The stink bug, Cletus punctiger (Hemiptera: Coreidae), is widely distributed throughout Japan, and is considered a serious pest that feeds on rice ears, thereby leading to pecky rice. In 2019 and 2020, we studied egg parasitoid species of C. punctiger in a field of gramineous grasses, and examined the seasonal trends in parasitism. Four parasitoids, Gryon japonicum, Gryon marina, Gryon nigricorne (Hymenoptera: Scelionidae), and Ooencyrtus nezarae (Hymenoptera: Encyrtidae), emerged from C. punctiger eggs. The percentage parasitism attributed to these four parasitoids was less than 40% in both years of the study. Among the identified parasitoids, G. marina was predominant, whereas parasitism by the other three parasitoids was comparatively limited. It has been established that these parasitoids parasitize the eggs of several species of stink bugs; however, to the best of our knowledge, the present study is the first to identify G. marina, G. nigricorne, and O. nezarae as parasitoids of C. punctiger eggs.

In Shiga Prefecture, the critical photoperiod for inducing adult diapause in the stink bug, Cletus punctiger, is 13-14 hours. In September, the percentage of diapausing females that had no mature eggs in their ovarioles increased in the fields, and the diapausing females were assumed to migrate to hibernating sites as the temperature declined. In spring, the adults that were not in diapause were thought to leave the hibernating sites in early April, and begin laying eggs in late April.

I investigated the effects of a Beauveria bassiana spray, used at intervals of three times weekly, for pest control in a greenhouse growing eggplant and kidney bean. The control effects of Bemisia tabaci Q-biotype, Tetranychus kanzawai, Myzus persicae, and powdery mildew on eggplant were assessed. Meanwhile, the insecticidal effects of B. tabaci Q-biotype, T. urticae, and T. kanzawai were assessed on the kidney beans. The direct effects of spraying the B. bassiana formulation on parasitoid wasp mummies of B. tabaci and predatory mites of Tetranychus spp. were not found in the kidney bean.

The seasonal prevalence of the tortoise beetle, Laccoptera nepalensis Boheman, recently introduced to the Kinki region in Japan, was investigated in southern Osaka Prefecture. This was done once a month from May to December 2021. The numbers of larvae, pupae, and adults were recorded at four sites on morning glory vines, Ipomoea spp., and three sites on sweet potato, Ipomoea batatas. Adults were found on the morning glory vines in all months investigated. Adult density decreased in June and gradually increased in summer and autumn. Larvae were found after June at all sites and the densities were relatively high in June, September, and October. At the sweet potato sites, adults were first recorded in July, August, and September, depending on the site, and densities were relatively high in September and October. The larvae were observed between August and November. A rearing experiment was conducted on the southern Osaka population under various temperature conditions. The mean periods between oviposition and adult emergence were approximately 54 and 31 days at 20 and 25°C, respectively. The developmental threshold (t₀) and thermal constant (K) for the entire immature stage were 10.8°C and 637 day-degrees, respectively. The number of possible generations estimated from the effective accumulative temperature and temperature was calculated to be up to three in the southern Osaka population.

Some viruses, including the peanut stunt virus (PSV), have been reported to cause mottling of the soybean seed coat. In addition, the seed coat pigmentation phenomenon in yellow soybean has been reported to occur via spontaneous mutation of the I gene, which inhibits seed coat pigmentation by environmental factors such as chilling temperature. The pigmented seeds frequently show multiple defective cracks in the seed coat. Senda et al. (2017) suggested that lignin deposition might affect the physical properties of buff seed coats and lead to defective cracking. In this study, the incidence of seed coat mottling depended on PSV infection, as previously reported, and lignin accumulation in the mottled parts of the seed coat was assessed using phloroglucinol-HCl reagent for histological analysis. PSV was detected in the mottled parts of the immature seed coat. The infectious PSV was also present when the soybeans (Enrei) were inoculated with sap from the mottled parts of the immature seed coat. These results suggest that PSV infection is closely related to the mottling and cracking of the soybean seed coat.

