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Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is an important agricultural insect that infests a wide range of vegetables and fruits. To investigate the occurrence of thelytokous and arrhenotokous types of onion thrips and the effects of insecticides on them, we collected individuals from onion and Welsh onion fields in Shiga Prefecture, Japan. Of the 16 sampling sites, only thelytokous-type individuals were found at 12 sites, whereas arrhenotokous-type individuals co-habited four sites alongside the thelytokous type. Arrhenotokous-type individuals were subsequently eliminated from three sites, but they remained dominant at one site. The effects of insecticides (corrected mortality) were investigated using the leaf dipping method and a Bayesian model on five strains of the thelytokous type and one strain of the arrhenotokous type. The results showed that acephate (500 ppm), acetamiprid (100 ppm), spinetoram (48 ppm), fluxametamide (50 ppm), and flometoquin (100 ppm) were sufficiently toxic, and more than 70% corrected mortality at the lower limit was achieved for both the arrhenotokous and thelytokous types after 48 hours of exposure to these insecticides. The corrected mortality of cypermethrin (30 ppm) was over 90% at the lower limit for the thelytokous types but was 73.6% at the upper limit for the arrhenotokous type. The corrected mortality of pyridalyl (100 ppm) for the thelytokous types varied among the strains； it was over 70% in one strain and under 70% in four strains at the lower limit and less than 50% for the arrhenotokous type at the upper limit. [ABSTRACT FROM AUTHOR]

We evaluated the effectiveness of vapor heat treatment on Thrips palmi Karny, Bemisia tabaci(Gennadius), and colonies of powdery mildew, Sphaerotheca fuliginea(Schlechtendal)Pollacci, on greenhouse melon seedlings. Air was gradually heated to a set temperature(48°C)over 45 min while the relative humidity was maintained at 95%. The set temperature was then held for 8 min. The numbers of T. palmi adults and larvae, B. tabaci adults, and colonies of powdery mildew were lower on seedlings held at 48°C for 8 min than on untreated seedlings. The hatchability of T. palmi and the ratio of emerged adults were lower on treated than on untreated seedlings. Treatment at 48°C for 8 min did not visibly damage the seedlings. These results suggest that vapor heat treatment at 48°C for 8 min can effectively reduce the population densities of T. palmi eggs, larvae, pupae, and adults, B. tabaci adults, and powdery mildew on greenhouse melon seedlings. [ABSTRACT FROM AUTHOR]

Liothrips wasabiae Haga and Okajima (Thysanoptera: Phlaeothripidae) was previously found only on field-cultivated wasabi (Eutrema japonicum) in the Chugoku region ( west Honshu, Japan) . However, it was found on water-cultivated wasabi in Shizuoka Prefecture (central Honshu, Japan) in 2016, where wasabi is cultivated in terraced fields with high humidity saturated by mountain streams. Unlike fieldcultivated wasabi, sprayed insecticide on water-cultivated wasabi is susceptible to dilution due to the high humidity and mist. Therefore, we conducted an experiment to determine the lethal effects of three neonicotinoid insecticides on adult and larval L. wasabiae at concentrations below the normal dilution, since both the adult and larval insects usually occur concurrently. The three neonicotinoid insecticides registered to the insect are dinotefuran, nitenpyram, and imidacloprid. The results revealed that dinotefuran and nitenpyram demonstrated greater insecticidal activities against both the adult and larval L. wasabiae than imidacloprid; however, all three insecticides, when used in lower concentrations than normal, proved less effective. This indicates that dinotefuran and nitenpyram may be used when sprayed insecticide is likely to be diluted, such as in water wasabi fields, even when both adult and larval insects occur simultaneously, taking into consideration the reduced insecticidal effect. [ABSTRACT FROM AUTHOR]

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We evaluated the effectiveness of using an indigenous generalist predatory mite, Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae), to control Thrips palmi Karny (Thysanoptera: Thripidae) in greenhouse melons. In a growth chamber experiment, the density of T. palmi was lower on plants exposed to 20 N. barkeri per plant than on plants grown without a biological control. In a greenhouse experiment, the density of T. palmi was lower in the N. barkeri release plots than in the no-release plots. These results suggest that N. barkeri is an effective biological control agent against T. palmi. [ABSTRACT FROM AUTHOR]

