The population ecology of the azuki bean beetle, Callosobruchus chinensis (L.) was studied on two wild leguminous hosts; annual Vigna angularis (WILLD.) OHWI & OHASHI var. nipponensis (OHWI) OHWI & OHASHI and perennial Dunbaria villosas (THUMB.) MAKINO. Both legumes bloom from mid-August to late-September, and produce mature pods from mid-August to late October. Adult beetles occurred on the colonies of the two wild legumes from mid-August to mid-October. Females laid their eggs on the mature pods of both legumes from mid-September to mid-October. Most active oviposition was in late September. Eggs were deposited contiguously on mature pods, but larval density was less than one per seed. the larval survival rate decreased rapidly until the 1st instar larvae penetrated into pod seeds. After penetration, the survival rate slightly decreased until pod dehiscence. These ecological characteristics were similar to those observed in the cultivated azuki bean, Vigna angularis (WILLD.) OHWI & OHASHI. Percentage of seeds infested by C. chinensis in each colony of D. villosa ranged from 0% to 13.5%. the percentages changed yearly, but were almost always less than 5%.

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LD₅₀ values of some pyrethroids in the housefly, Musca domestica L. (Lab-em-7-em strain) were obtained by means of a quantitative oral application method. Oral LD₅₀ values of all the pyrethroids tested-phenothrin, cyphenothrin, permethrin, cypermethrin, cyfluthrin, deltamethrin and fenvalerate, were 5-10 times as large as topical LD₅₀ values. Piperonyl butoxide and S, S, S-tributylphosphorotrithioate induced higher synergistic effects in the oral application than in the topical application. As a result, the differences of the LD₅₀ values between oral and topical applications were smaller, though the oral toxicities did not exceed the topical toxicities. This suggested that pyrethroids applied orally could be more vulnerable to degradation by mixed function oxidase and esterase.

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This study was taken up to examine the relationship between the susceptibility or resistance of six sorghum lines to Chilo partellus and dietary quality of their leaf tissues, incorporated in an artificial diet, to support larval development. The diets tested were agar based basic medium with or without cellulose powder, dry leaf powder or fresh leaf-paste of the sorghum lines. The basic medium alone or with cellulose powder showed the poorest dietary quality in-as-much as it did not support more than 26-32% larval development. the tolerant sorghum IS 18520 leaf tissues, incorporated in the artificial diet as dry powder or fresh leaf-paste, were most efficient in supporting as high larval development as natural host plants. the diets with the leaf-pastes of the susceptible IS 18363 and IS 2146 as well as the moderately resistant IS 4660 also supported equally high larval development but the dry leaf powder of these lines was somewhat inferior in its dietary quality. In contrast, the leaf-paste of the highly resistant IS 1044 and of moderately resistant IS 2205 rendered the quality of the artificial diet as poor as the basic medium, reflecting deleterious effect on larval development due to antibiosis. Such an effect was eliminated by drying the leaves and incorporating their powder in the diet.

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Life table studies in the immature stages of Parnara guttata guttata BREMER et GREY were conducted in the northern peripheral area of its distribution, Joetsu, Niigata, Japan. The mortality by parasitoids in the 4th and 5th instar larvae and pupae was high. Egg parasitism rate was low. Fifteen primary and seven secondary parasitoids were recorded. Among them, four primary and four secondary parasitoids were newly recorded from P. g. guttata. A host-specific parasitoid, Apanteles baoris WILKINSON and an oligophagous parasitoid, Pediobius mitsukurii (ASHMEAD) were predominant even in Joetsu where the hibernation of the host species is impossible. In addition, two subsidiary mortality factors were detected: 1) predation of the 5th instar larvae and pupae by large predators (mainly birds) in the 1st generation, and 2) failure in settlement of hatchlings on leaves in the 2nd generation. The latter was more important on the normal planting rice than on late planting rice. these results were compared to those in central and western Japan where P. g. guttata can hibernate.

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Pine wilt caused by Bursaphelenchus xylophilus has heavily damaged Pinus densiflora and P. thumbergii forests in Japan. The degree of susceptibility of pine stands to the disease sometimes varies even between stands that are located near to one another. We constructed a simple time-delayed model in which a transmission coefficient is used as an index of the stand's susceptibility to the disease. By applying the model to field data, we showed the usefulness of this coefficient as the susceptibility index. It may, thus, be helpful in evaluating the effectiveness of control techniques used against the disease over a period of some years.

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The prolonged effect of larval treatment with chlorfluazuron on pupation and adult emergence in the diamondback moth (DBM), Plutella xylostella (L.) was investigated. Two chlorfluazuron resistant and two susceptible strains of DBM were tested. The leaf-dipping technique was adopted and the insecticide was applied to third instar larvae. Larval mortalities were counted one week after application then pupated larvae were observed until adult emergence. Results indicated that chlorfluazuron applied to larvae exhibited a prolonged effect on pupae observed as pupal death or failure of emergence and on adults observed as deformed or dead adults. The failure of emergence was more obvious in the chlorfluazuron resistant strains, which were exposed to higher doses, than in the susceptible strains.

