• Korean journal of applied entomology
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• v.42 no.4
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• pp.301-305
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• 2003

This study investigated the ecological characteristics of Frankliniella occidentalis on four horticultural crops. On red pepper leaves, larval developmental period and survival rate of F. occidentalis were 6.4 days and 67%, respectively. While adult female lived longer on cucumber leaves as long as 16 days, on Petal lived 8.1 days. F. occidentalis adult female preferred tomato to eggplant, cucumber and red pepper, and higher number of hatched larva were from leaves of middle part of egg-plant compared with those from other parts. F. occidentalis adult female fed preferably on petal compared with leaves and Petals of eggplant, and among petals of four tested plants, the most preference was those of red pepper.

• Korean journal of applied entomology
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• v.53 no.1
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• pp.65-71
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• 2014

Frankliniella occidentalis is attracted to flowers and is a major pest of chrysanthemums. Even when some chrysanthemum plants are not flowering, the ones that have already flowered attract F. occidentalis. Therefore, we investigated the efficacy of chrysanthemum as a trap plant that attract F. occidentalis by using an olfactometer. The numbers of F. occidentalis collected from the flowers of pink, wihte and yellow standard chrysanthemums on a tray with wet paper during the flowering period were 18.4, 56.6, and 52.6 respectively; the numbers of F. occidentalis collected from leaves were 7.8, 16.6, and 15.4 respectively. the numbers of F. occidentalis collected from the buds of pink, white and yellow standard chrysanthemums were 15.2, 45.8, and 41.6 respectively; the numbers of F. occidentalis collected from the leaves were 2, 8.8 and 3.4 respectively. In the Y-tube olfactometer test, the number of F. occidentalis attracted to the 2-way arms of the Y-tube was not significantly different for the yellow, red, violet and white flowers. In the four-choice olfactometer test, when the same visual cues and odor cues were provided, the frequency of F. occidentalis was higher in the yellow (10.7) flowers than in the red (1.3), violet (3.7) and white (2.0) flowers. When visual cues with disturbed odor cues, F. occidentalis preferred yellow (10.0) color over red (3.3), violet (1.3) and white (3.0) colors. When the same visual and odor cues, except for yellow visual cues, were provided, F. occidentalis preferred white (8.3) color over red (4.7), violet (4.7) and yellow (2.0) colors. Therefore, F. occidentalis were attracted to buds before the flowering of chrysanthemum plants and attracted to yellow flowers after the flowering.

• Korean journal of applied entomology
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• v.61 no.3
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• pp.409-422
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• 2022

Two dominant thrips in hot pepper (Capsicum annuum) cultivating in greenhouses are Frankliniella occidentalis and F. intonsa in Korea. This study investigated their overwintering physiology. These two thrips were freeze-susceptible and suppressed the body freezing temperature by lowering supercooling point (SCP) down to -15~-27℃. However, these SCPs varied among species and developmental stages. SCPs of F. occidentalis were -25.7±0.5℃ for adults, -17.2±0.3℃ for pupae, and -15.0±0.4℃ for larvae. SCPs of F. intonsa were -24.0±1.0℃ for adults, -27.0±0.5℃ for pupae, -17.2±0.8℃ for larvae. Cold injuries of both species occurred at low temperature treatments above SCPs. Thrips mortality increased as the treatment temperature decreased and its exposure period increased. F. occidentalis exhibited higher cold tolerance than F. intonsa. In both species, adults were more cold-tolerant than larvae. Two thrips species exhibited a rapid cold hardening because a pre-exposure to 0℃ for 2 h significantly enhanced the cold tolerance to a lethal cold temperature treatment at -10℃ for 2 h. In addition, a sequential exposure of the thrips to decreasing temperatures made them to be acclimated to low temperatures. To investigate the overwintering sites of the two species, winter monitoring of the thrips was performed at the greenhouses. During winter season (November~February), adults of the two species were not captured in outside of the greenhouses. However, F. occidentalis adults were captured to the traps and observed in weeds within the greenhouses. F. occidentalis adults were also emerged from soil samples obtained from the greenhouses during the winter season. F. intonsa adults did not come out from the soil samples at November and December, but emerged from the soil samples obtained after January. To determine the adult emergence due to diapause development, two thrips species were reared under different photoperiods. Adult development occurred in all photoperiod treatments in F. occidentalis, but did not in F. intonsa especially under short periods. Tomato spotted wilt virus, which is transmitted by these two species, was detected in the weeds infested by the thrips during the winter season. These results suggest that F. occidentalis develops on weeds in the greenhouses while F. intonsa undergoes a diapause in the soil during winter.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.229-236
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• 2009

