Acrolepiopsis nagaimo Yasuda, n. sp. is described from Japan. It is a leaf feeder of Dioscorea oposita Thunberg and has long been confused with A. suzukiella (Matsumura). Its allied species, A. japonica Gaedike, a borer of bulbil of D. japonica, is redescribed. Illustrations of the adults and genitalia of these species and biological notes are given.

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The Samia cynthia ricini chorion was observed for its surface and inner structures by scanning electron microscopy. A micropyle opening was present at the anterior pole region of the chorion surface, surrounded by 12 to 20 petal-shaped cell imprints forming a single rosette. There were 6 to 10 “sperm ducts,” dangling from the inside surface of the chorion at the anterior pole region; these were connected to the micropyle and probably facilitated the polyspermy. All surface areas were confirmed to have network patterns made of comparatively uniform polygonal imprints. Aeropyles opened at the junction of three polygonal units, and there was an additional large hollow at the intermediate region of each polygonal unit. Cross-sections of the chorion revealed three layers, the outer, middle and inner layers. The middle layer, which was the thickest, was further divided into the upper, intermediate and lower parts; the aeropyles and the additional hollow penetrated almost to the intermediate part. The intermediate part was characterized by irregular lamellae, which were porous and thus may facilitate gas changes.

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The oviposition season and developmental time of Sipalinus gigas were investigated by periodic setting and collection of cut pine bolts at different times in a Pinus densiflora stand in central Kyushu. The number of S. gigas colonized in the bolts was estimated as the sum of the number of holes that were 3 mm or larger in dia. without scolytids and the ones less than 3 mm dia. with S. gigas larva. The oviposition season of S. gigas in the study stand was normally late April through mid-August with a peak in early summer. The eggs laid early in the oviposition season could grow to adults emerging in the autumn of the same year, although many overwintered as larvae and some of the survivors emerged as adults by November of the following year.

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Dispersal of reared adult male sweetpotato weevils, Cylas formicarius (F.), was examined in different seasons using a mark-release-capture method in Okinawa, Japan, where a sterile insect release project has been conducted to eradicate the weevil. Release and capture were replicated 7 times in different seasons in the same locality consisting mainly of sweet potato and sugarcane fields. About 8,000 males were marked each time, thus 54,444 males in total were released, and 14,746 of them were captured by pheromone traps (27.1%). Population parameters, including dispersal, capture and survival rates of released males, and population density of wild adult males were estimated. Percentage captured and dispersal distance were positively correlated with mean temperature during each experiment. The highest estimated population density of wild males was found in the summer. The results offer strategical parameters for a successful eradication project against the weevil using the sterile insect technique.

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We investigated the development and adult survival of Cylas formicarius (Fabricius) during winter on Amami-Oshima Island, Japan. Every developmental stage of the weevil (except for eggs, which were not examined) was found in sweet potato tuberous roots during winter, and adults and third instars were dominant. The weevils in sweet potato roots continued to develop during winter, although their development was delayed due to low temperatures. In addition, adult weevils continued to emerge from the host plants throughout winter. Most adult weevils were found under stones and fallen leaves on the ground surface and within the top 5 cm of soil in a sweet potato field during the daytime in winter, and scarcely dispersed from the host plants in winter. The adult weevils released in a sweet potato field and a field cage in December or later survived until the following late March or late April. The results suggest that most of the females that started to oviposit after overwintering came from eggs laid in the previous September and October.

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Effects of sex, age, mating status and temperature on flight activity of the smaller tea tortrix, Adoxophyes honmai, were evaluated by a computer-aided flight mill system. Flight activity of both sexes peaked at 2 days old and they were capable of flying about 5 km a night. Between 1 and 4 days old, there was no significant difference in flight activity between the sexes, while females flew longer than males between 5 and 8 days old. Mating status, whether mated or unmated, did not affect flight activity of females. Both females and males flew most actively at 23°C, and their continuous long flights were reduced at temperatures under 18°C. Compared with flight activity of another tea tortrix, Homona magnanima, males of both species showed an identical pattern of age-specific flight, and flight activity of females of H. magnanima peaked at 5 days old, later than conspecific males. Suitable temperatures for female flight ranged from 20.5 to 28°C in A. honmai, and 15.5 to 23°C in H. magnanima.

