A recombinant of the Heliothis/Helicoverpa single-enveloped nucleopolyhedrosis virus (RcHzSNPV), carrying a gene encoding an insect-specific toxin from the scorpion, Leiurus quniquestriatus, herbraeus, significantly increased the rapidity of kill and reduced feeding by larvae af Heliothis virescens and Helicoverpa zea over that of its parental, wind-type strain (WtHzSNPV). The RcHzSNPV at 1.0 occlusion bodies/mm² killed or paralyzed H. virescens and H. zea larvae ca. 1.5-fold and 1.7-fold quicer, respectively, than the WtHzSNPV strain. Larvae not exposed to virus produced 3-to 5-fold more frass than larvae exposed to RcHzSNPV, and ca. 2-to 3-fold more frass than larvae exposed to WtHzSNPV. Increasing the rapidity of kill and reducing larval feeding are attributes that enhance the use of recombinant baculoviruses as potential biorational pesticides.

抄録全体を表示

Females of Phytoseiulus persimilis deposit eggs with a female-biased sex ratio under an ample prey condition, but deposit smaller eggs with an unbiased sex ratio under a poor prey condition ; in this condition male eggs and female eggs are produced alternately. The relationship between the size of the eggs and the life history characteristics of the immature and adult stages was examined by rearing two different sized eggs, which are laid under the ample and poor prey conditions, to clarify the changes in sex ratio and the alternate production of sexes. Female offspring produced under the poor prey condition developed more slowly than those produced under the ample prey condition did, and the former consumed fewer prey eggs daily during the nymphal stage. However, the total prey consumption during the entire nymphal stage and the body size of adult offspring showed no differences between the two prey conditions. In addition, females from both conditions had similar reproductive abilities. Male offspring showed the same trend in developmental and preyconsumption rates, whereas adult males from the poor prey condition showed a lower fertilization potential than those from the ample prey condition. The decreases in the developmental rates of both sexes and in the reproductive abilities in males are disadvantageous characteristics, but the alternate production of sexes may compensate and assure female offspring of insemination even under the poor prey condition.

抄録全体を表示

The role of plant odors in the host finding behaviors of aphids was investigated by examining the olfactory responses of 3 Uroleucon species, U. gobonis (Matsumura), U. adenophorae (Matsumura) and U. kikioense (Shinji), against host and non-host plant odors. All the tested Uroleucon species were attracted to their host plant odors. U. gobonis was repelled by Aster scaber, a non-host plant. However, U. gobonis and U. adenophorae were attracted to the non-host plant, Platycodon grandiflorus, and U. kikioense was attracted to the non-host plant, Adenophora triphylla. Therefore, the aphids tested were allowed to choose between their host plants and non-host plants having attractancies by using an olfactometer. No differences in the preferences of aphids were observed in the olfactory responses between host and non-host attractive plants. However, all the tested aphid species settled and reproduced on these non-host plants only rarely. These results indicated that plant odors are not the only factors that these aphids use in finding host plants. The olfactory behaviors of oligophagous and polyphagous aphids belonging to genera other than Uroleucon to host plant odors were also examined in order to investigate the relationship between the olfactory behaviors of aphids against their host plant odors and the host range. Polyphagous aphids such as Myzus persicae (Sulzer), Aphis gossypii Gloger, A. craccivora craccivora Koch and Macrosiphum euphorbiae (Thomus) were not attracted to host plant odors, whilu Capitophorus formosartemisiae (Takahashi), an oligophagous aphid, was attracted to its host plant odor. The findings suggest that oligophagous and monophagous aphids tend to find their host plants by both visual and olfactory cues, while polyphagous aphids have a tendency to find their host plants mainly by visual cues.

抄録全体を表示

By crossing experiments between selected diapause and non-diapause strains of Tetranychus kanzawai, we clarified the inheritance mode of diapause of the mites. The results showed that the "diapause" of T. kanzawai is a dominant character over "non-diapause" and that the diapause character is controlled by a simple Mendelian inheritance. This inheritance mode is different from that of T. urticae, in which the diapause is under polygenic control with a strong maternal effect involved.

