A probit analysis method is presented for the analysis of preference data from a behavioural assay of animals, where responses were observed as animals' choice between the treatment and control sides or areas. Standard probit models designed for all or nothing phenomena are not applicable to preference assays, because a log dose metameter only indirectly correlates with the choice. The present method enabled analysis by regressing the probit transformation of the proportion of net responders, expressed in a preference model equation, on a log dose metameter. The computer program includes the maximization routine of the log-likelihood function, a test of homogeneity and a calculation of potency with fiducial limits. After the explanation of the basic model, as well as generalized regression models including the parameters of natural preference and immunity, a computer output demonstrated the analysis of an olfactometer assay on two cockroach attractants by reporting statistics. By comparing differently generalized models for fitness to the data, a preferable experimental design was formulated.

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The impact of several insecticides has been studied on a Spodoptera littoralis cell line and their effects on the replication of S. littoralis nucleopolyhedrovirus (Sl NPV). Four chemical insecticides, Chloropyrifos Fenitrothion, Cypermethrin and Carbaryl which belong to three different groups of pesticide, organophosphorus, pyrethroid, and carbamate, respectively, were used. The results demonstrate an increase of more than 25% in the multiplication of Sl cells when treated with Chloropyrifos dilutions compared with untreated cells. The most destructive pesticide was Cypermethrin, which caused 84% inhibition of cell development (0.4×10⁶ cell/ml) at a concentration of 10^-3 μg/ml in preliminary tests. In the presence of both Sl NPV and sublethal doses of these insecticides, the TCID₅₀ values revealed that the Cypermethrin (10^-8 μg/ml) was the most toxic (ID₅₀ was 6.48×10⁵/ml) whereas Chloropyrifos was the least toxic (ID₅₀ 9.29×10¹²/ml) at a concentration of 0.731 μg/ml. The PFU values confirm the results that the same concentration of Chloropyrifos (0.73lμg/ml) was the least toxic (PFU 6.41×10¹³/ml) and Cypermethrin was the most toxic (4.47×10⁶/ml PFU) for the other concentrations as well as the different insecticides the PFU values ranged between 2.8×10⁸ for Chloropyrifos at a concentration of 10^-3 μg/ml and 9.76×10¹² for Carbaryl at 10^-5 μg/ml. A comparison with the results obtained using Sl NPV without chemicals (the PFU 3.5×10⁹/ml) indicates an increase in the production of virus and titer, and a synergistic effect of the chemicals. These results confirm the effect of these insecticides in vivo. As the Cypermethrin may have a potent effect on the exchange of ions through the cell membrane in vitro and in vivo, it could be partially explain the impact of the insecticides and their mode of action.

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Although the body size of 1st-instar soldier nymphs was larger than that of ordinary morphs of the bamboo aphid, Pseudoregma koshunensis (Takahashi), the diameters of the honeydew droplets excreted by these two morphs did not differ significantly. Soldiers excreted honeydew droplets significantly less frequently than ordinary 1st-instar nymphs. Total sugar and sugar per droplet excreted by soldiers were significantly less than those excreted by ordinary 1st-instar nymphs. However, the amino acid content of each honeydew droplet was slightly greater for soldiers than for ordinary 1st-instar nymphs. In the soldier's honeydew, asparagine was the most abundant amino acid, and constituted as much as 62 mol% of the total amino acid content, while in the honeydew of ordinary 1st-instar nymphs, both asparagine (32 mol%) and serine (20 mol%) were abundant. These results suggest a difference in nutritional requirements between the two morphs.

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In Riptortus clavatus, females received about 550 sperm from a male during one copulation. The number of sperm remaining in the sperm storage organs (spermathecae) decreased exponentially as the days after copulation increased. The pattern of sperm depletion was almost in accord with that estimated from the oviposition pattern. The efficiency of sperm use (=number of sperm that fertilize eggs/total number of sperm released from spermathecae) was approximately 30% and was stable throughout the entire reproductive period. A copulation interruption experiment indicated the following : the percentage of sperm used for fertilizing all eggs laid by females was nearly 30% of the total number of sperm initially received from males during an insemination (irrespective of sperm number). These results suggest that the number of sperm remaining in the female sperm storage organs was influenced by the utilization of the sperm for egg fertilization, and the consumption ratio was approximately egg : sperm= 1 : 3.

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A non-alkaloidal extract obtained from rhizomes of Dioscorea hispida was isolated and purified by thin layer chromatography. Each fraction was examined to evaluate feeding deterrent activity, developmental effects and toxicity against larvae of the diamondback moth (DBM), Plutella xylostella. Activity was shown in the benzene fraction, which was further fractionated into 5 fractions (Frs. 9 to 13). All fractions showed feeding deterrent activity at higher concentrations, however, Frs. 11, 12 and 13 exhibited feeding deterrent activity at lower concentrations of 10, 25, 100 μg/ml, respectively. These fractions significantly reduced larval weight and caused higher larval and pupal mortalities at 40% (Fr. 11), 37% (Fr. 12), and 27% (Fr. 13). No delay in larval development was observed in any of the fractions.

