After the injection of ¹⁴C-urea into mature larvae of the silkworm, radioactivity level in feces, urine, cocoon shell, larval exuvium and body of young pupae was compared between the individuals reared on mulberry leaves and those reared on an artificial diet. In the individuals reared on an artificial diet, ¹⁴C-urea was recovered at levels as high as 30% both in the feces and in the urine, 10% in the cocoon shell, 0.5% in the exuvium and 20% in the pupal body. On the other hand, recovery of ¹⁴C-urea in the feces and urine in mature larvae fed on mulberry leaves was less than 0.5%, and the radioactivity level in the cocoon shell, pupal body and exuvium was also significantly lower than in those fed on an artificial diet. In the individuals reared on an artificial diet, total recovery of ¹⁴C-urea was 99% or more, whereas that in larvae fed on mulberry leaves was as low as 2.5%. Degradation of ¹⁴C-urea was determined subsequently by means of capturing of expired ¹⁴CO₂ at intervals of 30min for 2hr. In the individuals reared on mulberry leaves, cumulative ¹⁴CO₂ expired in the 4-day-old larvae of the last instar was approximately 5% of the radioactivity injected, whereas that in mature larvae was 9%. Furthermore, ¹⁴C-urea injected into the prepupae, pupae and adults was degraded completely to CO₂ in 2hr. On the other hand, in the individuals reared on an artificial diet ¹⁴C-urea injected into the 4-day-old larvae in the last instar was respired as ¹⁴CO₂ at the level of 2% in the male and 0.6% in the female, and degradation of ¹⁴C-urea was very low in mature larvae, prepupae, pupae and adults, respectively. These results suggest that urease is activated after the spinning period in the larvae fed on mulberry leaves, while in the larvae fed on an artificial diet, activation of this enzyme is not induced.

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In order to use radiolabelled benzomate for the study of permeability and metabolism of benzomate, ³H-benzomate was synthesized from ³H-dimethylsulfate and 3-chloro-2, 6-dihydroxybenzo c acid through four-reaction steps. The yield of synthesized ³H-benzomate was 81.3% and its specific activity was 1.09m Ci/mmol. Female adults of five citrus red mite strains were dipped in 200ppm solution of ³H-benzomate for 5sec. At 24hr after treatment, 17, 41, 49, 60 and 66% of the dose applied had penetrated through the cuticle of the Okitsu R, Shizuoka R, Fukuoka R, Shizuoka S and Fukuoka S strains, respectively. It was suggested that in the Okitsu R strain, the low rate of benzomate permeability through the cuticle was one of the mechanisms of benzomate resistance in citrus red mite. Metabolites of five strains of citrus red mite were compared 24hr after dipping in 200ppm solution of ³H-benzomate. About 60 to 75% of the ³H-benzomate applied was recovered as benzomate itself from each strain of mites. The main metabolite was ethyl-³-chloro-2, 6-dimethoxybenzohydroxamate. There was a slight difference in the metabolism among the five strains. It is suggested that the metabolism of benzomate may not be an important factor of benzomate resistance in the citrus red mite.

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The flight muscles of overwintering adults collected at hibernation sites were poorly developed, but the muscles developed after the adults fed on grasses present in these areas. The ovaries were undeveloped or showed discrete evidence of development. The flight muscles of all the adults which were flying around the hibernation sites had fully developed and the width of the epipleural muscles was 156-216μm. The ovaries were poorly developed and most of them had no mature eggs. After the adults immigrated into paddy fields and fed on rice leaves, their flight muscles began to degenerate, whereas their ovaries developed and had mature eggs. The newly emerged adults, had poorly developed flight muscles just after emergence, but the flight muscles soon developed during the adults stayed in the paddy fields. The flight muscles of all the adults caught into vinyl sheet traps had fully developed and the width of the epipleural muscles was 156-216μm. After the adults moved under fallen leaves at the hibernation sites, their flight muscles started to degenerate. Ovaries of newly emerged adults caught during late July to early August were poorly developed. It is considered that overwintering and newly emerged adults develop full grown flight muscles and are able to show active flight behaviour only during the period of migration.

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Mating behavior of the udo longicorn beetle, Acalolepta luxuriosa was observed in the field and the laboratory. Mating behavior of the male consisted of wandering (searching for the female), orientation to approaching the female, grasping, mounting, licking, and copulation. The wandeing behavior of the male was the only means for the male to meet with the female. Copulation lasted about 20sec to 10min with an average of about 4min. After copulation and during oviposition by females, males still remained in contact with the female in a position of amplexus, and copulation took place many times with an interval of about five minutes. Sexual maturity or reaction of the female to the male sexual activity increased as the female aged, reaching the maximum on the 6th day after emergence attraction of the male to the female also increased with the age of the male but more slowly, reaching the maximum on day 10. The competition between males for the access to the female was strong and males fought each other by grasping, pushing and taping with the antennae. The significance of repeated copulation in A. luxuriosa was discussed from the viewpoint of spermatozoon competition.

