Reproductive characteristics of a commercial strain of Amblyseius californicus were compared with those of populations native to Japan to estimate their ability to control spider mites in crop fields. Reproductive characteristics differed among strains. The commercial strain showed unique characteristics among the strains examined: short developmental period, high daily fecundity, and long post-oviposition period. Consequently, the intrinsic rate of natural increase (r_m) of the commercial strain was highest among strains. The commercial strain grew faster than did native populations. Thereby, it could control spider mites. On the other hand, high performance of reproduction showed the potential to displace genetically native populations in crop fields and natural vegetation. This study showed that the long post-oviposition period in the commercial strain is the only character that could lead to displacement or competitive exclusion.

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The composition of shiso oil which showed strong repellency against the adult cigarette beetles was analyzed by GC and GC-MS. Twelve components of shiso oil were identified. The repellency of the 12 components against the beetles was investigated with an olfactometer. α-Terpineol, linalool and (−)-perillaldehyde strongly repelled the beetles at a dose of 1 μl. However, they tended to attract the beetles at a ten or hundred fold lower dose. The mixture four major components of shiso oil, (−)-perillaldehyde (60.51%), (−)-limonene (14.42%), farnesene (11.26%) and β-caryophyllene (8.47%), exhibited a strong repellency against the beetles at a dose of 1 μl, but did not repel the beetles at a dose of 0.1 μl, and attracted them at a dose of 0.01 μl. The mixture repelled the beetles at a dose of 10 μl even in the presence of the cured tobacco odor. Also (−)-perillaldehyde and (−)-limonene being, in the ratio found in shiso oil, exhibited similar repellency and attractiveness against the beetles to the four components combined.

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A method was established to rear the entire larval stage of Ostrinia palustralis, an oligophagous species that feeds on dock plants Rumex spp., on artificial diets. Silkmate L4M (an artificial diet for the “polyphagous” silkworm mutants) supplemented with 20% R. japonicus dried leaf powder was initially provided to the neonate larvae, and the diet was switched to Silkmate 2M (a standard diet for silkworms) 14 days post-inoculation. These diets supported larval growth with a pupation rate of about 70%. This rate was comparable to that for conventional rearing using fresh host plant leaves. Although the larval period was significantly extended as compared with the conventional rearing, no difference in the pupal weight was found between the two groups. The number of eggs laid by the resultant adult females and the hatchability of the eggs were also comparable. Utilization of the two kinds of artificial diets enabled rearing of this species throughout the year with much reduced labor.

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We compared the densities of the apple snail, Pomacea canaliculata, between fields that had been planted with soybean or rice in the previous summer. The densities of overwintered snails soon after irrigation at the beginning of rice planting were all very low in the fields after soybean. These values were much lower than the control threshold for the apple snail in direct seeding. Therefore, crop rotation with soybean seems to be a good economic measure to control the apple snail in direct seeding. The snail populations increased very rapidly in both types of fields, in particular, after soybean. Within two and a half summer months, the snail densities in the fields after soybean reached almost the same level as those in the fields after rice. This rapid population recovery in fields after soybean seems to be caused by density-dependent growth and reproduction in this species.

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Summer diapause in the cotton bollworm, Helicoverpa armigera (Hübner), is prolongation of the pupal stage, particularly in males, induced by high temperatures. The effects of exposing a parental generation to temperatures of 33 to 39°C on the development, survivorship, longevity and fecundity of their offspring were determined in the laboratory. Three groups of offspring were examined: A, the progeny of control female moths reared as larvae at 27°C mated to male moths that had undergone summer diapause when exposed to high temperature; B, the progeny of control female moths mated to males that had not undergone summer diapause after exposure to high temperature; C, the progeny of control females mated to control males reared at 27°C. The developmental times of the immature stages were significantly different between groups. The survival rate in the immature stages varied significantly from 69.8% (Group C) to 34.7% (Group B). The average number of eggs produced per female and the longevity of females and males were not significantly different. The indices of population increase of Groups C, A and B were 286.2, 256.8 and 145.0, respectively. These results indicate that Group A offspring had physiological advantages, such as survival and population increase, compared to Group B offspring. The adaptive significance of summer diapause in the cotton bollworm is discussed in relation to the performance of offspring.

