The onset and termination of reproductive seasons in insects are determined by various environmental factors under natural conditions. These factors will be reviewed in seed-feeding heteropterans that have winter adult diapause in Japan. Most species use photoperiod to time the induction of adult diapause and therefore the termination of reproduction in autumn. In some species, however, temperature or the quality of food are also used as seasonal cues. For initiation of reproduction in spring, a temperature increase above the lower thermal threshold for postdiapause development is essential. The appearance of host plant seeds primarily determines the onset of reproduction in Dybowskyia reticulata, and the photoperiod plays a definitive role in Cletus punctiger. However, the proximate factors that determine the onset of reproduction in spring have not been examined as intensively as those for the termination of reproduction in autumn.

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Although cows are protected from their natural enemies, they form herds when grazing in a manner that is similar to protective aggregations of wild animals such as insect swarms, fish schools, bird flocks, and other mammal herds. This study examined how distances between individual grazing cows are determined. In a herd of cows, complicated interrelationships operate between individuals. We assumed that the distance between any two individuals was based on the following five factors: the behavior of the entire herd (measured as the distance between the leftmost and rightmost cows: the herd length effect); repulsive and attractive forces operating directly between two individuals within the herd (direct effect); the effect of third individuals on the distance between two individuals (half-indirect effect); the effect of unconnected pairs on the distance between two individuals (indirect effect); and residual effects that cannot be explained by the other four factors (random/involuntary movement effect). These five factors were analyzed using regression analysis. We applied our model to a grazing herd of cattle. The coordinates of six cows in a one-dimensional, fenced grassland were recorded every 5 min. For each pair of cows, the contribution of each of the five effects was calculated using the sum of squares of data, based on the temporal changes in the distances between individuals. Overall, the random movement effect made the largest contribution (38.8%) to the temporal variation in the distance between two cows, followed by herd length (25.6%), direct (21.0%), and half-indirect (12.5%) effects. The contribution of the indirect effect was negligible. The results revealed that one of the six cows was persecuted by the other cows.

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The within stand spatial distribution of flying Platypus quercivorus adults was quantified by sampling populations with four types of sticky screen traps. The greatest numbers of adults were captured in long traps located at lower positions (0.5–2.5 m height) both at the forest edge and in the forest interior. The numbers of adults captured in square screens hanging from anchored balloons were also greatest at a height of 1 m. Lower numbers were captured in square screens located at the top of the forest canopy and in square screens located above the canopy. Many adults were captured under the forest canopy near the forest edge, but only small numbers were captured inside gaps. We conclude that adult P. quercivorus is generally associated with the forest edge, a trait shared by several other bark and ambrosia beetles.

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Adults of Dacne picta (Coleoptera: Erotylidae) show heavy aggregation in the field and they also vary considerably in size. To investigate the factors influencing the size and the effect of larval density on post-embryonic development and adult size, we conducted a laboratory experiment in which we varied the food quantity available to each larvae. The stage of larvae most critical for intraspecific competition was also estimated by the food consumption and adult size. Experimental manipulation of larval density revealed that adult size is affected by larval density, and adults of various sizes emerged from the high density plot. Larval density had no effect on pupation, though there was severe intraspecific competition at high densities. Thus, the typical competition among larvae was considered to be of the scramble type, but it changed to contest at extremely high larval densities. For female adults, lifetime and lifetime fecundity were reduced with decreased size. These results suggest that the beetles show a mainly scramble competition of larvae, but emerged adults inevitably suffer reduction in reproductive traits.

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Seasonal abundance and parasitism of the citrus leafminer, Phyllocnistis citrella Stainton were investigated in controlled and uncontrolled citrus groves from June 2001 through May 2002 on Citrus iyo (iyotangor) in Ehime Prefecture. No significant difference in mean monthly frequency of P. citrella infestation and its parasitoids was found between controlled and uncontrolled groves. There were two peaks of P. citrella infestation, in July and October. These peaks were strongly related to favorable temperature for P. citrella development and continuous flushing of new shoots. At least seven species of the parasite wasps of P. citrella were observed, of which Chrysocharis pentheus (Walker) and Sympiesis striatipes (Ashmead) were the predominant species. The population drastically increased from July to August, and also from October to November, which coincided with heavy infestation of P. citrella in the iyotangor grove. In spite of a high percentage of parasitism (about 70%) in summer and autumn, the damage to tender leaves was noticeable, because all native parasitoids attacked mature larvae and pupae of P. citrella after they had nearly completed their feeding period.

