Denegri (1993) reviewed worldwide instances of oribatid mites as an intermediate host of Anoplocephalid cestodes (tapeworm). In Japan, only four records of cysticercoids in oribatid mites have been reported, although many investigations have been made on grazing lands. The oribatid species as an intermediate host previously reported from Japan are Eporibatula sakamorii, Scheloribates laevigatus, Mixacarus exilis and one unidentified species. The distribution of intermediate species is discussed according to the systematic scheme of suborder Oribatida.

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The oak platypodid beetle, Platypus quercivorus (Murayama) (Coleoptera: Platypodidae), could be reared under a 16L : 8D light regime at 25°C on logs of the deciduous oak tree, Quercus serrata Thunb. ex Murray, which had been immersed in water for 10–14 days at 23–25°C. Adult males bored holes into the water-soaked logs, but not on unsoaked logs when they were both provided together. Male adults were released in plastic boxes containing soaked log(s) and allowed to bore holes into the logs 4 days before introducing female adults. Thirty days after introducing the females, about 70% of the individuals in the galleries were in the egg stage. Thirty days later, about 70% of the individuals were 5th stage larvae. About 0.7–3.9 times as many new adults emerged as released from each log. The number of emerging adults per emerging gallery for each log ranged from 18.5±1.5 to 36.0±7.5 (mean±SE). The reproductive performance of the borer reared on a small diameter log was lower than that of the borer reared on a large diameter log. The 50% cumulative adult emergence day ranged from 92 days to 127 days after the females were introduced to the galleries.

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Overwintering females of Pseudaulacaspis pentagona (Targioni) entered a reproductive diapause, and the ovary development in females collected before December 22 was retarded at 20°C under short (L10 : D14) and long (L15 : D9) days. In contrast, ovarian eggs in females collected after the beginning of the year developed normally. I examined the effects of temperature on the development of overwintering females that infested tea branches and on the hatch of the first generation at various constant temperatures. The base temperature was determined to be 10.5°C and 10.9°C for 50% of the females to begin laying eggs and for the egg hatch to reach a peak, respectively. Seasonal changes in oviposition of the overwintering generation and hatch of the first generation were monitored from 1998–2002 at Kanaya, Shizuoka Prefecture. When the base temperature was assumed to be 10.5°C and day-degrees (DD) were summed from January 1, 50% of the females began laying eggs when an average of 149 DD had accumulated, and the peak of hatching coincided with an average of 288 DD. The logistic equation y=1/[1+exp{−(α₀+α₁x)}] (y, proportion of parous females or hatch; x, DD accumulations; α₀ and α₁, constants) was used to model a sequence of the population events and to predict the optimum timing of insecticide application for controlling the first-generation larvae of P. pentagona.

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Liriomyza leafminers comprise a pest group that causes both considerable economic losses and serious quarantine problems. In this study, morphological studies were performed to assist in the species identification and discrimination of six Liriomyza pest species of quarantine importance: L. brassicae, L. bryoniae, L. chinensis, L. huidobrensis, L. sativae, and L. trifolii. The discriminative ability of some traditional morphological characters, such as abdominal color patterns and male genitalia, was re-evaluated. In addition, electronmicrographic and geometric morphometric methods were introduced for separating different species. Illustrative plates of the preceding morphology were collated into mappings for further applications in quarantine inspection; some analyses and evaluations in separating similar species are also discussed in further detail. The results show that the abdominal color patterns can only separate two species from others; nevertheless, the ultrastructures of the thoracic microsetae and male genitalia are useful morphological characters to prevent misidentifications. On each species, the thoracic microsetae show their unique arrangement and pattern in both length and density; meanwhile, photography of male genitalia using a larger focal depth was also proven to be taxonomically valuable in practice. Although not all pairs between any two species have significant differences in wing shape, wing morphometric results do reveal that the most variant area of wing shape is located around the cross veins; this suggests that the morphology of this area might be easily and efficiently used for differentiating these species.

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Because the ingredients of the artificial larval diet (the basic diet) used to mass-rear the West Indian sweetpotato weevil Euscepes postfasciatus were expensive, so we substituted materials at 1/3 of the price (the low-cost diet). There was no difference in the survival rate of the weevil between those reared on the basic diet and those on the low-cost diet. As the quantity of artificial diet per rearing tray was increased, the survival rate of the weevil rose significantly up to 30 g of diet. The survival rate of the weevil was increased 1.6 fold by inoculating eggs in scratching lines 1 mm deep and 1 mm wide on the surface of the artificial larval diet. One hundred fifty eggs per rearing tray was probably a reasonable number because the survival rate and the actual number of surviving weevils at 150 eggs did not differ significantly from their respective maximums for other numbers of eggs. Rearing of 45,000 weevils per month was established using these methods. This represents a 4.5 fold increase compared to culturing by the conventional method. The new mass-rearing method could produce 1.6 adult weevils per gram of diet.