Cage experiments by artificial infestations with different initial densities of Frankliniella occidentalis were conducted to analyze damages and develop control thresholds of F. occidentalis on greenhouse eggplant in 2005 and on greenhouse sweet pepper in 2007. In the eggplant experiment, the infestations of F. occidentalis resulted in direct damage on fruit surface and non-marketable fruits which had several thin or thick lines or bleaching patches on the surface. F. occidentalis adults were frequently found on the flowers of eggplants, while nymphs were mainly observed on leaves. The fruit yield of eggplants was not significantly different among experimental plots with different initial density of F. occidentalis. Relationship between % non-marketable fruits among harvested fruits of eggplant and sticky trap catches of F. occidentalis (no. thrips/trap/week) at two weeks before the harvest showed a positive correlation. Using the estimated relationship, the control threshold of F. occidentalis on greenhouse eggplant was estimated at 10 adults per week at two weeks before the harvest when 5% of non-marketable fruit was applied for the gain threshold. In the experiment of sweet pepper, the direct damage by F. occidentalis was observed on the fruit surface and calyx, and the marketable grade of the damaged fruits decreased. The significant yield loss of marketable fruits was found in plots with high initial introduced-densities. There was a high relationship between thrips density and percentage of damaged fruits. Assuming 5% yield loss (non-marketable fruit) for the gain threshold, the control threshold of F. occidentalis on greenhouse sweet pepper was 4.8 adults per trap and 0.9 individuals per flower at two weeks before harvest.

• Korean journal of applied entomology
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• v.37 no.1
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• pp.53-58
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• 1998

Comparative studies on some ecological characteristics of three phytoseiid mitespecies (one native; Arnblyseius womersleyi Schica, and two introduced species; A. fallacis Garmanand Typhlodromus occidentalis Nesbit) were carried out. The two-spotted spider mite (Tetranychusurticae Koch) was supplied as prey. Under four constant temperatures of 20, 23, 25 and 30f OS$^{\circ}$C,duration of growth from egg to adult for A. womer.vleyi was 11.5, 7.7, 6.7 and 5.6 days. While twoother species needed slightly shorter time but not significantly different. Critical temperature andeffective degree-days (DD) of A. womerslevi females were 83$^{\circ}$C and 1 1 1.6 DD, whereas those of A..fallacis were 10.7"C and 86.0 DD, and those of 7: occidentalis were 10.7"C and 94.1 DD. Also, thoseof males were similar to their females. Average longevity of females of A. womersleyi, A. fallucisand 7: occidentalis were 18.2 k 8.67, 19.6 3~7.18 and 13.0f5.66 days, total fecundity were 34.3 $-11.93, 39.8k 12.64 and 23.6k8.86, respectively. Under four constant temperatures of 20, 23, 25 and30-t0.S$^{\circ}$C, A. womersleyi consumed 9.1 f2.49, 9.7 k2.00, 9.7 f 2.61, and 10.3 k2.33 eggs of 7:urticae throughout their development. A. ,fizlluc~i.sc onsumed 10.2 k 2.52, 9.7 f2.29, 10.7 f 2.37 and10.1 k2.62 eggs, while, 7: occidentalis consumed 1 1.9 k3.43, 14.2 f4.50, 14.8 k 3.2 1 and 12.7 f2.95 eggs, respectively. Gravid females of A. womersleyi, A. f~zllacis and 7: occidentalis consumed11.4f1.59, 12.5k1.43 and 11.7k3.07 eggs, or consumed 11.9f 2.63, 12.4k3.82, and 12.5f 3.73protonymphs of 7: urticae in a day at 25-30$^{\circ}$C.e in a day at 25-30$^{\circ}$C.