In recent years, damage caused by flower thrips, Frankliniella intonsa（Trybom）（Thysanoptera: Thripidae）, has spread in strawberry fields throughout Japan. Furthermore, cases of F. intonsa developing resistance to existing insecticides have been reported. In this study, to investigate the presence of symbiotic bacterial infections, F. intonsa samples were collected from strawberry fields in Oyama City, Tochigi Prefecture. Symbiotic bacteria are known to affect the survival, reproduction, sex ratio, and insecticide susceptibility of their hosts. Diagnostic polymerase chain reaction and sequencing analysis showed that a portion of the surveyed population of F. intonsa（30.8%） were infected with the symbiotic bacterium Wolbachia. Notably, the Wolbachia infection rate of larvae rapidly increased from 17.4 to 44.8% within just 1 month. These results suggest that Wolbachia infection may have benefitted the host. This is the first report of Wolbachia infection in a population of Japanese F. intonsa. Future studies investigating the function of Wolbachia may facilitate the development of novel methods for controlling thrips using symbiotic bacteria. [ABSTRACT FROM AUTHOR]

The phlaeothripid fauna of Okinawa Prefecture, Japan was investigated in and around cultivated fields during 2009–2018. A total of 295 individuals representing four species belonging to the genus Haplothrips were collected from weeds comprising a wide range of plant taxa. The collected specimens included Haplothrips chinensis (87.5%) as well as H. aculeatus, H. ganglbaueri, and H. gowdeyi. Haplothrips brevitubus, which is commercially available in Japan, was not found. Almost all the phlaeothripid individuals collected from the crop fields were identified as H. chinensis. The most common phlaeothripid thrips in our surveys, H. chinensis, was often collected with thripid thrips. We first evaluated the predatory potential of H. chinensis and H. gowdeyi for Thrips palmi in the laboratory. Our results demonstrated that H. chinensis could consume as many larvae of T. palmi as was observed for H. brevitubus. The mean developmental periods of the three species were also examined at 25, 20, and 15°C under long-day (16L:8D) and short-day (10L:14D) conditions. The results of the laboratory tests and field surveys indicated that H. chinensis may have a high potential as one of the key indigenous natural enemies of thripid thrips in subtropical areas. [ABSTRACT FROM AUTHOR]

The effects of insecticides on arrhenotokous and thelytokous types in adult females of onion thrips, Thrips tabaci Lindeman, collected from a total of 13 sites of Welsh onions, cabbages, and onions in Kyoto Prefecture, Japan, in 2016 and 2017 were evaluated. Susceptibility to the tested insecticides varied among the reproductive types, populations, and years. Among the 14 insecticides tested on female adults in arrhenotokous type using the kidney bean leaf dipping method, spinetoram, spinosad, avermectin, cyantraniliprole, fluxametamide, and flometoquin were the most toxic. In addition, cypermethrin, imidacloprid, spinetoram, spinosad, avermectin, cyantraniliprole, fluxametamide, and flometoquin caused a high mortality rate in female adults in thelytokous type. Overall, the mortality rate in thelytokous type was higher than that in arrhenotokous type. [ABSTRACT FROM AUTHOR]

The relative abundance of the reproductive types of Thrips tabaci Lindeman was occasionally surveyed by collecting female adults from the foliage of commercially grown Welsh onions, onions, and cabbages at various locations in Kyoto Prefecture between 2016 and 2018. Arrhenotokous females were found at 39 of the 46 surveyed sites and coexisted with thelytokous females at 26 sites, of which the arrhenotokous composition was higher than that of thelytokous at 19 sites. The arrhenotokous type was dominant in Kyoto City and Kumiyama Town, and thelytokous females were found to be dominant in the areas north of Fukuchiyama City. In cabbage, only arrhenotokous females were observed. The seasonal composition of T. tabaci reproductive types was additionally surveyed in Welsh onion plants grown in greenhouses in Kameoka City, Kyoto Prefecture, between November 2016 and June 2019. Thelytokous females were dominant between November 2016 and March 2017 and arrhenotokous females dominated between April 2017 and March 2018, except for January 2018. After May 2018, the thelytokous type dominated again. [ABSTRACT FROM AUTHOR]

