Behavioral and electroantennogram (EAG) responses of the cotton bollworm, Helicoverpa armigera were tested using volatiles from wilted leaves of a non-host plant, Chinese wing-nut tree (VWLCT), Pterocarya stenoptera. Virgin females responded to the VWLCT, but mated females and males did not. The virgin females responded to the VWLCT in the late part of the scotophase with a photoperiod of 14L : 10D, which coincided with their calling behavior. Males were strongly attracted to a combination of a virgin female and VWLCT. EAG results showed that adults of both sexes could respond physiologically to VWLCT. There was no significant difference in the EAG responses to VWLCT of virgin females and mated females. EAG response of males to a combination of crude extract of female sex pheromone and VWLCT was stronger than to either alone. We speculate that the purpose of female orientation to VWLCT is to locate sites for pheromone calling and mating.

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Flufenoxuron, an insect growth regulator (IGR), promoted infection of Bombyx mori nucleopolyhedrovirus (BmNPV) in 5th-instar B. mori larvae, when the chemical was dissolved in acetone and incorporated into the larval diet. The median lethal dose (LD₅₀) of BmNPV was decreased as the concentration of flufenoxuron was increased. Undissolved flufenoxuron did not exert such an effect when it was incorporated into the diet as a powder form. Four other IGRs tested, chlorfluazuron, diflubenzuron, lufenuron and teflubenzuron, had no effect on BmNPV infection.

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Although neral [(Z)-3,7-dimethyl-2,6-octadienal] has been known as the alarm pheromone of Schwiebea elongata, reinvestigation of the pheromone resulted in recognition of another function as an attractant. The alarm pheromone activity was confirmed at a dose of one female equivalent of the hexane extract, whereas the attractant pheromone activity was observed at 0.1 female equivalent. Although no attractant activity was recovered in fractions of the silica gel (SiO₂) column eluate, the synthetic neral manifested both activities; the attractant activity at 3 ng and 1 ng with a convex dose-response relationship, and the alarm pheromone activity at 30 ng. A female contained 30.4 ng of neral on average and a male 0.7 ng on average. This is the first example among astigmatid mites demonstrating that a single mite compound emitted from the opisthonotal gland exhibits two pheromonal functions, alarm pheromone and also attractant, at different doses.

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Monthly changes in densities of Beauveria bassiana in the air and soil of forest stands were measured using selective media to investigate the density dynamics of this fungus. In a windbreak forest of Pinus thunbergii along the coast where B. bassiana has been introduced for the experimental control of Monochamus alternatus, fungal density was higher than in a neighboring untreated forest. Wild B. bassiana was also isolated from inland forests of Quercus serrata, and Chamaecyparis obtusa; in particular, the density of B. bassiana in the soil of the Q. serrata forest was extremely high. Utilizing the same selective medium, conidial dispersal from a nonwoven fabric fungus carrier was also investigated. The fungal conidia were dispersed by the air; however, the density of the fungus in the air at more than 50 m from the source did not differ from the natural density of the fungus. This result was compared with the lethal density of the fungus on mulberry leaves for the silkworm, and the risk of infection is thought to be very rare.

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We developed a sticky screen trap to investigate the aerial population of the ambrosia beetle Platypus quercivorus (Murayama). The beetle is believed to be an important vector of an unidentified ambrosia fungus belonging to the genus Raffaelea that causes oak dieback in Japan. The trap was made of a 1-m² of polyethylene screen, 2.4 mm×2.6 mm mesh size, to obtain light, wide traps that allow air movement through the intercepting surface. An adhesive substance (Kinryusupurei, Maruzen Co. Ltd.) was sprayed on both sides of the polyethylene screen once a week. In 1999, 18 traps were set in the understory of a secondary oak forest in Ishikawa, Japan. Adults of P. quercivorus were captured from 6 July to 22 November. A total of 24,225 beetles was captured by the traps. The average number per trap was 1,345.8 (range, 353–3,408), which was greater than the trap catches in any of the previous studies. Our results showed that this trap was useful for analyzing the seasonal changes in the aerial population of P. quercivorus and its directional movement. On each surface of the traps, the distribution of the trapped adults was aggregative, that is, some parts of the trap had many beetles and others had few or none. Although in a given trap the distribution of beetles on the uphill-facing surface was spatially correlated with that on the downhill-facing surface, the parts of the trap in which the beetles tended to be caught varied widely among traps and among collecting dates. Significantly more P. quercivorus were captured on the downhill-facing surface than on the uphill-facing surface. On the downhill-facing surface of the traps, more adults were caught in the bottom half of the traps than in the top half of the traps, but on the uphill-facing surface, the catches in the bottom half of the traps were not significantly different from the catches in the top half of the traps.