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The aim of this study was to provide empirical data on the effect of ambient carbon dioxide (CO₂) under high pressure on the mortality of Callosobruchus maculatus (F.) eggs at different ages. The mortality of the eggs was assessed in combinations of four CO₂ pressures (15, 20, 25, and 30 bar) and five egg-age groups (one, two, three, four and five days old) with 5, 10, 15, and 20 min exposure periods. The investigations were carried out in an automated pilot plant (volume: 1.1 l) at 25°C and 70% r.h. After each exposure period the gas pressure was decreased to atmospheric level in one second. One-day-old eggs were found to be the most tolerant, requiring 30 bar and 20 min exposure for complete extermination. On the other hand, five-day-old eggs were the least tolerant, requiring only 20 bar and 10 min. The tolerance of the eggs declined with age and the mortality was influenced by the pressure level and the exposure period. To achieve 100% mortality, increasing pressure was more effective than increasing exposure time. Decisions regarding pressure and exposure time of CO₂ should be made case by case, because the effect of CO₂ appears to vary depending on the age of the egg.

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Despite considerable research into the impacts of herbivores on plant gas exchange activity, there is minimal knowledge of photosynthesis and transpiration of plants at the time arthropod oviposition occurs. During oviposition, the small white butterfly (Pieris rapae L.) use visual and chemosensory cues to allocate most eggs to larger, more nutritional host plants (Brassica oleracea L.) with characteristically higher gas exchange activity. However, it is not known whether biogenic gradients of CO₂ or H₂O have a direct influence on host plant choice. During caged assays, watered cabbage plants with higher transpiration/photosynthetic rates were preferred, but only during extreme water deficits that led to wilting. Shorter assays permitted gas exchange to be manipulated but did not reveal preferences for plants exposed to elevated levels of water or PAR and, therefore, with higher gas exchange activity. These findings support previous field observations that there is no mechanistic basis to female preferences for plants with higher gas exchange activity, although associated characteristics relating to the plant status (in this case superior water relations) were preferred. The implications of using caged assays (some of short duration) to decipher egg-laying preferences are considered.

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Infectivity and post-infection development were investigated at 25°C for infective juveniles (IJs) which originated via endotokia matricida in hermaphrodites and/or female adults of the entomopathogenic nematodes, Heterorhabditis bacteriophora, Steinernema glaseri and S. carpocapsae. The IJs spontaneously emerging out of larval cadavers of Galleria mellonella were designated as normal IJs and used as comparison. Nematode invasion was the most prompt and numerous for normal IJs, followed by IJs produced via endotokia matricida in the 1st, 2nd, and 3rd generation adults of the three nematode species examined. Post-infection development and reproduction of nematodes also occurred more promptly and numerously when inoculation was made with normal IJs. The insecticidal activity of IJs originating from endotokia matricida was inferior to that of normal IJs which retained a significantly higher density of symbiotic bacteria than the former IJs of the respective nematode species. The IJs reproduced in and emerged out of host cadavers showed similar pathogenicity and bacterial retention, irrespective of the origin of the IJs used as inocula.

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Five thrips species known as vectors of tospoviruses in Japan, Frankliniella occidentalis, F. intonsa, Thrips setosus, T. palmi and T. tabaci, were studied for their transmission competence of Impatiens necrotic spot virus (INSV). The competence was examined for adults that acquired the virus as newly hatched larvae using a petunia leaf disk assay. No members of the genus Thrips transmitted the virus; the INSV-N protein was not detected in them by DAS-ELISA. On the other hand, two species of the genus Frankliniella were confirmed as vectors of INSV. Both sexes of F. occidentalis transmitted the virus efficiently (males: 80.5%, females: 78.7%). In F. intonsa, however, the transmission efficiency was relatively low and differed between the sexes (males: 18.3%, females: 3.7%). Most F. occidentalis adults showing ELISA-positive values transmitted INSV; however, only one third of ELISA-positive F. intonsa adults did so. The amounts of the INSV-N protein in ELISA-positive and transmitting adults were larger in F. occidentalis than in F. intonsa by sex. These results show that the transmission of INSV may be characteristic of the genus Frankliniella, and that F. occidentalis is probably the primary vector of INSV in Japan.

