The larval development in the first and the second generation of Chilo suppressalis from the rice fields of the Ebro Delta was characterized by the number of larval instars and their mean duration. The results showed clear differences between the two generations: larvae of the first generation tended to undergo higher number of molts and to develop more slowly than did larvae of the second generation. The air temperature was probably the most important environmental parameter to cause such differences.

View full abstract

Newly emerged adults and first instar larvae of Trogoderma granarium EVERTS were exposed to various temperature-humidity and temperature-photoperiod combinations to determine their effects on oviposition and developmental period. There was a significant difference (p<0.05) in the number of eggs laid at different temperature-humidity combinations. As temperature increased from 27°C to 35°C, the number of eggs oviposited showed little variation. The developmental period of larvae was prolonged at lower humidities. Oviposition was influenced by photoperiods at every temperature. At 35°Cand 27°C, oviposition occurred at all photoperiods. Fecundity increased as the temperature-photoperiod regimens increased. The developmental period of larvae was prolonged as the photoperiod decreased at 20°C and 27°C. At 35°C, there was no effect of the photoperiod on the developmental period.

View full abstract

Ultrastructure of sex-pheromone-sensitive sensilla, sensilla basiconica, of the male cigarette beetle was examined. The sensilla have single-walled hair with many perforations of about 30 nm dia. and 20/μm² in density. The sensillum contains 2 sensory cells that have unbranched sensory processes growing up to the apical part of the sensory hair. These results are consistent with those of electrophysiological experiments, which show that one of two sensory cells in the basiconic sensilla responds to a natural pheromone and the other responds to a behavioral inhibitor.

View full abstract

Effects of temperature, photoperiod conditions during the larval stage and parental body size on flight ability of the male adult were investigated in the diamondback moth, Plutella xylostella, using a flight mill device. Larvae reared at a lower temperature developed into larger adult moths with the ability to fly longer and further than smaller moths reared at a higher temperature. Relative wing length (forewing length/thoracic length) was almost constant irrespective of temperature condition. Photoperiod had no effect on either forewing length or flight ability. Furthermore, parental body size did not significantly influence the flight ability of male adult progeny. It was experimentally verified that flight ability is influenced by adult body size in terms of forewing length. Forewing length is determined solely by temperature conditions during the larval stage, and flight ability (duration and distance) was significantly correlated with forewing length in P. xylostella. However, the potential of this species for long migration cannot be predicted from the present data, because the rates of moths with long consecutive flight and flight velocity were not significantly correlated with either larval rearing temperature or adult forewing length.

View full abstract

Co-culture of ovarian cells in young larvae with brain induced meiosis and endomitosis of the silkworm, Bombyx mori. This suggests that a substance secreted by the brain controls meiosis and endomitosis. When preparations from Bombyx heads were tested for meiosis-inducing activity, both the crude and highly purified preparations of bombyxin induced meiosis in vitro, but the crude preparation of prothoracicotropic hormone (PTTH) showed much lower activity. This indicates that bombyxin is the brain substance that induces meiosis. 20-Hydroxyecdysone also induced meiosis, but only at a low concentration.

View full abstract

At 20°C, amount of food consumption of Argopistes biplagiatus adults collected from the field in early autumn was greater under short-day conditions (11L-13D, 12L-12D and 13L-11D) than under long-day conditions (14L-10D, 15L-9D and 16L-8D). Females laid no eggs when they were transferred from 11L-13D, 12L-12D, 13L-11D, 14L-10D, 15L-9D or 16L-8D to 12L-12D, and from 14L-10D, 15L-9D or 16L-8D to 15L-9D, but they laid eggs when they were transferred from 11L-13D, 12L-12D or 13L-11D to 15L-9D. These results, together with those in previous field and laboratory studies, suggested that A. biplagiatus undergoes aestival (summer) diapause which is maintained by the long day-lengths and terminated by the short (or decreasing) daylengths and autumnal-hibernal (winter) diapause which is induced (and maintained) by the short (or decreasing) daylengths and terminated by the long (or increasing) daylengths in the adult stage.

View full abstract

The feeding response of six chrysomelid beetles to alkane, alcohol, and carboxylic acid fractions in the leaf surface wax of their respective host plants was investigated. The false melon beetle, Atrachya menetriesi, was stimulated to feed by an alkane fraction from the soybean Glycine max leaves. The feeding of Chrysolina aurichalcea was stimulated by an alcohol fraction from the mugwort, Artemisia princeps. Both alkane and acid fractions from the strawberry, Fragaria ananassa, stimulated the feeding of the strawberry leaf beetle, Galerucella vittaticollis. Feeding of the viburnum leaf beetle, Pyrrhalta humeralis, was stimulated by alkane fraction from the viburnum, Viburnum awabuki. Feeding stimulation by authentic homologous chemicals was also tested. Series of alkane, C₂₁-C₂₅ and C₃₀-C₃₆ were stimulating for A. menetriesi, alkane C₃₁-C₄₀ and acid C₂₄-C₂₆ for G. vittaticollis, alcohol C₂₁-C₂₄ for C. aurichalcea, and alkane C₂₈ and C₂₉ for P. humeralis. Gas-liquid chromatographic analysis suggested that the beetles were stimulated to feed by dominant wax components of each of the host plants.

