Orthellia pacifica ZIMIN was tested for the effects of larval intraspecific competition. Newly hatchaed larvae were transferred to cattle dung and reared until adult emergence at thirty-one densities of between 1 to 301 larvae per 50 g of dung. A s the density increased, reduction in the size of emerged adults, increaseing mortality and shortening of the developmental period from larvae to adults were observed. These density effects, however, did not begin to occurat the same density levels. The adult size and developmental period began to decrease at the density of 21 larvae. On the other hand, increase in the mortality did not occur until the density of 121 larvae where the adult size had reached almost the lowest limit. These findings were discussed in relation to competitive advantage and larval habitat characteristics.

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German cockroaches, Blattella germanica, were collected from the field (O-colony) and their susceptibility to 12 insecticides was determined by a topical application. This population exhibited resistance to all pyrethroid compunds tested and to DDT, but not to fenitorothion, diazinon, propoxur and methoxadiazon. Piperonyl butoxide, an oxidase inhibitor, had no synergistic activity with permethrin against the O-colony. However, NIA 16388, which can act as both an oxidase and esterase inhibitor, exhibited the synergistic effect with permethrin. Electrophysiological study suggested that nervous system insensitivity (kdr-factor) might be involved in this colony. The nervous system of this coloby was also insensitive to aconitine which blocks the inactivation of sodium channels, so it was assumed that the nerve insensitivity could be due to modification in the sodium channels. These results suggested that the increase of esterase activity and insensitivity of the nervous system contribute to pyrethroid resistance in this insect.

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Gall formation and oviposition of the unisexual adults of Andricus mukaigawae (MUKAIGAWA) were tested to substantiate variations in ability ot infest three plant species of the genus Quercus. Under caged conditions, the unisexual wasps which had developed on Quercus mongolica FISCHER and Q. serrata THUNB. were able to produce a bisexual generation on these palants and also on Q. dentata THUNB. However, they did not oviposit in the buds of Q. dentata when the three host plant species were exposed at the same time. On the contrary, unisexual females which had developed on Q. dentata did not lay eggs in the buds of Q. mongolica and Q. serrata but did on Q. dentata in a forced oviposition experiment. Field observations indicate that the gall-forming ability of the bisexual generation of this wasp is similar to that of the unisexual gereration. On the basis of conspicuously qualitative difference in ovipositional preference of unisexual females, shape of the unisexual galls and gall-forming ability, two host races can be recognized in A. mukaigawae.

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Electrophysiological investigation of the antenna of the onion fly, Hylemya antiqua MEIGEN was made in relation to the specific oviposition stimulativeness of the propylthio compounds. 1. The compounds with a propylthio moiety elicited high electroantennogram (EAG) respones in general, though some non-stimulants also raised high EAG resopnses. 2. EAG responses for sulfur compounds were similar to those obtained with single cell recordings from DNPD cells, a group of cells characterized by resonsiveness to dipropyl disulfide. 3. Analysis of dose-EAG response regression lines for obiposition stimulants and related non-stimulants indicated that all oviposition stimulants are received by the same receptor. 4. It was thus concluded that the specific oviposition stimulativeness of the propylthio compounds can be explained in part by the specificity of olfactory receptors on the antenna.

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The sturctural proteins of an entomopoxvirus isolated form the smaller tea tortrix, Adoxophyes sp., were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Thirty structural proteins with molecular weights ranging from 14, 000 to 112, 000 were detected. The viral genome was examined with the restriction endonucleases, HindIII, BamHI and EcoRI. Gel electrophoresis of the digested DNA yielded 13-18 fragments and total molecular weight of the virus DNA was ca. 130.9×10⁶-149.4×10⁶.

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The nymphal period of Palomena angulosa MOTSXHULSKY was the shortest under 12L-12D photoperiod and shorter under 14L-10D than under 15L-9D. The relationship between the nymphal period from the 2nd instar to the adult and the length of stationary photophase was similar to that under changing (decreasing) conditions of photoperiod. The profiele of food consumption after moulting in the 5th instar differed markedly between the 12L-12D and 15L-9D groups. The activities of five kinds of enzymes in the digestive sysmtem were higher in the 15L-9D group than in the 12L-12D group, when assayed at the middle of the 5th instar. Taking the protein content in the midgut as well as the food consumption into consideration, it was suggested that photoperiod influenced the feeding activity of P. angulosa nymphs.