The species composition of rice stink bugs in Shizuoka Prefecture, Central Japan, was investigated. In the eastern region of Shizuoka Prefecture, the number of rice stink bugs and the proportion of Stenotus rubrovittatus were low. In contrast, in the western region of Shizuoka Prefecture, the number of rice stink bugs and the proportion of S. rubrovittatus were high. There was a weak positive correlation between the percentage of Lolium multiflorum that emerged around the field, and the number of S. rubrovittatus captured in the rice paddy levees and the surrounding weeds. Additionally, the proportion of Lagynotomus elongatus has increased in the western region of Shizuoka Prefecture since 2018. The effects of four insecticides (MEP [fenitrothion], ethiprole, etofenprox, and dinotefuran) on adult S. rubrovittatus individuals were investigated. The results showed that all insecticides, especially MEP and etofenprox, were effective.

In 2016, 2017, and 2021, the early detection and excision of overwintering twigs with spring cankers (caused by Xanthomonas arboricola pv. pruni) were performed to understand the growth of peach twigs prior to disease outbreak. A survey was conducted at the peach cultivation field, Hikawa Hakuho, in Nagakute City, Aichi Prefecture. Twigs with spring cankers tended to have a lower leaf germination rate and shorter average leaf length than those without spring cankers. In 2017 and 2018, early resection of the spring canker was performed in fields where chemical control against peach shot hole disease from the germination stage to the end of harvest had not been practiced. In the plots where early elimination was practiced, the incidence of diseased leaves tended to decrease in 2017 and 2018 compared to the plots where early elimination was not practiced. When the peach twigs that were perforated bacterial disease were isolated from the early eliminated and healthy twigs using a medium, the detection rate of the early eliminated twigs was higher than that of the healthy twigs.

For 3 years we investigated the insects captured by laying synthetic sex pheromone traps set to lure the white peach scale, Pseudaulacaspis pentagona (Targioni Tozetti), in the tea fields of Shizuoka Prefecture, Japan. Adult males of P. pentagona, and natural parasitoids and predators of these scale insects, such as Arrhenophagus albitibiae Girault; Pteroptrix orientalis (Silvestri); Thomsonisca amathus Walker; and Cecidomyiidae, including Dentifibula sp., were captured in traps. The ratio of the captured insects in the pheromone traps to blank traps ranged from 4.4–6.0 for P. pentagona, 323–685 for T. amathus, 0.8–1.5 for A. albitibiae, 0.9–1.5 for P. orientalis, and 0.8–1.2 for Cecidomyiidae. Statistical analysis revealed that the sex pheromone traps for P. pentagona significantly attracted only scale insects and the parasitoid, T. amathus. The pheromone appeared to act as a kairomone against the parasitoid. Moreover, there was a significant positive correlation between the number of captured T. amathus and P. pentagona individuals per generation. The capture peak date in each generation of both species coincided in approximately half of the generations, indicating the synchronous occurrence of both species.

I evaluated the rainfastness and residual efficacy against citrus green mold with the simultaneous application of benzimidazoles and iminoctadine triacetate or a single application of a combination of tebuconazole and trifloxystrobin. The simultaneous application of benzimidazoles and iminoctadine maintained a notable inhibitory effect for approximately 30 days under a cumulative rainfall amount of 177 mm after application. In addition, the results of the in-vitro test showed that the effect of this simultaneous application might not decrease even if there is a cumulative rainfall of approximately 300 mm; however, this point needs to be confirmed in a field test. The combination of tebuconazole and trifloxystrobin was considered less practical for use in the control of citrus green mold because of its poor rainfastness and residual efficacy.

To examine simple density monitoring, the mean number of Aphis gossypii (Glover) on strawberry plants was estimated from the proportion of leaflets parasitized by A. gossypii. The relationship between the mean number of aphids and the sample variance of aphids fits Taylor’s power law better than Iwao’s m^*–m regression. The relationship between the proportion of parasitized leaflets and the mean number of aphids on leaflets at various census dates fits the Kono–Sugino equation. The mean number of aphids was estimated using the proportion of parasitized leaflets. To estimate populations with a fixed level of precision, the smallest sampling size was obtained from Kuno’s equation. For this estimation 168 strawberry leaflets were examined. The mean density of A. gossypii was estimated from the proportion of parasitized leaflets between 10% and 90%, with a fixed level of precision.