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The West Indian sweet potato weevil, Euscepes postfasciatus, was internally marked by incorporating Calco Oil Red N1700 dye into the larval diet, and the effects of the dye and its solvent on fecundity, longevity and sexual maturity were examined. There were three types of diet used in this study : standard diet, corn oil diet (standard diet+corn oil), and Calco oil diet (standard diet+corn oil+the dye). Neither dye nor corn oil affected either adult longevity or fecundity. The pre-oviposition periods of females reared on the Calco oil and the corn oil diets were significantly longer than those of females reared on standard diet, and the age at which males started mating showed a significant difference among weevils reared on the three types of diet. Thus, the solvent oil affected female sexual maturity, whilst the dye had a negative effect on male sexual maturity. None of these effects, however, is considered sufficient to prevent use of the dye for marking released weevils for the sterile insect technique (SIT).

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We studied the degree of overlap of spatial distribution and life history parameters of two sympatric whiteflies, Trialeurodes vaporariorum Westwood and Bemisia argentifolii Bellows & Perring, on tomatoes under greenhouse and laboratory conditions. The association of the micro-spatial distributions of the two species was investigated using interspecies mean crowding analysis. This association was neutral in the immature stages (nymph and pupa), whereas no consistent tendencies were seen in the adult stage in the greenhouse. In 2 out of 4 cases in the immature stages and 3 out of 4 cases in the adult stage, the mean relative leaf height of the distributions of the two species were significantly different, showing that T. vaporariorum has a tendency to occupy a higher leaf position than B. argentlfolii. For both species, the mean numbers of eggs laid per female per leaflet under two thermal conditions (20°C and 30°C) were not significantly different between two rearing situations, but the total developmental period in the isolated situation was longer for both species under both thermal conditions. At 30°C, the survival rate of T. vaporariorum was significantly lower in the isolated situation than in the mixed one, while that of B. argentifolii showed the reverse tendency. These differences in the survival rate in response to rearing treatments could be caused by l) a specific difference in the optimum density, or, 2) an asymmetric interspecific interaction during an early developmental stage.

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The mating behavior of the astigmatid mite, Caloglyphus rodriguezi Samsinak (Acarina : Acaridae), was observed in the laboratory. The typical sequence of the behavior can be classified into the following four phases : (I) encounter, (II) recognition and mounting by males, (III) positioning to achieve the correct posture between both sexes and (IV) sperm transfer. In phase (I), males searched for females more vigorously than females did for males. Further, approaches to males by females tended to end with unsuccessful mating. It was concluded that males play a more active role in the search for sexual partners at an early stage in mating behavior.

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We examined the occurrence of interspecific competition among egg parasitoids of Riptortus clavatus (Thunberg) (Hemiptera : Alydidae) in within-plant microhabitats of soybean fields in Fukuoka during the planting seasons from 1985 to 1987. R. clavatus eggs were found mainly on leaves and pods, and rarely on stems of soybean plants. They were parasitized by Ooencyrtus nezarae Ishii (Hymenoptera : Encyrtidae), Gryon japonicum (Ashmead) and G. nigricorne (Dodd) (Hymenoptera : Scelionidae). During three planting seasons, O. nezarae was more abundant than Gryon spp. O. nezarae parasitized more than 70% of hosts on leaves but less than 50% of those on stems and pods. Gryon spp., especially, G. nigricorne, parasitized more hosts on pods than on leaves or stems. Multiparasitism by O. nezarae and Gryon spp. rarely occurred in hosts from all three parts of the plant. Exploitation competition was more likely to occur in the early part of the season during 1985 and 1986 when overexploitation by O. nezarae was likely to reduce reproduction of Gryon spp. in soybean. Since interspecific competition was infrequent, the different parasitism patterns by O. nezarae and Gryon spp. on various plant parts were probably due to their differences in microhabitat preference.

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Gut proteases of 20 species from 13 insect orders were characterized by activity staining after polyacrylamide gel electrophoresis and the effect of class-specific protease inhibitors on their zymogram. Species in Orthoptera, Dictyoptera, Lepidoptera and Hymenoptera mainly had serine proteases in their gut. Those in Ephemeroptera, Odonata, Plecoptera and Hemiptera had cysteine proteases. Those in Coleoptera, Neuroptera, Mecoptera and Diptera had both serine+cysteine proteases in their gut. The protease class of each species tended to reflect phylogenetic relationship rather than feeding habits.

