The stored rhizomes of ginger, Zingiber Mioga ROSCOE, are attacked by the larvae of two sciarid pests, Psilosciara flammulinae SASAKAWA (1983) and Phytosciara zingiberis SASAKAWA, n. sp. in Nagasaki Prefecture, Kyushu. The latter new pest has become especially troublesome in many storages year by year. About 16 per cent of total rhizomes stored was infested during the period from November to May, 1982-1983. The damage in the storage seemed to be caused by the rhizomes which were laid the eggs by the females or mined the larvae before or at the harvest in the field. At the end of storage period the damaged rhizomes became sponge-like with remains of fibre. During the storage period it seemed to be able to pass through two to three generations (thermal constant throughout the immature stage was 270.2 day-degrees).

View full abstract

The critical photoperiod for the induction of diapause in the 3rd generation of the apple leaf miner was about 14hr in the Asahikawa (43°40′N), (about 13.5hr in the Morioka (39°42′N)), about 13hr in the Suzaka (36°40′N) and the Nîmi (34°59′N: 400m height), about 12.5hr in the Hamamatsu (34°34′N) and the Amagi (33°26′N) populations at 20°C. It was indicated that the critical photoperiod is generally longer in the northern than in the southern population, and varied at a rate of approximately 30min per 3.5 degrees of the latitude. The critical photoperiod was also variable with the altitude. From these results, the day on which the photoperiod reached to the critical point in each location was estimated as August 27 in Asahikawa, September 14 in Suzaka, September 20 in Hamamatsu, September 13 in Nîmi, and September 27 in Amagi, respectively. In the Suzaka population oviposited from August 20 to 30, 96.4% of larvae which attained the tissue feeding stage before the critical photoperiod (September 15 at Morioka) became non-diapaused pupae, while 70.6% of the sap feeder became diapaused pupae. From the critical photoperiod and monthly mean temperature, it was calculated that this leaf miner has 3 generations in Asahikawa, and 6 or more generations in Amagi in a year.

View full abstract

Three species of aphidophagous coccinellids, Coccinella septempunctata brucki, Propylea japonica and Scymnus (Neopullus) hoffmanni were studied on their fecundity in laboratory condition (25°C, 14L-10D). The values of the net reproduction (R₀), the mean length of one generation (T) and the intrinsic rate of natural increase (r) were calculated as 575.4, 43.8 and 0.145 for C. septempunctata, 179.8, 27.8 and 0.187 for P. japonica, and 126.9, 20.5 and 0.236 for S. hoffmanni, respectively. The oviposition was continued for 66 days and 1, 660 eggs were laid in C. septempunctata, 77 days and 1, 481 eggs in P. japonica, and 49 days and 110 eggs in S. hoffmanni, respectively. It is interesting to note that the females of S. hoffmanni showed protecting behavior of their eggs, covering them with exuviae of their prey aphids. The hatchability was 40-60% for C. septempunctata and P. japonica and 60% for S. hoffmanni.

View full abstract

The predatory characteristics of Microvelia reticulata BURMEISTER and its seasonal changes in the population density were investigated in paddy fields in Yamagata Prefecture. The first multiplication took place in early summer in peripheral areas along dikes of a paddy field. After late June, M. reticulata was increased in number up to August throughout the water surface in a paddy field. M. reticulata is likely to have more than three generations a year and hibernates at adult stage in peripheral areas near dikes. The functional response of M. reticulata showed that the rate of predation decreases with the increase of prey density. M. reticulata caught almost all small arthropods dropped on the water surface but preferred midges and aphids to others because they were easy to catch.

View full abstract

Two kinds of traps baited with cue-lure and naled, and with sliced pumpkin and naled respectively, were distributed in different habitats of the melon fly, Dacus cucurbitae, to investigate its diurnal pattern of attraction. When both kinds of traps were distributed in a bitter gourd field, the intermediate site, which was the transition area of vegetation from bitter gourd field to forest, and forest, attraction to cue-lure traps was observed in each of those sites. Many flies were attracted to pumpkin traps within the bitter gourd field and intermediate site, but only a few were attracted to the forest site. The total number of males caught in cue-lure traps was lower than that in pumpkin traps. Attraction to cue-lure traps was observed in the morning, whereas the attraction to pumpkin traps took place throughout the day time. The number of captured male flies in the pumpkin traps was higher than that in the cue-lure traps, and furthermore, a similar number of female flies was captured in the pumpkin traps. Most of these female flies were immature. Attraction of mature female flies occurred later in the day than that of the immatured ones, i.e., the number of captured mature flies increased in the afternoon or early evening. Percentage of female flies captured in pumpkin traps was higher in the bitter gourd field and intermediate site than in the forest. These results suggest that the number of flies caught in cue-lure traps varied temporally during the day time but did not vary with the trap sites. In contrast, the number of flies caught in the pumpkin traps did not vary temporally, but varied with the trap sites.