The biological control agent Haplothrips brevitubus (Karny) (Thysanoptera: Phlaeothripidae) exhibits female reproductive diapause, and the incidence of diapause under short-day conditions differs among geographical populations. The influence of storage at 5°C for 50 days on mortality in both diapausing and non-diapausing females and the number of eggs laid at 20°C were investigated in a strain with a higher diapause incidence. In addition, the inheritance of diapause was examined by crossing strains with higher and lower incidences of diapause. The survival percentage during cold storage in diapausing females was higher than that in non-diapausing females. However, the total number of eggs laid per survivor after cold storage did not differ between the diapausing and non-diapausing females. The crossing experiments showed that diapause is under polygenic control, and diapause-suppressing factors exist in both the autosomal genome and cytoplasm. Being able to keep diapausing females in cold storage might contribute to the achievement of low-cost, mass-produced, and high-quality H. brevitubus individuals for controlling pest thrips.

Female fecundity of Aromia bungii (Faldermann) was promoted by coiling peach branches with grafting tape in laboratory experiments because it offered slits for oviposition sites. The toxicity of the insecticides was determined by the number of larvae in the inner bark of the peach branches that were treated with the insecticides. Both acetamiprid and cypermethrin were toxic to the beetles. Acetamiprid had high contact toxicity to adults and cypermethrin suppressed oviposition.

Japanese apricot scab is an agriculturally important fungal disease caused by Cladosporium carpophilum, which is presented on fruits as black spots of approximately 1–3 mm. A quinone-outside inhibitor (QoI) fungicide, kresoxim-methyl, has been used to effectively control this disease since 2005. Another QoI fungicide, azoxystrobin, has been in use since 2011. However, resistance to these fungicides was suspected in some Japanese apricot orchards in Wakayama Prefecture in 2012. Therefore, we investigated the susceptibility of C. carpophilum isolates from 19 orchards to kresoxim-methyl and azoxystrobin. First, a culture test was performed where the 41 isolates tested with kresoxim-methyl were divided into nine isolates with an EC₅₀ value of 0.02 ppm to 0.81 ppm and 32 isolates with an EC₅₀ value greater than 100 ppm. The 22 isolates tested with azoxystrobin were divided into five isolates with an EC₅₀ value of 0.09 ppm to 1.99 ppm and 17 isolates with an EC₅₀ value of 69.2 ppm or more. Thus, the frequency distribution of EC₅₀ for kresoxim-methyl and azoxystrobin had two distinct peaks, considered to be high susceptibility and low susceptibility, respectively. Thereafter, the inhibitory effects of three isolates with low susceptibility in the culture test and one control isolate with high susceptibility were investigated using a bioassay. The protective value for the control isolate was 100 for the two fungicides, whereas, for the three isolates with low susceptibility, the protective values for kresoxim-methyl and azoxystrobin were 0–41.6 and 0–58.8, respectively. Thus, we observed a measurable decrease in the protective values. These results strongly indicate the development of Japanese apricot scab resistance to QoI fungicides in Wakayama Prefecture.

In this study, insectary plants were evaluated for their effectiveness in the conservation of the predator mite, Amblyseius swirskii Athias-Henriot in greenhouse eggplants. We investigated the population dynamics of A. swirskii, thrips, and other arthropods, on five plant species. These plants included the blue fan flower (Scaevola aemula), sweet alyssum (Lobularia maritime), lemon beebalm (Monarda citriodora), floss flower (Ageratum houstonianum), and verbena (Verbena × hybrid Tapian). The floss flower preserved the largest A. swirskii population per stem and leaves, while sweet alyssum and blue fan flower preserved the largest A. swirskii population per flower cluster. Moreover, populations of this species preserved in lemon beebalm and verbena were consistently low in density; thus, they were not suitable for preserving this predatory species. Floss flowers had the highest numbers of eggplant pest species; thus, they were not suitable for preserving this predatory species. Therefore, in this study, the most effective insectary plants for A. swirskii among greenhouse eggplants were sweet alyssum and blue fan flower.

