Pheromone gland components of virgin female silkworm moths were further investigated. One-fifth part of ether extract of the pheromone gland was studied by capillary GC-MS in applying splitless injection method. Seven major peaks were observed in the total ion chromatogram. The most abundant component was identified as bombykol where amount exceeded 1μg/gland. The other components were considered to n-tricosane, n-pentacosane, n-heptacosane, hexadecanol, hexadecenol and octadecanol+(E, E) isomers of bombykol. Identification of these seven components was carried out using the pheromone glands of 1, 000 virgin female moths. The results of silica gel and argentation silica gel chromatography, retention indices in GC and mass spectra agreed with the results obtained by capillary GC-MS. Double bond position and geometric configuration of hexadecenol was found to correspond to (Z)-11, by ozonolysis and synthesis. Bombykal that had been reported by KAISSLING et al. (1978) was not detected in our study. (Z)-11-Hexadecenol may have been produced through biosynthesis from (Z)-11-hexadecenoic acid that had been identified as a characteristic fatty acid in the pheromone gland of the female silkworm pupa and moth. (Z)-11-Hexadecenol may play an important role in the biosynthesis of bombykol.

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Twenty-three derivatives of 4-(phenylazo) phenol were evaluated for their effectiveness as molluscicides. Five of the compounds of the formula: where R¹ is a halogen or nitro, R² and R³ are halogen, or halogen and nitro substituents, showed strong toxic effect on Acusta despecta sieboldiana. This structure-activity relationship was similar to that observed in the previous experiments on aquatic oligochaetes which inhabit muddy holes. The toxicity of P-99 (Yurimin^®), 2, 6-dibromo-4-(4-nitrophenylazo) phenol, which was selected from among the five compounds, was evaluated on several species of snails and slugs. P-99 was toxic to the snails and slugs. P-99 in dust formulation was also toxic to A. despecta sieboldiana after application of the surface of certain objects, on which the crawling snails were occasionally observed under field conditions. Lethal effect on snails was observed only for P-99 when compared with the effects of some conventional molluscicides applied as dusts on cabbage. The effectiveness of P-99 was mainly due to its contact as well as oral toxicity. The effect of P-99 on the motility of the slugs was examined in applying the MAGNUS method. P-99 induced excitability and strong contractions in slugs. Histopathological observations of the dermal and hypodermic tissues of slugs immersed in P-99 solution revealed a swelling of the cells, along with degenerative and destructive changes of the tissues.

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Differences of urea contents in the hemolymph between the silkworm larvae reared on artificial diet and those on mulberry leaves were investigated during the course of the 5th instar. In the individuals reared on artificial diet, urea-N content in hemolymph was kept at an approximately constant level ranging from 200 to 300μg per ml during the feeding period, but after spinning the level increased markedly up to 700-800μg per ml. On the other hand, urea-N content in the hemolymph of the larvae fed on mulberry leaves gradually decreased from the highest level of 600μg per ml during the feeding stage, to reach a level of below 50μg per ml in mature larvae. Even when larvae fed on artificial diet were subsequently reared on mulberry leaves for only two days before spinning, urea sharply decreased in the hemolymph as in the larvae reared on mulberry leaves throughout. Urea content in the hemolymph of mature larvae tended to increase with the increase of the content of soybean meal or mulberry leaf powder in the artificial diet. When the larvae fed on artificial diet where any of the soybean oil, salt mixture and sucrose components was omitted, urea content in the hemolymph of mature larvae increased more than in the hemolymph of those fed on the complete diet. On the other hand, omission of mulberry leaf powder, soybean meal, potato starch or antiseptic from the diet caused a decrease in the urea content in the hemolymph, though the decrease never reached the level of that observed in rearing on mulberry leaves. When larvae were reared on artificial diet, the urea content in the glandular tissue including sericin of the middle division of the silkgland was almost identical with that in the cocoon shell. These facts strongly suggest that urea in the cocoon shell is excreted with sericin from the silkgland at spinning.