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In the yellow-spotted longicorn beetle, Psacothea hilaris (Pascoe), variation in body size is conspicuous, especially in males. Size-related difference in male response to females and dummies treated with female extract were examined in the laboratory. Smaller males more frequently located and mounted females than did larger males when introduced to females. Smaller males responded to dummies treated with lower doses of female extract. This result indicates that small males were more sensitive to female sex pheromone and more active in their mating search and pre-copulatory behavior. However, females preferred large males to small ones. They displayed mate refusal behavior to small males much more frequently than to large males. A higher sensitivity to sex pheromone and subsequently higher copulatory activity in small males may compensate for the disadvantage of lower female choice. This hypothesis was supported by a field investigation: body size distributions were not significantly different between mounting males and solitary males.

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Experiments were carried out to examine the role of chemical and acoustical stimuli in the detection of fully matured queens just prior to emergence by virgin honeybee queens. When the empty queen cells, which had previously housed either 9-day-old broods or adult queens just before emergence, were presented in pairs to virgin queens in the experimental cages, the virgin queens preferentially destroyed the queen cells that had housed emerging queens. We also found that virgin queens tended to destroy queen cells housing emerging queens that were allowed to move freely inside the cells much earlier than queen cells with movement-restricted emerging queens. These results suggest that both olfactory stimuli derived from the queen broods and acoustical stimuli caused by the movement of emerging queens are factors that virgin queens use to distinguish queen cells containing fully matured queens from those with younger ones.

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The nutritional status and ovarian development of Halyomorpha halys adults collected in an apple orchard and in coppiced trees were investigated in 2000 and 2001, and those of adults reared on apple trees with fruits were investigated in 2002. Adults were observed earlier in the apple orchard than in the coppices; adults immigrated into the apple orchard in May of each year. Female adults had developed ovaries and produced mature eggs. Adults were seldom observed in the orchard after early June, when many adults were observed in the coppices. However, many adults were observed in the apple orchard from mid-July to early August in 2001; the nutritional status of these adults was inferior to that of adults collected in the coppices, and many of the females had undeveloped ovaries. The nutritional status and the number of deposited eggs of the adults reared on apple trees with fruits were significantly inferior to those of adults reared on peanuts and soybeans, foods which were similarly suitable as mature fruit of Japanese flowering cherry. These results suggest that apple fruit is not as good a food for H. halys adults as other plants, but apple is satisfactory when more suitable foods are in short supply.

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Emergence pattern and mating behavior of the pink borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae) were studied in the laboratory at 25°C under 14L10D photoregime. Both sexes emerged most frequently at 1.5 h after lights off, but males emerged significantly earlier than females. 0-day-old females started calling at an average of 4.9 h after lights off, while 1- to 4-day-old females did so at around 3.8 h after lights off. For mating among different ages, the highest copulation rate for females was observed at 0-day-old (83.3%) and the lowest at 4-day-old (56.7%). The mating time of 4-day-old females was irregular, and some unmated females conducted oviposition behavior. Therefore, S. inferens females appear to mature early. Mean mating duration of S. inferens was 1.29±0.71 h (mean±SD).

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Newly-hatched nymphs of the rice grasshopper, Oxya yezoensis Shiraki (Orthoptera: Catantopidae) were reared on artificial diets. The artificial diets consisted of dry leaf powder from one of three Gramineae plants, dried brewers' yeast, milk casein, wheat germ powder, sucrose, β-sitosterol, Beck's salt mixture, ascorbic acid, vitamin B mixture, L-cysteine, sorbic acid, propionic acid, agar, and water. There were no significant differences in the nymphal period, percentage of adult emergence, adult weights, and the number of egg-pods laid per female between hoppers reared on the artificial diet and those reared on fresh rice seedlings. The present study is the first report on the successful rearing of the Catantopidae species on an artificial diet.

