Prothoracicotropic hormone (PTTH) activity assayed in brainless pupae of Samia cynthia ricini is present in the mature eggs of the silkworm, Bombyx mori. Comparable activity was also found in eggs which had matured in brainless moths and in isolated abdomens. No significant differences in chemical components were shown in the eggs developed at three different hormonal milieus. It is possible to conclude that the ovarian PTTH is synthesized during egg maturation.

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Growth and reproduction were compared between Toxoptera citricidus and Aphis citricola. Comparisons were also made among the first generation, which consisted of fundatrices, the second generation, and the subsequent summer generations of each species. In both species, fundatrices developed more slowly than second and subsequent generation individuals. The fastest development took place in the summer generations in T. citricidus and the second generation in A. citricola. Capacity for increase, net reproductive rate and the maximum fecundity were largest in the second generation in both species. The difference in maximum fecundity between the summer generations and the first two generations in A. citricola was less than that of the same category in T. citricidus. Net reproductive rate of T. citricidus was usually larger than that of A. citricola. Reproductive schedule as displayed by the distribution of age specific fecundity changed with temperature and among generations. As for cohort generation time, the second generation was intermediate between the first and summer generations in T. citricidus, while in A. citricola the first and second generations were nearly the same.

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The amount of any free amino acid in the eggs of the emma field cricket, Teleogryllus emma, was less than 1 μmol per 1, 000 eggs maximum during the first 2 days after oviposition, but subsequently increased rapidly through the pre-diapause period and initial stage of diapause. Alanine concentration in eggs 6- and 10-days old was 7.8 and 30.1 μmol per 1, 000 eggs, respectively. Chilling to induce diapause development resulted in a notable 3.6-fold increase in glutamine, which reached 10.3 μmol per 1, 000 eggs during a 40 day period after 20 days of chilling. In addition, asparagine, AMP and glutamine partially broke diapause when 5-day-old eggs were treated with solutions of these amino acids.

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Up to the present, only two species have been recorded as aphidophagous Phycitine in the world. One is Conobathra aphidivora (MEYRICK), and the other is Cryptoblabes aphidivora YOSHIYASU and OHARA. In 1986, we found two aphidophagous pyralid larvae at Shuri, Naha, Okinawa : "Conobathra aphidivora" feeding on the sugar cane woolly aphid Ceratovacuna lanigera (ZEHNTNER) and "Cryptoblabes aphidiwora YOSHIYASU and OHARA" feeding on Pseudoregma bambucicola (TAKAHASHI). The results of a crossing experiment between the "two species" suggested that they are conspecific. The morphological and biological characteristics of "Cryptoblabes aphidivora" were also identical with those of "Conobathra aphidivora". We interpret these results as indicating that "Cryptoblabes aphidivora YOSHIYASU and OHARA" is synonymous with "Conobathra aphidivora (MEYRICK)". A new genus, Dipha YOSHIYASU, is proposed for aphidivora MEYRICK. The species is widely distributed in the Ryukyu Islands and all developmental stages were recognized all the year round.

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Nine non-commercial colored aerosol dyes were screened in the laboratory to determine their suitability for marking the adults of Plutella xylostella in the field. The satisfactory dyes were Solar Pure Blue, Acid B. M. Green, Solar R. B. and Acid Scarlet B. A. These dye marks were easily recognized on the moths. None of the dyes tested did not affect the longevity of the moths and the dyes remained better on the body than on the wings when water was applied. Solar Pure Blue and Solar R. B. marked moths did not differ significantly from unmarked moths in longevity, fertility and the number of mating pairs. A method of marking P. xylostella adults in the field was described. The survival rate of moths in a summer cabbage plot, estimated using JACKSON'S (1939) 'positive method' was 0.67 per day.

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The genetics of resistance to cyhexatin in Tetranychus kanzawai, one of the major pests of tea plants in Japan, was investigated using homogeneously resistant and susceptible strains of the mite. Similar dosage-mortality lines obtained in the F₁ progenies from reciprocal crosses indicated the absence of sex-linked inheritance. The dosage-mortality line in the F₂ progeny from backcrossing the F₁ hybrid to susceptible males was significantly different from that in the expected response estimated on the basis of monogenic inheritance. These results for F₁ and the backcross indicate that cyhexatin resistance in T. kanzawai is due to autosomal, polyfactorial genes.

