Repeated visits of Polistes jadwigae DALLA TORRE to its hunting site were investigated in a small citrus grove where the 5th instar larvae of Papilio xuthus LINNÉ were artificially placed as prey for wasps. The prey-searching wasps that had entered the grove from outside areas were individually marked and their behavior was observed for a maximum of four consecutive days. After hunting prey, each wasp carried a piece of dissected meat to its nest which was far from the grove. They returned to the grove more frequently than the wasps that had left it without finding prey. Returning to the grove, the wasps with hunting experience tended to go to the citrus trees on which they had previously hunted their prey. Most of the wasps that had hunted prey on the previous day visited the grove again on the following day and some repeated the behavior four consecutive days. Such repeated visits of the experienced wasps to the grove resulted in a daily increase of the number of prey hunted by them.

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The effect of temperature on the rate of development of pupal stages of the melon fly and a technique to control the timing of adult emergence were studied. The regression equation, V=0.58t-5.32 was obtained for temperature (t) and relative velocity of development (V). No adult emerged at 32°C and only a few emerged at 14°C. The developmental threshold 9.16°C was obtained from the equation. The average total effective temperature from pupation to adult emergence was 172.7 degree-days. In order to synchronize the adult emergence of five populations of different ages, we successfully used a combination method of three temperature levels based on the relative velocity of development.

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An artificial substrate for oviposition, a cylindrical plastic container perforated with small holes and lined with a sheet of tissue paper wetted with squash juice, was found to be highly effective in stimulating oviposition of wild flies collected from field-infested fruits. However, because of a slow rate of development of wild flies in fecundity, it was necessary to select a colony with efficient egg production and a short preovipositional period. A mixture of sugar and protein-hydrolysate was found to be a better adult food for increasing fecundity than the individual components separately presented. An increase in the protein-hydrolysate content in the mixed food and in the number of flies per cage increased the amount of excremental deposit in the cage, but also caused an increase in egg production within a short period after emergence. A large cage for 50, 000 individuals producing 4.5 millions eggs within 7 weeks after emergence was designed based on tests of egg production. The oviposition substrate mentioned above was further improved by substituting the tissue paper with a polyethylene net.

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The carbohydrates, starch, glucose, and sucrose affected the selective oviposition of L. brunneus. The female adults laid most of the eggs in veneer blocks treated with carbohydrates. Among treatments of glucose, starch, and a mixture of both carbohydrates, the last was the most suitable for stimulation of oviposition. Since few differences in influence on oviposition between glucose and starch were observed, it was concluded that soluble sugars (glucose, sucrose, etc.) were very important substances for selective oviposition, in addition to starch. There was a positive relationship (n=35, r²=0.76) between the number of the ‘tasting mark’ and that of eggs laid. Although the female adults laid most of the eggs in the veneer blocks through natural pores of wood vessels, the females laid a few eggs through the pores (‘tasting mark’) opened by themselves. Therefore, it was presumed that making the mark included the function of admitting the ovipositor.

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Cartap (CTP) concentrations in rice plants were measured by gaschromatography after treatment with CTP granules in a nursery box. Insecticidal activity of the plant to two species of insects, Nephotettix cincticeps and Laodelphax striatellus, was simultaneously tested. It was shown that CTP which was brought into the paddy field with the soil at transplantation was absorbed by the plant, and therefore, a high level of insecticidal activity was maintained for more than two weeks. CTP concentrations calculated from the mortality of the two insects based on the CTP concentration-mortality curves did not correspond with those analyzed by gaschromatography. The later was much higher than the former. One of the reasons for this difference is thought to be the CTP accumulation in the part of the leaves. CTP seemed to be conveyed in two ways in the rice plant. One was in the xylem, but the other was not clear. It took about two days to go up to the leaf from the root by the second way. The insecticidal activity could not be interpreted by CTP concentrations in the xylem exude because these were much lower. CTP in the phloem sap, therefore, seemed to have an important role in insecticidal activity to sucking insects.

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The estimate of the summer population density and survival rate of the melon fly, Dacus cucurbitae COQUILLETT, males was carried out by the mark and recapture method in the countryside near Naha City, located in the southern part of Okinawa Island. A single release and repeated recapture system was adopted. The data obtained were analyzed by HAMADA'S z-index method. The density was estimated to be 200-300/ha in a suitable habitat, and about a half of this in an unsuitable one. The survival rate was about 0.8/day in both habitats. The accuracy of these estimates was discussed with respect to seasonal change in the number of flies caught by ‘monitor traps’ baited with cue-lure, a male attractant, and comparison was made with estimates obtained in other islands of Okinawa. It was concluded that the estimates described above are reasonably accurate.

