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Thrips palmi KARNY, originating from the tropics, is a newly-occurring thrips with a wide range of host crops in southwestern Japan. Among 11 chemicals tested on field potatoes in October and again in November, effective control of the pest was possible by carbosulfan EC at a rate of 0.25 kg Al/ha and prothiophos EC at a rate of 0.45 kg AI/ha sprayed at a volume of 1, 000l/ha. Oxamyl G applied at a rate of 1.5 kg AI/ha was outstanding for its long-lasting residual control. Mecarbam EC, TIA-230 EC, and a mixture of chlorfenvinphos EC + mancozeb WP reduced the thrips population to 50%. No phytotoxicity on potato plants was observed for any treated plots.

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Five life tables for eggs to adults of the bean miner, Ophiomyia phaseoli, were constructed based on an examination of young kidney bean seedlings sampled from the field at 2-4 day intervals during July-August in 1979 and '81, December-March in 1979-'80 and 1980-'81, and April-May in 1980. About 500 kidney bean seedlings were planted in the field at the beginning of each survey season and the plant growth was checked at 2 developing leaf stages by hand-picking the ensuing leaves so as to reduce variation in the amount and period of eggs deposited among the plants. At each sampling, 20 seedlings were taken at random from the seedlings showing signs of egg deposition or larval inhabitation. The differences in the initial number (1x) of eggs were not great among four of the five life tables, e.g. 265-432 eggs per 20 plants, except the one experiment where only 91 eggs were laid per 20 plants. However, the total survival rate from eggs to adults was apparently seasonally dependent since it was much higher in summer (14-20 %) than in winter (3-6 %) or in spring (8 %). The causes of such seasonal dependence in the total survival rate seems related to the pupation site probably located at the lower part of the plant stem or beneath the soil in summer in contrast to the pupation site frequently seen at the upper part of plant stem in winter. Such a seasonal change in pupation site would affect the action of pupal parasites (Pteromalids) and cause more or less the escape of the fly population in summer.

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[in Japanese]

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Effects of temperature and photoperiod on the development of Plusia agnata STAUDINGER, one of the major defoliators of soybean, were investigated in the laboratory. The number of moults in the larval stage varied from five to seven, and the appearance rate of the 6th instar type was higher than that of the others under the condition of 17-30°C. The threshold temperatures for the development in egg, larva, pupa and egg to adult emergence were 8.9, 7.9, 10.5 and 9.0°C and the thermal constants 56. 5, 263.2, 109.9 and 434.9 day-degrees, respectively. Neither larval nor pupal diapause was induced by a short photoperiod of 8L-16D. The factors affecting the number of instars, the number of generations a year and the possibility of overwintering in Fukuoka Prefecture were discussed.

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[in Japanese]

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An ID ₅₀-time course study was conducted to elucidate whether Chilo iridescent virus (CIV) is capable of replicating in the frog, Rana limnocharis. A young frog (body weight: 235-270 mg) was intraperitoneally inoculated with 5 μl of CIV suspension containing 10 ^5.63ID ₅₀. At 24-hr intervals, the ID ₅₀ value in the supernatant of a 10% emulsion of the individual frog was assayed using Galleria mellonella larvae. The results showed that there was no increase in the titer of virus infectivity during the test period of 96 hr. The ID ₅₀ value detected 96 hr postinoculation was approximately 2% of that obtained 30 min postinoculation. This indicates that the acute lethal toxicity (OHBA and AIZAWA, 1981) of CIV for the frog, R. limnocharis, is not caused by the replication of the virus.

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Recent studies (YUKAWA, 1980; YUKAWA et al., 1981) on the life history, host plant range and parasite complex of the Japanese Asphondylia species indicated that the soybean pod gall midge, Asphondylia sp. might be identical with some of those inhabiting wild hosts other than Leguminosae. To detect the identical species, the distribution pattern of the gall midge was compared with that of the other Asphondylia species. The soybean pod gall midge exists only in Japan, being distributed in Honshu, Shikoku and Kyushu (NAITO, 1964). Since this species has never been found in Hokkaido, special attention was paid to the distribution pattern of the other species in this area. Among the 13 species investigated, A. baca on Ampelopsis, A. diervillae on Weigela, A. sp. on Aucuba and Diplosis morivorella on Morus (transferred to Asphondylia soon) were recognized to be distributed in Hokkaido as well as in other places. A. sp. on Alpinia was obtained only from the southern parts of Japan. The ligustrum fruit midge, A. sphaera was collected from various localities in Honshu, Shikoku and Kyushu, except Hokkaido. The distribution data for the 7 remainder species were obtained only from certain restricted places in Honshu and Kyushu. Thus, the distribution pattern of A. sphaera best coincided with that of the soybean pod gall midge. In addition, the fruit and flower bud galls produced by A. sphaera were commonly found on Ligustrum japonicum growing as hedges or garden trees, particularly in south-western Japan where the soybean is often seriously attacked by the gall midge. These results indicate the close relationship between the two species, and require a host-exchanging experiment between the soybean and Ligustrum species.

