Localization of cholinesterases in the tissues of the American cockroach was studied histochemically by thiocholine method which was developed by Koelle and his coworkers. For the quantitative estimation of the activities of cholinesterases, the manometric method was used, and the effects of the fixatives and the salt concentrations used in the histochemical procedures on the activities of cholinesterases were estimated.
The optimum pH for the maximum activity of cockroach cholinesterases was 7.2 to 8.0, and the optimum acetylcholine concentration of the substrate was 0.03 to 0.008M. Therefore, cholinesterases of the cockroach are very similar to the specific or true cholinesterases of mammals.
For detail observation of the sites of cholinesterases in the tissues of the cockroach, it is desirable to prepare the sections as thin as possible. On the other hand, to keep the activities of the enzymes as high as possible, it is better to prepare the sections from fresh tissues, but it is difficult to cut thin sections from fresh materials. To facilitate thin sectioning, tissues were fixed in 10 per cent neutral formaline for 48 hours at room temperature varied from 5 to 13°C. By this treatment, activities of cholinesterases decreased to 54 percent as compared with that of the fresh tissues. Fixation of the tissues in pure acetone for two hours also gave good result, but prolonged fixation destroyed the cholinesterase activity. Fixation with ethyl alcohol for more than two hours badly destroyed the enzymes, so it is not recommendable.
Media that contained 25 per cent of sodium sulphate were used in histochemical study for the purpose of eliminating artifacts which caused diffusion of cholinesterases, but sodium sulphate itself destroyed 42 per cent of cholinesterase activity. Incubation media used in histochemical method contained 25 per cent of sodium sulphate and some of cupper sulphate and glycine, and their pH were 6.0. In these media, activities of cholinesterase were adout 20 per cent as compared with that of optimum condition. Though these media were far from the optimum condition for the maximum activity of the enzyme, but were sufficient to detect sites of cholinesterases in the tissues.
Activities of cholinesterases were found in all nervous tissues such as brain, ganglions, nerve cords, and peripheral nerve fibres in muscles and both digestive organs and reproductive organs. No choliesterase activity was found in dorsal vessel, fat bodies and trachea. Low activity of cholinesterases was found in hemolymphs, but their localization in the hemocytes were not detectable.
In general cholinesterases in the American cockroach were of specific type and hydrolyzed acetylthiocholine more easily than butylthiocholine. But cholinesterases of the digestive and reproductive organs hydrolyzed much more butylthiocholine than that of other tissues, so they might be of both specific and non-specific types. Whether the activities of cholinesterases in the muscles, digestive organs and reproductive organs would be derived from the nervous system which ended in these tissues or from the cells of these tissues themselves were not determined.
Cholinesterases were found in cytoplasms, but not in nuclei. In nervous system, activities of cholinesterases were high on the nerve sheaths and surfaces of neurons, and we could detect the runnings of neurons by the distribution of the enzymes. A very high activity of cholinesterases was found in the brain, but their distribution in it was not uniform. In some parts of the brain little or no cholinesterase activity was found. This might indicate the different physiological functions in the different regions of the brain.

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As reported in the previous paper (1957), engorged adult female tick, Boophilus caudatus, can not be killed easily even when the maximal dose of γ-BHC is given, but various physiological changes appear with a dose that is much smaller than the lethal dose. Especially, the inhibitory effect of oviposition will make it possible to control the multiplication of ticks.
1. The effects of various insecticides as applied topically, upon the loss of body weight and the oviposition were investigated at 27.5°C and 100% R.H.
2. The percentage of loss of body weight increased abruptly with a dosage of more than 6μg/g of γ-BHC. Parathion, allethrin and TEPP showed a similar tendency in a dosage of more than 6, 100 and 135μg/g, respectively.
3. No loss of body weight was demonstrated in a range of the dosage of the following insecticides; α-BHC (2.82∼35.6mg/g), pp'-DDT (10.0∼1110μg/g), and op'-DDT (100∼3000μg/g).
4. The degree of loss of body weight was almost parallel to the severity of the characteristic symptoms of poisoning, such as wetting and clarification of the cuticle, secretion of watery droplets at certain portions of the cuticular surface, contraction of the dorso-ventral muscles, craniocaudal bending of the body, and decrease of body tension.
5. It was assumed that the loss of body weight was caused by elimination or secretion of water probably according to the activity of the epidermal cell, but this phenomenon disappeared in cases where the higher dosage was applied.
6. In the dosage of such insecticides as γ-BHC, parathion, allethrin and pp'-DDT which caused the loss of body weight, the inhibition of the oviposition of ticks occured. So far as this investigation goes, 3mg/g of op'-DDT and α-BHC partially interrupted the oviposition.