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Oviposition experiments using sugarcane stems cut into 7 cm lengths were conducted. The results show that the Asiatic palm weevil, Rhabdoscelus lineatocollis oviposits no eggs on the hard and soft sugarcane varieties, F172 and NiF4, at any developmental stage where cracks were absent. Oviposition occurred, however, when the stems were artificially cracked by a knife and 0.45 eggs/female/day was laid in the cracks. When the epidermis was totally removed, about 0.5 eggs/female was laid per day. The survival rates of the larvae in the stem were more than 60% at 28±1°C, 90 days after innoculation. Most adult weevils stayed in the narrow space between the stem and the leaf sheath.

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Effects of sex, mating status and temperature on flight activity of the Oriental tea tortrix, Homona magnanima, were evaluated by a computer-aided flight mill system. Adult moths reared through 22 to 25 generations were used to measure flight activity. Two to 8 day-old, females always flew more than males. It is likely that survival and flight duration of males were reduced due to exhaustion resulting from flight behavior. Mating status, whether mated or unmated, did not affect flight activity in either sex. Females showed high flight ability within the temperature range from 15 to 23°C, and their flight activity and survival greatly decreased at temperatures over 25.5°C.

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Daily records of Spodoptera litura males caught in pheromone traps at Saga and Kagoshima (150 km south of Saga on the Kyushu mainland) were compared during 1990 and 1995, in relation to meteorological conditions. The temporal patterns of occurrence were similar at the two locations, but the total number of males caught at Kagoshima was two or three times larger than that at Saga. Prominent peaks in catches during the rainy seasons in early summer and early autumn were also characteristic of the Kagoshima but not the Saga records. There were essentially no correlations between the numbers of males caught in any years and the catches of the preceding autumn. The most conspicuous feature of these records was the sudden increases in many cases in the male catch recorded at the time of the approach of typhoons in these areas, after mid-August. Our estimations of developmental rates based on the effective accumulative temperature of this species generally failed to indicate local emergence of moths corresponding to peaks in trap catches at about a one generation interval preceding a typhoon's approach. These typhoons generally passed the Southwest Islands of Japan and ran through the East China Sea before approaching Kyushu. Thereafter, the male catch tended to increase prominently in autumn. The possibility of overseas long-distance migration of this non-diapausing species when typhoons approach Kyushu is discussed.

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Extracts from the abdominal tips of female moths of the cotton caterpillar moth, Diaphania indica (ca. 15.4 ng/female and 7.6 ng/female, respectively) yielded major EAG-active components that were identified as (E)-11-hexadecenal (E11-16 : Ald) and (E, E)-10, 12-hexadecadienal (E10E12-16 : Ald). Hexadecanal (16 : Ald) was also found and determined to be at a ca. 2% level compared with Ell-16 : Ald. Mixture of synthetic E10E12-16 : Ald and E11-16 : Ald showed attractiveness to males in the field, although it was inferior to three 2-d-old virgin females. The addition of 16 : Ald at 0.5% to 10% amounts of E11-16 : Ald did not effect the trap catches.

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The possibility that insecticide hormoligosis might be amplified by resistance in the diamondback moth, Plutella xylostella, was tested. The fecundity of females treated with sublethal doses (LD_12.5 LD₂₅ and LD₅₀) of fenvalerate or methomyl in the non-selected generation increased in comparison with the control group treated with acetone. The number of eggs laid by treated females in the 10th generation of the fenvalerate-selected strain, which had developed about 10, 000-fold resistance, was the same or smaller than that of the control. On the other hand, fecundity in the 8th generation of the methomyl-selected strain, which had about 4.9-fold resistance, was slightly higher in the LD_12.5 and LD₂₅ than that of control. The intensity of insecticide hormoligosis did not depend on the dose of the insecticide although a sublethal dose of the insecticides stimulated reproduction in the susceptible DBM. Furthermore, the hormoligosis was not amplified in concert with the development of resistance in the DBM.

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An insecticidal crystal protein (ICP) gene was cloned from Bacillus thuringiensis strain AF101 which has a low toxicity to the silkworm, Bombyx mori. The cloned AF101 ICP gene encoded 1, 182 amino acid residues and shared 93% homology with the cry1Ab gene of B. thuringiensis serovar kurstaki HD-1. In the amino-terminal portion of the activated toxin region of AF101 ICP, there were 18 amino acid differences when compared with HD-1 Cry1Ab, but only three amino acid differences in the hypervariable region of the activated toxin. The AF101 ICP gene was also found to contain the Cys-rich region observed in cry1Aa and cry1Ac in its carboxyl-terminal portion of the non-toxin region. In a bioassay of the cloned gene product, toxicity with intact AF101 ICP was nearly 17% less than that of HD-1 Cry1Ab. On the other hand, the activated toxin prepared from ICP by removing the non-toxin region was 9% less than that of HD-1 Cry1Ab. These results suggested that the specific toxicity of AF101 ICP against the silkworm correlated not only with its activated toxin region, but also with the non-toxin region.