抄録全体を表示

The photoperiodic clock in Drosophila triauraria was analyzed with thermoperiods and temperature pulses. In thermoperiods of TCs (thermophase : cryophase) 10 : 14, 12 : 12 and 15 : 9h, a light pulse at the warm (18°C) phase lowered the rate of diapause incidence, but a light pulse at the cool (5°C) phase did not. This suggests that the process measuring night length is retarded at low temperatures (5°C). Both low-(2 and 8°C) and high-temperature (23°C) pulses also decreased the rate of diapause incidence when applied during the scotophase, but not when applied within the photophase. It is assumed that the temperature rising stimuli reset or stop the night-length measurement processes ; i. e., acts as a Zeitgeber. The effectiveness of temperature change as a Zeitgeber was modified by the duration of the temperature pulses. The temperature pulse showed two maximum peaks for this effect, one at 0-4h and one at 8-10h after the onset of teh scotophase. The complex response of the species to low-temperature pulses is considered to be attributable to the combined effects of low temperature itself and temperature changes.

抄録全体を表示

The olfactory response of adults of Luehdorfia japonica (Papilionidae) to floral volatiles from Prunus yedoensis (Rosaceae) was investigated by means of a behavioral test (reflex extension of proboscis : REP) and electroantennographic (EAG) responses. Chemical analysis of the flower extract revealed that the floral scent consisted mainly of aromatic compounds, among which benzaldehyde (BAL, ca. 33%) was the dominant component. Of 10 floral volatiles tested, phenylacetaldehyde (PAL) elicited the highest REP response from both sexes. The REP-eliciting activities of benzyl alcohol, 2-phenylethanol and BAL, though a little lower than that of PAL, were also relatively high (ca. 50%) compared with those of other floral components. These four compounds, therefore, were considered to be the olfactorily active principles that stimulate foraging behavior in the butterfly. In EAG experiments with ten test chemicals, differences in responsive intensities among these compounds were not remarkable at a dose of 1 μg. In contrast, males displayed stronger EAG responses to ethyl phenylacetate, linalool, BAL and PAL at a dose of 100μg. The present findings indicate that the antennal sensitivity of the butterfly is not necessarily correlated with the REP behavior. Although we found no explanation for conspicuous male EAG responses to particular components, this phenomenon seems suggestive of additional and as yet unknown functions(s) of these compounds in the life of the male butterfly.

抄録全体を表示

Larval development and some characteristics of newly ecdysed adults of the common cutworm, Spodoptera litura, were compared when the final stadium larvae were reared on diets varying in qualiry, by reducing the percentage of artificial diet (100, 80, 60 and 40%) and adding pulp flock. As the quality of the diet was reduced, the larvae fed on smaller amounts of diet, but for longer periods, and so consumed similar amounts diet during the final stadium, the effect being proportionately the greatest for the 40% diet in males. The effects in adults were sex related for the following characteristics : body weight, forewing length and wing loading index declined more prominently in females, but triacylglycerol (TG) content appeared to decline more prominently in males. Although the fatty acid composition of TG was not affected by diets of different quality, it differed greatly from the composition of those given soybean leaves. These results emphasize the importance of considering the effects of larval diet on morphological and physiological features related to flight ability when investigating the possibility of immigration of this moth.

抄録全体を表示

Effects of photoperiod and temperature on the induction of adult diapause were examined in Graphosoma rubrolineatum (Westwood) collected in Osaka (warm temperate region) and Hokkaido (subfrigid region), Japan. Many insects of the Osaka population entered diapause even under a long-day photoperiod at all temperatures used. Less than half of the insects showed a long-day photoperiodic response for the induction of diapause. In contrast, the higher the temperature, the greater the incidence of reproductive insects under a long-day photoperiod in the Hokkaido population. In Osaka where host plants of G. rubrolineatum produce seeds for only a limited period, an absence of suitable food is the primary factor which determines the timing of diapause induction. In contrast, temperature plays an important role in regulation of the life cycle of this species in Hokkaido.

抄録全体を表示

The effects of temperature and photoperiod on the development and diapause induction of Helicoverpa armigera (Hb. ) were examined under laboratory conditions. The larvae reared at 20°C under short as well as long photoperiods entered diapause at different rates in the pupal stage, except at 17L : 7D. The critical photoperiod for diapause induction was between 12L : 12D and 13L : 11D. Irrespective of photoperiod, the larvae reared at 15°C entered diapause, while those reared at 30°C did not. The developmental periods for eggs, larvae and pupae (non-diapausing) shortened with increasing temperature were 5.7 and 2.3, 29.0 and 10.6 days, and 25.9 and 9.2 days at 20°C and 30°C, respectively. The developmental threshold temperatures for the egg, larva and pupa were 10.8°C, 13.6°C and 14.6°C, respectively. Furthermore, the effective temperature sums for development were 45.5, 200.0 and 142.9 day-degress (D°), respectively. The heat requirements indicate that the insect may complete a maximum of four generations per year in southern Okayama Prefecture, western Japan.

