1. When active prothoracic glands or brains are implanted into diapausing Chilo larvae, extramoulting followed by prothetely occurs immediately after operation. But, in case of brain implantation, development towards pupation in some larvae, which have not initiated prothetelic moulting, is somewhat accelerated as compared with that of non-operated controls.
2. Active prothoracic gland from Barathra prepupa is able to cause the immediate termination of diapause in decapitated Chilo larva as well as its isolated abdomen.
3. Brain obtained from Chilo larva at critical period can also induce abrupt termination of decapitated, diapausing Chilo larva.
4. If diapausing Chilo larva is decapitated so as to remove corpora cardiaca and allata but leaving the brain intact, the termination of diapause occasionally occurs.
5. It is suggested that there is a hormone centre in the head of diapausing Chilo larva, which is inhibitory in action on the development of larva. This centre is considered to be corpus allatum itself.
6. There is a possibility that the inactive brain can be abruptly changed to active one in the medium where the inhibitory principle likely from corpora allata is lacking.

View full abstract

High skilfulness has so far been required to record the heartbeat of insect. The new method devised by the present authors made it much easier to record the heartbeat of an intact insect.
This method was based in principle on photoelectric effect: a constant beam of light was thrown on the heart of the dorsal vassel which was seen through the middorsal cuticle. The apparatus for this method consisted of a photocell, an amplifier and a pen-writing oscillograph. The changes in a reflected light associated with heartbeat were converted to changes of potential difference by means of the photocell, and were recorded as mechanocardiogram.
The action potentials associated with heartbeat could easily be recorded from an intact insect. The apparatus consisted of one pair of electrodes, an amplifier and a pen-writting oscillograph.
The action potentials were either led off from the cuticular surface of ether-anaesthetized larva by means of one pair of forceps-type electrodes or led off from the inside of ether-anaesthetized larva by means of one pair of needle-type electrodes, and were fed to the amplifier. Thus the action potentials were recorded as electrocardiogram.
Observations on the heartbeat by these two methods were made with both the last instar larvae of grubs, Xylotrupes dichotomus L., and those of the silkworm, Bombyx mori L. The mechanocardiograms or the electrocardiograms observed with these insects were compared with those reported by other investigators.
1. The shape of waves in the mechancoardiogram from the silkworm was similar to that of the cockroach, Periplaneta americana L., studied by YEAGER (1938). Each phase in a mechanocardiogram described by YEAGER could be observed with the silkworm, i.e., i) an ascending limb associated with systole, ii) a descending limb representing diastole and iii) a slight period of diastasis. A presystolic notch appeared immediately before the beginning of the next cycle.
2. In the mechanocardiogram from Xylotrupes there appeared two notches immediately before the beginning of the period of systole and of diastasis. But these notches were lacking in the electrocardiogram and the shape of its wave differed greatly from those reported by many other investigators.
3. The highest action potential associated with heartbeat was recorded by means of the needle-type electrodes from the region where the alary muscles were located.
4. The magnitude of the action potential associated with the heartbeat of larva anaesthetized by ether was 9-15μV when it was recorded from the surface of the body, and of the order of 150μV when it was recorded from inside of the body.
5. Simultaneous recordings were made from two distant points of the dorsal vessel. It was classified from these records that each peristaltic wave originated from the posterior end of the dorsal vessel and moved toward the anterior part.
6. These methods of recording the mechanocadiogram and the electrocardiogram are considered to be available for studying the effects of insecticides, electricity and other treatments on the heartbeat of insect.

