Bacterial wilt caused by Ralstonia solanacearum is a major source of damage during the production of green bell pepper (Capsicum annuum). The grafting of susceptible but high-quality pepper cultivars onto highly resistant rootstocks has been adopted to manage this disease. Recently, however, bacterial wilt has begun to occur again during summer-autumn cultivation in Yamaguchi Prefecture. To enhance the resistance provided by the rootstocks and control infection, we developed a new high-grafting strategy. In this approach, grafting is done at a higher position (11 to 14 cm above the ground) than usual (3 to 4 cm). In greenhouse experiments in Yamaguchi and Ibaraki prefectures, high grafting slowed disease development and resulted in less-severe wilting than with grafting at the usual height. In healthy plants, plant growth, yield, and the quality of the peppers did not differ significantly between the grafting treatments. Our results indicate that high grafting could be an effective strategy for managing bacterial wilt of green bell pepper.
Sex pheromone lures usually attract the target species very specifically; however, non-target species are often also specifically attracted. Non-target species attracted to a sex pheromone lure could lead to technical problems in pest monitoring, for example in counting mechanically. In this study, non-target lepidopteran species specifically attracted to the sex pheromone lures for the diamondback moth, Plutella xylostella (Linnæus) were examined in four open fields in Tsu City, Mie, Japan. In addition to specific attraction by the target species, six (Acrolepiopsis sapporensis (Matsumura), Microchilo inouei Okano, Glyphipterix nigromarginata Issiki, Eupsilia tripunctata Butler, Orthosia lizetta Butler, Anorthoa angustipennis (Matsumura)) lepidopteran species were specifically attracted to the lures for P. xylostella. Among these, A. sapporensis, M. inouei and G. nigromarginata were considered to be the species susceptible to be erroneous determination when P. xylostella are counted mechanically.
We compared the mortality of mites between two susceptibility test methods, chemical spray and leaf dip, with bifenazate, emamectin and cyenopyrafen for the two-spotted spider mites on strawberry. When using bifenazate and cyenopyrafen, there was no difference in mortality of mites between the two methods. However, when using emamectin, the mortality by the leaf dip method was significantly lower than that by the spray method.
A new method of placing mites on the leaf of kidney beans without using a fine brush was developed. That is, a small strawberry leaf infested with mites was placed by an intact stem of kidney bean with one primary leaf for a day. Most mites on the strawberry leaf moved onto the kidney bean leaf by themselves. There after the kidney bean leaf with mites was dipped in the acaricides for five seconds. By using this placement method followed by the leaf dip method, the mortality was similar to that of normal placement method using a fine brush followed by the spray method.
Population of the foxglove aphid, Aulacorthum solani on green peppers and eggplants after releasing an aphid parasitoid, Aphidius gifuensis was investigated in greenhouses. The numbers of the foxglove aphids rapidly decreased and those of less than 20% remained on the original plants 5 days after releasing parasitoids. Eleven percentages of the aphids moved to the other plants infested with no aphids before the parasitoid introduction. The aphids in another greenhouse with no parasitoids did not decreased rapidly. These results suggest that introduction of A. gifuensis can lead to quick suppression of the foxglove aphids.
The rot and blackening symptoms of the root on Japanese radish infected with Pseudomonas syringae pv. maculicola is occurred by entering pathogens into the interior of the root from the petiole base. When injury is present in the petiole base of the radish, infection of the pathogen is promoted. Infection of the pathogen that causes the root symptoms, there is always a chance in the growth period of radish. The varieties of radish that is likely to develop the root symptoms is ‘Hatsuhomare’. On the other hand, the varieties of radish that are less likely to develop the root symptoms are ‘Shunsai’, ‘Tokuhomare’, ‘Hukuhomare’, ‘Huyumisaki’, ‘Natsutsukasa’, ‘YR Kurama’, ‘Taibyousoubutori’.
The western flower thrips, Frankliniella occidentalis (Pergande) is an important pest insect in strawberry fields, and their larvae attack and spoil strawberry fruits. Because this pest has developed resistance against a number of pesticides, biological control methods using natural enemy species are needed for the establishment of IPM program. In this report, I tried to use a new predatory thrips, Haplothrips brevitubus (Karny) in order to control the pest thrips populations occurred on the two varieties of strawberry, “Sachinoka” and “Benihoppe”. I experimentally found that the predator individuals were mainly distributed on the flowers and juvenile fruits of strawberry plants where the pest thrips were also observed. I also found that the predator could control the pest thrips population effectively.