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Here we report direct evidence that cuticular hydrocarbons are responsible for nestmate recognition in Formica japonica distributing in Southern Honshu in Japan. Workers showed aggressive behavior against foreign workers but not against nestmates. A similar response was observed when a glass dummy was treated with isolated hydrocarbons from foreign workers or nestmates. Among the isolated hydrocarbons, ten hydrocarbon components were identified: five n-alkanes and five (Z)-9-alkenes with odd number of carbons from 25 to 33, in different ratios in different colonies. When synthetic hydrocarbons blended in the same ratio as natural blends were presented to workers, they showed aggressive responses against foreign blends but paid less attention to those of nestmates. Neither n-alkane nor (Z)-9-alkene blends, however, caused aggression response in foreign workers. Thus, both n-alkanes and (Z)-9-alkenes are necessary to discriminate nestmates from foreign conspecifics.

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The insecticidal activity of the entomopathogenic fungus Beauveria amorpha (strain HpBa-1) to larvae of the yellowish elongate chafer, Heptophylla picea was estimated under various temperature conditions. High mortalities were obtained and the mortalities of H. picea rose rapidly at 25°C and 20°C. Insecticidal activity of HpBa-1 was observed at 15°C and 10°C and infection of the fungus resulted under these temperatures. HpBa-1 showed little infectivity at low temperatures under the field conditions. Hence, HpBa-1 recovered infectivity when the temperature increased. These results suggest HpBa-1 is useful as a microbial control agent against larvae of H. picea.

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To test a hypothesis that workers in social Hymenoptera can identify male broods at early stages of development and eliminate them to avert excessive investments in male brood, the ability of larval sex discrimination and the timing of male brood elimination by honeybee (Apis mellifera L.) workers were determined. A comparison between the egg sex ratio and the sex ratio of 5 day-old larvae showed that male larvae might selectively die and/or be eliminated in colonies with low survival rates of broods. Nurse bees conditioned by the extracts of male larval cuticles responded significantly more frequently to male extracts than female ones extracted from 3 and 4–5 day-old larvae. It is known that during the developmental stage of 4–5 days, the weight sharply increases in male larvae. The nurse bees conditioned by the extracts of male comb cells failed to distinguish between male and female extracts. Honeybee workers can thus discriminate the sex of broods for male elimination based on cuticular substances during the larval periods with the highest growth rates, which may avert excessive investments in male brood.

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Demographic bioassays were carried out in the laboratory to assess the demographic responses of Tetranychus urticae Koch to fenpyroximate and pyridaben at three levels of sublethal concentrations (LC₁₀, LC₃₀ and LC₅₀). Life table data were used to generate an age-classified projection model in each sublethal treatment. The elasticity of population growth rate (λ) to changes in each of the individual life traits was calculated. Exposure to fenpyroximate and pyridaben treatments reduced the net reproduction rate (R_o) in a concentration-dependent manner. The treatment of pyridaben had dramatic effects on egg hatchability. The hatch rate dropped from 0.83 at untreated control to 0.27 at LC₁₀. Two different scales of population-level endpoint were estimated to compare the total effect on T. urticae between the treatments: the first endpoint, λ values were determined based on the net reproductive rate (fecundity λ); the second endpoint incorporated the mean egg infertility rate into the net reproductive rate (vitality λ). The fecundity λ decreased in a concentration-dependent manner in both acaricide treatments, but the vitality λ decreased abruptly after treatment of pyridaben. The relative difference between the two λ values was great in pyridaben treatment. Contributions of survival probability (P_i) and fertility (F_i) to the population growth rate were markedly different between the two population-level endpoints. In fecundity λ, the contribution of F_i to the λ was always higher than that of P_i. These dramatic changes in elasticity patterns reveal that acaricide effects at the population-level are strongly dependent on the life history characteristics of T. urticae and mode of action of the chemicals.

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A phytophagous lady beetle, Epilachna vigintioctomaculata, feeds mainly on potato (Solanum tuberosum) leaves. The methanol extracts of potato leaves showed feeding stimulative effects on the adult of the beetle. The feeding stimulants were isolated and identified as methyl linolenate from a lipid-soluble fraction, and glucose and fructose from an aqueous fraction. Although methyl linolenate alone was inactive, it acted synergistically with sugars. Methyl linolenate maximized the feeding activity of sugars at the concentration contained in the potato leaves. It is suggested that methyl linolenate plays an important role in the host selection of E. vigintioctomaculata.