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Highly resistant strains of the brown planthopper were obtained after 30 generations of laboratory selection by carbofuran or fenobucarb. Topical LD₅₀ for fenobucarb increased 93–101-times and topical LD₅₀ for carbofuran increased 51–68-times on selection by either carbofuran or fenobucarb, while the LD₅₀ for diazinon increased only 6–7-times by the same selections. Sensitivity of AChE to carbofuran or fenobucarb was reduced remarkably in vitro in the resistant strains while sensitivity to diazoxon changed only slightly. Insensitive AChE was considered to be the major resistance mechanism of the carbamate-resistant strains of the brown planthopper.

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Semi-solid meridic diets for rearing two related species of Pentatomidae, Nezara viridula and N. antennata, were developed. For N. viridula, development times from second nymphal stadium to adult were 27.6 to 28.2 d for females and 26.8 to 27.5 d for males reared on the meridic diets at 25°C. The nymphal survival rate of N. viridula on the diets was more than 87%. Body weight at adult emergence ranged from 157.6 to 160.1 mg for females and from 123.1 to 128.3 mg for males. The pre-oviposition period was 20.8 to 25.8 d at 25°C when fed on the meridic diets, longer than when fed on peanut and soybean seeds. Fecundity and egg hatchability of the bugs fed on the meridic diets were almost the same as those for bugs fed on seeds. Casein was the only ingredient of the meridic diets essential for nymphal development of N. viridula. Nymphal duration of N. antennata fed on the meridic diet was 31.1 d for females and 29.2 d for males at 25°C, not much different from those fed on seeds. The pre-oviposition period of N. antennata fed on the meridic diet was 23.3 d at 25°C.

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Mass flight activity of the apple leafminer Phyllonorycter ringoniella was observed in the field to explore whether it was associated with mating. Flight activity started around the time of sunrise. About 15 min later, small swarms joined to become a larger, and denser swarm. This lasted about half an hour before the insects dispersed. Although female moths were present in the tree crown throughout the day, they did not participate in the swarms, which were composed of only males. The swarms actively responded to the females that were present among the branches as well as those that were experimentally offered to them to test their response. Mating usually occurred on leaves. Mating began only while the male moths were massively and densely swarming, and lasted about 1 h at the most.

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The beneficial effects of application of spores of the mycorrhizal fungus Glomus sp. and the nematode parasitic bacterium Pasteuria penetrans to Meloidogyne incognita-infested soil on tomato growth and nematode reproduction were assessed in pot and microplot experiments. Tomato shoot and fruit weights in M. incognita-infected plants receiving a combined application of Glomus sp. and P. penetrans were greater than in untreated nematode-infected plants. In addition, the use of the mycorrhizal fungus and the nematode parasitic bacterium together conferred greater beneficial effects than their use alone. Final densities of M. incognita juveniles in soil were lower than the control by 40% and 18% in mycorrhizal plants (cvs. Kyoryoku-beiju and Pritz, respectively), by 38% and 53% in P. penetrans application, and by 61% and 57%, when both treatments were applied together. M. incognita did not affect root colonization by Glomus sp. when mycorrhizal inoculum was added two or three weeks before nematode inoculum. No significant effects of the mycorrhizal treatment on P. penetrans attachment to M. incognita or number of females infected by P. penetrans were observed.