Effectiveness of augmentation of Amblyseius swirskii (Athias-Henriot) against the three pest species: Thrips palmi Karny, Bemisia tabaci (Gennadius) and Polyphagotarsonemus latus (Banks) occurs on the eggplant cultivated in open fields were evaluated from August to September in 2014 and from September to October in 2015. Released numbers and times of A. swirskii were 50 individuals/m2 and tree times in 2014 and 25 individuals/m2 and tree times in 2015, respectively. Maximum numbers of A. swirskii per 30 leaves on eggplant were ca. 50 individuals in 2014 and ca. 30 individuals in 2015, respectively. Populations of T. palmi and B. tabaci decreased or remained at low levels on eggplant after release of A. swirskii in both years. Numbers of above two pest species on eggplant where A. swirskii was released were significantly lower than non-treatment eggplants in both years (Repeated measures of ANOVA, p < 0.0001). Proportions of plants damaged by P. latus where A. swirskii were released were significantly lower than non-treatment eggplants in both years. We considered that augmentation of A. swirskii would be available against main three pests; T. palmi, B. tabaci and P. latus on eggplant cultivated in open fields.
Hoverflies are important natural enemies against aphids. Pollen and nectar provided from floral resources in agricultural fields are effective for conservation and enhancement of local hoverfly populations. We investigated some basil Ocimum basilicum L. variations, holy basil O. tenuiflorum L., buckwheat Fagopyrum esculentum Moench and Phacelia tanacetifolia Bentham from April to August in 2015 in order to select useful insectary plants for hoverflies. Based on the seasonally changes of coverages, the number of flowers and hoverflies, we concluded holy basil was suitable floral resources for adult hoverflies from May to July. Decrease of hoverflies after July might be caused by high temperature or their parasitoids.
The effect of a red insect-proof net, a predatory mite, Amblyseius swirskii Athias-Henriot, and granular formulation of an entomopathogenic fungus, Metarhizium anisopliae (Metschn.) Sorokin on melon thrip, Thrips palmi Karny, was investigated on greenhouse cucumber from August to November in 2013, 2014, and 2015. A red insect-proof net was placed in the treated plot, and 50,000 A. swirskii were released per 10 a, and 5 kg of M. anisopliae granules were applied per 10 a. In the control plot, a white insect-proof net was used and no biological pesticides were applied. In 2013 and 2015, the population density of thrips was lower in the treated plot than in the control plot. In 2014, the population density of adult thrips was similar in both plots, and the number of larval thrips was lower in the treated plot than in the control plot. These results suggest that the IPM system utilizing a red insect-proof net in combination with A. swirskii, and M. anisopliae can effectively control thrips.
Infestation of chestnut weevil, Curculio sikkimensis (Heller), and black rot fungus, Botryosphaeria dothidea (Mougeot) Cesati & De Notaris was consistently observed in the nuts of Japanese chestnut cultivated in Osaka Prefecture Japan. Treatment of the nuts by immersing in hot water at 50°C for 30–40 min or 51°C for 25–30 min, followed by water cooling and air drying, eradicated the chestnut weevil and reduced the incidence of black rot infection. However, the treatments caused the surface of nuts to lose gloss and become moldy, regardless of the differences in the heating conditions.