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We investigated the developmental period, survival rates during the larval and pupal stages, adult longevity, and fecundity of Micromus numerosus, M. angulatus and M. linearis at five constant temperature conditions (10, 15, 20, 25 and 30°C), under a 15L–9D photoregime with Aphis craccivora as prey. The lower thermal thresholds and thermal constants for total development were estimated, respectively, at 7.7°C and 343 degree-days (DD) for M. numerosus, 9.0°C and 297 DD for M. angulatus, and 5.2°C and 447 DD for M. linearis. M. linearis eggs did not hatch at 30°C. At 20°C, the mean total number of eggs laid by a female was 544 in M. numerosus, 399 in M. angulatus, and 614 in M. linearis. The mean longevity of female adult in days was 55 in M. numerosus, 46 in M. angulatus, and 46 in M. linearis. From these results, we evaluated suitable temperature ranges as approximately 20°C for M. numerosus, 15–25°C for M. angulatus, and 10–25°C for M. linearis.

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The parasitoid wasps Torymus sinensis (Ts) and three strains of T. beneficus (early-spring strain: TbE; late-spring strain: TbL; autumn strain: TbA) are respectively introduced and indigenous natural enemies of the chestnut gall wasp Dryocosmus kuriphilus, an invasive chestnut pest. In this study, the genetic relationships among Ts and three strains of Tb from Japan, China and Korea were investigated by sequencing a portion of the mitochondrial cytochrome oxidase subunit I (COI) gene. Three distinct groups were recognized in a constructed phylogenetic tree, the first group further consists of three subgroups. Ts belongs to two subgroups, whereas TbL belongs to the remaining subgroup. TbE and TbA belong to the second group, indicating that TbL is genetically more closely related to Ts a different species than to TbE and TbA strains considered the same species. This requires a reconsideration, especially for TbL, of their taxonomical treatment. The third group consisted of an indigenous Torymus parasitoid that we were unable to identify morphologically, indicating that an unknown Torymus parasitoid that is both genetically and morphologically different from the Ts and the Tb strains exploits D. kuriphilus in Japan.

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Effects of application of three insecticides (imidacloprid, pymetrozine and lufenuron) on host searching and oviposition behavior of Neochrysocharis formosa (Westwood), a larval parasitoid of the American serpentine leafminer Liriomyza trifolii (Burgess), were investigated in the laboratory. Female wasps spent more than 89% of their time on a leaf of host-infested kidney bean when introduced into a container containing the leaf treated with each insecticide or distilled water. However, wasps spent more time resting near or away from hosts and less time foraging for hosts on the leaves treated with imidacloprid than the other treated leaves. As a result, they encountered, oviposited and fed on hosts less frequently with imidacloprid treated leaves than any other treated leaves. The numbers of host findings, ovipositor insertions and host feedings were also significantly lower on the leaves treated with lufenuron than the control. These results suggest that imidacloprid and lufenuron reduced wasp host searching efficiency.

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Three Japanese species of Adoxophyes (A. orana fasciata Walsingham, A. honmai Yasuda, A. dubia Yasuda) are pests of various fruit trees and tea plants. Although they sometimes occur on the same farm or in the same garden simultaneously, only Honma (1970) has studied identification of the immature stages. In this study, we revised the taxonomy of the immature stages of Adoxophyes. In pupa, we examined frontal setae, head shape and the number of dorsal spines. Head shape and the number of frontal setae distinguished A. orana from the other two species. The number of dorsal spines distinguished typical individuals of A. dubia from A. honmai. In larva, we examined the shape of the frons, color patterns in the stemmatal area, ratio of the diameters of the third to second stemmata and development of the inner tooth of the mandible. The color patterns in the stemmatal area and ratio of the diameters of the third to second stemmata distinguished the larvae of the three species. In addition, we recorded new host plants for A. dubia. We discuss how identification is facilitated by using the combination of characters mentioned above.

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Mating behavior of the green chafer Anomala albopilosa sakishimana Nomura (Coleoptera: Scarabaeidae) was observed in Miyako Island, southwestern Japan from 28 to 29 May 2003. Females and males were present on patches of the beach naupaka, Scaevola sericea Vahl, throughout this time and showed clumped distribution within the patches. Males were observed to mount the backs of females for several hours during a day and successfully defend females from intruding males. Copulations took place only from 19:00 to 20:00 (JST) and most frequently at 19:40 (light intensity: 24 lx). Mean copulation duration was 18.1±2.6 min (mean±SD, N=16). After mating, both sexes remained on the same leaf to feed. When females guarded by males were collected before mating time and subsequently reared in the laboratory, about 65% (11/17) laid fertilized eggs. This indicated that most of the females mounted by males are not virgin. In laboratory observations, several females mated more than once on different days, indicating A. a. sakishimana females are polyandrous. Since mounted males successfully defended the females from intruding males in the laboratory, long-lasting mounts appear to comprise precopulatory mate-guarding behavior. This is the first record of precopulatory mate guarding in scarab beetles.