View full abstract

The effectiveness of maternal care in the bug Elasmucha putoni feeding on wild mulberry was studied by individual marking of females and their egg masses in the suburbs of Kanazawa from early June to middle July in 1981. When disturbed, females standing over the eggs and young larvae showed a characteristic guarding behaviour. Of 57 guarding females, 6 (10.5%) deserted their eggs before hatching, 6 disappeared while the larvae were in the first instar and 45 (78.9%) still guarded the second instar larvae. Loss rate from egg to second instar was 25.3% when egg masses were guarded by the females until the 2nd instar, while the rate was 74.3% when the females were removed from the egg masses. The increased loss rate in the unguarded egg masses was due to the increase of egg predation and dispersal of first instar larvae. The ant, Lasius niger, was frequently seen attacking the egg masses, but no parasitization of eggs occurred. The eggs and larvae were lost in an “all or none” manner in the unguarded groups, while a small number of individuals were lost randomly in the guarded groups.

View full abstract

Spatial distribution pattern of the rice leaf roller, Cnaphalocrocis medinalis, in an experimental paddy field was analyzed using the regressive relation of mean crowding (*m) to mean density (m) (IWAO, 1968) to develop sampling techniques of the species. In young instar larvae the values of the slope (β) of the regressions were slightly larger than 1, indicating a weak tendency to aggregation in the dispersion pattern. This tendency decreased as the larval instar advanced. The slopes reached the value of 1 and the intersections (α) of the regressions were near 0 in the final instar larvae and the pupae. These values of the parameters indicated that each individual was distributed randomly. Although the parameters in the *m-m relation in the moths suggest random dispersion, they were unevenly distributed in the experimental paddy field, i.e., about twice as many as moths were observed in one side of the field as compared with those observed in the other side. Applications of the regressions for the sample size necessary to estimate the mean density for a certain confidence probability and the sampling techniques including sequential sampling were discussed using the distribution data obtained.

View full abstract

The experiments were performed in order to define whether the heated-cells of Bacillus thuringiensis subsp. thuringiensis would activate the alternative pathway of complement system in human serum. The heated-cells of Bacillus thuringiensis subsp. thuringiensis were added to human serum, and the mixtures were incubated at 37°C for 30min. The hemolytic activities (CH50) of complement in this serum were titrated using sheep red blood cells. Then, the activities (SFU) of both C3 and C4 complement components in this serum were also titrated using intermediate cells. These cells were found to decrease in >86.4% of the titers of CH50 of complement in human serum. They also consumed 86.3% of the titers of SFU of C3 complement component in human serum. However, the consumption of C4 complement component was found to be only 22.8%. On the immunoelectrophoresis, conversion of C3 complement component from β1C to β1A region was observed in the serum treated with the heated-cells of Bacillus thuringiensis subsp. thuringiensis. Factor B component, which activates C3 complement component in this serum, was also converted from B to Ba and Bb. The results of these experiments strongly show that the heated-cells of Bacillus thuringiensis subsp. thuringiensis are able to activate complement system in human serum, mainly via the alternative pathway.

View full abstract

Radiosensitivity between phosphine (PH₃)-resistant and -susceptible strains of the red flour beetle, Tribolium castaneum, to γ-ray was studied in the various stages of adults, pupae, larvae and eggs. Adults of the susceptible strain were completely killed by 150 Gy while 200 Gy was needed for those of the resistant strain. Radiotolerance also appeared in both stages of pupa and larva of PH₃-resistant strain to some extent while eggs were quite similar in their radiosensitivity in both strains. Sterility of the beetles irradiated at adult stage were not different significantly in both strains except the irradiated female where the fertility of the resistant strain was in some cases much higher than that of the susceptible one.

View full abstract

The three molters were induced highly from the four molter silkworm larvae administrated fungicide (imidazol group, 1-[N-(4-chloro-2-trifluoromethylphenyl)-propoxyacetimidoyl]-imidazole). Therefore, its administrating intervals and ratio of inducing three molters were investigated.

View full abstract

Pseudaletia separata occurred in high-larval densities, 32-180 larvae/m² along the northwesterly part of the Japan Sea coastal areas during the mid-July in 1984 resulting in considerable losses to pasture and wheat. The percentage of parasitism on the larvae, collected from the wheat field at Oogata in Akita, by hymenopterous insects was low, 1.4%. But 42.5% of the larvae died from diseases except viruses. Moths captured in a molasses bait trap suggested that there were two waves of moth immigrations carried by cyclonic winds on June 10 and 17-18. Possible sources of the migratory populations were discussed.

View full abstract