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The attractiveness of the sex pheromone of Pseudococcus cryptus to adult males and natural enemies was tested in citrus orchards in 1999 and 2000. Males were caught by the pheromone trap during two periods in 1999 and three periods in 2000, whereas natural enemies were not attracted in either year. When seasonal degree-day accumulations reached 302 DD above a base of 10°C from the periods that males were trapped, the first instars emerged.

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Chemical analyses were conducted on defense secretions from two species of millipedes, Parafontaria tonominea and Riukiaria semicircularis semicircularis (Polydesmida: Xystodesmidae). Hydrogen cyanide was detected in both species using test papers impregnated with picric acid, while the foul odor of these millipedes changed to that of benzaldehyde. n-Hexane extracts of the two species indicated different profiles of gas liquid chromatograms. Benzaldehyde and mandelonitrile were detected as the common components in both species, while benzoyl cyanide and mandelonitrile benzoate were limited to P. tonominea. These results indicate a difference in the chemical composition of the defense secretion between the two species. The high performance liquid chromatograms of methanolic extracts from the two species looked similar, consisting only of mandelonitrile as the major and benzaldehyde as the minor components. On the other hand, benzoyl cyanide and mandelonitrile were not detectable in the methanolic extracts from P. tonominea despite their high solubility to methanol, indicating that, for some reason, the two cyanogenetics are not secreted during methanolic extraction.

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The insecticide susceptibility of the small brown planthopper, Laodelphax striatellus Fallén, collected from East Asia in 1992–1994, was examined by the topical application method. The LD₅₀ values of organophosphorus insecticide for the northern Vietnam populations (HAI, HAN, VIN) and the JIN population (Yunnan Province, China) were smaller than those of the FU (Zhejiang Province, China), IB (central Japan) and KU (southwestern Japan) populations. The LD₅₀ values of organophosphorus and carbamate insecticides for the northern Vietnam populations were almost the same as that for the Fukuoka (western Japan) population examined in 1967. The LD₅₀ values of organophosphorus insecticides did not differ among the FU (Zhejiang Province, China), IB (central Japan), and KU (southwestern Japan) populations. The LD₅₀ values of carbamates for the KU population were the largest, and those for the northern Vietnam population were the smallest. The carbamate susceptibility of acetylcholinesterase in the KU population was lower than that in the HAI population. Therefore, we considered that insensitivity of acetylcholinesterase for carbamate was one of the carbamate resistant factors in the KU population. The LD₅₀ values of etofenprox, fenvalerate, and imidacloprid showed no differences among all the populations tested, respectively.

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Alternative host insects for simple stromata production of Cordyceps militaris were investigated to derive ascospores for infection tests. The stroma production of this fungus was examined by injecting a suspension of its hyphal bodies into three species of lepidopteran pupae (Mamestra brassicae, Spodoptera litura, Bombyx mori) and a species of coleopteran pupae (Tenebrio molitor). C. militaris killed the pupae of all four insects and produced mature stromata from them at between 20 and 500 lx, and at 20 and 25°C, showing a shorter maturation period at 25°C. Ascospores derived in this study germinated. Use of lepidopteran pupae is thought to be suitable for deriving ascospores because of nearly synchronous maturation of stromata compared to those of T. molitor. These findings suggest that artificial injection increases the range of insects that C. militaris can use to produce stromata.

