To evaluate the role of sorghum as an insectary plant for predators attacking aphids, we investigated the seasonal occurrence of aphids on sorghums（Sorghum bicolor（L.）Moench）, ‘Kazetachi’（late flowering and a long culm, commercial cultivar）, ‘Koutoubun’（sweet sorghum, commercial cultivar）and ‘Akaamakibi’（sugar rich, local variety）in 2007, varying the planting date. The aphid incidence started much earlier on the first two planting dates（25 April and 1 May）and aphids were significantly more abundant on ‘Kazetachi’, having peak abundance in middle to late August. In 2008, we investigated the seasonal occurrence of aphids on two cultivars, ‘Kazetachi’ and ‘Koutoubun’, planted on 15 April. Again significantly more aphids were found on ‘Kazetachi’, peaking in late July to early August with a high density of 1,500 individuals per leaf. During the survey in 2007 and 2008, Melanaphis sacchari（Zehntner）was predominant on sorghum irrespective of the cultivar. Our findings suggested that sorghums provide sufficient aphids as prey to aphidophagous predators and ‘Kazetachi’ is more suitable to be regarded as an insectary plant.
The local density of natural enemies, which provide biological control, can be affected by the surrounding landscape and by local field management. We examined how landscape factors and non-selective insecticides influenced the abundance of predatory bugs of the genus Orius, which provide effective biological control on eggplant, from June to September 2013. We investigated the numbers of these bugs in 13 eggplant fields across four regions of Nara prefecture, Honshu, Japan. Areas of different land-use types around the fields were estimated from GIS data in circular buffer zones with radii ranging from 100 to 1,000 m（intervals of 100 m）. Using a generalized linear model and Akaike’s Information Criteria, we analyzed the effects of landscape element, landscape heterogeneity and use of non-selective insecticides on the abundance of Orius spp. Landscape elements within a 200-m radius affected abundance: the abundance of Orius spp. was higher in landscapes with a mixture of urban and agricultural areas than in landscapes dominated by forest. On the other hand, non-selective insecticides did not affect the abundance of Orius spp. This result suggests the importance of landscape factors in determining the local abundance of Orius spp.
The effects of ultraviolet-B radiation over three hours at night on the survival and development of four agricultural pests of thrips and their predator, Haplothrips brevitubus（Karny）, were investigated at 20°C under 14L10D conditions. UV-B radiation ≤8.7 µW/cm2 did not affect the hatchabilitiy of terebrantian eggs inserted into leaf tissue, but the four pest species of thrips showed lower percentages of adult emergence and delayed larval development at UV-B radiation ≥6.5 µW/cm2. No adults emerged for Thrips palmi Karny, Frankliniella occidentalis（Pergande）, and Thrips tabaci Lindeman reared under UV-B radiation ≥6.5 µW/cm2, while 10% of Frankliniella intonsa（Trybom）reared under UV-B radiation of 8.7 µW/cm2 eclosed into the adult stage. Pest thrips emerging into adults under UV-B dose conditions exhibited curl and shortening of the forewings, and over 38% of adults had abnormal forewings even under a low dose of UV-B radiation of 1.5 µW/cm2. UV-B radiation ≤3.0 µW/cm2 after adult emergence did not affect the longevity and fecundity of female adult thrips in the four pest species. UV-B radiation decreased egg hatchability and the percentage of survival in the larval stages for H. brevitubus, and no thrips emerged into adults under UV-B radiation ≥4.8 µW/cm2.
The effects of temperature and photoperiod on the development（oviposition to adult emergence）of Liriomyza chinensis Kato at five constant temperatures（15, 18, 20, 25, and 30°C）under a 15L9D photoperiod and at 18°C under a 10L14D photoperiod, and its reproductive potentials and adult longevity at three constant temperatures（20, 25, and 30°C）under a 15L9D photoperiod were examined on Welsh onion plants. The total developmental period of L. chinensis decreased from 68.3 days at 15°C to 19.4 days at 30°C with a 15L9D photoperiod. A significantly longer developmental period was found with a 10L14D than 15L9D photoperiod at 18°C. The developmental zeros for the total development was 9.1°C. The effective accumulative temperature was 393.6 day-degrees. The adult emergence rates were the highest at 20°C. The next generation adults were highest at 25°C（103.6/female）. Female adult longevities at 20, 25, and 30°C were 17.8, 12.9, and 6.5 days, respectively. The intrinsic rates of natural increase at 20, 25, and 30°C were 0.06, 0.10, and 0.09, respectively.
We investigated application of superheated steam treatment for controlling overwintering apple snail Pomacea canaliculata （Lamarck） in post-harvest paddy fields. Vertical distribution of the snails in the soil showed that the majority （49%–93%） inhabit surface soil or shallow underground soil above 2 cm depth. Using a mobile steam chamber machine that blows out superheated steam, we measured increase in soil temperatures and the subsequent mortalities of the snail that were experimentally placed at different soil depths. Snails on the soil surface were effectively killed by exposure to superheated steam. When the machine was run at a speed of 0.5 km/h, the-soil temperature attained a maximum 91.5°C which caused 100% mortality of P. canaliculata on the soil surface and 23% mortality of snails buried at 2 cm depth. In the farmers’ field trials, the superheated steam treatment conducted during winter successfully reduced snail density and rice damage by snails in early summer after rice planting. These results show the effectiveness of superheated steam treatment using a mobile steam chamber machine for controlling overwintering P. canaliculata.
Effects of temperatures（15, 19, 22, 25, and 28°C）on the development of eggs, larvae, and pupae of Diomea cremata（Butler）, a pest of sawdust-based cultivation of shiitake mushroom, Lentinula edodes, were investigated. Hatchability was higher than 80% at 19, 22, 25, and 28°C, but was 58% at 15°C. Pupation rate was 62% at 25°C and 54% at 22°C, but was lower than 40% at 15, 19, and 28°C. Emergence rate from pupae was higher than 80% at all temperatures examined. Development time from hatching to adult eclosion decreased with increasing temperature from 15°C to 25°C, but not from 25°C to 28°C. Lower thermal threshold and thermal constant from hatching to adult eclosion were calculated as 11.2°C and 429.0 degree-days in males, and 11.3°C and 418.6 degree-days in females, respectively. These thermal requirements indicated that D. cremata might complete two or three generations in cultivation facilities.