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Effects of agonists for glutamate receptors, L-glutamic acid, quisqualic acid, kainic acid, domoic acid and ibotenic acid on mechanical responses of the hindgut isolated from American cockroaches were examined by measuring isotonic contractions with a mechano-electroc transducer. Ibotenic acid exerted an inhibitory effect, and all others had excitatory actions. L-glutamic acid and quisqualic acid produced phasic-tonic contractions, while kainic acid and domoic acid produced phasic contractions only. Verapamil at 5×10^-6 M abolished spontaneous peristaltic movements of the isolated hindgut and suppressed the agonist-induced contractile responses by 50% (at 10^-5-10^-4 M agonist concentrations). Ibotenic acid at 5×10^-5 M completely inhibited the peristaltic movements of the hindgut, and picrotoxinin, a chloride-channel blocker, prevented ibotenate from acting. Responses to L-glutamic acid and quisqualic acid were effectively blocked by glutamate dimethyl ester, but the resonses to kainic acid and domoic acid were more susceptible to blockage by 2-amino-4-phosphonobutyric acid, γ-D-glutamylglycine and D-α-aminoadipic acid. These results sults suggest that there may be three distinct types of glutamate receptors on the hindgut muscle of American cockroaches : the quisqualate-activated receptor (type I) is preferentially antagonized by glutamate dimethyl ester, the kainate/domoinate-activated receptor (type II) is more effectively blocked by 2-amino-4-phosphonobutyric acid and γ-D-glutamylglycine than by glutamate dimethyl ester, and the ibotenate-activated receptor (type III) is sensitive to chloride-channel blocker, picrotoxinin.

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Insecticide susceptibility of the white backed planthopper, Sogatella furcifera HORVATH, (WBPH), and brown planthopper, Nilaparvata lugens STAL, (BPH), was surveyrd by the topical application method in 1980 and 1987. Comparing the data obtained in these experiments with previous data, the susceptibility of the WBPH to organophosphate and carbamate insecticides was found to have decreased with years. Susceptibility of the BPH to organophosphates in 1987 was greater than that in 1980. The susceptibility of both insects to p, p'-DDT decreased with years, but that to lindane was almost the same as in 1967. In 1987 LD₅₀ values of the WBPH and BPH to synthetic pyrethroids were also evaluated.

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2-Hydroxy-6-methyl-benzaldehyde was identified as the alarm pheromone of the acarid mite, Tyrophagus pernicious, which is known as a pest attacking spinach culture and cucurbitaceous plants in the field and also in greenhouses. The compound, which was one of the major components of the hexane extract, was active at 10 ppm. Although this compound has been identified not only inmites, Acarus siro and Caloglyphus rodriguezi, but also int he common eucalypt longicorn Phoracantha semipunctata, this is the first report on its bilogical significance. Other than T. peniciosus, the compound is sporadically districuted among other species of the genus Tyrophagus, namely, four strains of T. putrescentiae among the five investigated and one of two strains of T. neiswanderi. It was not detected in T. similis.

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The Phenology of attacked and damage by the genus Vespa on Apis mellifera was analyzed with regard to three types of honebee colony : hived colonies whose entrances were equipped with hornet traps, hived colonies whithout artificial pretoction, and wild colonies. According to the investigation, performed in Suzuka City, Mie Prefecture, over a 10-year period, V. mandarinia was the dominant species, followed by V. simillima. V. mandarinia visited apiaries from mid- to late August through November every year, and mass-attacks started from their first arrival but ceased in late October. In hives with no protection and in nests of wild colonies, all colonies were exterminated by V. mandainia without exception. Since A. mellifera has no effective defensive strategy against V. mandarinia, A. mellifera colonies cannot be kept in the habitat of the hornet without artificial protection.

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Individual rearing of the gypsy moth, Lymantria dispar (L.), was carried out for over a quarter of a century (1956-1981) on 86 egg batches collected at 73 localities in Japan. Six and 7 larval instars in female and 5 and 6 instars in male were obtained for almost all races. In some races 5 and 8 instars in female and 4 and 7 instars in male were obtained. Any discussion of racial differences in morphological or physiological characters should terefore be made after the sorting of experimental records based on the number of larval instars and sexes.

