It is known that an acarid mite, Tyrophagus similis Volgin, feeds on algae and grows on the soil surface in spinach greenhouses. However, no study was conducted on the effect of plowing algae before seeding to promote the mite population in the soil. We carried out observations of mite increase and spinach damage under different algae managements in 2015, both in the laboratory and greenhouses at Yamaguchi Pref., Western Japan. Propagation and plowing of algae before seeding promoted mite numbers and spinach damage in the greenhouse. This result was also supported by a supplementary laboratory experiment. In the laboratory experiment, the population of mites increased around 4 times when algae were introduced into the soil. Furthermore, additional observations demonstrated that high growth and coverage of algae on the soil surface before seeding resulted in a high population level of mites（3.5 times）in the greenhouse experiment. Our findings suggest that algae management of the greenhouse soil is an important practice for mite control in spinach production.
Nesidiocoris tenuis（Reuter）has good potential as a biological control agent for Bemisia tabaci（Gennadius）on tomato. There is a possibility that this predator also controls Tomato yellow leaf curl virus（TYLCV）transmission by B. tabaci. In this study, four treatments were compared:（1）50 N. tenuis/plant×3 times released（150 NR）,（2）25 N. tenuis/plant×2 times released（50 NR）,（3）5 N. tenuis/plant×2 times released（10 NR）, and（4）insecticide treated as a conventional control, to evaluate the inhibitory effect of the predator on TYLCV in greenhouse tomato. The infection rate for TYLCV was significantly lower in 150 NR than 10 NR during the experiment. Additionally, the B. tabaci density was significantly lower in 150 NR and 50 NR than 10 NR. These results suggest that TYLCV transmission by B. tabaci was inhibited by N. tenuis. However, it is difficult to control TYLCV only by N. tenuis or insecticides, because the infection rates for TYLCV and rates of viruliferous B. tabaci of TYLCV were 89～100% and 70～80%, respectively, at the end of all treatments. Therefore, N. tenuis is recommended for use as a biological control agent in integrated pest management for TYLCV.
Suitability of four commercial crops, sweet pepper, eggplant, kidney bean, and snap pea, against the predatory mite Amblyseius swirskii Athias-Henriot were evaluated from its establishment and population growth on each crop at 24°C, suitability of their pollens as a food source, and effect of the phylloplane microscopic structure（presence and morphology of hairy tissue（trichomes and pubescence）and domatia）. The number of mites after release per plant significantly differed among the crops, the density on sweet pepper was the highest, followed by kidney bean, eggplant, and snap pea. Based on the suitability of pollen for mites’ oviposition rates, oviposition sites, and consumption against Thrips palmi Karny on each leaf disc, the causes of less population growth on kidney bean, eggplant, and snap pea in comparison to sweet pepper were considered to be as follows.（1）Kidney bean: lower suitability of pollen as food and unstable provision of pollen caused by flower’s fluctuation on the plant.（2）Eggplant: lower suitability of pollen and the obstruction on mite’s predation or oviposition behavior by sharp trichomes on phylloplane.（3）Snap pea: lack of phylloplane microscopic structure for oviposition sites and the obstruction on mite’s predation or oviposition behavior by epicuticular wax on phylloplane.
Phacelia tanacetifolia Bentham is known worldwide as a kind of insectary plant and is used in Japan as a green manure crop before Welsh onion planting. To explore the possibility of using P. tanacetifolia as a banker plant or an insectary plant for parasitoids of Liriomyza chinensis Kato, we investigated the seasonal abundance of agromyzid leafminers and their hymenopterous parasitoids on infested leaves and blooming flowers of P. tanacetifolia collected in Chiba Pref., Japan, in 2009, 2010, and 2012. We also investigated longevity increase in Diglyphus isaea（Walker）adults with a blooming P. tanacetifolia plant in the laboratory. Almost all agromyzid leafminers reared from leaves were Chromatomyia horticola（Goureau）. Twenty-one parasitoid species including seven species reported from L. chinensis mines by different authors in Japan were reared from leaves, and nine species including eight species reared from leaves were caught on flowers. The most abundant parasitoid species was D. isaea. In this study, Diglyphus crassinervis Erdös was reared from C. horticola for the first time in Japan. The longevity of D. isaea adults provided with a blooming plant and water was about 18 days at 24°C with a 16L : 8D photoperiod. The log-rank test, used to compare survival curves from the 2 treatments; with and without blooming P. tanacetifolia plant, showed a statistically significant difference between treatments. These results suggest that P. tanacetifolia has potential as a banker plant or insectary plant for parasitoids to control L. chinensis in Welsh onion fields.
To clarify the flight activity of Eysarcoris aeneus（Scopoli）, we used a simple method that involved counting the number of adults flying out of a cup. We confirmed that the flight activity was spontaneous. On examining the effects of sex and experimental conditions on the flight activity of adult bugs, no significant difference in the numbers of male and female adults flying out of a cup were noted. The number of adults flying out of a cup under outdoor conditions was significantly greater than that of adults spontaneously flying out of a cup under indoor conditions. Compared with indoor conditions, outdoor conditions triggered a 2.6-fold increase in the flying activity. The individual rate of flying under outdoor conditions ranged between 7% and 73%, and the peaks in the flying activity were observed between mid-May and late May, in late July, and in early September. We also investigated the rice field invasion method of E. aeneus adults using wave-type levee sheets. We found the number of adults invading by walking and flying to be 3.3-fold greater than that of invading by flying alone. Therefore, the invasion method of adult bugs in rice fields is estimated to be primarily via walking.
We investigated the seasonal occurrence of the stink bug, Glaucias subpunctatus Walker, using light traps in Kinokawa（34°28′N, 135°41′E）and Minabe（33°82′N, 135°34′E）, Wakayama Prefecture, Japan, in April–October, 2014–2016. We also examined the ovarial development of females. Glaucias subpunctatus females retained developed ovaries from July to early September, and the number of adults caught decreased during this period. Additionally, we caught new-generation G. subpunctatus adults only in the beginning of early August. These results suggest that G. subpunctatus is univoltine in this region.
An assessment method wherein an aphid colony-infected leaf disk was dipped in an insecticide for 10 s and placed in a plastic zipper bag was developed to easily estimate the number of surviving aphids. This number after 48 h could be estimated by counting the number of honeydew droplets produced by aphids in the bags after 24 h. Although this survey method cannot accurately calculate the mortality rate, it is easy and inexpensive. Therefore, this method is considered to be useful as a simple method for estimating the number of surviving aphids and as a method for easily determining insecticides with reduced effects.