抄録全体を表示

We studied oviposition preference of Pieris rapae females toward Rorippa indica plants exposed to different treatments (uninfested, artificially damaged and infested by P. rapae larvae)in a cage at an experimental field site. The females preferred uninfested plants to infested or artificially damaged ones and artificially damaged plants to infested ones. The data suggested that the females used chemicals emitted from damaged leaves to avoid unsuitable host plants. We conclude that the avoidance behavior of Pieris females towards infested food plants is adaptive for offspring from the viewpoint of not only resource availability but also parasitoid avoidance.

抄録全体を表示

An epizootic caused by Massospora and Nomuraea species occurred in a population of cicada, Meimuna boninensis, an indigenous species of the Ogasawara Islands, Japan. The infection rate of Massospora sp. was 34.4%, and the abdominal cavity of the host was filled with resting spores which were brownish, and spherical, (av. 41 μm in diameter) with reticular ornamentation. The infection rate of Nomuraea cylindrospora was 16.7%, and greenish long (av. 21.4×4.3 μm) and short (av. 4.6×2.7μm) conidia were formed on phialide in chains. M. boninensis is recognized as a new host species for these fungi. The genus Massospora has not been recorded in Japan since 1946.

抄録全体を表示

Outbreaks of the oleander hawk-moth (Daphnis nerii), a sphingid of tropic/subtropic origins, occurred in October-December 1997 and September-December 1998 over the area of Fukuoka and Saga Prefectures. This clearly shows that the range of summer migration of D. nerii is expanding from southern Kyushu to the north. Our observations suggest that (1) after arrival, there were at least two generations in natural environments of northern Kyushu and (2) this lepidopteran failed to survive our winter.

抄録全体を表示

The repellencies of 27 essential oils against Myzus persicae (Sulzer), a vector of PVY-T, were investigated with a linear track olfactometer. Fourteen essential oils, including ginger oil and white pepper oil, repelled the aphids at a dose of 10 μl. Ginger, white pepper and carrot seed oils repelled them at even a much lower dose of 0.1 μl. In the olfactometer test, repellencies of rosemary and ginger oils against other aphid vectors of PVY-T, Aphis gossypii Glover, A. craccivora craccivora Koch, Macrosiphum euphorbiae (Thomas) and Capitophorus formosartemisiae (Takahashi), were observed. Rosemary oil repelled A. gossypii and M.euphorbiae. Ginger oil repelled A.craccivora, M. euphorbiae and C. formosartemisiae. Therefore, the effects of rosemary and ginger oils on the alighting of M. persicae and on the incidence of yellow spotted streak caused by PVY-T were investigated in a tobacco field. The numbers of the aphids caught in the rosemary and ginger oil treated plots were 74% and 86% of their respective values in the control plots. The incidences of yellow spotted streak in both of the plots was about 50% that in the control plots. Rosemary oil showed the effect of reducing yellow spotted streak in larger areas than ginger oil. In order to develop more efficient application methods for repellents, the repellencies of rosemary oil against M. persicae were investigated using two application methods. Ethyl vinyl acetate beads soaked in rosemary oil placed on the ground around tobacco plants decreased the aphids by 31% compared with the control plot. Ropes containing rosemary oil encircling tobacco plants decreased the aphids by 37% compared with the control.

抄録全体を表示

The surface and internal chorion structures of the mottled gray egg (mgr) of Bombyx mori, a mutation which exhibits patched areas of gray or opaque regions, were observed in comparison with normal eggs using a scanning electron microscope. No peculiarity was exhibited in the mutant with respect to whole egg size, surface structures at the micropyle region and basic patterns as well as the average area of the network imprints (polygons) on the lateral flat region. When cross-sections of the chorions were observed, the middle layer of the mgr chorion corresponding to the gray areas was found to be deformed without a lamellar structure. Thus it can be concluded that the mgr alleles take part in the formation of the middle layer arcitecture during choriogenesis.

抄録全体を表示

Damage to direct-sown rice by th apple snail, Pomacea canaliculata, was investigated in two semi-field experiments using rain-free experimental plots (each 2 m² in area). Four snails (2 snails/m²), with shell heights of approximately 19 mm or 24 mm, were released in the plots at the time of sowing When the plots were irrigated soon after sowing (0 or 4 days after sowing), the snails fed avidly on young seedlings and no plants became established Drainage after sowing greatly reduced snail damage. Eighty seven to 94% of plants as compared to the control plots without snails were established when plots were drained for two weeks. Three weeks of drainage could almost prevent damage by snails (95-99% of plant establishment) when the plant age was at about the 5.0 leaf stage. Snail damage was more severe when herbicide was applied. Water management after sowing in direct-seeded rice is discussed in view of reducing snail damage.