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Several aspects of the reproductive biology of the white-spotted longicorn beetle, Anoplophora malasiaca THOMSON, were observed. Seventeen pairs of adults which emerged in early- to mid-June were reared under the conditions of natural temperature and daylength. The mean length (±SD) of sexual maturation period was 9.8±1.4 days. Mean life span of adult females was 77.6±20.3 days and mean total number of eggs laid was 193.8±65.2 per female. The fecundity curve was bell-shaped with a long rightward tail, having a peak about the 30th day after emergence. Remarkable decrease of the number of eggs with seasonal fluctuation seemed to coincide with the low mean daily temperature. From changes in the number of oviposition sites and the oviposition ratios (no. of eggs/no. of oviposition sites), the temporal pattern of oviposition could be divided into four phases. Hatchability of deposited eggs ranged from 0.78 to 1.0, and the mean hatchability in the study overall was 0.9.

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Conditions of cylindrical sound traps to maximize the capture of adult Mansonia were studied with this sound trap system in a field. Male and female Mansonia attraction to the odor of a guinea pig and CO₂ gas began at approximately 30 min before sunset. The mixed swarm developed after sunset. Male Mansonia responded to a sound of 350 Hz sinusoidal wave which was the same frequency as the female wing sound and were strongly attracted to the sound source in the dark after 20 : 00. However, few males responded to frequencies of the sinusoidal wave higher than 600 Hz. The effective range of the sound was a short distance from the sound source. On the other hand, few females responded to the frequency band between 350 and 1, 000 Hz. The combination of the odor of a guinea pig and the CO₂ gas produced by dry ice as the attractant was most effective for mosquito attraction near the sound trap. Mansonia were not attracted by visual stimuli. The height of the sound trap and the position of the dry ice influenced the catches. More than 99% of Mansonia caught in the traps were Ma. uniformis. Mass-trapping of male Mansonia by an attracting sound is promising.

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Supercooling point, inoculative freezing point, sugar content and frost resistance of four beetles were studied in winter to understand the overwintering strategies of soil insects. Adult Gastrophysa atrocyanea (Chrysomelidae) showed a weak frost resistance, with lower lethal temperature at about -10°C. In Agriotes fusicicollis (Elateridae) adults supercooled down to -20°C, but larvae only to -8.4°C, and both died from freezing. Larvae of Anomala testaceipes and Popillia japonica (both Scarabaeidae) were also freezing susceptible with supercooling points only at about -7°C. These scarabaeids and also larvae of Ag.fuscicollis descend to deeper soil layers in winter to avoid coldness. The overwintering strategies of the studied beetles thus can be classified into three types : frost resistant, supercooling, and cold avoidance.

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The ratio of the width of apical third segment of the antenna, Q, to the head width, C, was used as an index of antennal pectination in C. chinensis. Western (Ethiopian, Iranian and Indian) strains showed smaller values of Q/C than eastern (Chinese, Korean and Japanese). The reduced pectination of the male antennae in the western strains is assumed to be caused by the its long indoor life on the seeds of Vicieae legumes, i.e. peas, horse beans or lentils which serve as only storage host of the bruchid.

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The secretions of gall-thrips, Varshneyia pasaniae, Liothrips kuwanai and their gall-inquilineous species, L. piperinus (Thysanoptera : Phlaeothripidae) were analysed by GLC and GC-MS. Dodecane, tridecane, tetradecane, pentadecane and perillene were identified from these three species. Myristyl acetate, cetyl acetate and heptadecene were identified from V. pasaniae as new components which were also found from L.kuwanai. In addition, 2-methyl-butyric acid, a main active component of defensive secretion, was identified from V. pasaniae. In this species, perillene may serve as an alarm pheromone which stimulates emission of an anal secretion containing 2-methylbutyric acid against other individuals of the same species. It was confirmed that the components except for perillene were secreted from the anus of V. pasaniae, but the gland emitting perillene remains unknown.

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Parus major, Passer rutilans and Sturnus philippensis were new host records for Protocalliphora maruyamensis KANO et SHINONAGA, and Sturnus philippensis was also a new host record for Protocalliphora azurea FALLEN. Nestlings of Parus major were very often parasitized by the larvae of P. maruyamensis and sometimes by the larvae of P. azurea. The number of the larvae per nest was significantly more in P. maruyamensis than in P. azurea. The nestlings of Sturnus philippensis were also often infested with a large number of P. maruyamensis larvae. Nestlings of Passer rutilans were sometimes parasitized by a small number of P. maruyamensis and P. azurea larvae. In 1986, the number of P. maruyamensis larvae in the nest of P. major was large from June 15 to July 10 and thereafter decreased gradually till August 10, while in 1987, the number was very large from June 5 to 15, then decreased to the level in June of 1986 and remained constant until July 5. Thereafter it decreased rapidly and no parasite was found in the nests collected after July 15.