In tea fields, we estimated the day on which the number of adult tea spiny whiteflies (Aleurocanthus camelliae Kanmiya and Kasai) peaked using the effective cumulative temperature and compared it with the actual (observed) peak day, which was determined based on the number of adults captured by yellow sticky traps. We also estimated the number of generations produced each year in the tea fields. The days on which the number of adult tea spiny whiteflies peaked were estimated using the effective cumulative temperature, which was based on the temperature in each hour at Kikugawa-Makinohara point according to the Automated Meteorological Data Acquisition System (Japan) (AMeDAS). The peak days for each generation were compared in seven tea fields around the AMeDAS point in 2012 and 2013. As a result, it was found that the mean errors between the estimated and observed peak days of the first, second, and third generations were 4.4 (in 2012) and 4.7 days (in 2013), 4.3 and 4.9 days, and 6.6 and 4.0 days, respectively. These errors did not exceed 7 days, which was the trap exchange interval. The number of generations produced each year was estimated using the temperature data recorded at four AMeDAS points with different elevations. Our results suggested that in each year three generations were produced in Kawane-Honcho (290 m above sea level), four generations were produced in Omaezaki (45 m), and between three and four generations were produced in Kikugawa-Makinohara (191 m). Although the estimated peak day of the overwintering generation in 2013, which was forecast based on the observed peak day of the third generation in 2012, differed considerably from the observed peak day in Kikugawa-Makinohara, the peak day forecast from the peak day observed during the latter period of the second generation in 2012 was consistent with the observed peak day of the overwintering generation in 2013. These results suggest that in each year populations composed of three or four generations coexist in the tea fields in Makinohara district, which are located at 100–200 m above sea level.
We evaluated the effectiveness of controlling Bemisia tabaci (Gennadius) on tomato in commercial greenhouses by releasing Nesidiocoris tenuis (Reuter) and sustaining the N. tenuis on banker plants (Verbena × hybrida cv. Tapian) from 2013 to 2015 in Shizuoka Prefecture. The N. tenuis colonized the tomato plants, and toward the end of the growing period, as the population density of N. tenuis increased, the population density of B. tabaci decreased. The rates of yellow leaf curl on plants were the same as or lower in the N. tenuis release plots, where selective insecticide was applied, than in the conventionally managed control plots. The N. tenuis population colonized the banker plants and remained present throughout the experimental period. No economic damage to tomato by N. tenuis was observed. These results suggest that a combination of N. tenuis and banker plants is effective for controlling B. tabaci and has the potential to prevent the spread of Tomato Yellow Leaf Curl Virus outside the greenhouses.
The effect of releasing of natural enemy mites, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot on a population of two-spotted spider mite, Tetranychus urticae Koch was investigated in greenhouse strawberries in Osaka Prefecture. In the mite-release plot, N. californicus twice in October, and P. persimilis four times from January to March, were released in 2007-2008, and N. californicus once in November, and P. persimilis twice in February and March, were released in 2008-2009. The population density of the spider mite became lower in the mite-release plot than in the conventional chemical control plot in both years, and the number of applications of acaricides was reduced three or four times more in the mite-release plot than in the conventional chemical control plot. These results suggest that releasing natural enemy mites, N. californicus from October to November and P. persimilis from January to March, can effectively control the population density of the spider mite.
The Pyrifluquinazon hydrating agent is one of the efficient insecticides to Miridae pests and the selective insecticides that has low effect to natural enemies in egg plant fields that reducing pesticides. This insecticide as an insect behavior regulator is not clarified the mode of action. So we investigated the effect to biological features of Orius strigicollis as a model of the Orius’ natural enemies. We surveyed effect of the Pyrifluquinazon to survivorship, reproduction and feeding thrips of O. strigicollis. The preoviposition period of Pyrifluquinazon treated insects was significant longer than control, and the total number of eggs for 10 days after treated of the Pyrifluquinazon. But after starting oviposition, the egg numbers per a day of treated the Pyrifluquinazon was no significant different to control. So We consider the Pyrifluquinazon has less effect to biological features of the Orius natural enemies and can be used in combination with the Orius natural enemies in egg plants fields.
Mulberry scale, Pseudaulacaspis pentagona (Targioni), distributed in 70% of peach orchards in Wakayama Pref. in 2008-2011, resulting in occurred more widely than white peach scale, P. prunicola (Maskell). There were three peaks of the occurrence of 1st-instar nymph of P. pentagona: first one is in early May, second one is in mid-June and third one is the other in early to mid-Sep., which was 5-16 days later than the peaks of P. prunicola. The scale density of P. pentagona was well suppressed by application with buprofezin in autumn and machine oil emulsion in winter.
Effect of tomato tolerant cultivar to Tomato yellow leaf curl virus on acquisition and transmission by Bemisia tabaci was examined. Infected Solanum lycopersicon L. ‘TY Misora86’, showed asymptomatic infection of the disease, but contained detectable viral DNA in the upper leaves, which was evaluated by PCR analysis. Efficiency of virus acquisition by adult whiteflies fed on the infected tolerant cultivars for 72 hours was varied (25.0–81.3%), but was seemed to be lower than those of adults fed on the infected susceptible cultivars (92.0–100%). Subset of these adults were able to transmit the virus to susceptible plants, however, percentage of infected plants were 0–20.0%, which were relatively lower than those by viruliferous adults fed on infected susceptible cultivars (50.0–75.0%).
