Some simple polyols and related compounds were assayed by a filter paper method for the feeding-stimulative effect on the three species of cockroaches, Periplaneta americana, P. fuliginosa and Blattella germanica. Glycerol was further tested by a bait method for B. germanica. I. The results obtained by the filter method are as follows. 1) Glycerol is highly effective, but ethylene glycol, 1, 2-propanediol and 1, 3-propanediol are not. 2) The three hydroxyl groups in glycerol, therefore, seem to be essential for the strong activity of this compound. 3) Many compounds with neighboring three or more carbon atoms each of which has a hydroxyl group, especially sugar alcohols, are effective. However, there are also many ineffective stereoisomers among them, especially among sugars (Tsuji, 1965). 4) Therefore, not only the number of hydroxyl groups but the configuration of molecule is also one of the important factors which determine the effectiveness of the compound. 5) It is interesting to know that, a) among aldoses (pentoses and hexoses) Larabinose and D-galactose with the same configuration at C_2-C_3-C_4 were strongly effective for all or one of the three species, whereas other stereoisomers tested were not (Tsuji, 1965); b) glycerol can take all the imaginable arrangements in space of the three hydroxyl groups, and naturally can take the same arrangement of hydroxyl groups as at C_2-C_3-C_4 of L-arabinose; c) the same arrangement of hydroxyl groups as at C_2-C_3-C_4 of L-arabinose can occur more frequently in sugar alcohols than in corresponding aldoses, and many of the sugar alcohols tested were effective, whereas many of the aldoses tested were not effective; d) sorbitol which can take two sequencial sets of the same arrangement of hydroxyl groups as at C_2-C_4-C_4 of L-arabinose was exceptionally effective among the effective sugar alcohols. 6) One possible speculation is that glycerol, the effective sugar alcohols, and the effective aldoses stimulate the receptor of the cockroaches by combining with the same combining site which consists of sequencial sets of structures corresponding in some way to the arrangement in space of hydroxyl groups at C_2-C_3-C_4 of L-arabinose. 7) A few glycerides, including monoolein, triolein and tricaprin, are somewhat effective, though they have not three hydroxyl groups. In these glycerides, the cockroaches seem to respond to specific acyl groups in their structures. II. The results obtained by the poison bait method with the German cockroach show that glycerol is quite effective as a feeding-stimulant in practical poison baits, and is much more effective than maltose, the strongest feeding-stimulative sugar.

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[in Japanese]

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The segregation of the siphonal hair types in the type 3-3 population of Culex pipiens molestus was observed (Tables 3 and 4). The occurrence frequency of the type 4-4 larvae decreased, that of the type 4-3 had once increased and then decreased, and that of the type 3-3 larvae increased, when the selection progressed. These changes in the occurrence frequencies did not occur in one directional way, but with the occational increase or decrease (Fig. 1). Viability of the F'_8 population was too low to produce the next generation (Tables 1 and 2).

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Various methods have been proposed for the detection of mites in stored food, house dust, straw, and other materials with different characters. The authors carried out a seires of experiments with various methods for comparison of the efficiency in the recovery rates of living and dead mites, that in selectivity of mites from other debris, and from standpoint of economy and labour. The methods may be classified into the three categories, (1) those separating the mites by specific gravity of the media, (2) that separating from materials suspended in water by trapping in kerosine, and (3) the classical Berlese's method, or the collection of mites on water surface that escaped from the breeding media heated by eradiation with electric bulb. Two species of mites were used in the present experiments, Tyrophagus putrescentiae and Dermatophagoides farinae, both bred in artificial media. The living mites were marked by adding the dye azur II disolved in alcohol to the culture media (powder of laboratory mouse food), and were collected on water surface by placing the containers of culture media in a dish with water. The marked dead mites were produced by killing the mites on filter paper with heat from infra-red bulb, and by staining with eosine. The saturated NaCl solution with a specific gravity of about 1.2 was found to be an excellent media for separating the living mites from the breeding media either by floatation in Wildman flask, or by centrifugation of debris in centrifuge tubes, but the rates of recovery of dead mites were rather poor. The mites isolated with saturated salt were alive and intact, and could be used for further studies in immunology and biology. Some media with specific gravity of about 1.2, such as the pure lactic acid, glycerine or sugar solution, were found to be as useful but less economic than the saturated salt solution. The use of organic solvent with various specific gravity prepared by mixing carbon tetrachloride and ether were found to be not efficient in separating the mites by floatation, as the media were easy to penetrate into the mite body and gave balanced specific gravities. The classical method using Wildman's flask, mixing the materials with water and separating the mite bodies with kerosine, was found to be excellent also in isolating both living and dead mites from materials such as house dust, when small amount of kerosine such as 1ml to 500ml of water was used. Another classical method of the use of heat from electric bulb on straw and other materials as the media for the breeding of mites was found to be excellent also for separating the living mites under appropriately designed equipments.