We investigated the preventive effects of granular phosphorous acid fertilizer (GPAF) on basil downy mildew (BDM) caused by the oomycete Peronospora belbahrii Thines. In the pot experiments inoculated by a spray of BDM spores, 4 g or 8 g of GPAF suppressed BDM significantly by 100%. Furthermore, in the pot experiments inoculated with BDM-infected basil plants, 4 g and 8 g GPAF applications significantly suppressed BDM by 60% and 100%, respectively. In the field trials conducted in 2019, after the application of 2–16 g GPAF treatments three times every other month, the percentage of diseased leaves was significantly lower than that in the control, reaching approximately 50%. In contrast, in the field trials conducted in 2020, in which GPAF was applied only once before the occurrence of BDM, the percentage of diseased leaves with the 4 g GPAF treatment was significantly lower (by 55%) than that in the control. However, with the 8 g GPAF treatment, the percentage of diseased leaves was almost the same as that in the control. These results indicate that a single application of GPAF during the rainy season, when the infection pressure is high in the field, is not very effective. This may be due to the low phosphorus acid concentration in basil. Thus, we concluded that adequate absorption of phosphorous acid from the early growth stage effectively suppresses BDM. Consequently, GPAF is expected to contribute to the integrated pest management of BDM.

We designed new PCR primers targeting the hopZ3 sequence for the highly specific and quantitative detection of Pseudomonas syringae pv. theae (Hori 1915) Young, Dye & Wilkie 1978 (Pst), which is the causal agent of bacterial shoot blight of tea (Camellia sinensis (L.) Kuntze). Conventional and real-time PCR assays (intercalating dye-based analysis and probe-based analysis) using these primers detected the target sequence in all six Pst strains. However, this was not so in eight other P. syringae pathovars or in 11 other bacterial species, including P. syringae pv. actinidiae Takikawa, Serizawa, Ichikawa, Tsuyumu & Goto 1989, which causes bacterial canker of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferguson and A. chinensis Planch.) and is indistinguishable from Pst in PCR assays using the existing primers. These new primers will be useful for studying diseases in tea and kiwifruit.

In 2014, we collected 234 isolates of cucumber Corynespora leaf spot fungus (Corynespora cassiicola Berkeley & M.A. Curtis C.T. Wei) from 24 commercial cucumber fields in Okayama Prefecture, Japan and assessed their sensitivity to several fungicides. Among the tested strains, the proportion of thiophanate-methyl (T) highly resistant/dietofencarb (D) weakly and moderately resistant strains were 37% and 49%, respectively. Azoxystrobin (A)-resistant strains were 95%, whereas boscalid (B)-resistant strains were 39%. TD- and A-resistant strains were more widespread and more frequent than in 2000. B-resistant strains have only recently emerged.

Strawberry anthracnose (Glomerella cingulata) is an important disease of strawberries. We selected fungicides excluding azoxystrobin and benomyl, which are concerned about the development of resistant fungus, and examined fungicide control against strawberry anthracnose during the seedling raising period. The tests were conducted in an open field and in the facility. The control effect was high in the areas where additional chemicals were sprayed after rainfall.

We obtained 434 isolates of Fusarium fujikuroi Nirenberg collected from Hyogo Prefecture and examined their sensitivity to pefurazoate (Pf) and ipconazole (Ip). The minimum inhibitory concentration range profiles in sensitivity to Pf and Ip were from 0.78 μg/mL to 12.5 μg/mL and from 0.39 μg/mL to 1.57 μg/mL, respectively. The efficacy of seed treatment with Pf and Ip against rice Bakanae disease was evaluated using a seedling test with inoculated seeds. The treatment with the mixture of Pf, fludioxonil, and copper oxychloride, and the mixture of Ip-copper hydroxide flowable, showed high efficacy (protective values were larger than 96.0). In contrast, the treatment with the emulsion of Pf showed low efficacy (protective values were less than 90.0) in 7 out of 12 isolates. These results indicated that the sensitivity of some F. fujikuroi isolates to Pf decreased in the Hyogo Prefecture.