Bacterial shoot blight is a disease that has the potential to have a significant impact on tea cultivation in Shizuoka prefecture. To enable the easy and rapid detection of the causal agent of this disease, a direct polymerase chain reaction (PCR) method was developed using samples from tea leaves. A piece of tea leaf that included a water-soaked lesion was ground down in sterile water. After the debris had settled, the suspension was boiled and then used as a PCR template. When the undiluted supernatant was used as the template, marked PCR interference occurred. In contrast, a clear target band was detected when a 10-fold dilution of the supernatant was used as the template. This method was shown to be an easy and rapid way identifying the causative pathogen of bacterial shoot blight on tea plants.
We developed the Disease Infection Risk Prediction System for anthracnose in sweet pepper. After comparison of the results over a period of two consecutive years; based on the combination of the temperature and the duration of the wetness period; in relation to the ratio number of diseased fruit, it is obvious that the prediction of this index is highly reliable.
A simple method to survey a ratio of barley or wheat seeds infested by Pseudomonas syringae pv. syringae (Pss). Barley or wheat seeds were put in multi-well plate and immersed in 200 μl sterile water at 8°C for 3 days. A small aliquot of the seed immersed water was transferred on selective medium to detect Pss using 48-pin copy plate, and incubated at 25°C for 7 days. Black colonies of Pss were clearly detected without contamination of filamentous fungi. This is a simple and easy method to examine many seeds at a time, and it is expected to detect infested seeds more precisely.
Effects of amount of sowing seed and seeding date were studied to control bacterial black node of wheat (Pseudomonas syringae pv. syringae) for 2 cultural seasons from 2013 to 2015. As a result, it was revealed that late seeding is effective to control the disease.
Citrus mosaic virus (CiMV), a strain of Satsuma dwarf virus (SDV), was frequently detected on diseased citrus trees in Wakayama Prefecture using reverse transcription-polymerase chain reaction analysis. Moreover, we surveyed 308 citrus trees from 64 orchards using an immunochromatographic assay to detect SDV. A total of 114 trees from 38 orchards tested positive for SDV. CiMV was also frequently detected on these trees.
Apparatus for extracting Scirtothrips dorsalis washed from plants consists of a 1-mm-aperture polyester mesh sieve stacked on top of a 75-μm-aperture nylon mesh sieve. Both sieves have an inner diameter of 75 mm and are 40 mm in height. A plant sample is placed in a 2- to 5-L beaker and 0.09% detergent solution is added. Following vigorous agitation, the solution is poured on the upper sieve. The washing and extraction procedures are performed again using tap water. Absolute ethanol is sprayed over the mesh of the top sieve to eliminate foaming of the detergent. The bottom sieve, which retains small insects and debris, is mounted on a Petri dish covered with a circular OHP film. The film has a 10-mm square grid printed on it and is backed with adhesive white tape. S. dorsalis and other thrips on the mesh are observed and counted under a binocular microscope
The starvation tolerance of bagworm moths, Eumeta miniscula Butler and Mahasena aurea (Butler) (Lepidoptera: Psychidae), was evaluated. The survival rate of E. miniscula larvae was 100% at 25°C for the first 11 days of starvation conditions. More than 50% of individuals had died after 18 days, and all individuals had died after 35 days. Under the starvation conditions at 15°C, the survival rate was 100% for the first 4 days. After 56 days, more than 50% of individuals had died, and all individuals had died after 102 days. The mean survival periods at 25°C and 15°C were 15.3 days and 53.2 days, respectively. For M. aurea larvae, the survival rate was 100% at 25°C for the first 7 days of starvation conditions. More than 50% of individuals had died after 13 days, and all individuals had died after 18 days. At 15°C, the survival rate was 100% for the first 15 days. After 25 days, more than 50% of individuals had died, and all individuals had died after 45 days. The mean survival periods at 25°C and 15°C were 11.6 days and 24.5 days, respectively.