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Changes of urea contents in the hemolymph from pupation to adult emergence were compared between silkworms fed on mulberry leaves and those fed on artificial diet. Urea-N contents in the hemolymph of pupae from larvae reared on artificial diet ranged from 600 to 1, 200μg per ml. On the other hand, ureá-N was hardly detected in the hemolymph of pupae from larvae reared on mulberry leaf. Urea did not accumulate in the pupal hemolymph, even when the larvae reared on artificial diet were subsequently fed on mulberry leaves only for 2 days before spinning. Urea content in the hemolymph of pupae reared on artificial diet varied with the silkworm varieties and dietary conditions, but it always exceeded the level of that in the hemolymph of pupae reared on mulberry leaves. In the eggs laid by adults reared on artificial diet, urea-N contents ranged from approximately 300 to 750μg per g. Furthermore, urea contents in the hemolymph of adults which laid a large number of nonfertilized eggs, were higher than those of adults which laid normal eggs.

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Diel periodicity of male attraction in the smaller tea tortrix moths was studied using sticky traps baited with synthetic sex pheromones and virgin females during four different flight seasons in tea fields. The number of males trapped was counted every hour for three successive nights in each season. Male attraction commenced one hour earlier when synthetic sex pheromone trap was used compared to virgin female trap, but there was no difference in the peak time of male capture among the seasons. The peak time of male capture in the first flight season (overwintered generation) occurred earlier than that in the following three seasons. These results appear to be associated with the lower temperature and larger temperature drop recorded in those nights during the first flight season than during the other three seasons. Observation of night activity of males in the field showed that male flight activity increased immediately after dusk and was not necessarily correlated with the diel periodicity of attraction to sex pheromones.

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The toxicity of benzomate to the female adult of susceptible strains (Shizuoka S and Fukuoka S) and resistant strains (Shizuoka R, Fukuoka R and Okitsu R) was evaluated by the leaf disc method and slide dip method. By the leaf disc method, LC₅₀ values were in the order of Okitsu R>Shizuoka R>Fukuoka R>Shizuoka S≈Fukuoka S and by the slide dip method LC₅₀ values were in the order of Fukuoka R>Okitsu R>Shizuoka R>Shizuoka S≈Fukuoka S. Acaricidal acitivity was found to be more effective when the slide dip method was applied, compared with the leaf disc method.

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The critical photoperiod for the induction of diapause in the 3rd or 4th generation of the Morioka population of the apple leaf miner was about 13hr 30min (13.5L) at 15°C or 20°C, and about 12L at 25°C. In the autumn, the combination of 13.5L (from sunrise to sunset+30min) and 15-20°C of mean temperature occurred in early September, while the combination of 12L and 25°C was seldom observed. Therefore, 13.5L was used as the critical photoperiod for predicting the seasonal cycle of this leaf miner. Most larvae which attained the tissue feeding stage before September 3, became non-diapausing pupae, while the younger ones became diapausing pupae. Based on these findings, it was assumed that the eggs laid from mid-August to early September would develop into diapausing pupae. The lower threshold temperature for development from egg to pupation of the diapausing population was found to range between 5°C and 10°C based on rearing tests, but this estimation did not agree with the value calculated from the regression of the developmental velocity on temperature. The sum of effective heat units for the diapausing population varied, being smaller in individuals produced later in late summer and early autumn.

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Eleven compounds including and related to the pheromonal components of the smaller tea tortrix moth (Adoxophyes sp.) and the tea tortrix moth (Homona magnanima DIAKONOFF) as well as several mixtures of these chemicals were evaluated in the field for use as possible disruptants for both species. (Z)-11-Tetradecenyl acetate (Z11-14Ac), (Z)-9-tetradecenyl acetate (Z9-14Ac), and (Z)-9-dodecenyl acetate (Z9-12Ac) were selected as potential disruptants based on disorientation experiments under the conditions of evaporation within and outside the trap. Based on the mating suppression of tethered females of both species in 1-m² field-cages at evaporation rates of 833 and 100mg/hr/ha, Z11-14Ac alone and a 1:1:1 mixture of Z11-14Ac, Z9-14Ac and Z9-12Ac were finally selected as disruptants for the two species. Disruption effects by these chemicals and the respective pheromones in the two species were more significant in Homona than in Adoxophyes.