Phytoseiid mite species were surveyed on garden and wild plants in an experimental field in Japan. The above-ground part of the plants were collected from the field, and dried in the laboratory to collect phytoseiid mites from the plant-parts. When the plant-parts were dried on the bean leaflets rearing Thrips tabaci larvae, phytoseiid mites on the plant-parts moved to and remained on the leaflets during two-day treatment. Populations of Typhlodromips sessor and Neoseiulus makuwa were established when fed on T. tabaci. Then, the life history parameters of both species were examined in the laboratory. In comparison with the data from previous studies, the daily oviposition of both species was similar to that of Amblyseius eharai, Neoseiulus barkeri, and Neoseiulus cucumeris, and the survival rate during the development of both species was similar to that of N. barkeri. The mode of reproduction of T. sessor was confirmed by the experiment as parthenogenetic thelytokous reproduction. [ABSTRACT FROM AUTHOR]

he survival and development of strain C of Scirtothrips dorsalis Hood（Thysanoptera: Thripidae）reared on the leaves of Capsicum annuum, were studied at temperatures ranging from －5°C to 35°C, and the abundance of thrips of strain C living on strawberry（Fragaria×ananassa Duch.）plant bodies were investigated under outdoor conditions in Kochi Prefecture, Japan, from October to April 2013–14 and 2014–15. A positive linear relationship was observed between the development rate from egg to adult and temperature in the range of 17.5°C to 32.5°C, allowing the calculation of a lower threshold of 12.4°C for development and a thermal constant of 200.0 degree-days（DD）. An exposure time of nearly 3.5 days at 0°C and nearly 2.5 days at －5°C killed 50% of the adults. In contrast, over half of the 2nd instar larvae survived for more than 5.5 days at 0°C and more than 3 days at －5°C, while approximately 20% of the larvae exposed to －5°C for 3 days emerged as adults at 25°C. In the field experiment, both adults and larvae disappeared from the strawberry plants by the end of February 2014 and 2015, with no individuals being found from March onward in either year. These findings suggest that strain C of S. dorsalis is unlikely to survive for the duration of a mild winter under outdoor conditions in Kochi Prefecture, but individuals could survive for a few days, even at temperatures below －5°C. [ABSTRACT FROM AUTHOR]

Abstract: The potential for the successful overwintering of female tobacco thrips, Frankliniella fusca（Hinds）（Thysanoptera: Thripidae）, and seasonal changes in their oviposition and wing form composition were assessed through rearing trials under outdoor conditions in Kyoto City from 2009 to 2010. Almost all overwintering female adults did not lay eggs in January and February. Some laid only a few eggs in March and early April, although these eggs did not complete development to the adult eclosion stage. Hibernation at the larval and pupal stages was not observed during the study period. Macropterous females emerged between late May and late September, with their proportion peaking （72.1%）in August ; however, they did not emerge during other periods. In contrast, all females that moulted into adults between October and December as well as in mid-May were brachypters. These results suggest that under outdoor conditions in Kyoto the invasive agricultural pest F. fusca does not reproduce throughout winter and that macropterous females emerge into adults only in summer. [ABSTRACT FROM AUTHOR]

The effects of red-light irradiation and a reflective sheet cover on the population density of two thrips species（Thysanoptera: Thripidae）, the melon thrips（Thrips palmi Karny）and the onion thrips （Thrips tabaci Lindeman）, were investigated on eggplant and cucumber in a greenhouse in 2014 and 2015. Red fluorescent lamps were illuminated from above the plants and a light reflecting sheet was placed on the ridges of the treated plots. A greenhouse without either material was set up as a control plot. The population densities of the two thrips species on eggplant and T. palmi on cucumber were significantly lower in the treated plots than in the control plot. [ABSTRACT FROM AUTHOR]

