A release test was conducted to suppress the winter cherry bug, Acanthocoris sordidus Thunberg, using a scelionid egg parasitoid, Gryon philippinense (Ashmead), in a greenhouse with grown green bell peppers at Kochi University, Japan, from June to September, 2003. The study site was divided into two areas (6 m×5.4 m), a release area and a control area. Three pairs of field-collected A. sordidus were released to each plant in both areas on June 15. Just after the first oviposition of A. sordidus was observed, G. philippinense females (1-d old) cultured in a laboratory were dispersed in the release area. Starting on June 16, releases were made in 5 batches of 50 mated females 5–7 d apart. In the control area, the hatchability of A. sordidus was 98.4% in a total of 8,375 eggs. In the release area, the parasitism rate of G. philippinense was 98.8% in a total of 7,725 eggs, and its emergence rate was 99.8%. The last release of the parasitoid was on July 8; however, the emergence of G. philippinense continued until mid-September. G. philippinense persisted in greenhouse conditions with the highest temperature being 49.0°C in August. The density of new-generation adults of A. sordidus was extremely low in the release area. This study showed that G. philippinense could be considered a useful biological control agent of A. sordidus.

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Antibacterial peptide defensin isoform A was previously isolated from the midgut contents of Ornithodoros moubata blood-fed females. However, not only defensin A, but also three other defensin isoforms showed gene expression in the midgut, suggesting the possibility that these antibacterial peptides are secreted into the midgut lumen. To further understand tick immune mechanisms, the involvement of antibacterial peptides in midgut defense was investigated. Three antibacterial peptides with molecular masses near defensin isoforms B, C and D were detected in the midgut contents of blood-fed females. Enzyme-linked immunosorbent assay analysis revealed that the antibacterial peptides in the midgut contents cross-reacted with defensin A antibodies and increased as a response to blood feeding. Simultaneously, the antibacterial activity of the midgut contents was enhanced by blood feeding. Secretion of antibacterial peptides into the midgut lumen and an increase in the peptide concentration following blood feeding was also confirmed. These findings further support the hypothesis that antibacterial peptides play an important role in the midgut defense of ticks.

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To clarify the immigration process of a phytophagous insect to a new habitat, I examined seasonal changes in the abundance and parasitism of larvae and pupae of a leafroller, Eudemis gyrotis (Meyrick) (Lepidoptera: Tortricidae), at both a new and an old plantation of the bayberry Myrica rubra Sieb. et Zucc. (Myricaceae) on Mt. Tanakami, Shiga Prefecture, central Japan, in 1999. E. gyrotis adults singly lay eggs on only young leaves of M. rubra, and their larvae feed on the leaves. Therefore, the young leaves of M. rubra are necessary for the occurrence of E. gyrotis larvae. The number of E. gyrotis larvae per tree was correlated with the amount of young leaves per tree. At the old plantation where E. gyrotis had already been found in 1998, the larval occurrence of E. gyrotis began in late May. At the new plantation, which was at a distance of ca. 600 m from the old plantation, E. gyrotis larvae had not occurred by late July, although there was an abundance of young leaves of M. rubra in late May. These findings suggest that E. gyrotis adults that had emerged from the old plantation in July immigrated to the new plantation and laid eggs on the plants there. The parasitoids that attacked E. gyrotis at the new plantation just after immigration were polyphagous. This suggests that those parasitoids switched hosts from other herbivore species to E. gyrotis. In spite of the attack by polyphagous parasitoids, the E. gyrotis population successfully established itself at the new plantation.

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An artificial diet containing 2% L-ascorbic acid was given to silkworm (Bombyx mori) larvae throughout larval life, or only in some larval instars in order to make a comparison of larvae fed on a diet without L-ascorbic acid throughout larval life. Obtained results show that, when complete L-ascorbic acid deprivation is done during the larval cycle, it affects larval growth and cocoon production. Furthermore, L-ascorbic acid absence from larval food, particularly during the first and last instars, generates beneficial effects to cocoon production without affecting the survival rate or delaying the larval cycle.