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Spodoptera exigua nucleopolyhedrovirus (SpeiNPV) isolated in Shiga Prefecture, Japan, was bioassayed with all five stages of the beet armyworm to determine lethal doses and survival times at three rearing temperatures: 20°C, 25°C, and 30°C. Rearing temperature did not significantly affect the susceptibility of S. exigua larvae to SpeiNPV. The median lethal dose (LD₅₀) per insect for neonate, second-, third-, fourth-, and fifth-stage larvae was 2.5, 11.2, 5.5, 32.4, and 181.8 polyhedral occlusion bodies (POBs), respectively. These data demonstrate that this SpeiNPV isolate is extremely infectious, even to later stages of S. exigua larvae. The LD₅₀ values corrected per unit larval body weight tended to decrease with larval age, from about 60 POBs for neonates to just a few POBs for each of the last three stages. This pattern is atypical for NPV-lepidopteran host insect systems, emphasizing the high infectivity of this NPV isolate. Rearing temperature and larval stage at the time of viral treatment significantly affected survival times, while viral dosage did not. Survival time decreased with increased rearing temperature, and increased with larval stage at the time of treatment. Median survival time (ST₅₀) was between 3 to 14 d, depending on the rearing temperature and larval stage at the time of viral treatment.

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Fecundity and egg size were compared in adult of the females adult diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae) treated and untreated with sublethal doses of fenvalerate in order to understand the physiological significance of insecticidal hormoligosis. The 4th stadium larvae were treated with fenvalerate at LD₂₅ or LD₅₀. More eggs were laid by treated females at LD₂₅ than untreated females, although the difference was only marginally significant (p=0.07). However, the eggs laid by treated females at LD₂₅ and LD₅₀ were significantly smaller in size than those laid by the control. The reproductive effort (fecundity×egg size) did not differ between treated females and the control. The treatment of a sublethal dose (LD₅₀) against the parent affected the development and survival of offspring at immature stages of males. The hatchability of smaller eggs laid by treated females at LD₂₅ tended to be lower than those of controls under different humidity conditions, and the difference was apparent at a humidity of 29%. The survival rate of the offspring at immature stages was lower in the treatment group (LD₂₅) than in the control group, and development tended to be prolonged in the former group at temperatures higher than 20°C.

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Cut pine bolts were exposed to allow a field population of Sipalinus gigas to oviposit and the colonized insects in the bolts were examined periodically up to 29 mo after oviposition. The estimated survival rate of the immatures in the bolts decreased throughout the first and second season, and reached almost zero before the second overwintering. Predation was thought to be one of the major mortality factors of immature S. gigas. The increase of larval size and formation of a pupal chamber indicated that larval growth of S. gigas was completed within 4–5 mo after oviposition. The occurrence of pupae, callow adults and emerged adults suggested that S. gigas have bimodal adult emergence, namely they emerge in autumn of the year when they were laid as eggs as well as in the autumn of the following year. Although a small number of live larvae were found just before the second overwintering, they were less likely to grow into adults in the third season because of the high mortality of immatures in the second and third seasons.

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Whole body extracts from nymphs and adults of the brown planthopper, Nilaparvata lugens were analyzed for the known insect juvenile hormones (JHs) by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring. JH was separated successively by solvent extraction, chromatography on an aluminum oxide column and high performance liquid chromatography. JH III was identified as the only type of JH in both stages of this species. As the levels were very low for quantitative determination of JH III by GC-MS, we prepared haemolymph juvenile hormone binding protein (JHBP) of Locusta migratoria which had a high affinity for JH III and used it in a competitive binding assay to quantify JH III in the haemolymph of the brachypterous and macropterous pure lines of N. lugens. However, the JH III titer developmental profiles were similar in the brachypterous and macropterous fifth (final) stadium nymphs. JH III titers in the haemolymph of the brachypters were significantly higher than those of macropters, coinciding with earlier development of oocytes in the brachypters, which supported the regulation of ovarian development by JH III.