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Levels, genetic traits and stability of resistance to Bacillus thuringiensis (BT) of the Kohno populations (RO and ROO) of the diamondback moth Plutella xylostella were investigated by the leaf-dip method. The RO and ROO populations exhibited 78.5 and 704-fold resistance to BT (Toarow CT^&oR;), respectively, high levels of resistance to other formulations derived from B.t. subsp, kurstaki, and low resistance to BT derived from subsps, kurstaki and aizawai. Analysis of dosage-mortality relationships of F₁, F₂ and backcross progenies derived from the cross of susceptible (S) and ROO populations revealed that BT resistance was primarily controlled by an incompletely recessive, autosomal single allele. High levels of BT resistance in the moth have decreased within generations in the absence of insecticidal selection. The RO population exhibited 46- and 52-fold resistance to the tertiary amines, cartap and thiocyclam, respectively. Resistance to tertiary amines have remained at high levels without insecticidal selection.

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Population dynamics of stink bug Piezodorus hybneri adults in a soybean field were investigated from June to August in 1988-1990 by visual counting and mark-recapture method. The density of adults suddenly increased just after soybean plants reached pod development stage. Thereafter the density decreased, but increased again at the seed development stage. The second increase of adults was formed by new adults emerged in the soybean field. Spatial distribution of adults based on densities per plant was slightly aggregative and the distribution of males and females was more or less overlapping. Analysis by the JOLLY-SEBER method showed that daily survival rate was low and mean residence time was short, 2.9 days in 1988 and 4.9 days in 1989. The observed short residence time may be due to emigration rather than high mortality.

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Toxicokinetic analysis was employed to investigate significance of various factors responsible for resistance in susceptible and resistant strains of housefly to diazinon. Topical application and application by exposure to a residual film of the compound in holding vial was conducted. A significant difference was observed between the strains in the penetration rate of diazinon, the amount of diazoxon present, and the degree of AChE inhibition. the data also indicated a reversible exchange of diazinon between external surface of the flies and the holding vial by volatilization/rub-off and resorption of the compound by the flies. Certain k values estimated by computer simulation using the experimental data and differential equations derived from the toxicokinetic models proposed for the external and internal dynamics of diazinon demonstrated an inter-strain difference. In particular, the ratio of diazoxon degradation over activation of diazinon was much greater in the resistant strain than in the susceptible strain, suggesting that low accumulation of diazoxon was the most important resistance factor. Insensitive AChE also played an important role in vivo.

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A new trihaloimidazole derivative S-377 [1-(4-chlorobutyloxymethyl)-2, 4, 5-trichloro-imidazole] showed high insecticidal activities against pyrethroid-resistant (O-colony) German cockroach Blattella germanica and physical and chemical properties appropriate for an active ingredient of heating fumigant. Consequently, this compound presented remarkable lethal and knockdown efficacy, comparable to that of methoxadiazone and permethrin, against the O-colony by three types of heating fumigant formulation in wider chambers. As for the mode of actions, S-377 showed low inhibitory effect on acertylcholine esterase in the German cockroach. According to electrophysiological study, this compound induced bursts of spontaneous firing on the abdominal nerve cord of German cockroaches, which continued for 60 min after the application. These results suggests that the central nervous system of German cockroaches is affected by this compound in a certain manner different from that of organophosphates, carbamates and pyrethroids. At least three possible modes of action have been suggested: (1) inhibitory actions on inhibitory systems, (2) inhibitory action on inactivating system of Na channels in a manner different from that of pyrethroids, and (3) facilitation of the excitatory system including the stimulation of excitatory synaptic transmission.

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Distribution of glutathione S-tansferases (GST) activity in insect tissues was studied using 1-chloro-2, 4-dinitrobenzene (CDNB), 2, 4-dinitrophenyl benzenesulfonate (DNPES), 1, 2-dichloro-4-nitrobenzene (DTNB) and fenitrothion (0, 0-dimethyl 0-3-methyl-4-nitrophenyl phosphorothioate) as substrates. The highest GST activity was found in the Malpighian tubes. CDNB and DNPBS conjugation activities in the American cockroach, Periplaneta americana (Orthoptera: Blattidae), were distributed mainly in Malpighian tubes, fat body, guts nerve cord and testis, while blood and muscle had low activity. Similar results were obtained in the common cutworm, Spodoptera litura (Lepidoptera, Noctuidae) and the rice stem borer, Chilo suppressalis (Lepidoptera: Pyralidae). As for DCNB conjugation activity, each insect showed different distribution patterns among tissues from that of CDNB and DNPBS. Fenitrothion conjugation activity of the American cockroach and the common cutworm was also the highest in Malpighian tubes. Fenitrothion was degradaded mainly by 0-alkyl conjugation.