We investigated the effects of abiotic environmental factors on spring flight initiation of Scirtothrips dorsalis Hood（Thysanoptera: Thripidae）by monitoring the number of its overwintered adults captured by yellow sticky traps in a Japanese pear orchard from 2012 to 2015. More S. dorsalis were captured on sticky traps placed at 50 cm above ground level in the plot where pear trees were dense than in the plot where trees were sparse, which suggests that many adults overwintered inside of pear orchards. More S. dorsalis were captured on traps placed at 50 cm above ground level than at 200 cm above, which suggests that sticky traps at 50 cm above ground level were suitable for monitoring the overwintered generation of S. dorsalis. A logistic regression analysis revealed that the capture probability（Pc）of overwintered adults was positively correlated with the daily maximum temperature and the hours of sunlight, and negatively correlated with the daily mean wind speed. More than 99% of S. dorsalis were captured when the maximum temperature exceeded 17.5°C, the mean wind speed was ≤2.7 m/s, or sunlight was ≥3.7 h/d. The date of peak capture of overwintered S. dorsalis could be estimated more accurately from the total effective temperature calculated from January 1 combined with the Pc value than from the total effective temperature alone. [ABSTRACT FROM AUTHOR]

Blue and yellow sticky traps are often used for the monitoring of thrips（Thripidae）and whitefly（Aleyrodidae）, respectively, in tomato greenhouses. Little is known, however, about the appropriate number of traps that would facilitate monitoring of these pests using statistical methods. We analyzed the mean density and sample variance of thrips and whiteflies per trap, and it was revealed that both the trapped thrips and whiteflies were distributed contagiously. To monitor these pests with less effort, the precise density estimation method using a relative density index was considered. In this method, the mean density and sample variance of the low-density block are estimated from those of the high-density block. The distributed pattern of whiteflies did not change between the measured and estimated values, and the estimated proper number of traps was reduced with the estimation method. In contrast, that of thrips differed between the measured and estimated values, and the necessary number of traps should be calculated from the measured values. In this greenhouse, where a mass trapping with colored traps（each 200 sheets/10 a）was carried out, the estimation method was useful in monitoring whitefly. To expand the versatility of this method, further validation of different numbers of installed traps, types of cultivation, and greenhouses will be required. [ABSTRACT FROM AUTHOR]

The local density of natural enemies, which provide biological control, can be affected by the surrounding landscape and by local field management. We examined how landscape factors and non-selective insecticides influenced the abundance of predatory bugs of the genus Orius, which provide effective biological control on eggplant, from June to September 2013. We investigated the numbers of these bugs in 13 eggplant fields across four regions of Nara prefecture, Honshu, Japan. Areas of different land-use types around the fields were estimated from GIS data in circular buffer zones with radii ranging from 100 to 1,000 m （intervals of 100 m）. Using a generalized linear model and Akaike’s Information Criteria, we analyzed the effects of landscape element, landscape heterogeneity and use of non-selective insecticides on the abundance of Orius spp. Landscape elements within a 200-m radius affected abundance: the abundance of Orius spp. was higher in landscapes with a mixture of urban and agricultural areas than in landscapes dominated by forest. On the other hand, non-selective insecticides did not affect the abundance of Orius spp. This result suggests the importance of landscape factors in determining the local abundance of Orius spp. [ABSTRACT FROM AUTHOR]

We measured the phototactic behavior of the western flower thrips, Frankliniella occidentalis(Pergande) under the LED light of various spectral content and intensity. The light intensity required to elicit a 50% behavioral response to the stimulus yielded the action spectrum of the phototactic behavior. The action spectrum peaks at 525 and 355 nm, between 355 to 660 nm. This profile reasonably fits the spectral sensitivity of the compound eye as determined by the electroretinographic method. In a choice experiment where the insects were subjected to select either 355 nm or 525 nm of equal photon flux, they preferred 355 nm to 525 nm, indicating that the insects prefer ultraviolet (UV) radiation under the condition of multiple light sources. [ABSTRACT FROM AUTHOR]