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The systematic status of the green and the red forms of Tetranychus urticae Koch is still unresolved because the ability of the two forms to interbreed varies considerably depending on the populations used. First, to investigate the hybrid fertility between the two forms in the laboratory, we interbred them for five generations. The hybrids produced showed relatively lower fitness (lower hatchability, lower proportion of female adults and lower production of fertile offspring) than their parents, and in some crossings, no female offspring emerged. Second, we used phosphoglucoisomerase (PGI) allozymes as genetic markers to analyze the temporal changes in hybridization of the two forms under semi-natural conditions. The temporal changes of hybridization were analyzed by the F-statistic. Intra-form mating was initially predominant, but as the number of damaged leaves increased, inter-form mating increased because the mites dispersed more frequently. However, as the fitness of hybrids from inter-form mating was much lower than that from intra-form mating, most hybrids were unable to produce offspring or had become extinct on the rose leaves. Thus, the gene flow between the two forms appears to be extremely restricted, indicating that a strong genetic differentiation is present between the two forms.

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The effect of temperature on the development of the cotton caterpillar, Diaphania indica (Saunders) was examined by rearing cohorts on cucumber Cucumis sativus L. leaves at various constant temperatures. The developmental periods were 47.4, 24.4, 18.2 and 19.7 d at 20, 25, 30 and 35°C, respectively. The lower threshold temperature and total effective temperature for development of the pre-adult stage were determined to be 13.5°C and 294.1 degree days, respectively. At 25°C, the mean adult longevity of males (21.6 d) was significantly longer than that of females (16.7 d). Pre-oviposition and oviposition periods were 1.04 d and 14.8 d, respectively. The total number of eggs produced per female was 808.7. Pupal weights and total numbers of eggs oviposited were positively correlated. The intrinsic rate of natural increase (r_c) was 0.20 per day.

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Laboratory-reared and wild adults of Endoclita excrescens (Butler) showed a mating flight at dusk. They began to fly soon after sunset and stopped flying at the beginning of darkness both in the cage and in the field (a forest in Chiyoda Town, Ibaraki Prefecture, Japan) during the period from 1 June to 20 October 1998. It is suggested that their flight activity is closely related to light intensity. Usually, the males began their flying about 4 min prior to the female flight. Mean flight period of the males per night was about 15 min in the cage and about 7 min in the field. For the females, it was about 10 min in the cage and 2 min in the field. The flight behavior of males was strikingly different from that of the females. The males flew swiftly and often showed a swinglike pendulum flight but the females did not. The males flew around a branch of a particular tree in a particular spot and sometimes formed a small group consisting of 2 to 4 individuals. Although no actual copulation was recorded, all other phases in the mating behavior were observed.

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A gene encoding coleoptericin, an antibacterial protein from the beetle, Allomyrina dichotoma was cloned and the nucleotide sequence determined. The A. dichotoma (A. d.) coleoptericin genomic clone was full size and contained an intron between a putative transcription initiation site and a signal sequence region. The 5′-upstream regulatory region of the A. d. coleoptericin had a TATA box and other regulatory motifs such as a NF-κB site, a region 1 (R1), a NF-IL6 site, 2 GATA motifs and 3 CATT(A/T) motifs. Expression vectors consisting of different lengths of the regulatory region and a luciferase gene as a reporter were constructed to analyze the induction of gene expression by bacterial lipopolysaccharide (LPS), a strong trigger for insect antibacterial protein genes. A silkworm Bombyx mori cell line was transfected with the expression vectors treated with or without LPS and the luciferase activity measured. Results showed that luciferase activity was dramatically reduced when NF-κB site was deleted. Deletion of R1 resulted in 64% reduction of luciferase activity but no marked effect was observed with GATA motif mutation. These results suggest that the NF-κB site is indispensable for A. d. coleoptericin gene expression and R1 is also necessary for full gene expression.

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Actual copulations of the swift moth, Endoclita excrescens (Butler), were recorded both in field observations at Takasaki in Kukizaki Town, Ibaraki Prefecture, Japan and in a large cage at the Forestry and Forest Products Research Institute during a research period from 1 September to 7 October 1999. Copulations took place during the dusk flight and the complete process of successful mating behavior in E. excrescens was observed. This demonstrates that the dusk flight of E. excrescens is the mating flight. In the beginning of the mating behavior, the female(s) flew straight toward the male(s) showing a swinglike pendulum flight around a branch of a particular tree in a particular spot. This result shows female attraction by the males (male “calling”). Preliminary experiments suggest that females are attracted to the flying males by visual cues from a long distance and the male scent from a short distance in the final encounter. The male flight pattern including the swinglike pendulum flight may have a “calling” function in long-range female attraction.

