There were two outbreaks of Locusta migratoria on the first and second islands of the Kansai International Airport in 1994–97 and 2007, respectively. The characteristic two-toned pattern of black and orange colors in the hopper stage in phasegregaria was observed during the infestation. In 1995 and 2007, the locust population peaks were estimated at 13.4 million and 38.8 million, respectively, using the line-transect and quadrat methods, and the population was managed with fenitrothion EC. Increase in natural enemies, such as Entomophthora grylli and Latrodectus hasseltii, curbed both locust outbreaks. We hypothesized that the outbreaks were caused due to the infestation of some locust adults on reclaimed islands with a small number of natural enemies. The locusts were found mainly on the northwest of the islands and were thought to be caused by the south to southwest winds from June to September on the islands. L. migratoria is mainly bivoltine with embryonic diapause, but some individuals of the species hibernate during the adult and hopper stages on the islands. We adopted the following strategy for locust population estimation and management of the outbreak: (1) rapid estimation of the population, (2) mapping of the results to develop a perspective, (3) spraying the locusts from high to low densities, (4) evaluating the effectiveness of the control measures by rapid estimation of the locust population (similar to step 1), (5) repeating steps 1–3 in a cyclic manner, (6) pesticide suppression to preserve natural enemies in low-density areas. The locusts were sprayed to decrease the population from 38.8 to 0.14 million in 9 days on the second island from June 11 to June 19, 2007.
Five rice sclerotial disease fungi, Rhizoctonia oryzae, R. solani AG-1 IA, R. fumigata, R. oryzae-sativae, and Sclerotium hydrophilum, were surveyed for the influence of different concentrations of CO2 and O2 on mycelial growth, and sclerotial formation and germination. The ratio (%) of mycelial growth (mm) at two CO2 ∕ O2 concentrations, i.e., 0.1 ∕ 20% and 5 ∕ 5%, compared to mycelial growth at 0.03/20% (control) was similar among the five isolates of each fungus, resulting in a lower coefficient of variation (%) that ranged from 1.4 to 3.6%, except for R. solani AG-1 IA, showing 8.2%. A growth decrease of 22–53% and 23–47% occurred at 15% and 1% among four CO2 concentrations ranging from 0.03 to 15%, and four O2 concentrations from 1 to 20%, respectively. R. solani AG-1 IA proved to be most sensitive to relatively higher concentrations of CO2 and lower concentrations of O2. On the other hand, S. hydrophilum and R. oryzae-sativae, especially S. hydrophilum, was tolerant. In R. solani AG-1 IA and R.oryzae-sativae, sclerotial formation showed a 42–95% decrease at CO2: 5% and also a 57–100% decrease (non-formation for sclerotia) at CO2: 15%. Moreover, sclerotia kept under a low growth CO2 /O2 concentration of 5/5% for 60 days showed 86–99% of germination for R. solani AG-1 IA and R. oryzae-sativae. These results are possible to contribute better understanding of the fungal development of Rhizoctonia and Sclerotium spp. in soil, and consequently, the respective spread of disease in paddy fields.
Various treatment conditions were examined to ascertain an effective utilization method of Coniothyrium minitans. Results were confirmed that a sufficient control effect was achieved at a half dose rate of the currently actual dosage. Considering a treatment timing, a better control effect was obtained by spraying at the time of plowing in residues from the prior crop than by treatment before planting. Moreover, a stable efficacy was obtained by increasing the spray volume applied per unit area to avoid uneven spraying. The results presented above suggest that a stable effect is obtainable by further study of application technique.
An ethanol-spray treatment was evaluated as a practical method for forecasting strawberry anthracnose caused by Glomerella cingulata in Nara Prefecture, Japan. Evaluations were conducted on latent infections of the pathogen to determine the disease occurrence in commercial strawberry nurseries from 2010 to 2014. The latent infection was highest in early July and corresponded highly to disease occurrence throughout the experiments. The results showed that the ethanol-spray treatment was a reliable and useful method for forecasting anthracnose in strawberry nurseries.