The rice stink bug, Niphe elongata (Dallas) (Hemiptera: Pentatomidae), is a pest that siphons the nutrients from developing rice grains. In this study, the longevity and fecundity of overwintering adults collected at a hibernation site on February 15 and 16, 2021, were examined at 25°C under a photoperiod of 16L:8D. Females started mating 46 days later and laid eggs 60 days after rearing began. The mating and ovipositional start times of the females were later than those of other stink bugs that hibernated in their adult stages. This is thought to be related to the difference in active time among adults who finished overwintering. The mean longevity was 103.8 days for females and 99.1 days for males. The mean number of eggs per egg mass was 12.1. On average, each female laid 88.1 eggs under laboratory conditions.

Eupterix decemnotata Rey (Hemiptera: Cicadellidae: Typhlocybinae), an exotic species originating from Europe, was discovered in Mie Prefecture for the first time in two host plants, Salvia rosmarinus Schleid. and Mentha suaveolens Ehrh. (Lamiales: Lamiaceae). Notably, M. suaveolens is a host plant that is new to Japan. Since this insect did not have a trivial name in Japanese, the trivial name in Japanese “Tomon Yomogi Hime-yokobai” has been proposed for the insect species.

In 2015–2016, we investigated the wing forms of adult females of Thrips nigropilosus collected from chrysanthemums and nearby weeds in open fields in Shizuoka Prefecture, Central Japan. At all collection sites, the proportion of brachypterous female adults increased in October and February. Therefore, the populations collected in this study were noted to be brachypterous under a short-day photoperiod. Additionally, the proportion of individuals entering reproductive diapause was higher than that under long-day photoperiods.

The southern green stink bug, Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae), causes damage to various crops such as rice and soybean. The bug species is regarded to overwinter as adults among the foliage of plants such as Cryptomeria japonica (L.f.) D.Don, Juniperus chinensis L. var. chinensis, and Yucca recurvifolia Salisb. However, we found adults of the species in tea fields in southern Kyoto Prefecture where there were none of the above-mentioned plants in the neighborhood in May 2014. This observation led us to suspect that they overwintered in the tea fields. The 2015 to 2018 investigation of the bugs in the tea fields, found that each year they were among the folded cover materials of the tea fields, but not in the foliage of the tea trees. The proportion of surviving adults during winter varied from 22% to 40%, with year-to-year fluctuations. These results imply that the bugs used the cover materials of the tea fields as overwintering sites.

We made an insect trap for automatic monitoring by combining a commercially available IoT monitoring camera with a sticky pheromone trap to determine the number of daily trap catches of insect pests in real time. The IoT camera automatically takes a picture of the sticky board capturing insect pests every morning and then immediately sends the image to a designated e-mail address. The present study verified whether the IoT camera-equipped sticky pheromone trap is useful for monitoring the daily occurrence of Spodoptera exigua (Hübner) in a commercial chrysanthemum field in Osaka Prefecture. The number of trapped males, counted by viewing the e-mailed images of the sticky boards on the monitor screen of a personal computer, almost coincided with that counted by directly checking the same sticky boards that were collected at an interval of 14–27 days: the count via images was –4 to 1 more than the in-person counts (–5.6% to 1.9% of the in-person counts). The numbers of males peaked on July 14, August 9, September 4, and October 13. These results indicate that the IoT camera-equipped sticky pheromone trap is helpful for determining the daily catches of S. exigua males in commercial fields.

The effects of red LED light irradiation and reflective sheet cover on the population density of the onion thrips, Thrips tabaci Lindeman, were investigated on eggplants in a greenhouse in 2016. Four experimental plots were set up by combining the illumination of red LED lights and the cover of the reflective sheet. The eggplants were cultivated from May to June. As a result of the experiment, the population densities of larvae tended to be in order of low to high in the following plots: the plot with both the red LED lights and reflective sheet, the plot with the red LED lights and no reflective sheet, the plot with the reflective sheet and no red LED lights, and the plot without the red LED lights or the reflective sheet.

