Survivorship and Fecundity of adult Tribolim freemani HINTON were investigated at 30°C and 70-80% R.H. especially in relation to the influence of conditioned wheat flour. Adult lingevity of the beetle was extremely ling (over 500 days), and reproductive ability was relatively low (the intrinsic rate of natural increase (r_m) was 0.048 per day). The r_m decreased and pre-oviposition period was prolonged when the interval of medium renewal was increased. The reduction in fecundity and delayed onset of oviposition in T. freemani were confirmed using artificially conditioned media. The potentiality of T. freemani as a pest was discussed by comparing the reproductive abilities of this species with those of two related serious stored-products pests, Tribolium castaneum and Tribolium confusum.

View full abstract

A continuous cell line, designated as SES-BoMo-15A, was obtained from embyos of silkworm, Bombyx mori, strain "Kuroko". Cells were grown in MGM-448 medium with 10% fetal bovine serum (FBS) as well as in MM medium with 3% FBS. Cells were mostly spherical in shape and contained many granules. They multiplied in a suspended state, and the population doubling time was about 3 days in the MGM-448 medium at 25°C. Most cells had about 100 microchromosomes. The cell line was distinguishable from other lepidopteran cell lines by the isozyme patterns of some enzymes. The line was susceptible to B. mori nuclear polyhedrosis virus, B. mori cytoplasmic polyhedrosis virus and Chilo iridescent virus.

View full abstract

To determine the protozoacidal effect of tripropylisocyanurate (TPIC) on symbiotic protozoa in two Japanese subterranean termites, Coptotermes formosanus and Reticulitermes speratus (RHINOTERMITIDAE), we examined the movement of the protozoa by microscope. After exposing the termites to TPIC (40 mg/filter paper), the protozoa, Pseudotrichonympha grassi in C. formosanus and Trichonympha agilis in R. speratus, significantly decreased their movement (p<0.05) after 2 and 8 hr, respectively. These protozoa are considered to play a crucial role in cellulose digestion in the termites. TPIC was therefore considered to damage the cellulose metabolism of the termites by affecting their symbiotic protozoa. The termite C. formosanus did not become moribund or die within 24 hr after exposure to TPIC (40 mg/filter paper), so the effect of TPIC thus emerged in the symbiotic protozoa much earlier than in the termites themselves. R. speratus, however, became moribund within 2 hours after TPIC (40 mg/filter paper) treatment, and it was concluded that TPIC first exerted its effect on R. speratus themselves before affecting the symbiotic protozoa.

View full abstract

Adult populations of the pine spittlebug, Aphrophora flavipes were studied by individual marking, release and recapture technique at three study plots in the University Forest Experiment Station at Tanashi in 1984. The population sizes and survival rates were estimated by the JOLLY-SEBER method and seasonal fluctuation patterns were compared among the plots. The species had a relatively long adult life span : 20-30 days on average and a little over four months at maximum for both sexes. Females made up about 70% of the total population and the sex ratio was constant throughout the seasons. Dispersal and mating activities both increased in autumn. Also in autumn, the population at each plot, containing a high proportion of immigrants, fluctuated in size, possibly as a result of the balance between immigration and emigration.

View full abstract

Some candidate factors which seemed to influence the sex ratio in Ascogaster reticulatus WATANABE (Hymenoptera : Braconidae) were investigated. A. reticulatus in an arrhenotokous egg-larval parasitoid of the smaller tea tortrix, Adoxophyes sp. (Lepidoptera : Tortricidae).Females soon after mating (<30 min) lacked the ability ot sufficiently fertilize egges, so that the percentage of female progeny exceeded 50% one day after mating. This level (50-90%) was maintained throughout the rest of their life span. Neither the age (1-6 days) nor the size (91-242 egges) of host egg masses on which a mated female deposited her eggs affected the sex ratio of the progeny. In the course of oviposition (ca. 1 hr) of a mated female on an egg mass, there was no significant difference between the number of male and female progeny during the first 30 min when the rate of oviposition was relatively high, but the female progeny pre-dominated during the next 30 min when the rate was low. During the course of oviposition, the speed of deposition of female eggs was rather constant but that of male egges decreased gradually as time elapsed. These results suggest that one of the factors controlling the sex ratio of A. reticulatus is the rate of oviposition.

View full abstract

Galls produced by Andricus symbioticus supply ants with a sweet and sticky food. Interactions between the gall-attending ant, Lasius niger and the parasitoid, Caenacis sp. (Family Pteromalidae) were observed on the galls of A. symbioticus on Quercus mongolica var. grosseserrata at Chojabaru, Kuju Mts. of Oita Prefecture, Japan. On the basis of this observation the association between the gall and the gall-attending ant is regarded as trophobiosis.

View full abstract

The developmental success of Amblyseius sojaensis EHARA on 2 species of spider mites, Panonychus citri (McGREGOR) and Tetranychus kanzawai KISHIDA, and tea pollen was investigated on detached leaves of citrus and kidney bean. Amblyseius sojaensis readily consumed larvae and nymphs of P. citri, but almost no egges were utilized. The percentage of individuals attaining maturity was higher when the immature active stages of P. citri were provided than when all stages were provided. In both cases less than 50% individuals completed development whereas on tea pllen alone 80% reached maturity. Amblyseius sojaensis did not develop when either all stages or immature active stages of T. kanzawai were provided. In this case, A.sojaensis larvae frequently became entangled in the webbing of T. kanzawai and their survival was shorter than that on food-absent leaves. The results indicate that A. sojaensis is more dependent on other foods such as tea pollen than on spider mites.