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A family of highly repeated DNA sequences of the fern sawfly, Hemitaxonus japonicus (Polystichum tripteron race) has been cloned. Hybridization analysis of the EcoRI, SacI and Sau3AI digests of the genomic DNA isolated from H. japonicus (Polystichum tripteron race) against the recombinant plasmid, pYS354, containing tandemly repeated sequences showed ladders of each basic monomer unit having a length of ca. 270-bp. In addition to pYS354, the other two types of clones that also contain tandemly repeated sequences isolated from H. japonicus (Polystichum tripteron race) were cloned and the nucleotide sequences were compared with pYS354. Nucleotide sequences of these repeated sequences showed high homology between each other with highly AT-rich sequences. The presence of the homologous tandemly repeated sequences in the genome of ten species belonging to six genera of Tenthredinidae was analyzed by hybridization against pYS354 as a probe. Among them, only PP-race, the oligophagous population of H. japonicus and the sibling species, H. sasayamensis, possessed such tandemly repeated DNA sequences.

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To examine how the hatching period of the gallicolae of Adelges japonicus synchronizes with the bud burst of their host, Picea jezoensis, the oviposition schedule of fundatrices and the hatching schedule of their eggs were investigated under natural conditions in Sapporo, Hokkaido. The number of eggs deposited by the fundatrices which infested potted seedlings of P. jezonesis was counted daily, and the durations of egg stage were recorded. The fundatrices started oviposition from late April and each fundatrix continued to oviposit for 2 weeks. the durations of egg stage fluctuated between 9.0 and 13.5 d depending on the oviposition date, and became shorter for eggs deposited later. A part of the eggs hatched before fundatrices finished their oviposition. The eggs hatched 0 to 19 d after bud burst, and the mean duration between bud burst and hatch of the eggs was 8 d. Thus, the newborn larvae (gallicolae) could creep into buds immediately after hatching.

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In Nippolachnus piri the sexual generation produced by alate sexuparae attained maturity on Rhaphiolepis umbellata var. integerrima early in November. the ovipara laid eggs in an "ovipositional spot", which was formed by secretion from the tip of the abdomen onto a part of leaf undersurface. It was observed that oviparae alternated between two types of behavior; laying six eggs as a unit and expansion of the ovipositional spot. The area of an ovipositional spot was highly correlated to the number of eggs on it. Fresh eggs laid by surviving oviparae were found even in mid-January.

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The last male sperm precedence (P2) in a pentatomid stink bug, Eysarcoris lewisi DISTANT, was studied using females mated with both normal and sterilized males. The mean P2 value in the first egg masses was about 40%. The mean P2 value increased as deposition of egg masses progressed, and showed almost complete last male sperm precedence in the forth egg masses. Among first egg masses, there was a significant positive correlation between P2 values and duration from termination of the last copulation to beginning of oviposition. these facts indicate that the duration between copulation and oviposition is important in determining P2 values. Females began oviposition an average of 55±37 (mean±S.D.) h after copulation. The function of prolonged copulation in this species is discussed.

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A new fixation method for preparing mite specimens was developed. The dilutions of 99.5% methanol and 99.3% acetic acid (hereafter called as MA fluids) were useful for the fixation of cuticular epidermis and stretching the legs of tetranychid and phytoseiid mites. Comparisons between the MA fluids and the fixatives heretofore in use revealed that the 70% ethanol fluid, which had been usually adopted for mite fixative, was not good for making mite exo-skeletonic specimens. After fixation with the MA fluids, mites were maintained in good condition in 70% ethanol. there was no bad effect of the MA fixative on the length of leg I of mites mounted in HOYER's medium one week after the fixation. These fixatives were also useful as for the preliminary preparation of the mites for scanning electron microscopy.

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Two populations of the lesion nematode collected from the rhizosphere of composite plants, Chrysanthemum morifolium (in Miyazaki Pref.) and Artemisia Feddei (in Nagasaki Pref.) were described as Pratylenchus pseudocoffeae n. sp. The new species closely resembled P. coffeae, but was distinguished by its divided pattern in en face, short distance from spear base to DGO (1.8-2.3 μm vs. 2.6-3.3 μm in mean), narrower spear knobs (3.4-3.7 μm vs. 3.7-4.2 μm in mean) and frequent 3 lip annuli (28.5% on either side and 5.5% on both sides: n=91).

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Selections more than over 25 successive generations for specific wing form and body colour under low-density rearing conditions in Nilaparvata lugens failed to produce pure-bred lines with those characters. However, selections over 12 to 30 successive generations under high-density rearing conditions were successful in obtaining various lines predominantly producing specific wing form and body colour over a broad range of nymphal densities in both sexes: totally brachypterous lines with yellowish brown or highly melanized body colour and totally macropterous lines with highly melanized or yellowish brown body colour. Thus, wing form and body colouration are controlled by different genes. By successive selections based solely on wing form, two lines producing predominantly brachypterous or macropterous wing forms were obtained, but they exhibited an intermediate body colour between yellowish brown and black. When five field-collected strains were reared under high density conditions, their wing form and body colour responses to rearing density remained unchanged for more than over 20 generations. On the other hand, maintenance of these strains under low density conditions rendered them to exhibit considerable different responses from original ones, even though no special selection has been given. These results suggest that genetically controlled characters can be stably exhibited under high density conditions, while phenotype expression under low density conditions is largely influenced by the physiological situation of the individual hoppers.

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