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The effects of parasitized aphids as food on development, growth, and survival of fourth stadium larvae were assessed in three species of aphidophagous ladybirds, Coccinella septempunctata Linné, Harmonia axyridis (Pallas), and Propylea japonica (Thunberg) in relation to development of parasitoid larvae. The effects of eating aphids, parasitized aphids or mummies on larval performance were the same in the three species except for survival: parasitized aphids were good food for the three species, while developmental time of fourth stadium larvae of the three species was significantly longer when fed on mummies than when fed on aphids or parasitized aphids, and mummies also produced a negative effect on growth of the three species. Survival of C. septempunctata larvae was significantly lower when offered mummies rather than aphids or parasitized aphids as food, though H. axyridis and P. japonica were not affected by the type of prey supplied in terms of survival, indicating that mummies were not a suitable food for the three species, in particular for C. septempunctata.

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Interspecific relationships between indigenous ladybird species, Coccinella septempunctata L. and Harmonia axyridis Pallas, and an exotic species, Adalia bipunctata (L.), were assessed in relation to prey abundance. The nature and relative strengths of interactions between indigenous and exotic ladybird species differed in relation to prey availability and species involved. Under conditions of high prey abundance, the negative effect of interactions was limited to slower larval development of A. bipunctata in the presence of H. axyridis larvae. Under conditions of limited food availability, intraguild predation often occurred and C. septempunctata and H. axyridis were intraguild predators and A. bipunctata was intraguild prey. H. axyridis larvae was a stronger intraguild predator of A. bipunctata than C. septempunctata larvae. Possible causes for limited habitat of A. bipunctata after invasion into Japan, and the decrease in abundance of native populations of A. bipunctata in the U.S.A. after introduction of C. septempunctata and H. axyridis are discussed in relation to interactions of A. bipunctata with C. septempunctata and H. axyridis.

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Mass flight activity of Phyllonorycter ringoniella was observed early in the morning soon after sunrise from 16 to 20 September 1999. The number of moths in a swarm varied from about 30 to 50. Swarms were composed of only males, possibly because the observations were conducted late in the season when all the females had finished ovipositing, and their numbers had decreased. The male moths were flying in a repeated, wave-like movement close to the canopies of some apple trees. The observations indicated that the mass flight activity was not dependent on the presence of female moths, but was controlled by male-specific circadian rhythms.

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The dimorphism of weapon size in a stag beetle, Prosopocoilus dissimilis okinawanus Nomura was examined. The relationship between weapon size and body size became curvilinear when head length was included as a part of body size. However, when it was used as a part of weapon size a sigmoid relationship was obtained. Males could not be separated into two groups when nine traits were analyzed using principal component analysis (PCA). However, when the angle of the mandible (AN) was used in addition to the nine traits, males could be separated into two distinct groups (i.e. S and L types). When the size of each of the nine traits was plotted against the AN, males of the S type could be separated into two sub-groups in all combinations (i.e. S1 and S2 groups). The relationship between body size and weapon size showed that weapon size increased with body size in a quadratic manner in the S type, whereas it increased in a diminishing quadratic manner with body size in the L type. The difference in the relationship between weapon size and body size in the S and L types is discussed in relation to their combat behaviors.

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This study was aimed to elucidate the developmental and life history characteristics of Coboldia fuscipes (Diptera:Scatopsidae) which causes serious damage to the oyster mushroom, Pleurotus ostreatus, in Korea. The average number of eggs oviposited by a single female was 282. Eggs are usually laid in a mass on the spawn. The total life span was 44.8, 34.4, 24.5 and 18.9 days in males and 43.2, 33.3, 24.1 and 17.9 days in females at 18, 21, 25 and 28°C, respectively. The developmental zero temperatures (t₀) for each stage were estimated from the regression lines as follows: 11.6°C for eggs, 11.5°C for larvae, 9.2°C in male pupae, and 8.8°C in female pupae. The required heat units were 38 degree-days for egg development, 180 for larval development, 66 for male pupal development, and 67 for female pupal development. The developmental threshold based on the total pre-emergence period was 11.6°C for males and 11.1°C for females, and the required heat units were 277 and 283 degree-days for males and females, respectively.