View full abstract

Differences in several morphological and physiological characters between two wing-forms of the brown planthopper Nilaparvata lugens STÅL, the white-back planthopper Sogata furcifera HORVÁTH and the small brown planthopper Delphacodes striatella FALLÉN were studied.
1. The macropterous form has normal forewings and hindwings, and the brachypterous form has short and incomplete forewings and rudimental hindwings. Similar differences are found in scutellum, the brachypterous form being smaller in length and width of it than the macropterous form.
2. In length of femur and tibia of hind leg, on the other hand, a reverse relation is observed between the two wing-forms. Body weight at emergence and during ovipositional period of the brachypterous form exceed in some degree those of the macropterous form. It is supposed from the facts mentioned above that the flying organs of the macropterous form are superior to those of the brachypterous form, but that it is inferior in general body size.
3. Number of eggs deposited shows a wide variation, some being over a thousand, and little difference between wing-forms is observed, though the brachypterous form shows a little higher fecundity in the white-back planthopper. Reproductive rate is clearly correlated with adult longevity in both wing-forms.
4. Pre-ovipositional period is shown to differ from each other in two wing-forms, the macropterous form having a longer pre-ovipositional period than the brachypterous form. It is shown in the brown planthopper that the pre-ovipositional period is considerably lengthened by low temperature after emergence in the macropterous form, while the period is shorter in the brachypterous form.
5. The macropterous form has a longer adult longevity without any food excepting water than the brachypterous form, in both sexes.
6. By daily weighing of body after emergence until the 14th or 15th day, it is found that a rapid increase of body weight occurs from the next day of emergence in the brachypterous form, and after attaining to 1.7 times the weight at emergence oviposition begins. In the macropterous form the initial increase of body weight shows a little lag, and therefore, oviposition begins later. This lag is supposed to be responsible for the clear elongation of pre-ovipositional period of the macropterous female under low temperature. During ovipositional period body weight fluctuates within a range of 20 to 30 per cent of the average weight. No fluctuation of the body weight was found in the male, continuing to show a constant value from emergence.
7. The macropterous-barchypterous form relation is considered as the adult-juvenile relation, and the adaptive significance of each form to the life of the planthoppers was discussed.

View full abstract

In this paper I gave some notes on three chalcidoid parasites reared from various species of diaspidine scales in Japan.
1. Records of their hosts are summarized as follows:
1) Arrhenophagus chionaspidis AURIVILLIUS (Encyrtidae: Arrhenophaginae) Aulacaspis yabunikkei KUWANA (new host record)………Cape of Ashizuri, Shikoku. Phenacaspis cockerelli COOLEY (=P. aucubae COOLEY=P. dilatita GREEN=P. eugeniae MASKELL)………Cape of Ashizuri, Shikoku. Pinnaspis aspidistrae SIGNORET………Shizuoka Pref., Honshu (After Shizuoka Agr. Exp. Sta; ISHII). Host unknown………Atami, Honshu. (After HOWARD).
2) Aspidiotiphagus citrinus CRAW (Aphelinidae) Aonidiella aurantii MASKELL………Kagoshima Prefecture, Kyushu (After SAKAI). Aspidiotus destructor SIGNORET………Matsuyama, Shikoku. A. cryptomeriae KUWANA (new host record)………Sakurasanri, Ehime Prefecture, Shikoku. Pinnaspis aspidistrae SIGNORET (=P. ophiopogonis TAKAHASHI)………Oita, Kyushu; Matsuyama, Shikoku. Host unknown………Yokohama, Honshu (After HOWARD).
3) Azotus capensis HOWARD (Aphelinidae) Aulacaspis difficilus COCKERELL (new host record)………Matsuyama, Shikoku. Pseudaonidia duplex COCKERELL (new host record)………Matsuyama, Shikoku. Pseudaulacaspis pentagona TARGIONI………Tokyo, Honshu (After KUWANA; NAKAYAMA).
2. The male of Arrhenophagus chionaspidis AURIVILLIUS was described from a unique specimen from Macao, South China, by Howard in 1898. It is remarkable that I had the good chance to rear the second male of the same species from Phenacaspis cockerelli COOLEY which was collected at the Cape of Ashizuri, Shikoku. After careful examinatian of this specimen which was mountedin balsam, I could find the noteworthy fact that the male antenna consists of 9-joints, and contrary to the original description of Howard (1898) the funicle is apparently 6-jointed and the club is solid (fig. 2: B), as is the case of many Encyrtid males. Therefore, I can assume that the male specimen examined by Howard (loc. cit.) might have been a malformed individual.