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Some experiments were made in order to compare efficiencies in sampling mosquito larvae of two types of dippers, equal in size but different in bottom lining; one is an improved type screened with wire netting at the bottom (Fig.1), and the other is a conventional one. (1) A series of preliminary laboratory experiments were carried out with Culex pipiens pallens larvae. Alternate single-stroke sampling was made repeatedly by two operators with the two different dippers from each of two equal-sized containers, in which 200 larvae in same instar had been released. Average sizes of larval samples collected with the improved dipper (ID samples) were 1.51 to 1.90 times as large as those collected with the conventional one (CD samples) (Table 1). In the similar type of experiments carried out in the field with a mixed population of Culex species, the above values were 3.23 to 3.78 (Table 2). (2) In these experiments, there was no significant difference in the relative frequencies of the component species between ID and CD samples (Fig.2). But, there was a slight difference in age structure of C. tritaneiorhynchus larvae which were dominant at that time; frequencies of the first and second instar larvae in ID samples were somewhat lower than those in CD samples (Fig.3). (3) Such a difference in larval age structure, however, was not observed between ID and CD samples in the case of additional laboratory experiments with C. pipiens pallens larvae (Fig.4). In these experiments, 100 larvae of each instar i. e. 400 in all, were released together in a single container so as to expect equal chance of their being sampled. But the frequencies of the first to third instar larvae were significantly lower than that of the fourth instar in both of ID and CD samples, probably because of their different vertical distributions in water.

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Effects of some organophosphorus insecticides against the last instar larvae of Genji firefly, Luciola cruciata Motschulsky and their prey, Japanese melanial snail, Semisulcospira bensoni Phillipi collected in the streams of Nagato city, Yamaguchi-prefecture were studied in a laboratory and some field tests also carried out. Insecticides used in this study were fenitrothion 10% wettable powder (WP), fenthion 5% WP, ABATE 5% WP and fenthion 5% emulsifiable concentrate (EC). In the laboratory tests, fenitrothion, fenthion WP and ABATE were considered to be practically non-toxic to both firefly larvae and snails. Whereas fenthion EC was apparently toxic to the both species, no significant difference was observed among the toxicity of the three insecticides formulated as wettable powder. In the field tests, application of fenitrothion WP and fenthion WP for control of the larvae of Black fly, Prosimulium hirtipes Fries (stream application of 0.5 to 1.0 ppm of the active ingredients for 10 minutes) was entirely harmless to both firefly larvae and snails in the streams.

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1. The feeding preference of Norway rats, Rattus norvegicus, on poison baits with 4 acute rodenticides, i. e. norbormide, scilliroside, zinc phosphide and thallium sulfate, as well as the killing effect of these rodenticides, was studied in a laboratory. 2. Rats showed poor feeding preference on dry baits with 1% norbormide, resulting in a low mortality of the rats. They appeared to be remarkably shy to the baits of norbormide as high as 0.5% of the toxicant, though only slightly shy to 0.25% baits. Raw sweet potato baits with 1% norbormide were preferred to the dry baits, causing a higher mortality of them. The rats which consumed the dry baits showed rapidly the sign of intoxication. The killing effects of norbormide showed much variation, which was shown by the fact that doses of the toxicant taken by the rats killed and by the survivors were similar; the former 33-100mg/kg and the latter 27-147mg/kg. 3. With 0.017% scilliroside dry baits, rats did not take lethal dose, probably because of their shyness to such a higher concentration of the toxicant. They seemed to show shyness, if the concentration in dry baits is higher than 0.083%. Raw sweet potato baits with 0.017% scilliroside were prefered to the dry baits, causing a higher mortality of them. The rats which consumed a lethal dose of scilliroside were killed 1 to 4 days after feeding. Doses of scilliroside taken by the rats killed were 1.4-4.5mg/kg, and by the survivors were 0.3-1.9mg/kg. 4. With 1% zinc phosphide dry baits, rats did not take lethal dose, probably because of their shyness to such a higher concentration of the toxicant. The action of zinc phosphide was rapid, but its effects were manifested with much variation. Doses of zinc phosphide taken by the rats killed were 65-143mg/kg, and by the survivors were 69-330mg/kg. 5. Rats preferred both dry baits and raw sweet potato baits with thallium sulfate, showing a higher mortality. Shyness to the dry baits was not shown, if the concentration of the toxicant was as low as 0.15%, though they were slightly shy to 0.3% baits. The action of thallium sulfate was slowly manifested; the killing effects appeared 2-5 days after feeding. Doses of thallium sulfate taken by the rats killed were 41-187mg/kg.

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There was monofactorial inheritance of parathion-resistance in larvae of the strain of Culex pipiens pallens that was selected with ethyl-parathion for 18 generations and showed twenty-fold resistance to the selecting insecticide. The factor for parathion-resistance was incompletely dominant and calculated to be linked with a recombination value of 17-20% to the malathion-resistance factor which has been reported to be in linkage group 2.

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Octachlorodipropyl ether, a synergist for pyrethroids, was studied as a synergist for carbamates to the house fly. Octachlorodipropyl ether showed a remarkable synergistic activity, as compared with the activity of PHC (Baygon), MPMC (Meobal). CPMC or NAC (Sevin) alone.

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