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The effects of five constant temperatures (15°C,20°C,23°C,25°C and 30°C) under 16L8D photoperiod on development, reproduction and population growth of Thrips tabaci reared on a diet of pollen and honey solution were studied. Although hatchability was more than 80% at temperatures between 15 and 25°C, it was low at 30°C. Survival rates from hatch to adult were higher than 65% at all temperatures. Developmental rates increased linearly as rearing temperature increased. It was estimated that 232.6 degree-days, above a developmental zero of 10.8°C, were required to complete development from egg to adult oviposition. These data were related to records of field temperatures in Kurashiki, western Japan, to estimate the potential number of generations per year that could complete development under outdoor conditions. Using this data, a maximum of between seven and 11 generations could have developed annually between 1990 and 1998. Mean adult longevity decreased with increasing temperature, from a maximum of 86.6 days at 15°C to a minimum of 12.8 days at 30°C. The mean fecundity on pollen and honey solution was the highest at 23°C and 270 eggs per female. The intrinsic rate of natural increase (r_m) was highest at 25°C and 0.1709.

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We found that Ceratothripoides claratris (Shumsher) causes damage to tomato in central Thailand by infesting tomato leaves; severe infestation resulted in plants drying out. The eulophid wasp, Goetheana shakespearei Girault was reared from the larvae of this thrips species; parasitization rate was about 30%. A few specimens of Ceranisus menes (Walker) also emerged from parasitized C. claratris larvae. Plant quarantine agencies in countries, where C. claratris is not presently distributed should be on the lookout for invasion by this insect.

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[His⁷]-corazonin is known to play an important role in the control of body-color polymorphism in the migratory locust, Locusta migratoria (Orthoptera: Acrididae). Another neuropeptide, [Arg⁷]-corazonin, which has been isolated from other insects, is also known to induce darkening in this locust. These two neuropeptides were injected into nymphs of other orthopteran species to determine if they could induce darkening in those species. The test species belonged to 4 families: Acrididae (Acrida cinerea, Gastrimargus marmoratus and Nomadacris succincta), Catantopidae (Oxya yezoensis), Pyrgomorphidae (Atractomorpha lata) and Tettigoniidae (Euconocephalus pallidus). Except for the katydid, E. pallidus, all species injected with 1 nmol of [His⁷]-corazonin turned dark as compared with oil-injected controls. [Arg⁷]-corazonin showed a similar effect in the two acridid species tested, but no effect in the katydid. These results suggest that [His⁷]-corazonin or a similar neuropeptide may be involved in the control of body color in the locusts and grasshoppers, but not in the katydid. When a brain and/or corpora cardiaca (CC) taken from nymphs of each test species were implanted in albino nymphs of L. migratoria, dark color was induced in the latter, indicating that all test orthopterans contained some factor identical or similar to [His⁷]- or [Arg⁷]-corazonin. Likewise, brain-CC complexes from 47 other species of 10 insect orders including Orthoptera, Dermaptera, Dictyoptera, Isoptera, Homoptera, Hemiptera, Odonata, Hymenoptera, Lepidoptera and Diptera induced darkening in albino locusts, whereas those from 8 species of COleoptera all failed to do so.

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We compared the host-searching behavior of two parasitoid species, Cotesia plutellae and C. glomerata on their respective host-infested leaf in the laboratory. We observed the host-searching behavior of C. plutellae on a cabbage plant infested by the host larvae Plutella xylostella, and found that the wasps showed their antennal-searching behavior only on the host-infested site. The plants and the regurgitant of the host larvae were both involved in the production of the infochemicals that promoted the antennal-searching behavior in C. plutellae. The searching time of C. plutellae on a piece of cabbage leaf infested by host larvae was significantly longer than that on a piece infested by nonhost (Pieris rapae) larvae and that on the artificially damaged piece. The same pattern in the searching time by C. plutellae was also observed when we used Japanese radish plants and Rorippa indica plants. Likewise, the searching time of C. glomerata on the host (P. rapae)-infested piece of cabbage or Japanese radish was significantly longer than that on the piece infested by nonhost (P. xylostella) larvae. Thus, the two wasp species could detect infestation of these plant species by their respective host through antennal contact.