View full abstract

1. The resistant varieties are characterized by the occurence of larval death during the first two instars.
2. The newly hatched maggots can bore into the leaf sheath of even the resistant varieties.
3. The percentage of injured ears should not be adopted as a method of measuring resistance.
4. The value of the resistance is best indicated by measuring larval mortality in the seedlings growing in the nursely bed.

View full abstract

In this account a record is given of the food-habits of 12 species of aphidophagous Syrphidae commonly found in crop fields in Nagasaki. Food lists of Ischiodon scutellaris FABR., Paragus quadrifasciatus MEIG., P. tibialis FALLÉN, Sphaerophoria cylindrica SAY, Sph, javana WIED., Syrphus torvus O.S. and Epistrophe aino MATS., with notes of their attacking dates of plant-lice, are given. Those of Syrphus ribesii L., S. serarius WIED., S. bilineatus MATS., Metasyrphus corollae FABR., and Epistrophe balteatus DE GEER were previously published by the writer in 1956. The plant-lice attacked by the 12 syrphids amount to 40 species, which belong to 20 genera, Aphis, Macrosiphum, Amphorophora, Capitophorus, Myzus, Rhopalosiphum, Hyalopterus, Macrosiphoniella, Brevicoryne, Phorodon, Pseudocerosipha, Megoura, Acyrthosiphum, Glyphina, Neophillaphis, Periphyllus, Prociphilus, Eulachnus, Lachnus, and Oregma, about 83 per cent of which belong to the tribe Aphidini of the Aphididae, being parasitic on 65 species of plants including common crops. Among these syrphids, Epistrophe balteatus may rank first in attacking as many as 37 species of plant-lice, while Syrphus torvus and Epistrophe aino may be the lowest ranking on the list, devouring merely 4 species of aphids respectively. The nonconcentricity of aphidophagous capacity is also discussed. With regard to to the aphidophagous capacity of syrphids, single aphidophagous capacity may be distinguished from complex aphidophagous capacity, the former consisting of any single species of syrphids and the latter being composed of more than two species of them. Because of their simultaneous employment of single aphidophagous capacity in the destruction of the same or different plant-lice on different kinds of plants, the aphidophagous capacity of syrphids can not be exclusively concentrated on the destruction of a spefcific plant-lice on a specific crop during the same season. Complex aphidophagous capacity, in the same way, can not be exclusively concentrated upon the control of a specific aphid on a specific plant. In other words, during the same season, any single or complex aphidophagous capacity employed in the destruction of a specific aphid on a specific crop may simultaneously be dispersed toward the same or different aphids on different plants.

View full abstract

In the previous paper, the vertical stratification of the insect community in an apple orchard has already been mentioned by the author (HUKUSIMA, 1956b). But a question has been raised here as to whether the numerical distribution of various insects and mites in orchard trees is horizontally all on the same level or not. In this paper, an account of the investigation carried out in an adult apple tree to compare the structures of community with each other as observed from a point of horizontal stratum is reported.
This apple orchard consisted of about 180 trees extending in the north-south direction. A single tree of Jonathan apple, planted in the central part of the west side of this orchard was selected as a subject. The survey tree has been free from treatment of any kind of insecticides during these three years. Insects were sampled quantitatively by hand and net sweepings of 100 times at an interval of a week within 1 square meter area and at the height of 1.5 meter above the ground. Mite counts were taken from 100 mature leaves collected at random in each stratum. In this case, the survey area was divided into five strata; viz., east, west, center, south and north respectively.
During the course of this survey, as was already seen in Table 1, although a total of 7, 214 individuals belonging to 17 different species were found, it will be noted that the numerical superiority was shown by the significant number of arthropods in the south stratum, and following to this stratum, west, north, east and center strata were recognized in this order. But the specific number did not always coincide closely with the above tendency.
From May through late October, so far as the seasonal changes of community in total direction are concerned, three noticeable peaks were obtained as in Fig. 1. In this case, the most similar fluctuation trends were observed in strata of the south and west. So, this leads to the suggestion that insect and mite abundance in apple tree maintains a high degree in existence by the help of the population on these strata.
The effects of temperature, relative humidity, intensity of illumination and solar radiation in certain areas of each stratum of the tree on the seasonal abundance of populations were analyzed. It is clear from Figure 3, that in comparison with the other strata, the east stratum is usually accompanied by a high temperature, a low humidity, a high intensity of light and a high solar radiant heat. When the population fluctuation graph conferred to the meteorological factors, it is obvious that there is no significant correlation between these two items. As to the apearance of population peak, it seems that it has a relation between the continuation of intermediate temperature at about 25°C rather than between the highest one. The central stratum is poorest in number. As a reason, here, it is perceived that the orchard community in general tends to have, a relatively dark, cool, moist climate because it is the internal stratum and therefore it is protected from the full force of wind.
Turning our attention from the interplay between climate and community to the seasonal prevalence of the community organization, it is recognized that in some extent, the numerical transition to the south direction is done among two species of the smaller green leafhopper (Chlorita flavescence FABRICIUS) and Lyonetia prunifoliella HÜBNER as the season advances. And also four species, the woolly apple aphid (Erisoma lanigera HAUSMANN) and Aphelinus mali HALDMAN, the apple leaf-curling aphid (Myzus malisuctus MATSUMURA) and Chrysopa septempunctata WESMAEL, show somewhat similar seasonal population growth and decline alternatively. All of these are shown graphically in Figure 2.
Finally, so far as the present survey is concerned, based mainly on the quantitative and qualitative analysis