The aim of this survey was to evaluate the effects of environmentally conscious farming (ECF) on the conservation of biodiversity by comparison with conventional farming (CF) in rice plant fields. In this survey, biodiversity was measured by using environmental indicator organisms. Water beetles, pond frogs (Pelophylax) and wolf spiders (Lycosidae) were more abundant in the ECF fields. However, The abundance of damselflies and web spiders (Tetragnatha) were not clear differences between in the ECF fields and in the CF field. In conclusion, it became clear that higher biodiversity was maintained in the ECF fields than in the CF field. This is the first verification that demonstrates the efficacy of ECF in Shiga Prefecture assessed using indicator organisms.
We tested two cultivars of barley and one of wheat as living mulch for the retention of indigenous natural enemies of pests of winter-harvested Welsh onion. ‘Hyakumangoku’ barley withered earliest and was therefore most suitable to precede soil hilling for the blanching of the onions in early September; it supported populations of Rhopalosiphum padi (Linnaeus) and Anaphothrips obscurus (Müller), which are food sources for the indigenous natural enemy Geocoris proteus Distant, and various predatory phytoseiid mites.
Effects of the cultivation of barley between rows of spring onion or holly basil around the farming fields on the density of ground wondering predators were investigated using pitfall traps. The barley attracted ground beetles such as Chlaenius micans and spiders such as Pardosa pseudoannulata to the fields. On the other hand, the holly basil had no such attracting effects; it decreased the density of spiders and the earwig Labidura riparia.
So far a number of studies have confirmed that organic farming and integrated pest management (IPM) enhance environmental conservation in terms of abundance of natural enemies, particularly in farm lands. In contrast, little is known for the corresponding effect in paddy fields. We carried out a factorial experiment, using azolla and paper mulch respectively as a bio-herbicide and a physical weeding measure, to examine whether these methods can enhance density of natural enemy, in paddy fields of Shiga prefecture. The results suggested that only weeding by azolla but not by paper mulch increased the density of natural enemies such as web spiders.
The durations of the influence of several insecticides for adult-stage Aphidius gifuensis Ashmead were evaluated based on the IOBC/WPRS guideline. The durations of the influence of spirotetramat, pyridalyl and pyrifluquinazon were less than 1 day, whereas those of malathion, acetamiprid, nitenpyram and emamectin benzoate were less than 7 days.
We examined the efficacy of preventing thrips from invading a fig (Ficus carica L.) field and preserving natural enemies through the use of the sorghum as barrier crops surrounding the fig trees.
From June to November, we counted the number of thrips that were captured with the blue sticky plate set in a fig field surrounded by either the sorghum or the petunia in addition to the sorghum. The total numbers of thrips invading the fig fields under these experimental conditions were about half that found in the control, conventional field surrounded by windbreak nets with 4mm mesh. Additionally, we also confirmed the efficacy of generating indigenous natural enemies such as the arachnids, the orius, and the neididae in the fig field surrounded by the sorghum.
The susceptibility of adults of the leafminer, Liriomyza trifolii (Burgess) and its three parasitoids (Chrysocharis pentheus (Walker), Hemiptarsenus varicornis (Girault), and Neochrysocharis formosa (Westwood)) to four conventional insecticides (malathion, permethrin, imidacloprid, and emamectin benzoate) was examined in the present study. To this end, a laboratory bioassay was employed using either one or two concentrations of each of the commercial insecticides. Low mortalities (8.5% and 6.8%) were observed in leafminers treated with malathion (3,000-fold dilution) and imidacloprid (2,000-fold dilution). In contrast, moderate mortalities (63.3% and 44.4%) were observed in leafminers treated with permethrin (5,000-fold dilution) and emamectin benzoate (2,000-fold dilution). High mortality (87.3%–100%) of parasitoids was observed for all the insecticides evaluated. The results of the present study suggest that large differences in insecticide susceptibility exist between the leafminer and its parasitoids. This information could be exploited for better management of L. trifolii.
In 2014, the seasonal abundance of adult thrips in paddy fields in Shizuoka Prefecture was investigated by using blue sticky traps, and the incidence of speckled rice damage by the insects was assessed. The most dominant thrips species was Stenchaetothrips biformis (Bagnall), followed by Thrips palmi Karny. From 26% to 38% of all speckled rice was black spotted rice. It is considered that many black spotted rice is caused by thrips.
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