• Journal of Microbiology and Biotechnology
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• v.33 no.6
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• pp.745-752
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• 2023

Gut symbionts play crucial roles in host development by producing nutrients and defending against pathogens. Phloem-feeding insects in particular lack essential nutrients in their diets, and thus, gut symbionts are required for their development. Gram-negative Pantoea spp. are known to be symbiotic to the western flower thrips (Frankliniella occidentalis). However, their bacterial characteristics have not been thoroughly investigated. In this study, we isolated three different bacteria (BFoK1, BFiK1, and BTtK1) from F. occidentalis, F. intonsa, and T. tabaci. The bacterial isolates of all three species contained Pantoea spp. Their 16S rRNA sequences indicated that BFoK1 and BTtK1 were similar to P. agglomerans, while BFiK1 was similar to P. dispersa. These predictions were supported by the biochemical characteristics assessed by fatty acid composition and organic carbon utilization. In the bacterial morphological analysis, BFoK1 and BTtK1 were distinct from BFiK1. All these bacteria were relatively resistant to tetracycline compared to ampicillin and kanamycin, in which BFoK1 and BTtK1 were different from BFiK1. Feeding ampicillin (100,000 ppm) reduced the bacterial density in thrips and retarded the development of F. occidentalis. The addition of BFoK1 bacteria, however, rescued the retarded development. These findings indicate that Pantoea bacteria are symbionts to different species of thrips.

• Korean journal of applied entomology
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• v.56 no.2
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• pp.179-186
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• 2017

This study was conducted to monitor the insecticidal susceptibility of western flower thrip, Frankliniella occidentalis, which damage horticultural crops in the Gyeonggi area. Bioassays were conducted under laboratory and greenhouse conditions by using the recommended concentrations of commercial insecticides being used for the control of thrips. Neonicotinoid insecticides, especially acetamiprid (8%) soluble powder (SP), clothianidin (8%) SC, imidacloprid (10%) wettable powder (WP) and thiacloprid (10%) water dispersible granule (WG) were not toxic to F. occidentalis collected from horticultural crops. However, F. occidentalis collected from vegetable greenhouses was extremely susceptible to acetamiprid + spinetoram (6 + 4%) suspension concentration (SC), clothianidin + spinetoram (6 + 4%) SC and methoxyfenozide + spinetoram (6 + 4%) SC, which resulted in over 90% control of thrips. In the greenhouse test, spinetoram (5%) WG, which caused 100% F. occidentalis mortality in the laboratory test, showed 87.4, 88.0, and 98.3% control at 3, 6, and 9 days after treatment, respectively, while imidacloprid (10%) WP showed below 44% control. From the results of this study, spinosin insecticides, such as more than over 4 and 10% of spinetoram and spinosad, and pyrrole insecticide, such as 5% chlorfenapyr, are recommended for the effective control of F. occidentalis.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.355-363
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• 2023

In addition to causing direct feeding damage to a variety of greenhouse crops, Frankliniella occidentalis also inflicts indirect harm by facilitating the transmission of the tomato spotted wilt virus. Historically, the prevention of F. occidentalis infestations has relied heavily on pesticide use. However, this approach has led to significant side effects in agricultural ecosystems, including the development of pest resistance and challenges in effective prevention. In response to these issues, research has been directed towards identifying alternative substances that circumvent the tolerance developed against chemical pesticides. Extracts from sixty-seven medicinal plants were prepared by soaking them in water for 24 hours at room temperature. These extracts were then applied to adult F. occidentalis, with particular attention to moutan extract treatment. This treatment demonstrated a 100% insecticidal effect on the first day. The moutan extract, specifically, was prepared using 50% ethanol, after which the ethanol and water were removed via a rotary evaporator. The resultant product was then lyophilized into a powder and used after being diluted with water. In indoor experiments, a 40% diluted solution was sprayed onto F. occidentalis, exhibiting a 100% insecticidal effect 24 hours post-treatment. Furthermore, a pot test indicated a 78% insecticidal effect on the first day of application. Ongoing research includes the analysis of active substances that demonstrate exceptional insecticidal properties and the conduct of on-site validation tests. The application of the aforementioned extract is anticipated to be effective in the prevention of F. occidentalis infestations.