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The distance from which hosts are perceived by foraging parasitoid females has been repeatedly considered to be an important behavioural trait that is supposed to be related to their efficiency as biological control agents. In the present study, such a ‘reactive distance’ was quantified using the automatic analysis of video-recorded females' walking paths. Inter-specific variation of this trait was analysed by comparison between Aphis gossypii Glover, Myzus persicae Sulzer, and Sitobion avenae Fabricius, and three of their parasitoid species known to present different levels of specificity to these hosts: Aphelinus abdominalis Dalman, Aphidius colemani Viereck, and Aphidius picipes Nees. Responses to two different host instars of different size were also compared in each combination. On average, parasitoid females were able to perceive aphids from a distance of about 3 to 4 mm. The only significant difference observed was between the Aphelinus and the two Aphidius parasitoid species. No difference was detected between the different host instars or species tested. Females seem to be unable to discriminate between host and non-host species from a distance. These results seem to confirm the hypothesis of the use of a cuticular contact kairomone for host recognition at the species level.

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Adults of the swallowtail butterfly Papilio polytes have a faint scent, which is stronger in males than in females. From the solvent extracts from adults, six relatively high-volatile substances including linalool, nonanal, and decanal were detected in small amounts. Since males contained more linalool than females in the average amount per individual, this compound is believed to be attributable the male's strong scent. The majority of the substances is somewhat concentrated on the wings rather than on the body, whereas acetoin is mainly present in the body, particularly in the thorax for both sexes. In addition, the solvent extracts were found to have large amounts of relatively low-volatile substances in which six n-alkanes, three n-alkenes, and four carboxylic acids possessing 10 to 29 carbon numbers were identified, and the major components were n-heptacosane, n-nonacosane, and hexadecanoic acid. In the extracts from individual whole 3-d-old adults, (Z)-7-tricosene and dodecanoic acid were significantly more abundant in males than in females, while (Z)-7-pentacosene and n-heptacosane were significantly more abundant in females than in males, indicating that the swallowtail adults have a sexual dimorphism in volatile composition. During the 3 d after emergence, most of the identified components averagely increased by twice the amount per adult.

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Some effects of low temperatures on diapause and non-diapause larvae of the pine caterpillar, Dendrolimus tabulaeformis Tsai et Liu (Lepidoptera: Lasiocampidae), were investigated in laboratory experiments. The results indicated that diapause larvae had higher survival rates than non-diapause larvae at earlier stages of exposure to the low temperatures (−10, −17 and −21°C). In general, the larvae lives were shorter when they were exposed to the lower temperatures. Exposure to chilling at 0°C (cold pulse) in advance increased the survival rate of larvae when they were exposed to −10°C, and the survival rate increased with the length of cold pulse (doubled at 50 min). No larvae could survive after the 50th day of daily exposure to −10°C for 1 h followed by exposure to 27±1°C for 23 h. The water contents of diapause and non-diapause larvae differed significantly, and the super-cooling points (SCPs) of non-diapause larvae were significantly higher than those of diapause larvae.

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This study investigated the cold tolerance of a laboratory-reared population and latitude-separated populations of the leafminer Liriomyza sativae in China in terms of low-temperature survival rate and supercooling capacity. Pupae of the laboratory-reared population are susceptible to freezing temperatures. The supercooling point of the pupae varied at a maximum of up to 10°C among the geographic populations. Both acclimation of the pupae at 5 and 10°C significantly increased the cold survival rate of laboratory-reared and field-collected populations. But the field population had a more active response to the same acclimation regime. Combining the experimental data with previous field investigations, the −2°C isotherm of the minimum mean temperature of January was proposed as the leafminer's over-wintering range limit. Meanwhile, with the widespread availability of greenhouses as a source of re-infestation in northern China, the leafminer's natural border of distribution should be determined by the minimum temperature in warm seasons. Our results suggest that biologically similar Liriomyza species may cope with the intensifying cold stress along the latitude by adopting a mixed cold-tolerance strategy, which is closely associated with the greenhouse microhabitats. The physiologically based modeling of the over-wintering limit provides a tool for guiding the management for greenhouse pests and predicting the source of pest infestation.