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Response behavior of specimens of the German cockroach (Blattella germanica) exposed to the Ca²⁺ signal inducing chemicals was characterized through implementation of two computational methods: the Fourier transform analysis and artificial neural networks. Ionomycin, thapsigargin, and their solvent (dimethyl sulfoxide) were topically applied to male German cockroaches, and the movement tracks were continuously observed through the image processing system under semi-natural conditions for 4–5 days. The specimens treated with the chemicals revealed different movement patterns: 1) shaky advancement and entanglement of the movement tracks with the ionomycin treatments; 2) continuous, circular movements with the thapsigargin treatments; and 3) shaky turning movements with the dimethyl sulfoxide treatments. The movement tracks in time domain were further analyzed with the two-dimensional fast Fourier transform (2-D FFT). The coefficients of the 2-D FFT efficiently revealed characteristics that resided in the two-dimensional data of the movement tracks in the frequency domain. Subsequently the magnitudes of the coefficients were trained by self-organizing map (SOM) through unsupervised learning. Classification of the different movement patterns was possible with the trained network. The combined use of the 2-D FFT and the SOM could be an alternative tool to automatically monitor behavioral changes in specimens exposed to stimulating chemicals.

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Comparative investigation of the characteristics related to prey consumption, reproductive rate and searching capacity among predators, which remain largely unexplored, could yield important information for selection of novel control agents. In this paper, the daily prey consumption rate of the immature stages and adult females until 20 days after eclosion of three predators, Stethorus japonicus (lady bug), Scolothrips takahashii (predatory thrips) and Amblyseius californicus (predatory mite), on eggs of Tetranychus urticae (red form) was determined, as well as the functional response of adult females to T. urticae eggs, on lima bean leaf discs in the laboratory at three constant temperatures (18–20, 25 and 30°C) and 16L : 8D. Female and male immatures of S. japonicus consumed the same number of spider-mite eggs, whereas more eggs were eaten by female immatures of S. takahashii and A. californicus than by male immatures at each of the temperatures tested. The total number of eggs consumed during the immature stages did not differ significantly among temperatures for any of the three predators. Consumption of T. urticae eggs by S. japonicus was fastest, followed by S. takahashii. Average daily consumption rates of adult females during the first 20 days after emergence at 25°C were 13.4 eggs for A. californicus, 23.0 eggs for S. takahashii and 294.4 eggs for S. japonicus. Adult females of the three predator species showed a type II functional response to prey density, regardless of the temperatures tested.

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Most cigarette beetle adults (Lasioderma serricorne) readily get into pipe rows of corrugated paper, and then settle there for a long time. Therefore, an insecticide application technique that takes advantage of this behavior was evaluated in the laboratory. Four strips of corrugated paper (23 cm in length, 2 cm in width) treated with the insecticides were arranged in a square on the floor of an insect cage (35 cm×35 cm, 50 cm in height), and then the insect adults were released. Residual efficacies of the corrugated papers treated with chlorpyrifos-methyl, pirimiphos-methyl, and fenitrothion (dosage: 125 mg AI/m²) on the insect adults consistently achieved almost 100% mortality. The minimum AI dosages which achieved more than 90% mortality after 4-months storage under conditions of 27°C and 60% RH were in 250 mg AI/m² of chlorpyrifos-methyl, 500 mg AI/m² of pirimiphos-methyl and 1,000 mg AI/m² of fenitrothion. The corrugated paper treated with these three insecticides showed no repellency to the insect adults immediately after treatment. These results suggest that corrugated paper treated with these insecticides would provide an excellent residual efficacy on the cigarette beetle adults. In contrast, corrugated paper treated with permethrin showed a low mortality of, and high repellency to, the insect adults.

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Reproductive potentials of an indigenous aphid parasitoid, Aphidius gifuensis, on Myzus persicae were measured in a laboratory at two constant temperatures, 20°C and 25°C. Single female parasitoids produced 529.0 progeny at 20°C and 536.7 at 25°C during their life spans. Longevities were 12.8 days and 12.3 days at 20°C and 25°C, respectively. The number of eggs laid by A. gifuensis peaked on the first days after the emergence at the two temperatures tested, indicating their proovigenic status. Intrinsic rates of natural increase for A. gifuensis were calculated as 0.350 at 20°C and 0.462 at 25°C. These values are higher than those for M. persicae, suggesting a significant character of A. gifuensis that indicates its great potential for use as a biological control agent for M. persicae.

