The seasonal changes in species composition and spatial distribution of the subcortical beetles infesting Japanese pine trees and their two major parasitoid wasps, Atanycolus initiator and Spathius brevicaudis, were examined to analyze factors causing the difference in parasitism patterns between the wasps in the trees. Both parasitoids emerged between April and November, during which time the species composition of the host larvae changed largely with the season. S. brevicaudis could exploit smaller host species in which A. initiator with its larger body size could not attain a successful development. Conversely, A. initiator with its longer ovipositor could parasitize the hosts distributed almost anywhere on the tree stems, prevailing over S. brevicaudis particularly on the lower part of the stems having a thick bark. It was suggested that the seasonal changes in the species and the size composition of host beetles, and/or their spatial distribution, are likely to be the crucial factors responsible for the differences in parasitism patterns between the two parasitoid species.

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Coexistence of the two closely related species, Eurydema rugosum and E. pulchrum was studied both in the laboratory and in the field at Takato in Ina district, Nagano Prefecture, Central Japan. We investigated the distribution, life cycle, seasonal changes of adult population size, host plant preferences, and the effects of host plants on the survival and development of nymphs of the two species. Eurydema rugosum was distributed widely, whereas E. pulchrum was distributed locally in mountainous areas. Therefore, coexistence of the two species generally occurred in the Ina district which has a mountainous terrain. Adult populations of E. rugosum were highest in early or mid-May and decreased gradually thereafter. On the other hand, those of E. pulchrum increased from early July or late August, and the latter out-numbered the former in the autumn. We estimated that E. rugosum had two generations, whereas E. pulchrum had three. No appreciable difference in host plant preferences was found between the two species : the nymphs and the adults of both species fed together on the same host plant throughout the season. In addition, no appreciable difference in the survival and development of the nymphs on different host plants was found between the two species.

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A three-female nest of Polistes jadwigae DALLA TORRE was observed before the worker eclosion in 1986. Female A was determined to be the 'dominant' because she frequently attacked the other two while being rarely attacked. But this female was the smallest in body size, did not oviposit nor eat eggs, spent more time off the nest, and engaged in foraging between at least May 17 and 31. This curious social relation was suddenly broken on 31 May due to falling fights among the foundresses. The features were quite different from those of multi-foundress colonies which have hitherto been reported in Polistes of Europe and North America.

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Survival rates from egg to adult, including the survival rates during winter, were studied in the field for two dung beetle species, Onthophagus lenzii and Liatongus phanaeoides, from 1984 to 1987. To examine the effect of insects coming into dung pats on the survival rates of the two species, the survival rates were assessed under two sets of rearing conditions, one with a dung pat and the other without a dung pat on the soil surface. The survival rates from egg to adult before overwintering were 50.0% (without dung) in 1985, 52.4% (without dung), 55.0% (with dung) in 1986 for O. lenzii. For L. phanaeoides the survival rates, including the overwintering larval survival rates, were 32.0% (without dung), 33.6% (with dung) in 1985, 50.0% (without dung) in 1986. For both species the survival rates from egg to adult in the plot with dung were not lower than those without dung. This suggested that the effect of the insects coming into dung pats on the survival rates was negligible. Onthophagus lenzii overwinters as an adult, and the overwintering survival rates were 68.0% in 1984/85, 25.0% in 1985/86, and 51.0% in 1986/87 for five pairs, and 63.8% in 1984/85, 12.0% in 1985/86, and 47.0% in 1986/87 for ten pairs. Liatongus phanaeoides overwinters as a larva. The survival rates were 52.9% in 1985/86 and 83.3% in 1986/87. The overwintering survival rates for both species were lower in 1985/86 when winter temperature was low. The survival rates from egg to pre-reproductive adult, including the survival rates during winter, were 9.0% in 1985 and 26.0% in 1986 for O. lenzii; 33.0% in 1985 and 50.0% in 1986 for L.

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A database for light-trap catches at 69 sites and density maps for the immigration of long-distance migratory planthoppers into Japan were developed on a personal computer. Geographical distribution and density gradient of immigrants during Baiu season in 1980 to 1985 were analyzed. There were 32 immigration waves of white-backed planthoppers detected, 24 cases showed a close correlation between the developmental scale and localization of low-level jet stream (LLJET) and the immigration areas. These immigration areas shifted from the Pacific Ocean to Japan Sea coastal areas in response to the localization of LLJET.

