Ishigakijima and Miyakojima showed 0.0319,0.0236 and 0.0220ppm respectively in (LC)_<50> value. In general, Ae. albopictus in Okinawa Prefecture was susceptible to all insecticides tested except p, p'-DDT.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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