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Seasonal occurrences of the diamond-back moth (DBM), Plutella xylostella were investigated on Ishigaki-jima Island, the southernmost part of the Southwest Islands of Japan. The number of DBM captured on Ishigaki-jima Island was relatively high from October to the subsequent May every year in the presence of a sufficient amount of cabbages; however, the number was very low or zero during summer, probably because the host plant was scarce and/or the air temperature was too high. Just after the passing of a typhoon near Ishigaki-jima Island in October 1998, sudden trap catches of DBM were observed, which is assumed to be based on immigration via air currents associated with the typhoon. Since many temperate exotic butterflies were collected on and near Ishigaki-jima Island at the same period, the sudden increase of the trap catch of DBM at that time is assumed to indicate that these DBM have the same regional origin as those butterflies, which was assumed to be central China or more northern areas. The impact of the migration of DBM associated with the typhoon on their population increase on Ishigaki-jima Island, however, did not appear to be significant.

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The effects of temperature, age and mating status on the flight activity of Carposina sasakii were examined using a flight mill system. Flight measurements were carried out for 24 h under dark conditions. No significant difference was observed for the total flight duration of 2-day-old moths at temperatures between 14 and 26°C. The proportion of individuals that did not fly at all was less than 10% at 14 to 29°C, whereas the proportion at 11°C was 67% in females and 83% in males. Total flight duration did not show a significant difference through the ages from 1 to 7 days in either sex. Two-day-old females flew significantly faster than 1-day-old females, whereas flight speed did not differ among ages in males. Flight activity of females was similar to that of males and remained high even after mating. These results are discussed in relation to the control of C. sasakii by mating disruption in the apple orchards.

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The last instar larvae of Spodoptera litura were reared on soybean leaves (SL), eddo leaves (EL), an artificial diet (AD), or AD supplemented with soybean oil (AD+O). Larvae fed on SL developed faster into adults with smaller sizes and lower levels of triacylglycerol (TG) than those from the AD or AD+O groups. The ratio of C18 unsaturated fatty acids in the TG fatty acids was similar (nearly 40%) among the adults of these three groups, as was the average total flight duration of about 6 h tested over 20 h of tethered flight. The ratio of C18 unsaturated fatty acids in the TG fatty acids tended to decline with longer tethered flight in the adults of these three groups. On the other hand, the development of individuals from EL was greatly retarded and they emerged as the smallest adults with the lowest level of abdominal TG with essentially no C18 unsaturated fatty acids in the TG. Adults from EL could barely fly when tested in tethered flight. These results support the notion that the flight capacity of S. litura depends greatly on the plants eaten as larvae and the C18 unsaturated fatty acids in the TG function as the major flight fuel.

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The effect of temperature on the development and survival of the legume pod borer, Maruca vitrata (Fabricius) (Lepidoptera: Pyralidae) was examined by rearing cohorts on a semi-synthetic diet containing cowpea grain and leaf at different constant temperatures in the laboratory. The developmental periods for eggs, larvae and pupae shortened with increasing temperatures from 14.4°C to 29.3°C. The thermal constants and lower thermal thresholds for the development in the egg, larval and pupal stages were 51.1, 234.7 and 116.5 degree-days and 10.5, 10.0 and 10.9°C, respectively. Development was delayed at higher temperatures for all the stages, and the upper thermal threshold was estimated to be in the range of 29.3–31.9°C depending on the developmental stage. At 34.3°C, the survival rates for eggs, larvae and pupae were below 10%, which were lower than those at other temperatures. The development of the larval population in the cowpea field of northern Nigeria was simulated based on daily temperature and the developmental data obtained from the laboratory experiments. The simulated dates of the midpoints in the 4th and 5th instars were concordant with the dates of 50% cumulative field collection for the respective instars. These results would be useful for forecasting pest incidence in the crop fields of the West African savanna.

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When arrowhead scales, Unaspis yanonensis Kuwana (Homoptera: Diaspididae), burrow and settle underneath conspecifics (i.e., burrowers), the burrowers are less vulnerable to attack by the parasitoid wasp Coccobius fulvus Compere et Annecke (Hymenoptera: Aphelinidae) than scales that settle singly (i.e., singletons). To examine how this differential susceptibility between settling modes occurs during the host-finding and oviposition processes of the parasitoid, we observed the foraging behavior of the parasitoids in the laboratory. Encounter rates between parasitoids and hosts were similar between settling modes. When scales that had been burrowed under (burrowees) were alive, the parasitoids oviposited in them as frequently as in singletons, however, the wasps did not lay eggs in burrowers. When burrowees were dead or parasitized, the parasitoids did not exhibit oviposition behavior and left soon after they had drummed these individuals several times with their antennae. Our results strongly suggest that the parasitoids were unable to identify the burrowers. Based on this study, we discuss which stimuli may be used by the parasitoids as cues to locate hosts.

