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From the 992 samples of culture extracts of microorganisms isolated from soil in Japan, we found that the extract of Streptomyces sp. no. 226 inhibited Orobanche minor seed germination without significantly affecting the seed germination of Trifolium pratense and the growth of Aspergillus oryzae and Escherichia coli. Using ESI-MS, 1H-NMR, and 13C-NMR, we identified the active compound as cycloheximide. Cycloheximide had half-maximum inhibitory concentrations of 2.6 ng/mL for the inhibition of seed germination of O. minor and 2.5 µg/mL for that of the conidial germination of A. oryzae. Since cycloheximide is known to inhibit translation by interacting with ribosomal protein L28 (RPL28) in yeast, we investigated whether RPL protein of O. minor plays a critical role in the inhibition of O. minor seed germination. Our data suggested that O. minor RPL27A was not sensitive to cycloheximide by comparing it to the strain expressing S. cerevisiae RPL28. These findings suggest the presence of an unidentified mechanism by which cycloheximide hinders O. minor seed germination. [ABSTRACT FROM AUTHOR]

The mango gall midge Procontarinia mangicola (Shi) that infests fresh leaves of mango is an important pest of this plant in southern Japan. We examined the effects of 16 insecticides on the mortality of P. mangicola to find an effective insecticide for the control of this pest insect. After dipping leaves infested by larvae in dilutions of 16 insecticides in the laboratory, corrected mortality defined as highly effective was observed when the leaves were treated with DMTP of organophosphate and ethiprole of phenylpyrazole, two neonicotinoids including nitenpyram and dinotefuran, two spinosyns including spinosad and spinetoram during the larval stage. Although the mortality was 0% at larval stage after treatment with pyrifluquinazon, 88.2% of gall midges died during from leaving the leaves as mature larvae to adult emergence. In greenhouses, the number of galls was significantly reduced on mango trees sprayed with DMTP or dinotefuran compared with non-sprayed control trees. The insecticidal effect was detected when spraying of dinotefuran was made even before the appearance of new leaves that were later infested by gall midges. These results would be useful in selecting effective insecticides for the control of mango gall midges and for the registration as agricultural chemicals. [ABSTRACT FROM AUTHOR]

Slow-acting fipronil is one of the best components for controlling invasive ants. However, its efficacy against invasive Lepisiota frauenfeldi, which recently invaded Japan, remains unclear. Here, its acute toxicity to Le. frauenfeldi was assessed, and its lethal concentrations were compared with those against other invasive ants (Linepithema humile and Solenopsis invicta). The LC10 and LC50 values of fipronil for Le. frauenfeldi were significantly lower than the previously reported values for Li. humile and/or S. invicta, and its LC90 value against Le. frauenfeldi was in the same range as that required for Li. humile extermination. Additionally, Le. frauenfeldi can be more sensitive to fipronil than non-target arthropods. Therefore, recent fipronil-based Li. humile and S. invicta eradication/control programs may be effective against Le. frauenfeldi as well. Moreover, applying fipronil at dosages appropriate for Le. frauenfeldi would lead to effective Le. frauenfeldi extermination/control with low damage to other native species/ants. [ABSTRACT FROM AUTHOR]

Prompt responses to invasive Latrodectus spiders introduced unintentionally are needed worldwide due to their medical and ecological importance. Latrodectus species are chemically controlled using pyrethroid insecticides despite concerns about the ecological impacts of these compounds on biodiversity/ecosystems. Here, the relative sensitivities (acute toxicity: 48-h LC50) of Latrodectus hasseltii Thorell and Latrodectus geometricus C.L. Koch from Japan to the conventional neurotoxic insecticide bifenthrin (pyrethroid) and a new candidate insecticide, fipronil (phenylpyrazole), were examined. Acute residual toxicity tests of these compounds in two nontarget spiders (Parasteatoda tepidariorum C.L. Koch (Araneae: Theridiidae), Badumna insignis L. Koch (Araneae: Desidae)) were conducted for comparison. To test whether bifenthrin and fipronil toxicities differed among the four spiders, corresponding species sensitivity distributions (SSDs) were compared, and hazardous concentrations were determined. Sensitivity (especially in the nontarget species) was two to four orders of magnitude higher for bifenthrin than for fipronil. The SSD patterns of the two insecticides differed significantly, with the spider communities being more sensitive to bifenthrin than to fipronil. The lethal bifenthrin concentration for Latrodectus may reduce spider populations by over 70–90%. If L. hasseltii (established throughout Japan) is targeted for effective population suppression rather than L. geometricus (with a limited distribution range) using the specified insecticide concentration (LC50 value) for fipronil, less than 20% of spider communities will be impacted. Chemical operations aimed at the effective population management and subsequent eradication of invasive Latrodectus spiders while supporting local biodiversity conservation would benefit from considerations of fipronil dosages and target species sensitivities. [ABSTRACT FROM AUTHOR]