Imported kiwifruit affected by soft rot on Shanghai fruit market was selected for pathogen isolation and identification. The pathogenicity of different strains was compared. Morphological detection was combined with molecular tools to identify the main pathogenic strains as well as their biological characteristics. The results showed that Phomopsis was the main pathogen causing soft rot, and Phomopsis vaccinii (P. vaccinii) had the highest pathogenicity. Soft rot in kiwifruit caused by P. vaccinii was effectively inhibited under 5°C. This article is a first report of the pathogens causing soft rot in kiwifruit in Chinese market. Valuable experimental evidence is provided for the study on the pathogens carried by kiwifruit imported from New Zealand and on the occurrence of soft rot on the market.
We compared the life history characteristics of two egg parasitoids: Trissolcus basalis (Wollaston) (TB), a non-native, invasive species, and the native Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) (TM) using the southern green sting bug Nezara viridula (Linnaeus) (Heteroptera: Pentatomidae) as a host, and analyzed effects of the interspecific competition between the two species. Observations of the color of parasitized egg masses of N. viridula indicate that the larval period of TM was shorter, but the developmental duration until adult emergence of TB was shorter than that of TM. Rapid growing of TM larvae is advantageous for survival in competition with TB larvae as confirmed by multiparasitism experiments. Further, TM does not have enough time to oviposit because adult female of TM shows strong aggressiveness against other TM individuals (and also against other species including TB) when multiple females oviposit in a host egg mass simultaneously, resulting in TM spending more time to oviposit. In contrast, TB can parasitize together with several other females of TB in a shorter period because it is less aggressive than TM. Interspecific competition between TB and TM when trying to oviposit in a host egg mass at different ratios of females (1:1 and 1:2) resulted in producing TM species in most emerged wasps, but TB emergence success was lower: 5.8% in 1:1, 23.4% in 1:2 ratios. The life span of TB females was about 90 days and that of TM was 60 days when inexperienced in oviposition, and the life spans of TB and TM with oviposition experience were about 48 and 23 days respectively, showing that TB females have a longer life than TM, regardless of oviposition experience. Total number of eggs laid during its lifetime was about 258 in TB and the female ratio was 0.48 (♀/(♂ + ♀)), while lifetime egg oviposition of TM was about 125 with 0.77 female ratio. About 21% of the TB wasps emerged successfully under dry conditions (20–30% humidity), but the TM could not emerge at all. Multiparasitism is reproductively disadvantageous for TB. However, these results suggest that TB has a greater ability to adapt to low humidity environments as well as complete the oviposition process more rapidly and produce more offspring because of its long adult life span and high fecundity when a large number of host egg masses are available due to its high relative host density.
The damage caused by insect pests on cabbage plants is often reduced when planted together with cover crops; the reduction is accompanied by an increase in the population of ground-dwelling predatory natural enemies including carabid beetles. However, whether the increase of carabid beetles is caused by the existence of the cover crop itself or by the occurrence of lepidopteran pests on cabbage plants and/or cover crops is not yet clear. The effect of the removal of lepidopteran larvae was examined by spraying selective insecticides on the populations of ground-dwelling predatory natural enemies and using a pitfall-trapping method in cabbage fields with cover crops planted together. The carabid Chlaenius micans was the most abundant and the carabid Dolichus halensis was the next abundant natural enemy in spring cabbage fields. Both species were significantly more abundant in unsprayed plots than in sprayed plots. This may imply that the removal of lepidopteran larvae leads to the reduction of its predator through food deficiencies. The earwig Labidura riparia was the most abundant natural enemy in autumn cabbage fields. However, there was no difference in the population of any natural enemy species between the unsprayed and sprayed plots. This may be due to low population densities of lepidopteran larvae in the unsprayed plots, although they were higher than those in the sprayed plots.