We examined the optimal height for dusting tomato plants with Beauveria bassiana wettable powder using an electric hand blower. Conidia were detected mainly in the leaflets at a height of 60–100 cm when dusting was performed from a height of >40 cm from the ground; however, they were hardly detected in the leaflets in the same area when dusting was performed near the ground. When greenhouse tomatoes were dusted from a relatively mid-level height every 7 days, the reduction in the number of Bemisia tabaci larvae was similar to that achieved by spraying a 1,000 times diluted solution. Therefore, dusting tomato plants with B. bassiana wettable powder from a mid-level height helps to prevent B. tabaci infestation.

To clarify the ripening stages likely to produce sterile grains due to damage by rice stink bugs Niphe elongata (Heteroptera: Pentatomidae), we individually released four rice stink bugs per four panicles for 10 days beginning at 0, 7, or 14 days after heading. Many stylet sheaths were present on the surfaces of grains that had been exposed to rice stink bugs beginning either 0 or 7 days after heading. These grains were both unfertilized and unfilled, which indicates sterility. This result suggests that it is the damage caused by rice stink bugs during the milk-ripe stage that causes rice grain sterility.

The susceptibility of the common cutworm’s (Spodoptera litura Fabricius) third instar larvae to 10 insecticides was evaluated. The corrected mortality rates associated with chlorfenapyr, metaflumizone, cyantraniliprole, and fluxametamide were >90% in many tested populations. The LC₅₀ values of flubendiamide, chlorantraniliprole, and pyridalyl for all tested populations were higher than those for the susceptible population and those reported in previous studies. In conclusion, although several insecticides worked effectively against S. litura, the insect’s susceptibility to flubendiamide, chlorantraniliprole, and pyridalyl was less.

Sarcandra glabra (Thunb.) Nakai (Chloranthales: Chloranthaceae), a dwarf evergreen tree, is a traditional auspicious plant in Japan that bears bright red fruits at the end of the year. Euops splendidus Voss (Coleoptera: Attelabidae) is a common beetle distributed on the Honshu, Shikoku, and Kyushu islands of Japan, as well as throughout Siberia. The adult beetles are polyphagous and feed on a wide range of plants. We found distinct oblong feeding scars and adults of the beetle on leaves of S. glabra among a cultivation field in Okazaki, Aichi Prefecture in central Honshu, Japan. The laboratory experiments revealed that the scars were caused by the feeding of the beetle. To our knowledge, this is the first report of E. splendidus as an agricultural pest feeding on S. glabra leaves.

The toxicities of various insecticides were determined using a bait twig method on larvae of the loquat psyllid, Cacopsylla biwa, collected from loquat trees in Wakayama Prefecture. Chlorpyrifos, malathion, methidathion, phenthoate, ethiprole, fenpropathrin, tralomethrin, acetamiprid, clothianidin, imidacloprid, and cartap were toxic and resulting in a corrected mortality rate >90%.

We investigated the effectiveness of 10 insecticides against Thrips tabaci collected from six onion fields and three scallion fields in the onion- and scallion-producing areas of Hyogo Prefecture. In all fields, over 90% of the thrips died from exposure to asephate, prothiofos, fluxametamide, and flometoquin, while approximately 70% to 90% died upon exposure to thiocyclam and cyantraniliprole. However, cypermethrin, acetamiprid, spinetoram, and pyridalyl showed varying levels of effectiveness depending on the field and the effectiveness was low, especially in the scallion fields and in the onion fields located near the scallion fields. Interestingly, the effectiveness of these insecticides was similar in both fields.

Bemisia tabaci (Gennadius) is an important pest in protected tomato horticulture in Mie Prefecture. Strategies for the management of this pest largely depend on the application of insecticides. We used the kidney bean leaf-dipping method to examine the insecticide susceptibility of adult Q-biotype B. tabaci individuals collected from tomato-growing districts in Mie Prefecture. Emamectin benzoate, lepimectin, pyrifluquinazon, and cyantraniliprole showed high levels of insecticidal activity, whereas dinotefuran, nitenpyram, sulfoxaflor, and spinetoram showed low activity levels. In 2013, dinotefuran, nitenpyram, and spinetoram showed high insecticidal activity levels against adults of the Q-biotype B. tabaci, and the activity of these insecticides in 2020 and 2021 was significantly lower than that in 2013.