View full abstract

The supercooling point (by spontaneous freezing) of Mamestra brassicae LINNE is about -20.0°C in both diapausing and non-diapausing pupae. The supercooling ability is considerably reduced by contact with moisture. Pupae begin to freeze at -4°C in muddy water and at -4.9 to -7.8°C in soil of various water contents. Trehalose content in diapausing pupae increases with days after pupation, attaining a maximum within 30 days, with a concomitant decrease of glycogen. Further, trehalose content tends to decrease with incubation (at 22°C) of diapausing pupae kept at 4°C for 40 days. In non-diapausing pupae trehalose accumulates less but the content is slightly increased over that in prepupae. Non-diapausing pupae develop a supercooling ability at a level comparable to that in diapausing pupae despite poorer trehalose accumulation. The supercooling ability in this species is thus probalby determined independent of trehalose accumulation.

View full abstract

The hydrocarbon components in the opisthonotal glands of six species of agriculturally important astigmatid mites were identifed. These included n-tridecane, n-tetradecane, n-pentadecane, Z-Δ⁵-tridecene, Z-Δ⁶- and Z-Δ⁷-tetradecene, Z-Δ⁶- and Z-Δ⁷-pentadecene, and Z, Z-Δ^{6, 9}-pentadecadiene. Tyrophagus neiswanderi and T. putrescentiae are characterized by abundant quantities of monoenes and dienes, whereas the hydrocarbons of T. similis and Carpoglyphus lactis are predominately n^alkanes, with only minor quantities of the alkenes. Aleuroglyphus ovatus and Rhizoglyphus robini contain only n-tridecane (>97%) and n-tetradecane.Scanning electron microscopy of the opisthonotal gland orifice revealed a novel and previously unknown "trapdoor" closure which appears to regulate the release of gland contents.

View full abstract

Adults of the small brown planthopper which is a vector of rice stripe virus (RSV), were reared under 17.5, 25.0°C, and their fertility, longevity and the rate of viruliferous nymphs of the next generation were investigated. The mean adult longevities of females were 44.8, 27.0, 20.3 days and those of males were 45.9, 26.5, 16.9 days at 17.5, 25.0, 32.5°C, respectively. The mean fertility at 25.0°C was the highest (289.0 hatchlings), which was not significantly different from that at 17.5°C (251.9), but the fertility at 32.5°C was low (69.5). Most of the females at 17.5°C showed high transovarial passage, i.e. 82.6% of viruliferous females passed RSV to progeny at the rate of more than 90%. The pernentage of females which showed high transovarial passage (>90%) was 60.9% at 25°C and 12.5% at 32.5°C; the higher the rearing temperature, the lower the percentage was. The lower rates of transovarial passage were observed from the begining of oviposition at both 25.0 and 32.5°C, and the rate decreased with the age of females especially at 35.5°C. RSV had no deleterious effect on the fertility or adult longevity of the vector.

View full abstract

The alarm pheromone was isolated from a hexane rinse of the bulb mite, Rhizoglyphus robini. The main component was identified as neryl formate (3, 7-dimethyl-(Z)-2, 6-octadienyl formate) and two minor components as citral (mixture of (Z)- and (E)-3, 7-dimethylocta-2, 6-dienal). The alarm pheromone activity of neryl formate was demonstrated against the bulb mite at 1 ppm hexane solution, which was ten times more active than demonstrated against the ceese mite Tyrophagus putrescentiae. The activity of citral was weak and demonstrated only at 1, 000 ppm solution.

View full abstract

It is known that the adult emergence curve of Torymus (Syntomaspis) beneficus, a native parasitoid of the chestnut gall wasp, Dryocosmus kuriphilus, has two peaks in the Ibaraki district. Samples of withered galls of D. kuriphilus were collected from various localities and placed in a meteorological screen in Fukuoka to investigate the seasonal prevalence of adult emergence of T. (S.) beneficus. It was evident that there were at least three ecotypes of the parasitoid with defferent curves of adult appearance. As these type sere complicated in their geographical distributions, they should not be regarded as geographical ecotypes which have adapted to the climatic conditions in each locality. Alternatively, it was supposed that these types may have originated from diffrerent ecotypes of the same species which attacked different native cynipid hosts before D. kuriphilus was accidentally introduced into Japan.

View full abstract

Inoculation experiments and histological/SEM observations revealed the invasion and succeeding growth of Steinernema feltiae (DD-136) in Spodoptera litura larvae. At an early time (3 hr) after inoculation, the infective juveniles were not always observed on the mouth or anus of a still active insect. Nematode invasion occurred as promptly as in 1 hr after inoculation with ca. 1, 000 juveniles and then increased with time. Twelve to 24 hr after inoculation, more nematodes were observed in hemocoel than in alimentary canal, especially in the hemocoel lying beneath the deeply invaginated intersegmental membranes. Generally, the most develped nematodes were in the insect head. Nematodes grew rapidly from 24 to 36 hr after inoculation, accompanied by the drastic disintegration of insect tissues in which they often embedded tehmselves. SEM observations clearly revealed a nematode living on and in a larva and also a nematode feeding on rather large pieces of various insect tissues.

View full abstract