The largemouth bass Micropterus salmoides (Lacépède, 1802) is a highly invasive freshwater species, and has a considerable impact on the diversity of indigenous aquatic organisms. We hypothesized that mature males released sex pheromones to attract mature females to their nests. To develop an effective method for controlling the population in a lake of northern Japan, we studied the efficacy of using bile collected from mature males with the bioactive function to attract mature females. A trap was devised to evaluate the attraction of sample solutions from males and to test practical uses of the pheromone. In the spawning season, when bile from reproductive males (RB) was introduced into the traps, female catches in the trap were significantly higher than when bile from non-reproductive males (NRB) or controls were used. In the non-spawning season, the female largemouth bass did not show any preference for RB. Other fish species did not show any preference for RB in both the spawning and non-spawning season. This study shows that RB contains a sex pheromone that attracts mature females, suggesting that pheromone traps could possibly be used to control largemouth bass populations. [ABSTRACT FROM AUTHOR]

The tomato red mite, Tetranychus evansi Baker and Pritchard, is a herbivore specialized on solanaceous plants, which has rapidly spread through the world during the last decade. It causes serious damage to a variety of crops in Africa and Europe but has not yet been reported to damage solanaceous crops in Japan. Tetranychus evansi is known to occur in Japan and it has the potential to become a severe pest on solanaceous crops here as well. The present study determined the susceptibility of nine T. evansi strains from various countries to 11 acaricides, because chemicals will be used as the first line of control against a new pest when it starts to cause severe damage to crops. Bifenazate, cyenopyrafen, milbemectin, spirodiclofen and tebufenpyrad showed higher toxicity - as indicated by 50% lethal concentrations (LC50) - for imagocidal action, and chlorfenapyr showed higher LC50 for ovicidal action in almost all T. evansi strains, compared with a susceptible strain of Tetranychus kanzawai Kishida. Still, the LC50 of imagocidal action of all acaricides, and for ovicidal action of all but one (cyflumetofen), on all nine strains tested was much lower than the recommended concentrations. These results suggest that mites from all nine strains could be controlled with acaricides as a first method, should they occur in high numbers on crops. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated the effects of two neonicotinoid insecticides (thiamethoxam and dinotefuran) on alien wood borer Aromia bungii, which invaded Japan recently. Small neonates and large larvae were fed artificial diet with different insecticide concentrations and then reared for 3 (neonates) or 12 (large larvae) weeks in the laboratory. Diet excavation immediately dropped in larvae exposed to high concentrations of both insecticides (≥1 ppm in neonates and ≥10 ppm in large larvae). Their growth was significantly suppressed, and the survival rate gradually declined over time (≥87% decline over 12 weeks in large larvae). These effects were similar between neonates and large larvae, but neonates were affected more by lower insecticide concentrations than large larvae. The two insecticides gradually debilitate A. bungii larvae. In practical use, rapid suppression of A. bungii wood boring damage can be expected by injecting these insecticides into infested trees. However, a relatively long–term retention of the insecticides may be required to kill the larvae in the trees, especially large larvae. Neonates may be controlled with less insecticides and shorter exposure than large larvae. In recent years, insecticide trunk injection was put into practical use for controlling wood boring pests. However, few studies have investigated the dose–response relationships between insecticides and wood–boring pests in detail. This study used two commercial formulations of the neonicotinoid insecticides thiamethoxam and dinotefuran and investigated their dose–response relationships with invasive wood borer Aromia bungii (Coleoptera: Cerambycidae) larvae. Neonates and late instar larvae were reared with an artificial diet containing different insecticide concentrations (0.01–100 ppm) in the laboratory, and their diet excavation activity, survival rate, and weight change were recorded. Diet excavation immediately dropped in larvae exposed to high concentrations of thiamethoxam or dinotefuran (≥1 ppm in neonates and ≥10 ppm in late instar larvae). The weight and survival rate gradually declined over 12 weeks in late instar larvae. These results suggest that the two neonicotinoids intoxicate and debilitate A. bungii larvae gradually to death. In practical use, rapid suppression of A. bungii wood boring damage can be expected by trunk injection of neonicotinoid insecticides. However, a relatively long-term retention of the insecticides may be required to kill large larvae. Neonates may be controlled with lower insecticide dosage and shorter exposure than larger larvae. [ABSTRACT FROM AUTHOR]

In Japan, Hirschmanniella diversa is an important pest in lotus cultivation in paddy fields and only lime nitrogen is registered for its control. Therefore, additional nematicides are required to control the nematode. The objective of this study was to screen for an effective nematicide. Fourth-stage juveniles and adults of H. diversa sampled from a lotus field were tested in in vitro solution experiments against 37 pesticides that are registered for the pest control of crops in Japan. Carbamate-based benfuracarb, organophosphate-based fenthion, nereistoxin-based cartap hydrochloride and cyanamide showed nematicidal effects against H. diversa. Benfuracarb at 1 μg/mL showed a nematostatic effect on H. diversa in an agar plate assay. Further, H. diversa treated with benfuracarb did not resume activity 7 days post nematicide treatment when transferred to distilled water. Benfuracarb was tested in micro-field experiments, in which H. diversa density and lotus tuber damage levels were monitored. Results showed that benfuracarb reduced H. diversa densities in the roots during the cultivation period in 2012 and consistently reduced damage levels during a five year study period. Thus, benfuracarb is recommended as an effective nematicide to be used for H. diversa control in lotus cultivation. [ABSTRACT FROM AUTHOR]