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We investigated the effects of tillage practices on the densities of wolf spiders and planthoppers and leafhoppers in rice paddy fields. Paddies were subjected to one of two different treatments (no tillage and conventional tillage), and seasonal changes in the densities of wolf spiders and hoppers were investigated over two growing seasons (1999 and 2000). In both years, the density of wolf spiders was significantly higher and the density of hoppers tended to be lower in no-tilled paddies than in conventionally tilled paddies, although the latter difference was not statistically significant. The Iwao's omega values, which represent the degree of correlation between the spatial distributions of wolf spiders and hoppers, were higher in no-tilled than in tilled paddies during August when the hopper density decreased in no-tilled paddies.

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For development of an F₁ hybrid of lettuce cultivars, an efficient pollinator must be found. To evaluate pollination effects of a candidate pollinator, Lasioglossum villosulum trichopse, the foraging behavior and pollination ability of this sweat bee were investigated on the flowers of male-fertile (MF) and genic male-sterile (GMS) lettuce. Females of the sweet bee visited three lettuce cultivars for a short time corresponding to each cultivar's full blooming time and showed unique foraging behavior on the MF lettuce flower. The flower heads thus visited by a single pollen-gathering female sweat bee indicated a seed set as high as that of self-pollinated flower heads on a fine day. On the GMS lettuce, the rate of seed set was significantly lower in the bee-pollinated flower heads than that of hand-pollinated flower heads which bloomed on fine days. The low seed set was considered to be associated with weather conditions during the experimental period. This is the first report of successful F₁ hybrid seed production of lettuce using a pollinator insect.

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Life history traits of Parnara guttata guttata hatched from large-sized and small-sized eggs were compared. Eggs were grouped into two sizes, larger than 0.19 mm³ (L group) and smaller than 0.16 mm³ (S group). Larvae from these groups were reared individually under a 16L8D photoperiod at 25°C. The survival rate in immature stages was significantly higher in the L group than the S group. Although not significant, the developmental time during immature stages of the L group was shorter than that of the S group. Notably, the pupal period was shortened significantly in the former group. The fecundity of female adults from the L group was higher, but not significantly so. Female adults in the L group laid significantly larger eggs than those in the S group. Phenotypic correlations between egg size and other traits were generally negligible. However, the correlation between the fecundity of females in the L group and the size of eggs they laid was significantly negative. These results suggest that egg size variation under fixed conditions affect fitness of offspring in P. g. guttata.

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An investigation was conducted to determine whether differences in host size of different species affect the body size, fecundity, and longevity of Trissolcus mitsukurii, a solitary egg parasitoid of stink bugs. The eggs of the Pentatomid bugs of Halyomorpha halys (large size), Plautia crossota stali (middle size), and Nezara viridula (small size) were supplied to T. mitsukurii and incubated until progeny emerged at 25±2°C and a photoperiod of LD 16 : 8. Both male and female parasitoids emerged with larger body sizes when they developed in large host eggs such as H. halys. Larger size parasitoids had greater longevity and larger size females showed higher fecundity.

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The survivability and the developmental rates of Dysdercus cingulatus when fed various cultivated and wild host plant species were compared in the laboratory. On this basis, Chorisia speciosa was regarded as a better-than-adequate host plant for D. cingulatus. Abelmoschus moschatus, A. esculentus, Hibiscus makinoi, Thespesia populnea and Gossypium arboreum were adequate, H. tiliaceus was relatively poor, and Abutilon indicum was very poor. Although D. cingulatus developed faster when fed cultivated species than when fed wild species, host plant properties such as the weight of seeds and habit (arboreal or herbaceous) could not explain the survivability and developmental rate of D. cingulatus when fed the different species. Estimations of a lower threshold temperature for the development of D. cingulatus nymphs fed with plant species except for A. indicum fell within a range of 0.5 degrees (13.9 to 14.4°C). However, the estimated total effective temperature for development varied so widely among food plant species that its value for A. indicum was more than twice that for Ch. speciosa. Developmental parameters obtained here may be applied to the design of control programs for D. cingulatus in cotton fields adjacent to or near vegetative stands containing alternative wild host plants.

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The efficiency of Tomato spotted wilt virus (TSWV) transmission by the dark form of Frankliniella schultzei was studied in Paraguay using the petunia leaf disk assay. Twenty percent of F. schultzei females collected in a field with TSWV-infected tomato plants were found to be transmitters of the virus. When larvae, up to 8 h old, were given a virus acquisition access period of 24 h, many adults, 88.9% and 72.2% of all males and females, respectively, transmitted the virus. These results indicate that the dark form of F. schultzei originating in Paraguayan tomato fields can transmit TSWV efficiently and is an important vector of the virus.

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