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Investigations have been made on the arrested development of fully grown larvae of the Indianmeal moth, Plodia interpunctella HÜBNER under the controlled temperature conditions in the laboratory using rice bran as the food of the larvae.
The onset of arrest in this species is governed by the temperature conditions. When they were reared at 30°C from their parental stage up to the egg stage, the 1st, 2nd and 3rd larval stages, and removed into 20°C respectively, all of them entered a state of arrested development at the fully grown stage.
However, when the larvae were removed at the 4th and 5th instar stages, some or no larvae entered an arrested state at the fully grown stage, and the larvae which have no resting stage pupated promptly even under the temperature condition of 20°C and produced adults.
The arrested larvae are not completely inactive, but differ from the non-arrested larvae not only in physiological but also in morphological and behavioristic characters as shown in the table.
When the arrested larvae are removed from 20°C to the high (30°C) temperature condition they pupate promptly without any interruptions.
The arrested larvae, however, show the characteristics, just like “diapause” insects, such as the interruption of pupation at about 20°C, the strong resistance to cold, the chilling effect of 5∼10°C conditions upon the pupation at 20°C.
It is also one of the features of the “diapause” that the stage of arrest is characteristic of the species. In adition to this, the changes of the body weight and the water content of the arrested larvae at about 20°C resemble those which are observed in the “diapause” larvae of insects.
In view of the results described above it can be suggested that the larval hibernation of the Indianmeal moth is not the “quiescence” owing to low temperature but one of the types of “diapause”. This type of diapause can be expected to exist among other insects.

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The bean webworm, Sylepta ruralis SCOPOLI, is a destructive leaf-roller of the soy bean plant in Japan. From the standpoint of its control, the authors studied some bionomics of said insect in the Takada district, which is a part of Japan sea shore belt, in 1953 and 1954.
In these experiments, the seasonal fluctuation and the sex ratio of bean webworms collected by a light trap, the durations of the egg, larval and pupal stages in the laboratory, the density of egg-masses laid and its difference among soy bean varieties in the field were investigated. The results obtained are summarized as follows:
1. The number of adults attracted to the light trap in every night begins to increase gradually from the beginning of July till it attains to the maximum in the middle of July, but it tends to decrease gradually after that date. The sex ratio of the adults at the beginning of July seems to remain at a low level, then tends to increase towards the end of July. But it seems to fall till a low level again at the beginning of August. The seasonal fluctuation curve of the egg-masses on the soy bean leaves in the field and that of the adults caught by the trap are considered to be parallel.
2. Number of egg-masses per hill were observed on 7th, 11th, and 21st of July, and the maximum number of egg-masses on each of these days were 3, 12 and 24 respectively. The number of egg-masses laid on a leaf were observed to be 1 to 14, but 1 egg-mass was most abundant and 2∼3 egg-masses were less in a descending sequence. An egg-mass contained 1 to 12 eggs but most of the masses contained only 1 or 2 eggs.
3. The correlation coeficient between the sex ratio of the adults caught by light trap and the egg-masses on the plant in 1953 is 0.8144 with significance at 1% level, and that in 1954 is 0.5392 with significance at 5% level, and there are the following relations between the sex ratio (x) and the egg-masses (y).
y=1.62x-83.15 (in 1953)
y=0.97x-52.95 (in 1954)
The correlation (γ) between the number of adults caught by light trap and the egg-masses on the plants in 1953 is 0.7834 with significance at 1% level, but this relationship is not significant in 1954.
4. The duration of the egg stage in the maximum oviposition period is about 5 days. The larva passes six instars. The duration of each instar of females is 2.6, 3.0, 2.0, 2.6, 3.2, and 4.4 days respectively and duration of each instar of males 3.3, 2.7, 2.0, 2.7, 3.2, and 3.4 days. The duration of pupal stage of both sexes are considered to be about 9 days.
5. The soy bean varieties can be classified in the following five groups according to the difference in the number of egg-masses laid and the degree of damage; I. Shin-4go, II. Akazaya and 3 other varieties, III. Dekisugi and 5 other varieties, IV. Kairyo-gionbo and Ishihara, and V. Shimokaburi. The egg masses are generally laid on the leaves of the varieties whose blooming time coincides with the peak period of the oviposition. Moreover, the oviposition seems to increase when the plant has a greater number of leaves, the plant is taller and the index of the plant growth (multipled width and height of plant) is larger.
6. When the soy bean plant had been kept in a dark box during the five days in the middle of July, the number of egg-masses laid on the said plant in the succeeding four days was half of that obtained on a non treated plant. This may show the fact that the oviposition response of this insect differs in relation to the amount of bio-chemical substances which are composed in the plant, but this question remains to be studied in the near future.