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An analysis of field sampling data of the bamboo aphid, Pseudoregma bambucicola, having sterile soldiers on Bambusa multiplex stems, shows that the soldier ratio is higher in large colonies than in small ones, and in colonies with alate adults than in those without them. The soldier ratio is also higher on thick shoots than it is on thin and small shoots from branches of old stems.

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Many kinds of 1-substituted-2, 4, 5-trihaloimidazole derivatives were synthesized and their insecticidal action against the pyrethroid-resistant colony (O-colony) of the German cockroach, Blattella germanica, which showed cross-resistance to various pyrethroid insecticides, was investigated by means of topical application and by a heating fumigant method. Also studied was their acute oral toxicity to mice. A strong correlation was observed between the insecticidal activity to cockroaches and the toxicity to mice in most of these derivatives, however, between the two species, 1-(4-halobutyloxymethyl)-2, 4, 5-trichloroimidazoles showed a superior selective toxicity. Among these compounds, 1-(4-chlorobutyloxymethyl)-2, 4, 5-trichloroimidazole (S-377) was finally selected as the candidate compound for controlling the pyrethroid-resistant colony of German cockroaches, especially as heating fumigant agent. The insecticidal activity of S-377 against the O-colony was higher than that against susceptible strains by both the topical application and the heating fumigant method. Therefore, the S-377 is expected to be applicable in the practical field of controlling German cockroaches as a new active ingredient of insecticides.

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The dispersion of field-sprayed Bacillus thuringiensis in the soil was assessed under naturally and artificially irrigated conditions. In tests on two field plots (mulberry plantations), there was no translocation of sprayed B. thuringiensis into the soil down to a depth of 10 cm, under a continuously rainwater-irrigated condition of the summer rainy season for about one month. When B. thuringiensis-sprayed soils were artificially irrigated with water equivalent to a 450-mm rainfall, B. thuringiensis was detected in the soil down to a depth of 3-6 cm. In irrigation tests using soil columns, B. thuringiensis was not capable of passing through the column of volcanic ash soil, but a few bacteria were detected in the flow-through water from a column of alluvium sand. The results suggest that the major factor causing the decrease in the level of B. thuringiensis is not a physical dilution due to the rainwater-mediated dispersion of bacteria into the soil.

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Insecticidal crystal proteins (delta-endotoxins, ICPs)from Bacillus thuringiensis subspp. kurstaki HD-73 and HD-1 were digested by trypsin and chymotrypsin that were immobilized onto CNBr-Sepharose 4B. In a six-hour digestion, both enzymes generated proteolytic resistant cores having 65 kDa molecular size from both ICPs. The ICP from HD-73 generated two other higher molecular intermediates, i.e. 95 and 80 kDa fragments, by the trypsin treatment. This suggested that the ICP of HD-73 might have three sites susceptible to trypsin. ICP from HD-1, however, was more quickly digested by both enzymes and the intermediate pattern in SDS-PAGE was completely different from that of the ICP from HD-73, suggesting that the main protein of ICP from HD-73, a product of crylA(c) gene, contains significantly fewer HD-1 crystals. N-terminus amino acid residue of the resistant core derived from HD-73 was the same as the sequence starting from the 29th residue in the crylA gene product, 130 kDa protein. The core generated by both enzymes from HD-1 and HD-73 showed insecticidal activity against the diamondback moth, Plutella xylostella, the smaller tea tortrix, Adoxophyes sp., and the common cutworm, Spodoptera litura.

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In Eysarcoris lewisi DISTANT, the critical photoperiod for reproductive diapause was between 14L-10D and 16L-8D. The total nymphal period was significantly longer under 16L-8D than under 12L-12D and 14L-10D. The age-specific food consumption in the 5th instar nymph was different between the 12L-12D and 16L-8D groups. The total food consumption of the female 5th instar was greater in the 16L-8D group in the 12L-12D group. Weights of the male nymphs and adults were not different among three photoperiodic groups, while those of the female 5th instar and adults were significantly greater in the 14L-10D and 16L-8D groups than in the 12L-12D group. During the 5th instar, amylase and invertase activities in the midgut were higher in the 16L-8D group than in the 12L-12D group, whereas acid phosphatase activity was higher in the latter than in the former.