抄録全体を表示

To create a system of yeast FLP recombinase-mediated recombination in the silkworm, Bombyx mori, we constructed plasmids for an extrachromosomal excision assay, a helper for producing FLP recombinase and an indicator for the detection of excision. The helper involves an open reading frame coding FLP recombinase and the indicator consists of a β-galactosidase gene interrupted with a neomycin-resistant gene cassette flanked at both ends with the two FLP recombinase target (FRT) sites. To examine whether FLP recombinase works in the silkworm, these plasmids were transfected into cultured cells. Strong β-galactosidase activity was observed when the cells were transfected with positive control plasmid, but no activity was observed when indicator alone was used. Weak activity was observed when the indicator was co-transfected with the helper. Cytochemical staining of these transfected cells gave data supporting this result. The same result was obtained when these plasmids were injected in the eggs of the silkworm and stained with X-Gal. Southern blot analysis showed that the DNA fragment caused by the recombination was detected in the DNA extracted from the eggs injected with both indicator and helper, indicating that FLP recombinase works in silkworm cultured cells and embryos, and suggesting that the constructs we made are useful for application of the FLP recombinase to genetic manipulation experiments with silkworms.

抄録全体を表示

Bacillus thuringiensis STB-3 which was isolated from a Korean soil sample showed high toxicity to Spodoptera exigua. Its crystal toxin was bipyramidal-shaped with a molecular weight of 130 kDa. The H-serotype of STB-3 was identical to B. thuringiensis serovar kenaye (H4a4c). However, PCR analysis using Spodoptera-specific cry gene primers showed that STB-3 had only the cry1E crystal gene, differing from that of serovar kenyae (reference strain) which contains cry1Ab, cry1Ac and cry1E crystal genes.

抄録全体を表示

We examined the morphological characters of two spider mite species, in order to identify characters that accurately reflect mite body size regardless of mounting methhod. Several body characteristics of flattened and non-flattened specimens of Schizotetranychus longus Saito and S. miscanthi Saito were investigated. There were several characters which were not influenced by mounting conditions regardless of sex and species, and which reflected body length and width well. The distance (DL1) between the bases of P1 (dorsal propodosomal seta) and CL (clunal seta) was a relatively stable character reflecting body size under both mounting conditions, i. e. flattened and non-flattened, and appears to be the best character to estimate body length. Body width was reflected by DW1 alone, the distance between the bases of paired P3 setae (dorsal propodosomal seta). It is, however, a stable enough character, under both mounting conditions, to be suitable for estimating body width.

抄録全体を表示

The deposition of chemicals on various parts of tea bushes was measured when the plucking surface was sprayed. The depositions at the middle of th leaf layer and at the bottom (about 15 cm beneath the plucking surface) were about 20% and only 1 to 2%, respectively, of that at the plucking surface. The leaf layer of the tea bushes effectively blocked the penetration of chemicals. The importance of The part of the bush inside the plucking surface for integrated pest management of tea cultivation is discussed.

抄録全体を表示

An endosymbiotic/parasitic bacterial associate was detected by diagnostic PCR experiments in the bruchid beetle, Kytorhinus sharpianus. Molecular phylogenetic analysis of the 16S rDNA sequence demonstrated that the bacterium is a new member of the genus Rickettsia. Among four bruchid species of three subfamilies examined, the Rickettsia was detected only in K. sharpianus.Not all in viduals of K, sharpianus possessed the Rickettsia, suggesting that the microbe is likely to be a facultative companion of the host insect, rather than an obligate symbiont.

抄録全体を表示

The entomopathogenic fungus, Nomuraea rileyi, was foung to be less virulent to younger instars of the cornearworm, Helicoverpa armigera, than the older ones, the LC₅₀ value to the 1st instars being ca. 625 fold higher than that to the 5th. However, body surface (mm²) was positively correlated to larval stage in days (γ=0.982). Furthermore, determination of conidial numbers on the body surface of each stadium also revealed a positive correlation between the conidial loading quantity and the body surface (γ=0.986). Therefore, it is evident that higher virulence of N. rileyi to older instars is due to their larger body surfaces. This permits adherence of more conidia on their body, indicating that body surface is an important factor affecting virulence of N. rileyi to H. armigera. In addition, the higher virulence at the 5th stadium appears to be related to its longer duration, providing suffciient time for conidia to penetrate into the hemocoel to cause mortality. During the 4th stadium, a lower virulence was obtained for those larvae close to molting than newly emerged ones, indicating that ecdysis is an important factor preventing conidial penetration into the hemocoel.

抄録全体を表示