View full abstract

The possibility of male Menida scotti (PUTON) donating their secretions to females through copulation was investigated. When adults of both sexes were reared in a jar, the volume of bursa of spermathecal duct (bursa) in the females increased, whereas the volumes of both the bulbus ejaculatorius and the reservoir of the ectodermal accessory gland (reservoir of the ectadene) in the males decreased. Isolation of the copulated females from males caused a significant decrease in the volume of bursa. Virgin females and males showed no changes in the volume of these reproductive organs. In the copulated females, spermatozoa were not observed in the bursa but only in the spermathecal bulb under microscopic examination. The volume of the bursa in the females showed a significant positive correlation with the total copulation time. In contrast, the volume of the bulbus ejaculatorius and of the reservoir of the ectadene in males exhibited a significant negative correlation with the total copulation time. Very high radioactivity in the bursa was detected in a female which had copulated with a male injected with [¹⁴C]isoleucine. These results show clearly that the males donate the secretions stored in the bulbus ejaculatorius and the ectodermal accessory gland secretions to the bursa of the females, and suggest that the females digest them.

View full abstract

In a chafer, Anomala schonfeldti OHAUS, collected from turfgrass in central Japan, 80.0% of male adults flew in a flight mill, as compared with only 5.9% of female ones. There was no significant difference in either the flight distance, flight duration or flight velocity between the male and female flyers. Whereas all males had flight muscles, only 23.5% of females had them .Thus the flightlessness of most female adults may be attributed to the lack of flight muscles. Nineteen percent of females reared in the laboratory did not have the muscles, suggesting that an intrinsic factor is responsible for the flight muscle development in A. schonfeldti.

View full abstract

The brown planthopper, Nilaparvata lugens STAL, is known to immigrate annually into Japan from overseas, primarily from mainland China. The susceptibility to insecticides of the brown planthopper in the Ono area, Hyogo Prefecture, was monitored annually for 8 years, from 1980 to 1987, by the micro topical application technique. The susceptibility to 8 insecticides tested fluctuated greatly at levels which indicated some degree of resistance. The brown planthopper collected in 1874 and 1985 showed extremely high LD₅₀ values to both carbamates and organophosphates. Data for other prefectures showed similar fluctuations. The LD₅₀ values for 1984 and 1985 were also high.

View full abstract

A parasitoid guild attacking eggs of a stink bug, Piezodorus hybneri, and seasonal trends of its parasitism were studied in 1989-1990 in soybean fields. Telenomus triptus and Ooencyrtus nezarae were identified as the parasitoids of P. hybneri eggs. The predominant parasitoid was T. triptus and high parasitism rates were recorded in both years, covering most of the ovipositional period of the P. hybneri that invaded the fields and laid eggs from early July to early August. The parasitism by T. triptus suppressed the hatchability of P. hybneri eggs to very low levels. Activity of this parasitoid accounted for almost all hatching failures. Female adults of T. triptus began to be caught by a sticky suction trap from mid-July in the field. Fewer males were trapped than females with time delay.

View full abstract

The contents of chemical components (alkaline extractives, ethanol/benzene extractives, holocellulose and lignin) were determined for the dead wood in which the larvae of Ceruchus lignarius (brown rot specialist) or Prismognathus angularis (decay type generalist) occurred. The variations of chemical components were small in the samples of C. lignarius and relatively large in those of P. angularis. It was established that C. lignarius occurred exclusively in the brown rotten wood in advanced stage of decay, whereas the occurrence of P. angularis was not as clearly associated with either decay type or its stage.

View full abstract

The response of tree sparrows, Passer montanus, to the distress call of its own species (DC) was compared with their response to the sound produced by a paper flag (FS) and their response to another noise (NS) in both laboratory and field settings. When these sounds were presented to young sparrows in a cage in the laboratory, FS evoked higher active movement than DC did, and NS produced the lowest movement. Repeated presentations of the same sounds and the order in which each sound was presented had no effects on the sparrow movement. When FS was played repeatedly at a longer interval, the intensity of response of birds decreased. When DC and FS were played back to the flock of sparrows assembling at a feeder, almost all individuals flew away, but the number remaining without flying increased gradually as trials progressed. The mean number of sparrows present 3 min after a playback was smaller for FS than for DC. The habituation rate in the former was also slower than in the latter. These results show that FS, which has a non-biological origin, induces a stronger aversive response by tree sparrows than their own natural distress call.

View full abstract

Thermotolerance of the silkworm, Bombyx mori L., varied with strains when reared at 28°C and 34°C, 70-85% RH for 12 h. The thermotolerance was positively relative to the activity of a hear-stable esterase (Hs EST) analyzed in larval body or midgut. This enzyme activity could be adopted as an indicator for the silkworm thermotolerance. Zymograms showed that an E5 band in midgut preparations is predominant and is thus related to thermotolerance. The activity of Hs EST, especially E5, increased with hear selection for 7 generations, indicating that this enzyme seems to be induced by rearing the silkworms under high temperatures.

View full abstract

A trehalase inhibitor, validoxylamine A (VAA), gave a lethal effect in Bombyx mori larvae. Overall activities were reduced soon after injection of VAA at the 2nd day of the last instar larva. However, the lethal effect was found at the later stages. NMR analysis showed that trehalose was the main blood sugar and its level was strongly enhanced by the VAA injection. It was supposed that utilization of the energy source was prevented due to the trehalase inhibition, and consequently the overall activities were reduced. But, how the trehalase inhibition caused the lethal effect in the later stages remained unclear.

View full abstract