We monitored the ladybird beetle Serangium japonicum Chapin, a potential predator of the tea spiny whitefly, Aleurocanthuscamelliae Kanmiya and Kasai, by using a light trap and yellow sticky traps in the tea fields of Shizuoka Prefecture, Japan. The S. japonicum adults were captured using a light trap and yellow sticky traps. The number of beetles captured by yellow sticky traps was much lower than that captured by the light trap. The maximum numbers of beetles captured per day by the light trap were 191 in 2013 and 14 in 2014, and those by the yellow sticky traps ranged from 0.2 to 1.0 in 2013 and from 0.2 to 0.8 in 2014. The pattern of seasonal changes in the number of beetles captured by the light trap and yellow sticky traps exhibited two peaks in June and August in both the years. This result suggests that two generations of beetles occur in the tea fields in a year.
The yellow tea thrips, Scirtothrips dorsalis HOOD, is a serious grapevine pest. Mulching reflective sheets (e.g., TYVEC®, DuPont) on the ground around fruit trees is known to be effective in reducing damage from this pest, for example in citrus orchards. In the case of espalier grapevine fields mulched with reflective sheets, the reflected light easily reaches the leaves and fruits, and damage by S. dorsalis may decrease, compared to the case of typical lattice-like shelves covered with leafy stems, which prevent sunlight from reaching the ground. We investigated the damage to ripe berries of the espalier grapevine (cv. “Neo Muscat”) in the case of mulching with reflective sheets. The damage indices for the stems and fruit clusters from the mulched trees were lower than those from unmulched trees without pesticide application, but higher than those from unmulched trees sprayed with insecticide (cartap). The density of S. dorsalis in the mulched trees was apparently lower than in the unmulched trees. The phytoseiid mite, Euseius sojaensis Ehara, known as a native predator of S. dorsalis, was also observed to be abundant on matured leaves of mulched trees. These results indicate that, for espalier grapevine, mulching reflective sheets is effective in reducing fruit damage by S. dorsalis.
Metarhizium anisopliae is a widely distributed soil-inhabiting fungus and is used as a microbial pesticide against thrips. We studied the effects of 11 fungicides and 11 insecticides on granule formulation up to the growth of hyphae in the microbial pesticide M. anisopliae. Hyphal growth was not observed in M. anisopliae under the treatment using agar culture medium supplemented with benomyl and triflumizole as chemical fungicides and with MEP as a chemical insecticide. The results of our study indicate that the use of these fungicides and insecticides should be avoided when using the microbial pesticide.
This study on the effectiveness of yellow LED illumination in suppressing damage from fruit-piercing moths was conducted in 2011 and 2012 at a citrus orchard in Minami-Ise, Mie Prefecture, Japan. In 2011, 19 yellow 0.6 W LED light sources were installed to illuminate the area of study, and in 2012, 5 yellow 4.3 W LED light sources of 4.3 W were installed. Results showed that in both 2011 and 2012, the occurrence of fruit with damage from fruit-piercing moths was suppressed in trees that received a maximum illuminance of ≥1 lx of yellow LED light. Although the total annual costs including electricity fees of the two installations was comparable, the 4.3 W yellow LED lights were deemed more effective due to the lower number of units required, reducing the barrier on the cultivation management processes.
Influence of cultivation pH of melon seedlings on transmission efficiency of Melon necrotic spot virus (MNSV) by the fungal vector Olpidium bornovanus was investigated. When melon seedlings were grown in plant culture medium, the transmission of MNSV was decreased under low pH values of 5.5 and 4.5. The application of 1% and 2% Ferosand (FeSO4·H2O) to decrease soil pH in artificially infested soil that was contaminated with O. bornovanus and MNSV, also decreased the transmission efficiency of MNSV. These results indicate that the transmission of MNSV by O. bornovanus is inhibited under low pH soil conditions.