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The attractiveness of the volatiles from females to adult males of Pseudococcus cryptus was tested in a glasshouse to verify the presence of a sex pheromone. Males were attracted to the volatiles from females, and therefore, the existence of the sex pheromone of this mealybug was confirmed. The attractiveness of the pheromone to adult males aged from 0 to 5 days at 0,2,4,6,8,10 h after lights-on was investigated in plastic petri dishes. Adults males were attracted to the pheromone under all these conditions, and it was considered that a bioassay in plastic petri dishes could be conducted using 0- to 5-day-old males within 10 h after lights-on.

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Virulence of the brown planthopper Nilaparvata lugens strains, which immigrated into Japan between 1997 and 1999, was examined on five rice varieties, Mudgo (carrying a resistance gene Bph 1), IR26 (Bph 1), ASD7 (bph 2), Norin PL10 (Bph 3), and Babawee (bph 4). Newly emerging brachypterous females of N. lugens were released on test rice plants at the tillering stage, and we defined the females that became heavily swollen or survived for five days as virulent. Between 45 and 87% of the females were virulent to ASD7, although such high virulence had not been detected before 1997. Between 49 and 98% of the females were virulent to Mudgo and IR26. Virulence to rice varieties carrying Bph 1 in the N. lugens population has continued to become stronger since the 1988-1990 period in which changes in virulence were first found. In contrast, virulence of the N. lugens strains to Norin PL 10 and Babawee was still at a low level, with 5 to 27% of the females being virulent. The results indicate that the resistance of Bph 1 has probably broken down and the resistance of bph 2 may be becoming ineffective for the N. lugens populations immigrating into Japan.

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The ability of a solitary parasitoid, Dinocampus coccinellae (Schrank) to discriminate between a parasitized and unparasitized host, Coccinella septempunctata L. (Coleoptera: Coccinellidae) was tested in the laboratory. AD. coccinellae female wasp was placed together with a host beetle and allowed to parasitize 3 successive times, and the time interval between these parasitizations was measured. The wasp successfully parasitized the host within 25 s on average and avoided superparasitism for 155 s after the 1 st parasitization. The period of rejection between the 2nd and 3rd parasitization further extended to about 4 min. Furthermore, the behavioral pattern of a parasitoid wasp and 3 host beetles monitored by a video camera confirmed the host discrimination of D. coccinellae. The wasp was unable to discriminate a host recently parasitized by her genetically identical sister. A possible reason for weak host discrimination of D. coccinellae is discussed.

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The host-quality preference and egg load of the hyperparasitoid Eurytoma goidanichi Boucek (Hymenoptera: Eurytomidae) were investigated under laboratory conditions. E. goidanichi parasitized young and old cocoons of Cotesia glomerata L. (Hymenoptera: Braconidae) without distinction. However, mortality, progeny sex ratio (proportion of males), and developmental period of E. goidanichi laid in old host cocoons were higher and longer than those laid in young host cocoons, indicating that old cocoons were less suitable hosts. Females lived more than 2 months, whereas males lived less than 2 weeks. Few mature eggs were present in the egg reservoir of newly emerged females, but the number increased up to 12 eggs within 5 days. This value was constant for more than a month and then gradually decreased to a few. Young (7 days old) females laid more than 10 eggs per day and old (age 80 days or more) females laid 5 eggs per day, corresponding with the number of mature eggs in the egg reservoir of females of their age. Females laid a similar number of eggs on successive attacks at one or several day intervals, indicating a high ability to produce new eggs. E. goidanichi is synovigenic, and it is thus advantageous to lay eggs immediately on whatever hosts in encounters.