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A model was built to analyze food selection in birds exposed to two different kinds of foods, including the effect of food exploitation due to the ingestion. An index of preference was derived from this model. The model could be effectively applied to the experiments, where foods treated with several repellents were given to tree sparrows, Passer montanus (L.), together with untreated foods. The determination of the index of preference for each type of food enabled to estimate the effect of various repellents on sparrows.

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The midgut epithelium of the silkworm larvae is usually damaged when larvae are fed crystal toxin of Bacillus thuringiensis (B. thuringiensis toxin). The present study reports the direct effect of B. thuringiensis toxin on the midgut epithelial cells in vitro. After dissection of the silkworm larva, the epithelial cells were separated from the midgut, put on a glass slide with Ringer's solution, and covered with a coverslip. B. thuringiensis (ssp. dendrolimus T84A1, ssp. sotto AF101 and ssp. israelensis) toxin solution was added from one edge of the coverslip with a Pasteur pipette, and subsequent morphological changes of the cells were observed by phase-contrast microscopy. The cells treated with T84A1 toxin which was digested by the gut juice of the silkworm swelled remarkably and burst. In the case of AF101 toxin, the cells showed less severe morphological changes than those treated with T84A1 toxin. The toxin from ssp. israelensis induced no morphological changes in the cells. T84A1 toxin solubilized with alkaline solution and intact crystal toxin caused no morphological changes in the cells.

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The occurrence of adult emergence and spermatogenesis of univoltine and multivoltine leaf beetles that diapause or hibernate at the adult stage was observed throughout their life cycle. Five species of univoltine leaf beetles were reared under natural conditions. All of them entered diapause within a month after adult emergence, and maintained it up to the next spring. Spermatogenesis usually occurred after 100-150 days of diapause in every species. In the diapausing males in which spermatogenesis was not initiated, the diapause was broken by the application of juvenile hormone which did not accelerate sperm production. It is assumed that the sexual maturation of univoltine adults requires a reproductive diapause. On the other hand, 13 species of multivoltine leaf beetles that hibernate at the adult stage were also investigated. In 9 species complete spermatogenesis was found to occur at adult emergence, and in 4 species spermatogenesis took place within 7 days after emergence. All the multivoltine leaf beetles hibernated and two species experienced summer diapause in their life cycles. Fully-mature sperms were observed in the males for which hibernation or summer diapause occurred. These results suggest that the existence of a reproductive diapause is not necessary for the spermatogenesis of multivoltine species.

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Analysis of population data showed that the principal ecological characteristic of the green rice leafhopper in Hokuriku district is the remarkable annual fluctuation of the population density as compared with that in Kyushu district. This was mainly caused by the mortality of hibernating nymphs due to heavy snowfall in this district. The population density before the second generation positively correlated to the density of the initial generation in paddy fields. Namely, the after-effect of snows persisted at least until the second generation (middle of August). In the third generation mentioned above the correlation was less significant and there was a negative correlation between the rate of reproduction and the density of the initial population. But since the third generation corresponded to the peak one, the duration of the period of density stabilization was insufficient to regulate the density of this species within a narrow range.

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Entomophthora aulicae caused an extensive epizootic in a population of Spilarctia imparilis larvae during July of 1981 in citrus orchards of Izu Peninsula, Japan. The same fungus caused high mortality in the larvae collected from fields. Several larvae collected were also killed by Paecilomyces fumoso-roseus and Metarhizium anisopliae.

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[in Japanese]

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