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The effects of photoperiod and temperature on the dormancy of two aphid parasitoids in Japan, Aphelinus asychis and A. albipodus, were studied in the laboratory. Adult (reproductive) dormancy was induced in A. asychis under 10L : 14D at moderate temperatures and under 15L : 9D at low temperatures. Dormant adults started oviposition 6–17 d after emergence under 10L : 14D at 15 and 18°C. Transferring newly emerged adults from 10L : 14D at 15 and 18°C to 15L : 9D at 20°C caused an apparent reversal of dormancy induction within 1–2 d. It was believed that adult dormancy in A. asychis conforms to “oligopause” rather than “diapause” sensu Mansingh (1971). Adults of A. asychis showed an apparent variation in abdominal coloration from yellowish brown to black. The proportion of females with dark abdominal coloration was higher under 10L : 14D than under 15L : 9D and high at lower temperatures. We regarded this polyphenism as a part of the “diapause syndrome” because oligopause and abdominal coloration were controlled by the same environmental factors. Aphelinus albipodus entered diapause as last instar larvae. The critical photoperiod for diapause induction was 11–12 h at 18°C, and diapause was terminated within six weeks by cold treatment (10L : 14D, 5°C).

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Helicoverpa armigera exhibits a facultative pupal diapause, which depends on temperature and photoperiod. Pupal diapause is induced at 20°C by short photoperiods and inhibited by long photoperiods during the larval stage. Sensitive stages for photoperiodic induction of pupal diapause were determined by transferring larvae of various instars between long and short photoperiods. When larvae reared at 20°C under a short photoperiod during egg to fourth instar were transferred to a long photoperiod at the early fifth instar, diapause was not induced. However, when larvae were transferred to a long photoperiod in the middle of fifth instar, diapause was induced. On the other hand, when larvae reared under a long photoperiod during egg to fourth instar were transferred to a short photoperiod at the early fifth instar, about 80 to 100% pupae entered diapause. These results show that the early fifth larval instar is the main sensitive stage for pupal diapause determination even though photoperiod has some effect in the third and fourth instars.

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In the 1991-strain of Aquarius paludum in Kochi, both critical photoperiods for wing-form and diapause shifted to longer values by 1 h when specimens were grown under gradually decreasing photoperiods. However, the 1999-strain didn't respond at all to decreasing (14.5L to 13.5L) or increasing (12.5L to 13.5L) photoperiods. Photoperiodic response for wing-form determination by the 2002-strain was witnessed only in a small range between 60% and 95% as the proportion of long-winged form, and the critical photoperiod (14L) was a little bit longer than the critical value of 13.75L for the 1991-strain. The critical photoperiod for diapause induction in the 2002-strain was estimated to be 13.5L-10.5D under a constant photoperiod, which was one-half hour longer than that of the 13L-11D shown by the 1991-strain. In August and September in Kochi, the critical day lengths for wing-form determination and diapause induction of the 1999–2002-strains remain to be 14L-10D and 13.5L-10.5D, respectively, even under decreasing day-length. Therefore, the two critical values were “shorter” than those of “15L-9D” and “14L-10D” of the 1991-strain. The annual average temperature (17.1±0.5°C) and annual average high and low temperatures (35.6±1.3, −3.1±0.9) in 1991–2000 were higher than those (16.4±0.5, 34.9±1.1, −4.4±1.4) a decade ago (1981–1990). In Kochi, the global warming in the last two decades may have caused A. paludum to select “shorter” critical photoperiods for the currently dominant strain (1999–2002-strain) in terms of wing-form determination and diapause induction under decreasing day-length in August to October (14.8 h to 11.5 h) in compared to the former strain (1991-strain) dominant a decade ago. This “shorter” critical photoperiod leads to a longer active fall season for reproduction and larval growth of A. paludum.