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Laboratory experiments were conducted to determine the effects of host age on oviposition and host-feeding by Diadromus subtilicornis, a pupal endoparasitoid of the diamondback moth Plutella xylostella. When given 6 hosts of single ages, females oviposited in hosts of prepupae, 1-d-old green and 2-d-old pupae 66-75% of the time. However, females oviposited in only 43% of 1-d-beige pupae, 31% of 3-d-old pupae and none of 4-d-old pupae. They often rejected those hosts after antennal examination or drilling. Total time taken for oviposition increased with increasing host age. When given 36 hosts of 6 different ages, females preferred hosts of prepupae, 1-d-old green and 2-d-old pupae for oviposition and hosts of 1-d-old beige, 2-d-old and 3-d-old pupae for host-feeding, suggesting host-age selective oviposition and host-feeding. Although 93% of parasitized prepupal hosts yielded emerged adult parasitoids, successful emergence rate decreased with increasing age. No parasitized 3-d-old pupal hosts yielded adult parasitoids. Sex ratio (% females) of parasitoids emerged from hosts ranged from 28.6% for 1-d-old beige to 44.4% for prepupae. Host ages did not affect developmental time and size of emerged adults. We suspected that D. subtilicornis has mixed host-feeding strategies of non-concurrent and concurrent types according to host availability.

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The exotic parasitoid, Diadegma semiclausum, was introduced and augmented to suppress the density of the diamondback moth, Plutella xylostella in cabbage fields at two localities in Iwate Prefecture, northern Japan, from 1996 to 1999. The parasitoids were released at densities of 0.8-3.4 copulated females per plant. In 1996, the numbers of both fourth-instars and pupae of P.xylostella in the field where parasitoids were released remained below five individuals per plant from release until harvest in late July. This was much less than the levels in the control field, where the peak density was 17.8 larvae and 11.2 pupae per plant. Percentage parasitism by D. semiclausum reached 53% in the release field in mid June. Successful overwintering of D. semiclausum in the northern Tohoku district of Japan was observed in the survey conducted from June to July of 1997. However, the percentage parasitism was reduced to a maximum of 29% in 1997 when no additional parasitoids were released. The release of the parasitoid was repeated in Nishine in 1997 and in Morioka in 1998 and 1999, resulting in successful suppression of P. xylostella.

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Functional responses of different stages of Orius sauteri to densities of Thrips palmi were studied. Most stage of O. sauteri exhibited Holling’s Type-II response. The number of T. palmi consumed by O. sauteri nymphs increased with the stage of O. sauteri, however late fifth stage O. sauteri nymphs consumed a much smaller number of T. palmi larvae than early fifth stage nymphs. O. sauteri adult females consumed a slightly smaller number of T. palmi larvae than early fifth stage nymphs. O. sauteri adult males consumed a smaller number of T. palmi larvae than adult females. O. sauteri nymphs killed more T. palmi larvae than T. palmi adults. However, there was no marked difference between the two stages of T. palmi killed by O. sauteri adult females. The number of T. palmi consumed by O. sauteri adult females increased with increasing temperature. Selective predation experiments on O. sauteri on different stages of T. palmi revealed that the preference for T. plami adults and larvae changed with the development of O. sauteri.

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The effects of the culture medium of Bacillus thuringiensis serovar japonensis Buibui on the insecticidal activities of B. thuringiensis formulations were investigated by a diet incorporation method using four lepidopterous insects, Spodoptera litura, Mamestra brassicae, Plutella xylostella and Adoxophyes honmai. Although the culture medium alone was not lethal to lepidopterous insects, its combination with δ-endotoxins from B. thuringiensis serovar kurstaki and aizawai, which were lethal only to lepidopterans, increased the toxicity higher than those by δ-endotoxins alone. The synergistic levels by the addition of culture medium reached a maximum of 42 fold based on a comparison of LC₅₀, but the rates differed among species of insects tested and the kinds of δ-endotoxins used.