Big rosette type brown-spot was found on tea (Camellia sinensis (L)O.Kuntze) leaves in 2013 and 2014. Fungi isolated from the diseased plants were identified as the Colletotrichum gloeosporioides species complex. Inoculation tests confirmed that this fungus was the causal agent of the disease. Big rosette brown-spot symptom is a special symptom of brown-blight disease on tea.
To estimate the initial infection period of Ceratocystis ficicola against fig cuttings via soilborne inoculum, one-year old cuttings were planted in a contaminated fig orchard. Two fig varieties, ‘Houraishi’ and ‘Masui Dauphine’ were employed in this study. Numbers of ‘Houraishi’ and ‘Masui Dauphine’ cuttings were 18 and 28, respectively. These cuttings were dissected at 69, 83, 97, 111, 125, 136, 150 and 171 days after planting, respectively. First infection of the fig plants was recognized at 97 days after planting, and then the infection rates of cuttings increased in both fig varieties. External symptoms, wilting and death, were not observed in the cuttings of either fig variety until three years after planting. These results indicate that infection of C. ficicola starts in the year of planting without any external symptoms. Soil applications of fungicide to prevent infection by C. ficicola should be carried out just after planting of fig cuttings.
Anthracnose was observed in Checkerberry plant (Gaultheriaprocumbens L.) in northern area of Hyogo Prefecture in October 2010. The causal agent was identified as Colletotrichum gloeosporioides on the basis of its morphology and molecular characteristics in an inoculation test, it was found to cause leaf rot. To the best of our knowledge,this is the first report on Anthracnose in Checkerberry plant in Japan.
Here, we investigated the effect of disinfection on seeds infected and damaged by Pyricularia oryzae parasitizing rice husk. In all the cases, seed disinfection was highly efficient in controlling the parasitic infection of the surface of rice seeds. Paticularly, application of a solution of benomyl, known for its fungicidal properties, had high efficacy in controlling this pathogen; however,sterol demethylation inhibitors had low efficacy. Further, the effect of disinfection on heavily damaged seeds showing later stages of infection was low.
We examined the effects of 10 fungicides in field conditions in order to establish an effective fungicide application program forsooty blotch in Japanese apricot. Captan, ditianon and difenoconazolewere more effective than the other seven fungicides tested duringtwo years of field testing. Therefore, we designed an effective fungicideapplication program, in which ditianon and captan were sprayed asthe initial application followed by difenoconazole. This is more efficientthan conventional fungicide application programs.
Control of bacterial soft rot in Chinese cabbage by fluazinam SC was evaluated in a vinyl-coated field. Fluazinam solution was applied onto the vinyl-coated field before or after opening the plantingoles. Both spray timings enabled to control bacterial soft rot. This application method can be used under the appropriate timing depending on the state of cultivation and can lead labor saving.
A population survey of thrips and of whitefly was conducted on eggplants and cucumbers in greenhouses with and without naturalenemies, Nesidiocoris tenuis and Amblyseius swirskii. Density of thrips and whitefly on cucumbers had been below the control threshold density (one individual per leaf) during survey period. Similarly, thrips density was below the control threshold density on eggplants in greenhouse with N. tenuis and A. swirskii. On the other hand, whitefly densities on eggplants were temporarily beyond the control threshold level. Nevertheless, no substantial economic loss was observed. Pesticide use in greenhouses with N. tenuis and A. swirskii was less than that in greenhouse without these natural enemies.
We investigated the effects of four insecticides on wolf spiders (Lycosidae). In the field, cypermethrin reduced spider populations until 1 week later, but acetamiprid, spinosad, and pyridalyl had no observable effect. In the laboratory, spinosad caused little harm to spiderlings of Pardosa astrigera L. Koch (Lycosidae).