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The annual life cycle and diapause characteristics of Eotetranychus tiliarium (HERMANN) were studied in two Sapporo populations on alders (Alnus japonica and A. hirsuta). Over-wintered females appeared on leaves in early May (A. japonica population) and in late April or early May (A. hirsuta population), and were observed on leaves until early November and late October to early November on their respective hosts. It was estimated that there were probably 5 generations a year in both populations. In the A. hirsuta populations, all stages of mites were seen on leaves until the end of October, but this was not true in the A. japonica population. The photoperiodic responses of the two populations were similar and the proportion of diapausing females reached 100% at 13.5 hr of light or less at 18°C. The critical photoperiods in both populations were abotu 14.0 hr. Based on the diapausing status of those collected from the field, all the females of both populations should have entered diapause in October, and thus survival of all stages of the A. hirsuta population in late October seemed unexplainable. These discrepancies between stage structure and diapause response were discussed from the viewpoint of differences in the host plant trait at defoliation time and the mode of life of the mites. Some females of both populations, collected from bark crevices in early October, began to oviposit when incubated at 25°C and 15L-9D. The number of days required for reactivation gradually decreased towards April, while the proportion of laying females, on the contrary, increased.

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Steinernema kushidai n. sp. is described from the cadavers of scarabaeid beetle larvae which were reared in soil collected in Hamakita, Shizuoka, Japan. This new species is closely related to S. feltiae and S. intermedia (=Neoaplectana intermedia), but distinguished from them by the distance from the head to the excretory pore of all stages, the shape of spicules and gubernaculum of male adults, and the body length of the infective juveniles. The life cycle of S. kushidai n. sp. is comparable to that generally accepted for the genus, but characterized by a rare production of second generation adult. The nematode was successfully maintained on either dog food agar or chicken offal medium.

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When pigmy mole crickets, Tridactylus japonicus DE HAAN, were grasped they often discharged a characteristic scent. It was believed this scent to be a defensive weapon against predators and some experiments were performed to confirm this idea. Two groups of crickets, one which had discharged the scent when held by human fingers prior to the experiment, and the other which was not held and had not discharged the odor were respectively introduced into petri dishes that had previously confined one Lacosid spider, Pardosa spp. The death rate of the scent-discharging crickets after 24 hr was 65% (N=20), while in the other group the death rate was 26.3% (N=19). A significant difference between them was found at the 5% level. Also, in another experiment, it was found that filter paper soaked with the odoriferous cricket's secretion repelled ants, Tetramorium caespilum L. These findings indicated that the scent emitted by the crickets acted as their defense against predators. This is the first report of a chemical defense utilized by Tridactyloid insects.

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Defensive secretions and hydrocarbons of Tribolium freemani, T. castaneum and their hybrids were analysed by GLC and GC-MS. The combination of the parent species affected strongly the chemistry of the secretions and the hydrocarbons of the hybrids. The secretions of the parent species were similar to each other, and hybrid-(I) from T. freemani (♀)×T. castaneum (♂) produced simple mixtures of the parental secretions, whereas hybrid-(II) from the reverse sex combination of the parents gave the same composition as that of T. castaneum. In the hydrocarbons, however, fairly large differences were present between the parents and their hybrids, although those of the parents were very similar to each other. n-Nonacosane was the most abundant hydrocarbon of the parents, whereas 11+13-methylheptacosane was the richest component of the hybrids. A small difference was also found between the two hybrids. Both n-pentacosane and 3-methylpentacosane in hybrid-(I) were about ten times more abundant than in hybrid-(II).

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n-Hexyl linolate, n-hexyl (Z, Z)-9, 12-octadecadienoate was identified commonly in all strains of four species of acarid mites belonging to the genus Tyrophagus; however, the compound was not detected in three other species of related acaricd mites. Although origin and function of the ester is obscure, it may be one component of the exudate from the opisthonotal gland and serve as a bio-solvent of the alarm pheromone present in the gland. The other possible function of the wax may be as a component of cuticle to prevent moisture loss from the body. The ester was demonstrated to be produced biosynthetically. This is the first example reported of the occurrence of n-hexyl linolate in nature.

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Colony development of a gall-forming thrips, Ponticulothrips diospyrosi, and the gall-associated arthropod community were studied in Kyoto. Each gall formed on a persimmon leaf by an overwintered female contained 160-190 of 1st generation offspring on the average (max. 760) at the peak of the colony size. The sex ratio of the 1st generation adults was female biased (females 80%). A small number of 2nd generation offspring occurred in galls formed by the 1st generation on secondary shoots in summer. Arthropods of 14 orders were collected from the galls, including both phytophagous such as Homoptera and Thysanoptera and predacious such as Araneae, Heteroptera, Neuroptera, Diptera, Coleoptera and Hymenoptera. Colony size of P. diospyrosi, and also the abundance of gall-associated arthropods, was positively correlated with gall size.

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