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The sexual dimorphism in the nymphal stages of Tingidae was observed by means of a scanning electron microscope on the basis of 9 Japanese species. The following morphological differences between male and female nymphs are externally recognizable on the 8th and 9th sternites of the 4th (excepting Cysteochila fieberi observed only on the 5th instar nymphs) and 5th instar nymphs of each species. In the female, the hind margin of the 8th sternite is distinctly projected posteriorly forming an arched sclerite. The lateral sides of the convexity of the 9th sternite are straight and convergent posteriorly, so as to form a V-shaped sclerite. A series of very minute holes are arranged in a row along the median line of the 9th sternite. The 9th sternite of the 5th instar nymph is provided with a small bifurcate (W-shaped) projection on its postero-central margin. In the male, the hind margin of the 8th sternite is not projected posteriorly. The converged lateral sides of the convexity of the 9th sternite are outwardly curved, so that it forms a U-shaped sclerite. The 9th sternite is provided with a minute hole near the posterior end of its median line, and with three to eleven minute processes around the minute hole.

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Soybean plants were artificially defoliated to simulate the feeding of leaf eaters. The effect of defoliation on the yield was assessed through the change in the recovery pattern of the plant. Based on the data obtained, a method was proposed to determine the economic injury level (EIL) and the control threshold (CT) for leaf-eating insect pests of soybean, e.g. the common cutworm, Spodoptera litura. The early-maturing variety of soybean (Bonminori) was sown on 10th June, 1981. The planting density was 8.33 plants/m² with an interval of 0.6m between ridges. Artificial defoliation was carried out at 6 different growth stages of soybeans with defoliation rates of 25, 50, 75 and 100%. The pattern of recovery of the plants after defoliation was determined at 10-11 day intervals in terms of leaf area, number of pods, dry weight of leaves, stems, roots and pods. The number of grains per plant and the mean grain weight were measured at harvest. The earlier the stage of growth of soybean at the time of defoliation was, the higher the recovery rate of leaf area. However, no detectable recovery was observed in the plants defoliated at the reproductive stage, especially after R3 (beginning pod stage). Defoliation in the early stages resulted in a yield loss through the reduction in the number of pods, while defoliation in later stages brought about a yield loss associated with the reduction both in the number and mean weight of pods. Based on the relationship between the yield loss and the weight of defoliated leaves at different growth stages of the soybean plant, the extent of defoliation that will cause any definite yield loss can be estimated. The EIL and CT for the common cutworm were calculated on the basis of published data on its feeding activity and survival during the larval stage.

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The parthenogenetic females of the rice water weevil were first identified in 1976 in Japan. To assess the damage caused by the rice water weevil to “early planting” culture of rice, the effect of adult density on the growth of rice plants and yield was analysed. The degree of leaf injury by the adults was correlated with the number of adults released. Leaf injury was severe when the rice plants were attacked by adults immediately after transplanting. The growth of the rice plants was retarded due to both leaf injury by adults and root injury by larvae. A significant difference in the number of tillers between infested and uninfested rice was observed 5 weeks after transplanting. Yield loss exceeded 10% when more than one adult per hill was released, but it was less in the “early-season” culture when the attack of rice plants by the adults occurred later. It was concluded that the decrease in the number of panicles due to the rice water weevil was mainly responsible for the yield loss.

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In Kagoshima Prefecture, Myzus persicae (SULZER) and Lipaphis erysimi (KALTENBACH) overwinter predominantly as viviparae. Seasonal prevalence of the aphids was surveyed by collecting alatae with yellow pan water traps and counting aphids on rapes and radishes in the Osumi district during the period 1978-1980. M. persicae population was high from April to June and from November to January, the peak density being higher in spring. The population of L. erysimi was high from October to January. The population density of both aphids was maintained at a very low level from July to October.

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Diapause, reproductive capacity and host preference were compared among the three populations of Panonychus citri occurring in the southern part of Okayama Prefecture. Two of the populations (Sairyuji and Momoezuki) originated from pear orchards and the other (Ushimado) from citrus. Of the two pear populations, the Sairyuji population laid only summer eggs, whereas the majority of the eggs oviposited by the Momoezuki population were winter eggs, when the entire immature stages were exposed to a 15°C: 8L regime. Under the same conditions, the citrus population oviposited only summer eggs. The intrinsic rate of increase of each of the nondiapausing populations (Sairyuji and Ushimado) was much higher, compared to that of the diapausing population (Momoezuki), and the rates of the nondiapausing populations were higher on pear than on citrus. On citrus the diapausing population did not develop at all into the adult stage, but the non-diapausing populations did develop both on citrus and pear. All the three populations including the citrus population strongly preferred pear to citrus. These facts indicate that the Sairyuji population from pear was quite similar to the citrus population with regard to diapause incidence and host preference.

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Diflubenzuron, 1 (4-chlorophenyl)-3-(2, 6-difluorobenzoyl) urea, showed good control efficacy on larvae of the rice water weevil, although leaf injury due to adults was not affected. Attempts were made to clarify the mechanism of insecticidal action of diflubenzuron against the rice water weevil. The number of eggs oviposited and the hatch-ability of eggs were determined when adults were fed on rice seedlings treated with diflubenzuron. It was concluded that control efficacy by diflubenzuron was caused by the inhibition of hatching of eggs.

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The stink bugs were released on the rice plants of different ripening stages and on harvested hulled rices. The brownish color ring which characterizes some of peckey rices seems to be formed by the rice itself.

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The susceptibity of the adult of rice water weevil to some synthetic pyrethroids and carbosulfan was tested. Among the insecticides tested, cyphenothrin, permethrin, cypermethrin, fenvalerate and carbosulfan were more effective than NK-8116, S-5436, phenothrin and fenpropathrin. The replacement of chlorines and cyano groups in the molecules of phenoxy benzyl esters boosted their toxicities to the rice water weevil.

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