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The cellulase activities of workers (or pseudoergate) of five species of common termites, Reticulitermes flaviceps, R. leptomandibularis, Coptotermes formosanus, Odontotermes formosanus, and Cryptotermes pingyangensis, were studied in China. The results indicated that R. leptomandibularis workers had the highest activity of β-glucosidase and cellulase against carboxymethyl cellulose (CMC), Cry. pingyangensis pseudoergate had the highest activity of cellulase against CMC and O. formosanus had the largest β-glucosidase activity in the head compared to other tested termites. R. leptomandibularis in the foregut and hindgut and C. formosanus in the midgut had the highest activity of cellulase against CMC, and R. flaviceps in the hindgut and C. formosanus in the midgut had the largest β-glucosidase activity among the five tested termites. The main digestive sites of CMC and salicin for Cry. pingyangensis were in the foregut and midgut. The strongest digestibility of CMC was in the foregut for R. flaviceps and R. leptomandibularis and in the foregut and midgut for C. formosanus. The digestion of salicin for O. formosanus and C. formosanus were concentrated in the head and midgut, respectively. R. leptomandibularis and R. flaviceps had the strongest digestibility of salicin in the head and hindgut.

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In order to estimate the potential of Phytoseiulus persimilis and Neoseiulus womersleyi (formerly called Amblyseius womersleyi) as control agents for Tetranychus kanzawai on greenhouse grapevine, the effects of their release and colonizing characteristics were compared between the two species. Release of either P. persimilis or N. womersleyi onto potted grapevine plants at a ratio of 10 adult spider mite females to one phytoseiid mite demonstrated that both species could suppress population densities of the spider mite, but the control ability was superior in the latter. Comparison of the colonizing characteristics of P. persimilis and N. womersleyi adult females at different densities of T. kanzawai adult females on grapevine leaflets revealed that the time of dispersal from the leaflet was much later in the latter than in the former. Also, the numbers of eggs laid and adult female spider mites consumed on the leaflet were both greater in the latter. Thus, N. womersleyi could colonize grapevine more successfully and suppress the population density of T. kanzawai more efficiently than P. persimilis. Consequently, N. womersleyi was considered to be more adequate as a control agent for T. kanzawai to introduce into grapevine greenhouse than P. persimilis.

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This is the first report on the nocturnal flight activity of the phlebotomine sandflies in the field by trap collection in Mukusu, Masinga, the kala-azar (visceral leishmaniasis in humans) area in Kenya. A total of 514 sandflies were collected with three different types of traps (sticky traps, CDC light traps and a goat-baited trap), and seven species of two genera (Sergentomyia and Phlebotomus) were identified. The number of Sergentomyia bedfordi Newstead individuals captured was the largest among these seven species. This suggests that S. bedfordi is the most common among the seven species in Mukusu. The result of the sticky trap collection suggests that the wild sandflies are nocturnally active, with the highest flight activity level soon after sunset, at least for S. bedfordi. The proportion of females collected was extremely high both in the sticky and light trap collections. It is suggested that this is due to site tenaciousness or weaker dispersal urge of males. Phlebotomus martini Parrot, S. bedfordi and S. schwetzi Adler, Theodor and Parrot were collected in the goat-baited trap. Examination of the physiological conditions of a total of 495 females collected showed that almost all females were unfed and nulliparous. This suggests that younger females show stronger nocturnal flight activity.

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Antilochus coqueberti predators of each developmental stage exhibited a relatively broad prey size range against their prey Dysdercus cingulatus when a single prey individual was provided in the laboratory. On the other hand, when two prey individuals of different developmental stages were provided together for a single predator in the laboratory, younger predators tended to attack younger prey and older predators tended to attack older prey. This tendency is similar to that observed in the field. During its nymphal developmental period, the predator killed fewer prey individuals when fed older prey, and more prey individuals when fed younger prey individuals. Predators of all nymphal instars examined exhibited a Holling's type II functional response to prey density, even if the developmental stages of the prey were different. The predatory properties of the predator elucidated in this study can provide a basis for a biological control program of D. cingulatus using its specialist predator A. coqueberti.