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Developmental, reproductive, and adult longevity, rates of Orius minutus (L) and Orius sauteri (Poppius) were studied in the laboratory using eggs of Ephestia kuehniella Zeller as prey. Immature development for both species took approximately 12 days and did not differ significantly between the sexes. Total fecundity rates were significantly higher for O. minutus (105.36) than O. sauteri (68.40) as were male longevity rates (18.11 days vs. 11.50 days) and female longevity rates for both virgin (16.73 days vs. 24.75 days) and ovipositing (13.90 days vs. 19.69 days) individuals. However, O. minutus suffered higher mortality rates in the laboratory, thus calculated intrinsic rates of natural increase were for O. minutus (r_m=0.137) and O. sauteri (r_m=0.132) were similar.

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To examine the factors regulating the adult color morph of the meadow grasshopper, Conocephalus maculatus, we carried out 2 series of experiments. In Series I, crosses between green and brown morphs were carried out to investigate the genetic effect. The percentage of green morphs in F₁ hybrids between green females and green males was about 70% and the percentages in F₁ hybrids between parent pairs of different color morphs were significantly different. The results suggested that color polymorphism in C. maculatus was partly controlled by genetic factors. In Series II, the F₁ hybrids were also reared under different conditions with respect to temperature, photoperiod, background color and relative humidity, to assess the effects on the proportion of color morphs. The body coloration of F₁ hybrids was lighter and paler at 30°C than at 25°C, especially the brown morph, which shows that temperature affects the intensity of body color rather than color morph determination in adults.

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Oligonucleotide-probed in situ hybridization targeted to bacterial rRNAs was attempted to detect, visualize and characterize the intracellular symbiotic bacteria of aphids. Using the EUB338 probe that hybridizes universally with 16S rRNA of eubacteria, the primary and secondary intracellular symbionts of various aphids were successfully stained on tissue thin sections. When in situ hybridization was conducted with GAM42A and BET42A probes that are targeted to 23S rRNA of γ- and β-subdivision of the Proteobacteria, respectively, it was shown that the secondary symbionts of Cinara pini and Nippolachnus piri belong to the γ-subdivision of the Proteobacteria whereas that of Tetraneura radicicola is a member of the β-subdivision of the Proteobacteria. This is the first report on the phylogenetic affinity of the secondary intracellular symbionts of aphids. Because insect tissues have strong autofluorescence in general, non-fluorescent in situ hybridization using biotin- and digoxigenin-labelled probes was more suitable for detecting symbiotic bacteria in aphid tissue sections.

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Bacillus thuringiensis strain AF101 produces the Cry1Ab type of insecticidal crystal proteins (ICPs) which are slightly toxic to the silkworm, Bombyx mori. Two chimeric cry1Ab genes were constructed using the cry1Ab genes of B. thuringiensis strain AF101 and serovar kurstaki HD-1 by exchanging their coding regions at the carboxyl-terminal portion of the insecticidal crystal protein (ICP). The effect of the carboxyl-terminal portion in the ICP on toxicity against the silkworm larvae, Bombyx mori, was examined using chimeric Cry1Ab ICPs produced in Escherichia coli transformants harboring the constructed ICP genes. Though no remarkable change in insecticidal activity was observed between parental and chimeric AF101 ICPs, the toxicity of the chimeric HD-1 ICP against the silkworm larvae was about one-fourth that of the parental ICP. These results indicate that the carboxyl-terminal portion in the AF101 Cry1Ab ICP, known as the non-toxin region, also affected the toxicity of B. thuringiensis against the silkworm larvae.

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Spores and parasporal crystals of a Bacillus thuringiensis serovar aizawai strain were fed to fifth instar larvae of the Mediterranean flour moth, Ephestia kuehniella, under laboratory conditions. Viable numbers of B. thuringiensis cells in E. kuehniella larvae were estimated by dilution-plating on peptone-polymyxin agar medium, and combined spore and crystal insecticidal activity was bioassayed with larvae of Bombyx mori. B. thuringiensis rapidly grew and sporulated in the larval cadavers of E, kuehniella regardless of inoculation dose. Spores that were produced in situ in E. kuehniella cadavers persisted for at least 90 d. Insecticidal activity of the homogenates of E. kuehniella cadavers fluctuated along with the viable cell numbers and persisted for at least 90 d. To examine horizontal transmission of B. thuringiensis in E. kuehniella larval populations, B. thuringiensis-infected and healthy larvae were released into containers in various proportions, but no reliable transmission was detected under our experimental conditions.

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