The feeding response of the strawberry leaf beetle, Galerucella vittaticollis Baly, to quercetin glycosides found widely in polygonaceous plants was investigated. Feeding was stimulated by five quercetin glycosides: avicularin (quercetin 3-arabinoside), hyperoside (quercetin 3-galactoside), isoquercitrin (quercetin 3-glucoside), quercitrin (quercetin 3-rhamnoside) and rutin (quercetin 3-rutinoside), but not by peltatoside (quercetin 3-arabinoglucoside). In a leaf-feeding test with 11 polygonaceous plant species, leaves of Fagopyrum esculentum were fed on most by the beetles. Next in preference order were Rumex japonicus, R. acetosa, Polygonum aviculare, R. obtusifolius, P. Blumei, P. Thunbergii, P. cuspidatum, P. sachalinense, R. acetosella and P. perfoliatum. The feeding stimulants, hyperoside, isoquercitrin, quercitrin and rutin were detected by HPLC and TLC analyses in all these plant species except R. acetosella and P. perfoliatum, which were least preferred by the beetles.

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The pathogenicities of five isolates of Beauveria bassiana to Plutella xylostella were investigated. Treatment of 4th-instar larvae with each isolate resulted in 0%-100% mortalities at 5 days after inoculation. Detailed studies were made on the most virulent isolate, MG-Bb-1, obtained from P. xylostella, to determine its efficacy at different developmental stages of P. xylostella, doses, and humidities. MG-Bb-1 had high pathogenicity to lervae of all instars, but little pathogenicity to eggs, and almost no pathogenicity to pupae. Humidity influenced the virulence to 4th-instar larvae; MG-Bb-1 caused mortality of over 80% at 76% RH or higher levels, but only 30% mortality at 52% RH. A conidial suspension (10⁷/ml) of MG-Bb-1 was sprayed on a cabbage field to control P. xylostella. A single application controlled P. xylostella as well as Flufenoxuron.

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BT-resistant (KR) and BT-susceptible (KS) Diamondback Moth populations were produced in the laboratory from a BT-resistant natural population in watercress greenhouse in Kishiwada, Osaka Prefecture. The two experimental populations were fed on three diets: artificial diet, radish seedlings, and watercress, and reared in a room at 25°C and 16L:8D. The LC₅₀ for a BT formulation (Toarow^® CT) for KR and KS was 25, 200 and 1.14ppm, respectively. KR showed lower hatchability, longer duration and lower survival rate in the larval and pupal stages on all the three diets, together with shorter adult longevity and lower fecundity than KS, suggesting much lower fitness and intrinsic rate of natural increase, than KS. The trade-off between BT-resistance and fitness (particularly delayed adult emergence) may explain the quick elimination of BT-resistant moths from a mixed population including both BT-susceptible and BT-resistant moths.

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In three species of rice grasshoppers, Oxya japonica (Thunberg), O. chinensis formosana Shiraki and O. yezoensis Shiraki (Orthoptera: Catantopidae), most unfertilized eggs begin developing, but the viability of unfertilized eggs is much lower than that of fertilized eggs. The hatchability of unfertilized eggs is 17.8% in O. japonica, 10.4% in O. chinensis formosana and 5.4% in O. yezoensis. The number of larvae developing to the adult stage is 9.7% in O. japonica, 6.3% in O. chinensis formosana and 1.4% in O. yezoensis. Thus, the rate of embryonic development, hatchability and adult emergence in parthenogenesis is highest in O. japonica, and lowest in O. yezoensis. All larvae and adults produced by parthenogenesis are female. The number of chromosomes in parthenogenetic embryos of all the three species is 24 and diploid.

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It has been observed that Phytoseiulus persimilis, a predatory phytoseiid mite, is unlikely to settle on tall host plants, such as woody plants. In 1995, an experiment was performed in a vinylhouse vinery (1, 000m²) in an attempt to manage the spider-mite population of Tetranychus kanzawai on grape leaves throughout the growing season, by releasing P. persimilis onto the grass ground cover in the spring. Two releases of P. persimilis (a total of 8, 000_??__??_) late in May and early in June drove the spider-mite population on the ground cover almost to extinction early in July. Throughout July, the spider-mite density was held at 10% of that in the control vinery where no predators had been released. Early in August, spider mites reoccurred in the vinery, because P. persimilis had died out due to lack of prey. However, since the population density of spider mites was very low (<1.73_??__??_/leaf), no chemical control was required throughout the growing season. A survey in the following March confirmed that no P. persimilis had survived the winter in or around the vinery.

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The mating behavior of Thrips nigropilosus, which consists of arrhenotokous and thelytokous populations, was studied under laboratory conditions. The variation in esterase isozymes of individual adult females from a thelytokous population and seven arrhenotokous populations was analyzed by polyacrylamide gel electrophoresis. Mating occurred between individuals of arrhenotokous populations from different localities. Although males of an arrhenotokous population approached and attempted to copulate with females of a thelytokous population from the same locality, the thelytokous females never accepted the arrhenotokous males. The arrhenotokous populations showed high variability in esterase zymograms, but the thelytokous population had no variation in zymograms. Females reproducing thelytokously and arrhenotokously could be discriminated from each other based on their zymograms. We conclude that arrhenotokous and thelytokous populations should be treated as separate species.

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Nymphs and adults of Orius tantillus (Motschulsky), a predator of Thrips palmi Karny, were reared on three different prey: (1) live adults and nymphs of Tyrophagus putrescentiae (Schrank), (2) frozen eggs of Ephestia kuehniella Zeller, and (3) live 2nd-instar larvae of T. palmi. The survival rate and development time of the predator nymphs and the survivorship and egg production of the predator adults were compared among these three types of prey. Frozen eggs of E. kuehniella were found to be a suitable alternative prey for O. tantillus.

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Apterous parthenogenetic females of the Pea Aphid collected in the Tokachi district of Hokkaido Island (Tokachi strain), were reared on chemically-defined artificial diets with different sucrose concentration and pH (25-55g/100ml, pH 6-10), after two days of reproduction on broad-bean seedlings, Vicia faba L., at 15±1°C, under 16L:8D. Survival rate, longevity and the number of offspring per aphid were maximum when reared on a diet of 45g/100ml sucrose concentration and pH 8.3. The survival rate (75%) at the 10th day of rearing and the mean longevity (17.8±2.0 days) of the aphids on the best artificial diet were not significantly different from the values for aphids reared on broad bean (85.7% and 20.5±1.7 days, respectively). The mean number of offspring (32.0±2.4) per diet-reared aphid was 45.3% of the value for aphids reared on broad bean. In our experiments, the best combination of sucrose concentration and pH for the artificial diet for the Pea Aphid (Tokachi strain) is different from the results of Akey and Beck (1972) for the same species (Wisconsin strain). This indicates that there are variations in optimum sucrose concentration and pH for artificial diet between aphid strains.

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