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Active components of the sex pheromone of the peach fruit moth, Carposina niponensis WALSINGHAM, have been isolated and identified as (Z)-7-eicosen-11-one and (Z) or (E)-7-nonadecen-11-one. Therefore, sex-pheromone activities of 7-alken-11-ones of carbon numbers 17∼23 were evaluated with an electroantennogram (EAG), field trapping, and laboratory tests of sexual stimulation. On the EAG, the male antenna of peach fruit moth was more sensitive to each (Z)-isomer than to the corresponding (E)-isomer. Among the 12 homologues, (Z)-7-eicosen-11-one wasconfirmed to be most active, followed by (Z)-7-nonadecen-11-one. On field trapping, the activity as attractant for males was confirmed only for (Z)-isomers of 17∼20 carbon homologues. Of these, (Z)-7-eicosen-11-one (A) and (Z)-7-nonadecen-11-one (B) were conspicuously attractive. Furthermore, the activity was synergistically enhanced by mixing the two compounds at the ratio of 20:1 for A to B. This synergistic action of the two compounds was also confirmed in sexual stimulation under the laboratory conditions. These results confirm that (Z)-7-eicosen-11-one and (Z)-7-nonadecen-11-one are the major and the minor components, respectively, of the female sex pheromone of the peach fruit moth.

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A simple method of laboratory attraction test for the sex pheromone of Chilo suppressalis was designed with a flight chamber (80×150×250cm) placed in an air-conditioned green house and box sticky traps. Conditioned air supply for the green house was introduced into the chamber to obtain an appropriate air flow requisite for the male orientation behavior. The traps were made of cardboard, of which entrances were narrowed to avoid male catches not by attraction. When two traps were used, around 40% of the males released were caught in a virgin female trap, whereas almost no moth was caught in a blank trap. Percent trap catch was slightly raised as the number of released males was increased ranging from 20 to 100. Trap height had little effect on the trap catch. It was also possible to use four traps in the chamber. Attractancy of three treatments of 0.1, 1 and 10mg of the synthetic sex pheromone on rubber septa was examined. Among them only the 1mg caught significant males, indicating that in this species relatively narrow range of evaporation rate of the pheromone was necessary for the male trap catch.

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The infection and multiplication site of a densonucleosis virus (Densovirus) in the silkworm, Bombyx mori, were studied by the fluorescent antibody technique. Among various tissues of infected larvae, only the midgut epithelium showed specific fluorescence. The fluorescence was restricted to the nuclei of the columnar cells, showing the site of virus multiplication. The fluorescence appeared sporadically in a few columnar cells 24hr after virus administration and became more intense and increased in number with time. At 72hr after virus administration, most of the columnar cells showed fluorescence. However, a few columnar cells near the cardiac valve did not show any fluorescence even in the later stages of the disease.

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The order of depth of larvae was vermiculite>silty clay loam>sand when the depth of the final instar larvae of the black cutworm in the daytime was determined under experimental conditions in three kinds of soil. Most larvae were found resting less than 4cm deep at the head position and less than 7cm deep at the tail-end position, even in vermiculite. Larvae were found somewhat deeper at 20°C and 25°C than at 15°C. At 5°C, a considerable number of larvae were found near the soil surface. The most suitable water content in vermiculite for the deepest underground concealment of larvae was from 50% to 67%. Most larvae could not enter deep into dried vermiculite as well as when the material was very humid. The pupation site of larvae was much deeper than the normal resting site, though the dry soil was not suitable for deeper pupation. When two larvae were placed in a test container, they took their places separately under different pieces of food. When three larvae were placed, 45% of them escaped from the test container. The results clearly indicate that they possess some exclusive behaviours. When insecticides were topically applied to larvae, the larvae could enter the soil but most larvae appeared dying on the surface of soil. The order of the number of dying larvae on the soil surface was isoxathion>methomyl>dichlorvos>diazinon>heptachlor, reflecting their effectiveness when topically applied. Under a regime of 16 hours light and 8 hours dark per day, fewer larvae appeared above the surface of soil within an hour after light off, but most larvae exposing their head or body above the surface of the soil for feeding hid themselves in the soil just after light on.

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The green rice leafhopper hibernates mainly at the fourth larval instar. The non-diapause larvae generally complete their development in about 20 days at 25°C, while the longest duration of diapause lasted more than 40 days. The diapause was induced under short-day conditions. The short-day conditions acting only on the larval stage was not effective. The short-day conditions in the egg stage alone were sufficient to induce diapause. The most sensitive stage was after the eye-spot formation stage, during the three days before hatching. The critical day lengths for the induction and termination of diapause were 12.5∼13.0 hours and 12.5 hours, respectively, at 25°C. At a low temperature of 20°C, the first instar larvae were also susceptible to photoperiod, but the induced diapause was about half the duration of that induced in the egg stage. Long-day conditions in the larval stage, however, terminated the diapause easily and accelerated the growth. It is inferred that the first occurrence of overwintering larvae is determined by the photoperiod before hatching, and thereafter the gradual reduction in photoperiod and temperature induces and maintains diapause.

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