Wild soybean consumption by four species of lepidopteran larvae was investigated to get basic data for an environmental assessment of Bt soybean. Fourteen species were preliminarily tested. The leaf area eaten by the last instar larvae were 295, 33.2, 17.3 and 16.3 cm2 for Cifuna locuples confuse, Pleuroptya ruralis, Paragabara ochreipennis and Archips semistructa, respectively.
Box-tree pyralid, Glyphodes perspectalis(Walker), is one of the serious lepidopterous insect pests of box trees. In late April 2014, this insect pest occurred and heavily injured the box trees in our center, which is located at Toyohashi city in Aichi Prefecture. Therefore, the susceptibility of G. perspectalis to 18 insecticides was evaluated by the leaf-dipping method. Of the 18 insecticides tested, 14 gave 100% mortality at their respective commercially used concentrations. In particular, fipronil, spinosad, and spinetoram exhibited very high insecticidal activity.
In addition, PAP, thiodicarb, flubendiamide, metaflumizone, and pyridalyl exhibited high insecticidal activity. Comparison of the insecticidal susceptibility of G. perspectalis with that of the common cutworm, Spodoptera litura (Fabricius), showed that G. perspectalis was more susceptible than S. litura except against lufenuron.
These results indicate that G. perspectalis can be easily controlled by using insecticides effective against S. litura.
The susceptibility of the white peach scale, Pseudaulacaspis pentagona (Targioni) (Hemiptera: Diaspididae) to pesticide was evaluated by potato tuber dipping method. Among nine pesticides tested on the white peach scale eggs, chlorpyrifos, DMTP (methidathion), pyriproxyfen, buprofezin, chlorfenapyr, and pyrifluquinazon caused high mortality. Among the 15 pesticides testedon first instar larvae, chlorpyrifos, DMTP (methidathion), fenpropathrin, pyriproxyfen, machine oil emulsion and chlorfenapyr were more toxic. Among the nine pesticides tested on second instar larvae, no pesticides were effective.
We designed two bioassay methods, leaf spraying and leaf dipping,to examine pesticide toxicity in the first instar larvae of melon thrips, Thrips palmi Karny. The corrected mortalities of the larvae for four pesticides (chlorfluazuron, flufenoxuron, spirotetramat, andpolyoxin AL) were 26.6–93.7% in the leaf spray method and 26.8–64.9%in the leaf dip method. Our methods could be used to evaluate pesticidetoxicity in the larvae of thrips.
The nematicide imicyafos applied to Malabar spinach (Basella alba) showed high control effect on the root-knot nematode. The agrochemical residues in the Malabar spinach were 0.04 ppm at the stems and leaves and 0.10 ppm at the broad leaves after 30 days of soil-mixing treatment; later, the imicyafos residues gradually decreased. Here we discuss the application for the registration of imicyafos for use in Malabar spinach.
The prevention of sweetpotato whitefly, Bemisia tabaci (Gennnadius) by combined application an entomopathogenic fungi, Paecilomyces tenuipes pesticide and physical control pesticides was examined under laboratory and greenhouse conditions. In the laboratory, the control effects by the combined application that two pesticides were mixed with under the half concentration of standard usage were higher than single pesticide treatment with standard concentration. Moreover, this effect was confirmed under low relative humidity, 40RH. Improvement of the control effect was confirmed under the greenhouse condition.
The diamondback moth (Plutella xylostella) is a serious pest to many cruciferous vegetables. Several entomopathogenic fungi were collected from the larvae of P. xylostella from fields in Gifu prefecture, Japan. We obtained four isolates of the entomophthoralean fungus, Erynia blunckii, which was considered a major natural enemy to P. xylostella in Japanese radish fields in Takasu, Gifu. The character of the fungus as a biocontrol agent was investigated. These isolates showed over 20 times higher conidia production than Zoophthora radicans isolates obtained from Takasu. A dose mortality assay on the E. blunckii isolate T10A showed that the LC50 value for 4th instar larva was 3.73 conidia/mm2.