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Most Monochamus carolinensis (Olivier) larvae over-winter in pupal chambers constructed in the trunk and branch xylem of host trees. The larval size of M. carolinensis and the pupal chamber size in the bolts of Pinus sylvestris and P. strobus were measured between December 1985 and February 1986 in Illinois. Larvae in P. strobus were larger and heavier than those in P. sylvestris. The pupal chambers in P. strobus were deeper and longer than those in P. sylvestris. The length and depth of the pupal chamber increased with increasing larval body mass for each pine species. Larvae of an equal body mass constructed 0.65 cm deeper and 0.95 cm longer pupal chambers in P. strobus than in P. sylvestris. Consequently, the difference in the length and depth of the pupal chamber between the two pine species was explained by the differences in the larval body mass and the wood hardness of the pine species. These results suggest that the host trees' wood hardness directly affects the length and depth of the pupal chamber and the inner bark has an indirect effect on them as a food resource.

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The effects of diet on life-history traits were compared among individual webworms reared on an artificial diet or the leaves of two host plants in a trivoltine population of Hyphantria cunea collected in Kobe, Japan. The lower threshold temperature for development and the thermal constant among one generation did not differ largely according to the diets. There were two variations in the larval instar numbers, those being the six- or seven-instar type. The incidence of the seven-instar type fed the artificial diet was significantly lower than those fed on the host plants. The pupal weight for the six-instar type was significantly heavier for those fed the artificial diet than those fed on the host plants. Seasonal host plant effects were detected in some developmental traits. The critical photoperiods for diapause induction at 20 and 25°C were similar between the host plants, and were shorter with the artificial diet than with the host plants. The present results suggest that the data for the artificial diet need not be modified in the parameters for the developmental rate, but that the critical photoperiod for diapause induction needs to be slightly lengthened when the data are applied to field insects.

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Field tests of three types of synthetic sex pheromone blend (Japanese blend: Z11-18:Ald (55 μg), Z13-18:Ald (500 μg), Z11-18:OH (120 μg) and Z13-18:OH (180 μg), Indian blend: Z11-16:Ac (50 μg) and Z13-18:Ac (500 μg) and Philippine blend: Z11-16:Ac (500 μg) and Z13-18:Ac (10 μg) based on geographic variations in sex pheromones so far reported) for the rice leaffolder moth, Cnaphalocrocis medinalis Guenée (Lepidoptera: Crambidae), were performed at Nanning, in southernmost China, Hanoi, in northern Vietnam, and on Bohol, an island in the southern Philippines. In all of these tests, only the Japanese blend attracted significant numbers of male C. medinalis, while neither the Indian nor the Philippine blend showed any attractiveness to the males. The results at Nanning and Hanoi, from which the Japanese population may originate from, support the current inference about the migration routes of C. medinalis. On the contrary, the results on Bohol, in the Philippines, were unexpected and showed the presence of a population responding to the Japanese blend, but not to the Philippine blend.

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Haptoncus ocularis is a candidate pollinator of the subtropical orchard tree cherimoya (Annona cherimola). To collect basic information for the use of this species as a pollinator by mass rearing and releasing in greenhouses, the developmental period and attained adult size at constant temperatures of 15, 20, 25 and 30°C were investigated. The photoperiod was 16-h light/8-h dark at all temperatures. The developmental period was shorter at higher temperatures, except at 30°C, which lengthened pupation. Mortality from last instar larva to adult eclosion was higher at 15 and 30°C than at 20 and 25°C. The thermal threshold (developmental zero) ranged from 8.2 to 12.2°C for different developmental stages and sexes. The thermal constant (total effective temperature) of the period from egg to the next oviposition was ca. 284 degree-days. Both head width and right forewing length of the adults raised were largest at 20°C and second largest at 25°C. The maximum number of generations in a year was estimated to be nine in Wakayama, Japan.

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Polyphagous twig-like caterpillars of the giant geometer Biston robustum resemble the host plants not only in the morphological appearance, but also the surface chemicals as they change their cuticular chemicals after switching host plants. The object of this study is to investigate whether the caterpillars adjust the cuticular chemicals through direct body contact to the twigs or the ingestion of leaves after changing their host plants. The caterpillars successfully adjusted their cuticular chemicals to the new host plant when they fed on the plant's leaves, regardless of the plant species. The caterpillars' behavior was continuously under scrutiny, but direct body rubbing on the twigs was not observed. Thus, the caterpillars adjusted the cuticular chemicals through ingesting the leaves of the new host plant. Continuous behavioral observation revealed leaf clipping and body bending-and-stretching behaviors in the late instar caterpillars. Although the ethological meanings of the body bending-and-stretching behavior is uncertain, the leaf clipping, as well as morphological and chemical phytomimesis, would be adaptive as a countermeasure to predators.