• Korean journal of applied entomology
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• v.60 no.4
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• pp.369-377
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• 2021

Mass trapping of the western flower thrips, Frankliniella occidentalis, has been considered as an option to control this pest. This study applied the commercial lures to the hot pepper-cultivating greenhouses and assessed the enhancement of the attracting efficiency by adding to sticky traps. There was no color difference in the attracting efficiency between blue and yellow sticky traps. However, the installation position of the traps was crucial in the greenhouses. The more thrips were captured within host cropping area than outside areas of the crop. In vertical trap position, it was the most optimal to install the traps at the crop crown. Using these installation parameters, the yellow sticky traps captured approximately 1% population of the thrips. To enhance the trapping efficiency, the commercial lures containing aggregation pheromone or 4-methoxybenzaldehyde were added to the yellow sticky traps. However, these commercial lures did not significantly enhance the trapping efficiency compared to the yellow sticky trap alone. In contrast, Y-tube olfactometry assays confirmed the high efficiency of the aggregation pheromone or another plant volatile (methyl isonicotinate) to attract the thrips. Interestingly, these lure components had lower attracting efficiencies compared to the hot pepper flowers. The high attractive efficiency of the flowers was supported by the observation that the commercial lure was effective to enhance the trapping efficiency of the yellow sticky trap against F. occidentalis in Welsh onion (Allium fistulosum) field without any flowers. This study indicates the limitation of the commercial lures in application to hot pepper fields for the mass trapping of F. occidentalis. It also suggests active volatile component(s) from hot pepper flowers to attract F. occidentalis.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.319-330
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• 2022

Andong is a place to culture the great amount of hot pepper (Capsicum annuum L.) in Korea. This study reports a yearly occurrence (March 31~October 25, 2021) of thrips infesting the hot pepper in Andong. Thrips caught to yellow sticky traps were diagnosed by morphological characters and showed two dominant species: Frankliniella occidentalis and F. intonsa. During this period, a total of 107,874 thrips were caught and included F. occidentalis at about 82%, F. intonsa at about 17%, and the other thrips at about 0.3%. There were two main peaks at May~June and at September~October, respectively, in which the total number of thrips was higher in the second peak and most were F. occidentalis. Interestinly, a low level of thrips occurred during July~August was observed and explained by their susceptibility to high temperatures. A laboratory experiment by exposing thrips to high temperatures showed that thrips were susceptible to temperatures higher than 35℃ and not tolerant to 45℃ for 1 h. Indeed, high temperatures higher than 45℃ were recorded in the greenhouses in Andong during July~August. F. occidentalis was more tolerant to the high temperatures than F. intonsa. On the other hand, the thrips showed the highest occurrence peak at July~August in hot pepper-culturing greenhouse in Kangwon, where the average temperatures were mostly lower than those of Andong and no high temperatures higher than 45℃ were recorded during July~August. A viral disease caused by tomato spotted wilt virus (TSWV) was observed in the hot peppers cultured in Andong greenhouses. Multiplex PCR was used to detect the virus along with identification of thrips. With a high record of about 30%, the virus-infected thrips were detected during all the monitoring period. The virulent thrips were identified to be only F. intonsa. These results suggest that F. occidentalis gives a direct damage especially during harvesting period with their high populations while F. intonsa gives indirect damage by transmitting TSWV.