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The soybean pod gall midge, Asphondylia sp. has been known as a serious pest of soybean particularly in south-western Japan. However, some aspects of the life history and host plant range of the species still remain unclear. In order to clarify the life history and establish a control method against the gall midge, it is necessary to evaluate the rate of infested beans through an investigation on the age structure of the species in association with the developmental stages of the host pods. The rate of infested beans was often underestimated owing to the following reasons: (i) overlooking the tiny midge eggs or immature larvae in dissection; (ii) successive invasion of adult midges into soybean fields; (iii) earlier fall of infested pods after emergence of adults; (iv) fall of puparia out of the infested pods; (v) emergence of parasitoid wasps which prevents recognition of the emergence holes of the gall midge. In this paper, the developmental stages of the host pods are expressed in terms of the percentage of young (less than 20 mm in length) to the total pods. The rate of infested beans was more accurately evaluated by sampling the host pods with 1 to 7 percent young pods for the two cultivars, "Wasemidori" and "Akisengoku", and 5 to 30 for "Kogane".

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Newly-emerged adults, having lived in the soil for 5-13 days, appeared on the ground and started to feed on host plant leaves in the laboratory. Females began to deposit their eggs in the soil 3-5 days after the feeding. In the test of June-July 1980, there was considerable variation in the oviposition period ranging from 2 to 71, 45 eggs on an average. The daily oviposition was intermittent indicating a fluctuation in the daily oviposition pattern. Mated females showed an alternation of active feeding and oviposition at a constant temperature of 25°C, whereas unmated females consumed a lesser amount of host plant leaves though they took much food in the first few days after feeding began.

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[in Japanese]

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The effects of repeated application of soil fumigant (1, 3-D) were investigated on soil nemic fauna and on the residual after-effects on invading pests. In the treated soil, kidney bean plants were voraciously attacked by the common cutworm (Agrotis segetum) causing 81.7% killing of the plants despite the application of DEP and diazinon granules soon after the damage appeared. However, two applications of entomogenous nematode, Heterorhabditis bacteriophora, with 3, 600/plant in the non-fumigated soil reduced the extent of plant killing to 17.7 %. Predacious mononchids disappeared from the treated soil. Inoculation tests of M. incognita showed that the infectivity and repro-duction of the nematodes were more suppressed in soil treated by the fumigant 40 days before. However, in the soil treated 140 days before, inoculated nematodes rapidly multiplied and caused more damage to the test plants than did those in the non-treated soil.

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[in Japanese]

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The DD-136 strain of N. carpocapsae was tested to see if it would provide biological control against the whitespotted longicorn beetle (Anoplophora inalasiaca) infesting citrus orchards. The first to 4th instar larvae and adults of the beetle were infected, and were then killed by N. carpocapsae within 2 days at 25°C. The nematodes multiplied in the host cadavers. The emergence of infective juveniles (J _III) from the cadavers began 8 days following inoculation and continued on each instar larva for 2 weeks, while on adult beetles the emergence began 13 days after and continued for 1 month. The average number of J _III emerging from 1st instar larvae (L ₁), L ₂, L ₃, L ₄, and adults was 3, 100, 6, 100, 13, 300, 29, 900, and 108, 000, respectively. Application of DD-136 to the L ₂ and L ₃ burrowing in the citrus limbs yielded satisfactory results. Topical application with gauze to the opening of the beetle gallery with ca. 1, 000 J _III in 0.5 ml distilled water gave 90% mortality 8 days after application at 25°C. Spraying of J _III suspension to the surface of the limbs gave ca. 60% mortality.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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A spore-crystal complex of Bacillus thuringiensis AF101 strain (serotype 4a:4b) was at least 25 times more toxic than that of B. thuringiensis A3Cl strain (serotype 4a:4b) tow and the larvae of the fall webworm, Hyphantria cunea. Toxicities of purified preparation of spores, crystals, and spore-crystal mixtures were tested using fourth-instar larvae of H. cunea to determine the effects of the existence of spores on toxicity. Spores of both strains showed low toxicity. In contrast, crystals of both strains show-ed high toxicity and AF101 crystals were at least 25 times more toxic than those of A3C1. By the addition of the spores of each strain, the toxicity of AF101 crystals increased about 4 times and the larvae were killed more rapidly. These results indicate that the presence of the spores intensifies the toxicity of AF101 crystals toward the larvae of H. cunea.

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[in Japanese]

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