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Mating behavior of the scarab beetle Dasylepida ishigakiensis was observed in a sugar cane field in Miyako Is., Okinawa, Japan. In field observations of tethered females on 6 February 2002, calling behaviors were observed only within 30 min of sunset time (18:25–18:55, JST), when light intensity decreased from ca. 500 lx to 1 lx. Mating was strongly affected by temperature: adults appeared and subsequent mating occurred when the temperature at 18:00 was higher than 18°C. Females appeared from the soil, flew to settle on sugar cane leaves and commenced rhythmical abdominal expansion and contraction. Males were attracted to the calling females from leeward, landed on or near the calling female, and immediately mounted. After genital connection, the male raised his legs and suspended himself with his genitalia. Mating lasted for ca 2 h. Most mated D. ishigakiensis females neither appeared from the soil nor attracted males until the end of March, so are considered monogamous. In contrast, males appeared from the soil after mating on evenings warmer than 18°C and probably repeat mating if females are available.

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The spider mite Tetranychus pueraricola infests kudzu vines throughout Japan and causes conspicuous brownish feeding scars. It is possibility that T. pueraricola may get out of hand after invasion of agricultural leguminous crops. To better evaluate its potential severity as a pest, we determined the development, survivorship and life-history parameters of T. pueraricola on kidney bean. At temperatures between 15 and 30°C more than 89% of eggs hatched and of the newly hatched larvae ca. 89% attained maturity. There was no significant difference in eclosion rate of eggs or survival rate of immature stages among the temperatures. The lower threshold temperature from egg to oviposition was 10.9°C and the thermal constant was 147.1 degree-days. Based on these data, the maximum number of generations that can theoretically complete development under average field conditions in Ibaraki, Central Japan is between 11 and 14 generations per year. At 25°C, females laid on average 125 eggs during a mean oviposition period of 12.6 days. The intrinsic rate of natural increase (r_m) was 0.102 at 15°C, 0.179 at 20°C, 0.299 at 25°C and 0.377 at 30°C. Thus, T. pueraricola has the second highest r_m-value among tetranychid mites reported so far at 25°C, with T. okinawanus having the highest (0.316). This indicates that T. pueraricola has the potential to become a serious pest on agricultural crops.

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The period of diapause termination in adults (collected in Yueqing 120.94°E, 28.14°N, Zhejiang) of the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), were determined by initially exposing diapausing adults to various constant temperatures (25–5°C) as well as to room temperatures (33–−1°C), and then transferring them at intervals to a climatically controlled chamber (26±1°C, using rice seedlings as adult hosts) where the dynamics of oviposition onset and the numbers of eggs deposited were observed. Under room temperature, the diapause in 1st- and 2nd-generation adults terminated around late September and early December, respectively, i.e. at ca. 2.5 and 2.0 months after collection. Diapause in both 1st- and 2nd-generation adults was significantly affected by temperature. When exposed to 10, 15 and 20°C, the diapause in most 1st-generation adults terminated after 75, 25 and 50 days, respectively, while in 2nd-generation adults it terminated after 50 days at each of these temperatures. The associated adaptive significance and geographical variation of diapause termination in this insect are discussed.

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The influence of food supply on the survival and oviposition ability of Cotesia plutellae, the larval parasitoid of the diamondback moth, Plutella xylostella, was examined in the laboratory. The longevity of the parasitoid decreased drastically under a lack of sugar availability. The oviposition ability, evaluated by functional response to host density, was highly suppressed by a lack of food supply. Thus, sugar availability is a very important condition for the effective utilization of C. plutellae as a biological control agent of P. xylostella in greenhouses.