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Synergism of spores from several Bacillus thuringiensis serovars and the δ-endotoxin of B. thuringiensis serovar kurstaki HD-1 and HD-73 were evaluated using two bioassay systems (artificial diet and leaf dip) against larvae of Plutella xylostella. The magnitude of the synergistic effect of the live spores from B. thuringiensis serovar japonensis strain Buibui with the δ-endotoxin of B. thuringiensis serovar kurstaki HD-1 was 120 times higher two days after feeding on the artificial diet. However, by 7 days after the treatment, the synergistic effect was lost. Thus, the synergism of live spores with the δ-endotoxin was only observed very early in the treatment. The live spores from kurstaki HD-1 or strain Buibui exhibited a 35% reduction in the killing time of P. xylostella when they were combined with the δ-endotoxin from kurstaki HD-1 or HD-73. No effects were observed when dead spores killed by gamma-radiation were combined with the δ-endotoxin. These results clearly indicated that live spores were necessary to express the synergistic effects on diamondback moth larvae.

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The efficacy of acetamiprid, a neonicotinoid insecticide, against four field populations of the diamondback moth, Plutella xylostella (L.), from Aichi, Hyogo and Kagoshima Prefectures in Japan was determined using the leaf-dipping method. The data obtained indicated that, compared to the reference Osaka susceptible strain (OSS), the four field populations were tolerant to the insecticidal effect of acetamiprid, displaying LC₅₀ resistance ratio (RR) of 4.5-9.0 Maintaining the population from Aichi Prefecture in the laboratory without exposure to acetamiprid resulted in a decline of the LC₅₀ RR from 9.0 to 1.6 over seven generations, suggesting that acetamiprid-resistance is not stable.

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Bombus hypocrita and B. ignitus are promising candidates for use in commercial pollination of greenhouse crops and have the same four oviposition phases as B. terrestris. Queens of both species switch from laying diploid eggs to haploid eggs (Switching Point: SP) in Phase 3. The worker productivity of B. ignitus is higher than that of B. hypocrita. The duration of fertilized-egg oviposition of B. ignitus (1997: 47.5 days, 1998: 47.6 days) is about 10 days longer than that of B. hypocrita (1997: 37.1 days, 1998: 35.2 days), resulting in the difference in the duration of Phase 3 before SP between B. hypocrita and B. ignitus. However, there is no difference between the number of egg cells built per day of both species. The foundress B. hypocrita. queen produced progeny queens from fertilized eggs in Phase 2. However, progeny-queen production occurred only after Phase 3 in B. ignitus. These results suggest that B. hypocrita has flexible production of the reproductive caste, possibly as an adaptation to its distribution in the sub-arctic zone; B. ignitus is only distributed in the temperate zone and may not require such flexibility. This difference in reproductive strategy between the two species suggests that B. ignitus might be a better choice for early commercialization than B. hypocrita.

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We studied the pattern of reproductive isolation between two groups of the subsocial spider mite species, Schizotetranychus miscanthi. S. miscanthi can be distinguished into two groups by differences in male-to-male aggressiveness, one has high and the other has low male-aggression. Habitats of these two groups are parapatric, and are not easily distinguished. We carried out cross experiments between populations taking the geographical factors into consideration. Results indicated that strong reproductive isolation acts on these different groups. Therefore, we concluded that there is little gene flow between the two groups, even when they are distributed in close proximity.

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In our previous report, we showed that there is strong reproductive isolation between two groups of the subsocial spider mite species, Schizotetranychus miscanthi Saito. S. miscanthi can be distinguished into two groups by differences in male-to-male aggressiveness: one has high and the other has low male-aggression. In this paper, we studied in detail the pattern of reproductive isolation between these two groups. We found isolation to occur at two different stages. Namely, the first barrier decreased the rate of egg fertilization (pre-zygotic isolation) and the second one hindered immature development (post-zygotic isolation). However, we did not observe obvious depression of hatchability, which is often observed in spider mites. Furthermore, there were significant differences in the patterns of incompatibility between females originating from different localities, when they were crossed with males of the other aggression group.These differences in incompatibility patterns were unusual and have been difficult to explain so far. The factors that account for these differences in this spider mite is a problem for future studies.

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