The resistance breaking population (RB population) of Meloidogyne incognita that damages resistant tomato cultivars grown in greenhouse was confirmed in southern Hokkaido in 1996. In this report, the emergence and factor analysis of the RB population of M. incognita occurred in Hokkaido are described, with the following results:(1) The RB population of M. incognita was detected in the production regions where resistant tomato cultivars were cultivated in greenhouse with successive cropping or at a high frequency.(2) The degrees of root gall of 29 resistant tomato cultivars grown in soil inhabited by the RB population were as high as those of the susceptible cultivars. No cultivars resistant to the RB population were found.(3) The degrees of root gall of resistant tomato cultivar grown in soil inhabited by the RB population, was formed from 22°C to 33°C the same as that in the case of the susceptible cultivar. On the other hand, no root gall was formed below 28°C in the resistant cultivar grown in soil inhabited by a common population of M. incognita, but the resistance was lost above 30°C.

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[in Japanese]

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We attended to breed a lettuce (Lactuca sativa L.)-feeding stock of the diamondback moth (DBM), Plutella xylostella (L), in order to develop a much easier mass-rearing system of DBM. The results show that DBM could be cultured consecutively for five generations using head-lettuce leaves, and for at least six generations with leaf-lettuce leaves. To our knowledge, this is the first report of DBM rearing for successive generations using non cruciferous plants. In the case of the “leaf-lettuce-feeding” lines, pupation rate and adult emergence rate of DBM were higher, larval period was shorter, and rate of naked pupae was lower than those in the case of the “head-lettuce-feeding” lines. The results also suggest that some substances found in lettuce, such as lactucine andlacturopicrin, likely affect the larval performances of DBM.

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The control of the stripe flea beetle, Phyllotreta striolata, by drench treatment of an entomopathogenic nematode, Steinernema carpocapsae, was examined on Japanese radish fields. Damages on Japanese radish roots by P. striolata larvae at harvest time were reduced by 3-5 times of treatment with 250-500 thousand nematodes/m² dissolved in water during the growing period of this crop. Moreover, damages were further reduced by 2-3 times of treatment with 250 thousand nematodes/m² in combination with seed furrow treatment of 4kg/10 a Tefluthrin G. The control of P. striolata by drench treatment of S. carpocapsae was more effective with treatments of many times than those of many nematodes.

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[in Japanese]

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[in Japanese]

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Several types of insecticide were sprayed on Vaccaria pyramidata (Charyophyllaceae) on which many adult Liriomyza huidobrensis (Blanchard) were found. The results showed that feeding and oviposition punctures made by the female flies were fewer on the plants sprayed with nereistoxins, cartap and thiocyclam. Living larvae were fewer on the plants sprayed with insect growth regulators (IGRs), cyromazine, flufenoxuron and lufenuron, followed by those sprayed with nereistoxins, emamectin benzoate and spinosad. No such effects were observed on plants sprayed with pyrethroids, organophosphates including isoxathion and chlorpyrifos, and neonicotinoids.

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Larvae of Liriomyza huidobrensis (Blanchard) were grown on the kidney bean, Phaseolus vulgaris, under 20°C, 11L-13D. Soon after pupation, which was followed by storage in 10°C for 2 days, the puparia were stored in 0°C for 0, 3, 7, 14, 21, 28, and 35 days. Then they were kept under moderate temperature (25°C) for observation of emergence of the flies. The percentage of emergence decreased after storage in 0°C for more than 7 days and all the puparia died within the 35 days of storage in 0°C. There was no difference in the pre-emergence period under 25°C (ca. 8 days) among the puparia with various duration of the preceding storage in 0°C between 0 and 28 days.

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[in Japanese]

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The seasonal phenology of the summer fruit tortrix, Adoxophyes orana fasciata, was examined from 1980 to 2002 using sex pheromone traps at seven apple orchards in Aomori Prefecture. From 1980 to the early 1990s, the trap catch pattern in the Tsugaru region (west Aomori) showed three peaks of moth abundance per year, corresponding to moths of the overwintering, first and second generations. However, the patterns after the early 1990s showed only two peaks per year. The peak of the overwintering generation occurred in the early to mid-June in the trivoltine pattern, whereas in the bivoltine pattern, it occurred in late June. The peak of the first generation also shifted from the end of July in the trivoltine pattern to the end of August in the bivoltine pattern. The total effective temperature (above 5.9°C) between adult flight peaks of two successive generations in the bivoltine pattern was 1060 degree-days, which was greater than that in the trivoltine pattern (approximately 700 degree-days). In contrast, the trap catch pattern in the Nanbu region (east Aomori) showed two annual peaks throughout the period examined (1980-2002).

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[in Japanese]

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[in Japanese]

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There has been much discussion on the environmental risks associated with the introduction of exotic natural enemy species on local natural enemy populations. Three species of exotic phytoseiid mites, Typhlodromus occidentalis, T pyri and Amblyseius fallacis from New Zealand, were released into several apple orchards at the Aomori Apple Experiment Station from 1986 to 1992 for the control of spider mites. In the summer of 2003, we surveyed the species composition of phytoseiid mites in the orchards where they were released. No exotic species were found in apple, cherry and willow trees where they were released, and three species of native phytoseiid mites, T vulgaris, A. womersleyi, and A. finlandicus, were found to be dominant. This result suggests that the introduction of exotic phytoseiid mites has no significant ecological effects on native phytoseiid mite species.

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[in Japanese]

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Since 1995, adults of the larch cone moth, Retinia perangustana (Snellen), have often been captured in the Abashiri district, northern Hokkaido. It is possible that the larch cone moth may he an invader of Hokkaido from some other area, because the endemic larch trees became extinct during the Pleistocene in Hokkaido. Diagnostic characters of the species in the adult stage are given in comparison with other congeneric conifer pests in Japan. A possible source and route of migration are discussed.

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