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A new cell line, designated NTU-Pn-HF, was established from the pupal ovary of Perina nuda Fabricius (Lepidoptera: Lymantriidae) and characterized by distinct morphological properties and molecular markers. Pn-HF cells are highly susceptible to P. nuda nucleopolyhedrovirus (PenuNPV). Surprisingly, some of the sub-cultural Pn-HF cells suffered an obvious cytopathic effect (CPE) and proceeded to die, while most of the cells remained healthy with good nutrition. Under electron microscopy, most of the Pn-HF cells were found to be carriers of a picorna-like virus. A specific anti-P. nuda picorna-like virus (PnPV) antiserum and RT-PCR with a primer set designed from the sequence of a putative PnPV's helicase gene confirmed that the picorna-like virus in Pn-HF cells is PnPV (Wang et al., 1999, J. Invertebr. Pathol. 74: 62–68), and Pn-HF cells are persistently infected with PnPV. This finding implies that the Pn-HF cell line can be a PnPV supporter for further work, and also a convenient tool in studying the pathogenesis of insect picornavirus and the mechanism of the picornavirus-persistent infection.

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Global warming may affect crop damage caused by insect pest, by changing the degree of synchronization between pest occurrence and the susceptible stage of crops. The epidemiological system of rice stripe virus disease (RSV disease) transmitted by the small brown planthopper, Laodelphax striatellus (Fallén), is greatly influenced by synchronization, because the susceptible stage for virus infection is within several weeks after transplanting. We calculated how the area potentially vulnerable to RSV disease will change under future global warming by using the results of the Global Climate Model (GCM) experiments reported by the Intergovernmental Panel on Climate Change. For simplicity, assuming that rice seedlings are transplanted from May to June, we made a map, in which the number of generations of the small brown planthopper on June 1 was plotted by calculating the effective cumulative temperature. The influence of solar radiation was also considered in this calculation. We judged that the area located near the boundary of generations is potentially vulnerable to disease prevalence, because planthoppers are in the adult stage there. Generation maps indicated that the Tohoku and Hokuriku districts, which are major districts of rice production in Japan, might be potentially vulnerable to disease infection under future global warming.

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Adult secretions of four Japanese Chrysomelinae, Gastrophysa atrocyanea, Plagiodera versicolora distincta, Chrysomela vigintipunctata costella, and Gastrolina depressa (Coleoptera: Chrysomelidae) were analyzed by TLC, HPLC, NMR and FAB-MS. Three nitropropanoyl isoxazolinone glucosides, 2-[6′-(3″-nitropropanoyl)-β-D-glucopyranosyl]-3-isoxazolin-5-one (1), 2-[2′,6′-di-(3″-nitropropanoyl)-β-D-glucopyranosyl]-3-isoxazolin-5-one (3), and 2-[3′,6′-di-(3″-nitropropanoyl)-β-D-glucopyranosyl]-3-isoxazolin-5-one (4) were found in all species. In addition, two nitropropanoyl glucosides, 1,6-di-(3′-nitropropanoyl)-β-D-glucopyranose (2) and 1,2,6-tri-(3′-nitropropanoyl)-β-D-glucopyranose (5) were also detected from these species. The secretions of the four species and compounds 3 and 5 showed strong deterrent effects against ants (Tetramorium caespitum), whereas compounds 2 and 4 exhibited low activity.