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During successive selection for adults with a special wing form from a population of the brown planthopper, Nilaparavata lugens, a negative correlation was found between the proportion of brachypters and the grade of black pigmentation in the adults : population including more blackish individuals tended to exhibit a lower ratio of brachypters. The selection for blackish macropters finally generated a population producing predominantly macropters, while the selection for yellowish brown brachypters produced a population exhibiting totally branchypters, over broad ranges of nymphal densities in both sexes. Two populations from Malaysia and the Philippines were quite similar to this brachypter producing population in their wing-from responses to density. All of 14 populations collected in Saga and Nagasaki Prefectures during 1986 and 1987 were highly macropterous and their body coloues were blackish. During these two years, population density of the immigrants in paddy fields was unusually high inthe rainy season in both prefectures, but the insects did not cause severe damage to rice plants in most districts. Whether these unexpected enects were due to the immigration of hoppers with highly macropterous character was discussed.

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A wild Bruchid Kytorhinus sharpianus has several characters peculiar to stored bean pests. Its life cylce was investigated in the field and it was found to the host plant, Sophola flavescens, in mid June. Females oviposited on small pods just after seeds had been borne. The first generation larvae developed within the fresh growing seeds and emerged as adults in mid August. The adults soon laid eggs on matured pods. The second generation larvae fed on matured-dry beans on the standing plants and adults emerged at the end of September. Eggs were the laid directly on dry beans inside the split pods and the beans were infested by the third generation larvae. The developmental period of K. sharpianus larvae fed on dry host beans was studied in the laboratory under various temperature conditions. The higher the temperature was, the earlier adults emerged. Males emerged several days earliery than females. Oviposition without feeding after emergence was found in summer insects but not in wintering insects in the laboratory. The dry bean infestation of K. sharpianus seems particulary adapted to the life cycle of S. flavescens, which has the longer period from flowering to the matured-dry bean state. The process of estabilishement as a stored bean pest was discussed.

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The white-backed lanthoppers lose their dry body weight and lipid contents on a long distance flight. We analyzed these variables of insects caught over the East China Sea (31°N, 126°E) and from various parts of the Japanese islands in June and July 1986 and 1987, and compared their discriminant functions. Mean numbers of newly immigrated planthoppers, so defined when they showed the same levels of variables as those of the East China Sea population, were 4.2 to 4.5 out of 12 analyzed in samples from Nagasaki and elsewhere in Japan. They were always found inassociation with the synoptical frontal systems developed over the Japanese Islands. This finding was in conformity with the previously proposed migraton theory. Significantly different dry body weights and triglyceride and fatty acid contents among the East China Sea populations caught in 1986 and 1987 suggested that their emigration origins differed.

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Cross-attraction among three Tribolium species, T. freemani, T. castaneum and T. confusum, and F₁ hybrids between the former two species was investigated using their aggregation pheromones. It was confirmed that (i) the male pheromone of Hybrid-I (hybrids between T. freemani (♀)×T. castaneum (♂)) was active to T. castaneum, but inactive to T. freemani and T. confusum; (ii) the pheromone of Hybrid-II (hybrids between the reciprocal sex combination) attracted the two species but not T. confusum; (iii) Hybrid-I was attractive to the parent species but not to T. confusum; (iv) Hybrid-II responded to all three species; and (v) the two hybrids were attractive to each other.

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The effect of the feeding site (Brood-area feding [BAF] vs. top-bar feeding [TBF]) of various pollen substitutes in hives on the consukmption of pollen substitute, and the production of royal jelly and queens was compared using caged colonies of Apis mellifera. Pollen substitute consumption and royal jelly produciton were 20-35% higher for BAF than TBF. Hypopharyngeal gland development and queen-producing capacity were also superior for BAF. However, no substantial difference was found between queens produced only on pollen substitutes and those from pollen-fed controls irrespective of the feeding method. The underlying mechanism of the effectiveness of BAF is discussed from both physiological and practical aspects.

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