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Chilo suppressalis transferrin cDNA was cloned by reverse transcription polymerase chain reaction (RT-PCR). The clone (2,248 bp) encodes a protein of 644 amino acids with a calculated molecular weight of 71,805 Da. The deduced amino acid sequence showed significant homology with known insect transferrins from Bombyx mori (82%), Manduca sexta (77%), Blaberus discoidalis (43%), Riptortus clavatus (42%), Aedes aegypti (36%), Sarcophaga peregrina (32%), Drosophila melanogaster (33%) and D. silvestris (32%). Transferrin expression was examined by RNA gel blot analysis using diapausing and non-diapausing larvae of C. suppressalis. As a result, higher levels of expression were observed in diapausing larvae.

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Mycelial growth and germination rates of Beauveria bassiana F-263 at various temperatures were investigated to determine efficient culture conditions and tolerance of this strain to higher temperatures. Mycelial growth was quantified by measuring colony diameters at constant temperatures and occurred from 6 to 33°C, with maximal growth at 30°C. The fungus could recover and grow when transferred to 25°C after exposure to higher temperatures, even if the fungus did not grow during high temperature exposures. The longest high temperature periods after which this fungus survived were 8 d at 35°C and 4 d at 36°C when initiated with hyphal bodies and more than 14 d at 35°C and 7 d at 36°C when initiated with conidia. At 25 to 30°C, the conidial germination rate rose to almost 100% within 20 h. At 34°C, germination was very low within 20 h, but almost 100% over 48 h. At 35°C, germination was only 4.6% even more than 4 d after inoculation, although most conidia inflated within 24 h. No germination was observed at 36°C, although most conidia inflated within 24 h. Growth rates of germ tubes from conidia were slower at temperatures higher than 33°C.

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The two-spotted spider mite, Tetranyuchus urticae Koch is an important pest in Korean apple production. We tested two release rates of the predatory mite, Amblyseius womersleyi Schicha for biological control of T. urticae in two varieties of apple, ‘Fuji’ and ‘Tsugaru’. Mass-reared A. womersleyi were transferred to apple canopies in an experimental apple orchard plot in early season when T. urticae densities were low. The effect of A. womersleyi release on T. urticae peak density was significant in both apple varieties. Tetranychus urticae peak densities were the reverse order of the release rates of A. womersleyi. Cumulative mite-days per leaf were maintained below 200 throughout the season regardless of the initial A. womersleyi release rate or apple variety. Initial settlement and subsequent conservation of A. womersleyi are suggested as important factors for successful biological control of T. urticae in apple orchards. Further research and implementation of the results are discussed relative to IPM.

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A novel technique to measure the virulence of an entomopathogenic fungus, Beauveria bassiana by exposing tarsi of adults to dry conidia was developed to evaluate effectiveness of nonwoven fabric strip formulation of this fungus for controlling adults of the Japanese pine sawyer, Monochamus alternatus. To regulate inoculum density without suspending conidia in water, conidia were killed by heating at 100°C for 1 h and a step dilution series of conidia was prepared by mixing dead conidia with live conidia at different ratios. The conidial mixtures were attached to tarsi of CO₂-anesthetized adults with a fine hairbrush. The 50% lethal doses determined by this method on 14 d were 5.5×10⁶ conidia/individual for aged adults and 1.9×10⁶ conidia/individual for young adults, and on 30 d were 2.8×10⁵ conidia/individual for aged adults and 2.4×10⁴ conidia/individual for young adults. The number of conidia produced on a nonwoven fabric strip was 3.5×10⁸ conidia/cm², and 8.5×10⁵ conidia/individual were attached to adult beetles which walked on the strip. Based on these results, the validity of a biological control method for M. alternatus to prevent vectoring of the pine wilt disease is discussed.