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We investigated the horizontal and vertical distribution of Tyrophagus similis in agricultural soils in two greenhouses between May 1997 and May 1998. Tyrophagus similis inhabited not only the cultivated soil, but also the uncultivated soil in the periphery of the cultivated area inside the greenhouse and the soil immediately outside the greenhouses. The mite density in the cultivated and peripheral soils increased in the cooler months and decreased in the warmer months. We collected only small numbers of T. similis from the adjacent outside soil during the survey period. In the cultivated soil, most T. similis inhabited soil at depths of 0–5 cm throughout the year, and their numbers decreased with depth. These results suggest that the main control point of T. similis is the 0–5-cm soil layer in cultivated and peripheral soils of the greenhouse.

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We evaluated the effect of visual stimuli, mainly of size and color, on male mate orientation in Anoplophora malasiaca by experimenting with oval-shaped glass-rod models treated with female elytra extract. The number of males orientating to black glass-rod models corresponded to model size with larger model preferred. When same sizes of models of six different colors were compared, orientation frequencies significantly correlated to the lightness of the colors. Darker colors were preferred. This was also confirmed in male orientation to a series of gray-tone glass-rod models with different lightness. Thus, male orientation was influenced by both size and color of models that serve as visual stimuli.

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Eight compounds (i.e., n-dodecyl acetate, (E)-8-dodecenyl acetate (E8-12:Ac), (Z)-8-dodecenyl acetate (Z8-12:Ac), n-dodecanol, (Z)-8-dodecen-1-ol, n-tetradecyl acetate, (E)-8-tetradecenyl acetate and (Z)-8-tetradecenyl acetate) were detected in extracts of the sex pheromone gland of individual female Grapholita dimorpha at the time of mating. The average ratio of E8- to Z8-12:Ac was 15 : 85. Field trap tests suggested that the two compounds were essential for male attraction, and the ratio of 15 : 85 was the most effective blend in the range of 40 : 60 to 5 : 95. The other six compounds found in the sex pheromone glands were not observed to be either synergistic or inhibitory. Seasonal monitoring using a lure impregnated with E8-12:Ac (150 μg) and Z8-12:Ac (850 μg) revealed that G. dimorpha had four generations in Yamanashi. These results suggest that the lure is a useful tool for monitoring G. dimorpha.

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A practical method for estimating the allele frequency in a population of the pinewood nematode, Bursaphelenchus xylophilus, was developed by employing the technique of PCR-RFLP image analysis, in which a relative quantity of DNA templates is determined. At first, nematode individuals of two isolates, a virulent (S10) and an avirulent isolate (C14-5), were mixed at various proportions, and then PCR-RFLP patterns of the heat-shock protein 70A (hsp70A) gene fragment were obtained from each mixture. Regression analysis between logarithmic values of relative intensity of isolate-specific bands and those of a relative number of individuals of the two strains showed a strong linear relationship. These regression lines were applied to pursue temporal changes in the frequency of the hsp70A alleles in several experimental populations. The changes observed in allele frequencies were well explained with an overdominance model.

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The ITS1-5.8S-ITS2 region of rDNA sequences from three Globodera species found in Japan, G. rostochiensis, G. tabacum and G. hypolysi, were sequenced and compared. Sequence lengths for G. rostochiensis, G. tabacum and G. hypolysi were 1,001, 1,003 and 1,016 bp, respectively. Sequence divergence within the three Globodera species ranged from 3.8 to 14.7%. Eight restriction enzymes (AfaI, AluI, FspI, HhaI, HinfI, MvaI, PmaCI and SacII) were selected on the basis of sequence information. These three species were easily distinguished according to species-specific patterns by digesting the amplified products with AluI or PmaCI. The FspI-digested pattern distinguished G. rostochiensis from the other Globodera species.

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