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Hexane extract derived from Histiostoma laboratorium HUGHES, possibly the opisthonotal gland secretion, contained hydrocarbons and monoterpene as major components. The monoterpene fraction indicated the alarm pheromone activity and consisted of a mixture of neral (10%, 3, 7-dimethyl-(Z)-2, 6-octadienal) and geranial (90%, 3, 7-dimethyl-(E)-2, 6 octadienal). The synthetic geranial was active at 1 ppm, while corresponding neral was inactive at 10 ppm. The alarm pheromone of Histiostoma laboratorium was, then, concluded as geranial. This is the first example that geranial is the active compound as the pheromone, although neral which is the other component of citral is well known as mite's alarm pheromone in at least 5 species.

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Host stage selection and the oviposition behavior of two parasitoids of Unaspis yanonensis was studied. In Aphytis yanonensis, the drilling per visit rate was not different among any pair of host stages : 2nd instar larvae, immature and mature adults. However, the oviposition per visit rate was higher on immature adults than on 2nd instar larvae and mature adults. Oviposition time in successful oviposition was longer on mature adults than on immature adults. Low parasitic rate of mature adults by A. yanonensis in the field is not due to the parasitoid preference for immature adults but to difficulty in oviposition on mature adults. In C. fulvus, both drilling and oviposition per visit rates were not different between immature and mature adults of the host. Thus, the vulnerable stage of U. yanonensis is more restrictive to A. yanonensis than to C. fulvus. Both parasitoids can discriminate between unparasitized hosts and those that had been parasitized by themselves.

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In the yellowish elongate chafer, Heptophylla picea MOTSCHULSKY, collected from tea fields in central Japan, all male adults had well-developed flight muscles, whereas most female adults did not have them. This indicates that there is a flight muscle dimorphism only in the female adults. Female non-flyers did not retain any flight muscles even just after eclosion. These adults reserved fat-body in their thoracic cavities. The ovaries of female adults without flight muscles developed with the degeneration of fat-body. Accordingly, the ovaries of female adults had already matured when they emerged on the ground. The number of eggs in ovaries of female adults collected from tea fields just after their emergence on the ground was lower in those with flight muscles than in those without them. This indicates that the latter ones were earlier in the development of ovary than the former ones.

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The feeding behaviour of Nephotettix cincticeps, N. virescens and N. nigropictus on suitable and unsuitable plants was investigated through an analysis of honeydew composition. Although a certain amount of honeydew was excreted on both kinds of plants, there was less sugar content and no sucrose in the honeydew from unsuitable plants. The influence of the extract from both kinds of plants on the survival and feeding behaviour of the three Nephotettix spp. was investigated. The water soluble extract of the unsuitable plant caused high mortality in the three Nephotettix spp. while that of the suitable plant, 'Nihonbare', did not. The basic fraction of the unsuitable plant extract resulted in high mortality. The acidic and neutral fractions also caused high mortality in N. virescens. The amphoteric fraction of unsuitable plants was found to be beneficial for their survival. Feeding behaviour recorded on an electric measurement device showed that the ingestion pattern duration of the three Nephotettix spp. became shorter when the basic fraction was added to the sucrose solution as compared with sucrose solution alone or with amphoteric fraction added. A special feeding pattern which was supposed to be a phloem ingestion pattern was recorded when N. virescens fed on sucrose solution augmented by the amphoteric fraction.

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The inheritance of fenitrothion resistance (22-fold) and pirimiphos-methyl resistance (500-fold) was studied in the OP-resistant Hata-f strain of the rice stem borer, Chilo suppressalis. The resistance was found to be incompletely recessive, and no extranuclear effects were found. The degree of dominance (D) for fenitrothion was -0.31 to -0.37 and that for pirimiphosmethyl was -0.14 to -0.21. Observed mortalities for the backcross progenies [F₁(Hata-f〓×S〓)〓×Hata-f〓] were almost identical with the expected on the basis of a single major gene inheritance. However, the observed mortalities at high dosages were significantly higher than expected, indicating that minor modifying genes might be involved in the resistance. The inheritance of the two fenitroxon detoxication activities (binding protein and hydrolysis) were also incompletely recessive.