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A light emitting diode (LED) color ray was used to determine the most effective light color to capture the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire). Preference tests were conducted using four colors of LED ray (blue, green, yellow and red) at fixed light quanta in the laboratory. The weevils preferred the green LED to the three other LEDs. The effectiveness of a green LED trap was subsequently compared with that of a sweet potato root trap in a sweet potato field with mature potatoes and the green LED trap was confirmed to be applicable for monitoring of the number of weevil.

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The development and adult longevity of Theocolax elegans (Westwood) were investigated at six temperatures (20, 25, 28, 30, 32 and 35°C), 70–80% RH and a 16L–8D photoperiod. Fecundity was also investigated at 25°C and 30°C. The hosts were larvae of Sitophilus zeamais Motschulsky reared on brown rice. As the temperature was increased from 20°C to 32°C, the developmental period decreased from 54.4 to 16.2 days for females and from 53.8 to 15.6 days for males. The developmental period at 35°C was longer than at 32°C. Males developed faster than females. Adult longevity decreased with increasing temperature from 14.5 to 4.5 days for females and from 20.6 to 3.6 days for males. The mean number of progeny produced per female over a lifetime was 161.0 at 25°C and 110.1 at 30°C. The intrinsic rate of natural increase (r_m) was 0.131 females per female per day at 25°C and 0.169 females per female per day at 30°C.

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Allotropa citri can parasitize all stages of Pseudococcus cryptus. Under experimental conditions, however, no difference was observed in the percentage parasitism between the first and the second instar hosts, while parasitism on the third instar and adult female hosts was lower than on the first and second instars. No difference was observed in the developmental duration of this parasitoid between the first and the second instar hosts. Therefore, the first and second instar nymphs of P. cryptus were considered suitable host stages for the parasitoid. The lower developmental threshold temperature and thermal constant of A. citri for the first and second instar nymphs of P. cryptus were 10.1°C and 518.1 degree-days (DD), respectively. The lower developmental threshold temperatures and thermal constants of Anagyrus subalbipes females and males on P. cryptus adult females were 13.0°C and 234.2 DD, and 12.1°C and 245.5 DD, respectively. A. citri produced five generations and A. subalbipes seven generations in a year in the field of Nagasaki where the host produced four generations.

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Scolothrips takahashii is an indigenous thrips in Japan that feeds on many spider mite species. To evaluate whether S. takahashii has potential as a biological control agent for spider mites, we investigated the development, survivorship and life-history parameters of S. takahashii on a diet of Tetranychus urticae (red form) eggs at different temperatures. More than 74% of thrips eggs hatched and more than 76% of newly hatched larvae attained maturity at 15–35°C. No females laid eggs at 37.5 or 40°C. The lower threshold temperature for development from egg to oviposition was 11.7°C and the thermal constant was calculated as 204.1 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan would be between seven and ten. Mating was unnecessary to induce oviposition but unmated females produced only male progeny. At 25°C, females laid a mean of 90.5 eggs during a mean oviposition period of 17.8 days. The values for the intrinsic rate of natural increase (r_m), one important life-history parameter, were 0.113 at 20°C, 0.195 at 25°C, and 0.246 at 30°C. These results suggest S. takahashii has considerable potential as a biological control agent against spider mites.

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Behavioral responses of the cigarette beetle to 73 chemicals were investigated with an olfactometer. The beetles were strongly repelled by hinokitiol (β-thujaplicine). The frequency of entering choice tubes treated with hinokitiol was significantly less than that of the control tubes. The resident time in the sample tubes was shorter than that in the control tubes. The repellency of hinokitiol in the presence of cured tobacco odor, which attracts beetles, was evaluated. Hinokitiol strongly repelled the beetles at a dose of 1 mg even in the presence of the tobacco odor. However, the contact and fumigant toxicity of hinokitiol against the beetles was not strong. The repellency of other troponoid compounds, tropone and tropolone, and other compounds with isopropyl groups were weaker than hinokitiol. Therefore, it appears both the tropone ring and isopropyl group play an important role in the strong repellency of hinokitiol.

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The present work covers original information on the aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) of Southeastern Europe. The individual parasitoid species were reared from identified host aphid and plant associations which are listed alphabetically. Twenty two aphidiine genera and 115 species from 208 aphid taxa occurring on 422 plant taxa were identified and 561 parasitoid-aphid associations are reported. The determined parasitoid fauna was divided into 9 faunal groups. Local information on some important biocontrol agents (Aphidius colemani Viereck) as well as on expansive/introduced species (Lysiphlebus testaceipes (Cresson)) in the area are presented.

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