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The cowpea weevil, Callosobruchus quadrimaculatus, has two distinctly different forms in the adult stage, fly and non-fly forms, which are induced by the effect of population in the larval stage. These two forms are very like to the "phase" dimorphism observed in the locust and army worm. In the present paper, different densities of comparisons were made between these two phases in their body weight and the chemical constituents of their body.
The body weight of adult weevil decreases with the lapse of adult life, but this decreasing tendency is different between these two phases and sexes. (ref. Fig. 1, fly female _??_, fly male _??_, non-fly female _??_, non-fly male _??_).
The water content of the body takes an almost constant value throughout the life, but takes a different value in each phase (ref. Fig. 2. similar sign as in Fig. 1). Crude fat content shows a definite difference between these two phases. That of the fly phase is higher in both sexes. A clear difference can be found in the acid value and iodine value of the crude fat, while there is no definite difference in saponification value. From these data, we can imagine that the fly phase has a kind of diapause in the initial stage of adult life.

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1. Coenzyme A and choline acteylase are essential for the synthesis of acetylcholine in the eggs of the rice stem borer, Chilo suppressalis, and of the cabbage armywarm, Barathra brassicae.
2. The absence of synthetic activity of acetylcholine in these eggs of early stage is due to the lack of the terminal enzyme, choline acetylase, nevertheless coenzyme A is present during the course of their embryonic development.
3. The fluctuations of acetylcholine and the related factors in the eggs of insects are shown in diagramatically.

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1. The cuticle of the membranous parts such as arthrodial membrane of body trunk, articular corium of thoracic legs and the membranous ring of abdominal legs of the larvae of the rice stem borer, Chilo suppressalis WALKER, consists of epicuticle and endocuticle, but sclerotized exocuticle is absent.
2. The epicuticles in all membranous parts are different in properties from those in sclerotized regions, namely, the wax layer is believed to have such a property and a thickness as to make the passage of liquids easier and the reactions to prove the presence of lipids and proteins in the outer (paraffin) and inner epicuticle (cuticulin) are both weaker compared with those of sclerotized regions.
3. The rate of entry of insecticides is generally faster through the cuticle of membranous parts than that of sclerotic regions. Topical applications of oil emulsions of BHC and Folidol made on various areas of integument resulted in the development of toxic symptoms of the larvae in the order of the rate of permeation, spiracles=thoracic and abdominal legs≥intersegmental membranes≥caudal legs>body sclerites.
4. Such differential penetrability of insecticides may be due to the differences in the structures and the properties of the cuticle of the body regions as described above.

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[in Japanese]

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1. The critical period of determination of future wing development of the apple grain aphid, Rhopalosiphum prunifoliae was determined experimentally at a constant temperature of 25°C, using high population density and starvation as the stimuli.
2. The action of starvation is in general far stronger stimulus for wing development than that of high population density.
3. In the larvae maintained at high population density during 40 hours following the birth or during the earliest stage of the second instar, the percentage values of the winged individuals produced in the third instar are very much larger than those in low density at the corresponding stage.
4. In the larvae forcibly removed from the food plant for 5 to 15 hours immediately following birth and after various hours from 5 to 35 hours following the emergence, high percentages of wing development are always obtained.
5. Maximum rate of wing development caused by the effect of 5 hour starvation is obtained in larvae of 21 hours old which correspond to a later stage of the first instar. And the percentage values greater than 50% are produced during the period extending from 14.5th to 27.5th hour after birth, i.e., from the middle to the end of the first instar.
6. The increase in the rate of wing formation can not be seen in the larvae starved at ages beyond the 10th hour of the second instar.
7. The increase in the rate of wing development is not so remarkable, when the starvation occurs in the earliest stage of larval development.

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[in Japanese]

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