View full abstract

Nous avons mésuré l'activité de la cytochrome oxidase chez Chilo suppressalis, au cours de la diapause et la nymphose, en utilisant la méthode spéctrophotométrique. Dans ce cas, le degré de dilution de la préparation était 1:1, 000 par gramme de poids corporel.
La courbe de l'activité de la cytochrome oxidase se montrait en forme de la lettre “U”, c'est-à-dire au cours du dernier intermue larvaire, l'activité en était grande; puis elle commence à diminuer pendant les premiers jours de la nymphose; enfin elle s'augmente de nouveau à mesure que la chrysalide s'approche de son papillonage.

View full abstract

It was found that the larval development of the cabbage armyworm, Barathra brassicae L., is accelerated when it is reared under crowded conditions (Hirata, 1956).
In this paper, the writer has analyzed some regulating mechanisms of the larval development comparing two population densities of 1 and 5 individuals per vessel which were kept in darkness under the controlled condition of temperature at 25°C. The results obtained are summarized as follows.
1. The larvae of crowded population complete their larval stage in 90 per cent of the length of time of that of the isolated population.
2. The accerelation rate of larval development in crowded population was higher in the feeding stages than in the moulting stages.
3. The frequency curves of the time of the beginning and end of the moulting stage were unimodal ones in young larval stages, but, with the growth of larvae, they became multimodal ones. This modality in the frequency curve was mainly the result of the daily rhythm of the beginning and end of the moulting. In the crowded population, the increasing trend of modality was not so conspicuous as the isolated population because it has a shorter duration of beginning and end of moulting as compared with the isolated population.

View full abstract

The almond moth, Ephestia cautella WALKER, is a serious pest of various stored grains and other foods. The effects of reduced air pressure and number of days of treatment on hatching at the temperature of 25°C were studied in the present paper.
20 eggs and 0.25g of milk cocoa were put in each test-tube totaling up to 99 test-tubes. They were divided into three groups of 190, 380 and 760mm-Hg pressures.
Three test-tubes were taken out of each group after 1, 2, 3, 5, 7, 9, 11, 14, 17, 20 and 23 days respectively, bringing them back to the normal pressure, and their number of the eggs hatched was determined and continued to be counted until the number of hatch stopped to increase.
The results of the experiment were as follows:
While a significant difference of haching rate was shown between the samples treated under 380mm-Hg and 760mm-Hg, no significant difference on the hatching rate and the increasing rate of hatching was observed in the length of treatment and days elapsed at the pressure of 380mm-Hg.
Under the reduced pressure of 190mm-Hg, the hatching rate of the sample showed a significant difference compared with the hatching rate of the other two groups. The length of days treated under the 190mm-Hg pressure showed a significant difference of the hatching rate to each other. At this presssure, the ones kept more than five days showed 100 per cent negative in the hatching rate.

View full abstract