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The strong repellency of hinokitiol (β-thujaplicine) to the cigarette beetle was reported in a previous paper. In this study, the practicability of using hinokitiol as a repellent against the beetle was evaluated. The effect of hinokitiol on the behavioral response of the beetle to food-attractant lure was observed with a video system. The frequency of the beetle approaching the hinokitiol-treatment filter paper on which a food-attractant lure was placed was much less than that to the control filter paper. The resident time on the treatment paper was also much less than that on the control paper. Filter paper tapes treated with hinokitiol prevented the beetles from entering the sticky trap with food-attractant lure when the tapes were attached near the entrance of the trap. Furthermore, repellency of hinokitiol was evaluated in a semi-field test. Tapes treated with hinokitiol attached around the openings of the cardboard boxes containing cured tobacco leaves prevented the beetles from entering the boxes. The number of beetles entering the treatment boxes was less than half that of the control boxes. It appears that hinokitiol is a useful repellent against the cigarette beetle.

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Diploid males are expected to occur in populations of some Hymenoptera because of the single-locus complementary sex determination (sl-CSD) mechanism. If sl-CSD is found in a species that produces gregarious broods and sib mates at a high frequency, a fraction of these sib-matings (matched mating) produces diploid male offspring. We developed models to predict the matched mating frequency in populations with different frequencies of sib mating and egg fertilization. The predictions of these models are used to determine if we can use the distributions of brood sex ratio and brood size to determine if a species has sl-CSD. The models show that sl-CSD can be detected from these brood sex ratios if the diploid male offspring survives. We applied our models to Cotesia sesamiae and its exotic congener Cotesia flavipes (Hymenoptera: Braconidae), to determine if sl-CSD occurs in these species. Parasitoids were reared from stemborer larvae sampled from maize fields in Kenya between 1992 and 1999. We found no evidence for the presence of sl-CSD with survival of diploid males in both braconid species, but we cannot exclude the possibility that sl-CSD with diploid male mortality takes place in these species.

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Sex determination in the order Hymenoptera is based on haplodiploid arrhenotoky; in which males develop from unfertilized eggs and are haploid, whereas females develop from fertilized eggs and are diploid. However, some hymenopteran species produce diploid males through a mechanism known as single-locus complementary sex determination (sl-CSD). In these species, heterozygous individuals at a single sex locus develop into females, whereas hemizygotes (haploids) and homozygotes (diploids) develop into males. Inbreeding leads to homozygosity and consequent production of diploid males. We investigated the presence of sl-CSD in the braconid Cotesia flavipes using a series of inbreeding crosses among five isofemale lines. Sex ratio (proportion of females) did not differ among the within-line crosses, between-line crosses and crosses carried out between isofemale lines and a mixed (outbred) colony. Brood size of within-line and between-line crosses did not differ. Culturing populations for 25 generations did not result in changes to more male-biased sex ratios. We conclude that CSD does not exist in C. flavipes. The implications of absence of CSD in C. flavipes are discussed in context of mass rearing for classical biological control programmes.

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Seasonal fluctuation in population density of phytoseiid mites and Scirtothrips dorsalis and species composition of phytoseiid mites were investigated from May to September in 1997 and 1998 in a Delaware vineyard in Osaka Prefecture. Phytoseiid mites were found in high densities from mid-July to mid-August in 1997 and from mid-July to mid-September in 1998. S. dorsalis was found in high densities from late June to late July both in 1997 and in 1998. The dominant species of phytoseiid mites investigated in 1998 were Euseius sojaensis from mid-June to mid-August and Amblyseius eharai from late August to late September. The numbers of S. dorsalis larvae consumed per hour and day by E. sojaensis were 1.4 and 5.4, respectively. The results suggest that the population increase of E. sojaensis corresponds to that of S. dorsalis and affects the population density of the thrips as a predator on grape.

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In the white-spotted longicorn beetle, Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae), body size shows a large diversity both in males and females. We compared behavioral responses of different sizes of males to intact females and glass-rod models treated with female extract. Holding, mounting and abdominal bending responses to females were more frequently observed in small males than in large ones. Furthermore, small males showed these behaviors in response to lower doses of female extract than did large ones. However, females refused small males more frequently than large males, and approached the latter more frequently. This suggested that small males have high sensitivity to female sex pheromone that may offset the disadvantage of lower preference by females.

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