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The size and age at first copulation and spawning of the apple snail, Pomacea canaliculata, were determined at three food levels under laboratory conditions (14L:10D; 25°C). Males fed at a low food level started copulation at smaller sizes than males at higher food levels. However, age at first copulation was similar among snails at all food levels. The food level appeared to affect the penis sheath length at maturity, although the difference did not reach a statistically significant level. Females fed at the low food level delayed both first copulation and spawning longer than those at higher food levels. Consequently, their sizes at first copulation and spawning were smaller. The albumen gland of poorly fed snails was smaller at first copulation but comparable at maturity. The adaptive significance of these patterns in sexual maturity and their possible implications for the integrated management of this snail are discussed.

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Hieroglyphus banian (Fabricius) is a major agricultural pest of paddy fields in tropical and subtropical countries. Although, this species consumes a wide variety of food plants from different families, the families Poaceae and Cyperaceae were found to be the most preferred. Among plants belonging to these two families, Cynodon dactylon (Pers.), Oryza sativa (Lin.) and Cyperus kyllingia (Endl.) were highly suitable for H. banian growth. The growth rate of H. banian, in terms of the percentage of weight gain after feeding for 8 and 16-d after fledgling (0-d adult), was maximum (38.7% and 76%, respectively) when C. dactylon was used as their food and minimum (14.9% and 30.1%, respectively) when C. kyllingia was used, whereas, it was moderate (26% and 48%, respectively) on O. sativa. The approximate digestibility (AD) of C. dactylon was in the range of 87.9–89.5%, followed by O. sativa (86.5–88.6%) and C. kyllingia (85.5–86.9%). The efficiency of conversion of digested food to body tissue (ECD) varied from 1.7–2.2% after 8 d, whereas, it increased to 3.3–9.1% after 16 d from fledgling. The efficiency of conversion of ingested food to body tissue (ECI) varied from 1.4–2.0% after an 8 d period and it also increased to 2.9–4.1% after 16 d. The survivability of H. banian fed on these plants did not differ remarkably, although their survivability was higher on C. dactylon followed by O. sativa and C. kyllingia at any stage of their lifetime.

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Two types of housefly acetylcholinesterases (AChEs) were expressed in a baculovirus lepidopteran cell system to elucidate the effect of point mutations from Ile₁₆₂, Gly₃₄₂ and Phe₄₀₇ in the organophosphate susceptible strains to Met₁₆₂, Ala₃₄₂ and Tnyr₄₀₇ in the organophosphate resistant strains. Concentrations resulting in 50% inhibition (I₅₀) of the expressed enzyme by an organophosphate, fenitroxon, with Ile₁₆₂, Gly₃₄₂ and Phe₄₀₇ was 4.02×10⁻⁷ M, and that of the AChE with Met₁₆₂, Ala₃₄₂ and Tyr₄₀₇ was 9.00×10⁻⁶ M. The ratio of I₅₀ values was 22.4, and was almost equivalent to the ratio of the inhibition assay of homogenates of housefly bodies from which the cDNAs encoding the housefly AChEs were derived. The insensitivity of the housefly AChE to fenitroxon in the insecticide resistant strains is attributed to point mutations in the structural gene.

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Calling activity in Cnaphalocrocis medinalis showed a distinct diel periodicity. Moths showed high activity during 5–7 h into the scotophase. To clarify the temporal change of pheromone titers in the pheromone gland within 1 d, age 4 females were used. The changes in the calling activity and titer of the four sex pheromone components, (Z)-11-octadecenal (Z11-18:Ald), (Z)-13-octadecenal (Z13-18:Ald), (Z)-11-octadecen-1-ol (Z11-18:OH) and (Z)-13-octadecen-1-ol (Z13-18:OH), in the pheromone glands were roughly synchronous. At age 4, however, the pheromone components could already be detected at the onset of scotophase, while calling began at 3 h into the scotophase. Furthermore, calling was most active between age 3 and age 7, whereas the highest level of pheromone titer at 6 h after light off was observed from age 3 to age 5. These findings suggest the presence of different controlling mechanisms between calling behavior and pheromone production. The ratio of the four sex pheromone components remained relatively constant at all times of the day and all ages.

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