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A sex pheromone of Ascogaster reticulatus WATANABE (Hymenoptera : Braconidae) which is deposited on the substrate by females and elicits male antennal-searching response, was analyzed and characterized. The hexane extract of the virgin females was subjected to silica gel column chromatography. An active fraction (active at 3.3×10^-1-10² ng/line) was analyzed with gas chromatography (GLC) and GC-MS, and three major peaks were identified as citronellal (44%), hexadecanal (12%) and hexadecenal (43%). Double bond location at ninth position in hexadecenal was determined by GC-MS after dimethyl disulfide derivatization. Geometric isomers of 9-hexadecenal were both co-chromatographed on GLC and (Z)-9-hexadecenal was identical to the natural 9-hexadecenal. Bioassay with these authentic compounds showed that only (Z)-9-hexadecenal elicited pheromonal activity (active at 5×10^-4-5 ng/line). Therefore, (Z)-9-hexadecenal was identified as the sex pheromone of A. reticulatus.

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Brachypterous L. stiratellus females, with the exception of the macropterous ones, exhibit a continuous variation in abdominal color ranging from milky white (W) to black (B). Brachypterous and macropterous males have two color variants, one with a white stripe on the mesoscutellum (S) and one without the stripe (NS, black scutellum). The adult body coloration in populations of L. stiratellus was darker at higher nymphal rearing densities. The inheritance of body color was studied by mass-crossing single phenotype of females or males with randomly colored individuals of the opposite sex. In addition, female and male body colors were selected simultaneously for 11 generations in the following combinations : B×S, B×NS, W×S and W×NS. The development of both female and male adult body coloration had a genetic basis, and the genetic determination of male body coloration was independent of female.

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Nymphal development of the small brown planthopper, Laodelphax striatellus, is delayed by short day photoperiod. The incidence of 'delayed development (DD)' individuals under 12L-12D at 25°C was compared among unselected parents, offspring of DD-type parents, and of 'non-delayed development (ND)'-type parents. The incidence of DD in the offspring of DD-type parents was 33.7%, and that of ND-type parents was 5%. The former was slightly higher and the latter was significantly lower than the incidence, 24.7%, of DD in the unselected parents. Both the incidence of DD and the incidence of macroptery in females increased with an increase in nymphal density. Moreover, the line which has been selected for macroptery for 15 generations showed a higher incidence of DD than the line selected for brachyptery.

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Embryogenesis of a polyembryonic wasp, Litomastix maculata, was studied in vivo and in vitro. In vivo, eggs cleaved holoblastically and then developed into morulae within the first 24 hr. Subsequently, the morula produced polygerms. A similar process was also induced in a modified MGM 450 medium. Bovine plasma albumin was required as a component of the medium for the embryos to develop up to the complete morula. Ovalbumin and conalbumin also supported the development of the embryos, whereas lactalbumin was rather detrimental.

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By changing the rearing conditions of different instars on an artificial diet, it was reconfirmed that larvae of the common cutworm, Spodoptera litura were sensitive to density during the fourth and fifth instars and exhibited phase characters in the last (sixth) instar: those from crowded rearing, but isolated during the last instar, had a greater degree of melanization, recovered more quickly from feigned death when dropped, and fed for shorter periods than those reared completely in isolation. There was a great variability in response to density between groups of larvae originating from different batches of eggs collected in the field. Only a few groups showed the typical responses to density for the three phase characters mentioned above, while most groups indicated characters which were slightly altered, and manifested low density-type responses even at high density. One group invariably showed high density-type responses, having a high degree of melanization, quick recovery from feigned death and relatively short feeding periods. Another group exhibited a yellowish brown colour and fed longer in both rearing conditions, but rarely showed feigned death, flipping over to normal position immediately after being dropped, instead. A crossing experiment revealed that the density response patterns of phase characters in S. litura are under genetic control.

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Daily migrational patterns of Pseudaletia separata (WALKER) larvae infected with Entomophaga aulicae and the nuclear polyhedrosis virus (PsNPV) were examined under laboratory conditions and compared to that of healthy larvae. The healthy larvae exhibited a daily rhythmic pattern of movement, i.e., feeding and movement on feeding plants at night and hiding them under the soil during the day through the 5th and 6th larval instars. When infected with either E. aulicae or PsNPV, the pattern of the movement was disturbed : the larvae crawled out from the soil even during the day and died near the top of the feeding plant. The symptoms first appeared two to three days and two days before the death in E. aulicae- and PsNPV-infected larvae, respectively. In the case of E. aulicae-infected larvae, a frequent vertical migration was observed during this period.

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