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Frankliniella occidentalis (Pergande) and Thrips flavus (Schrank) (Thysanoptera: Thripidae) cause considerable damage to agricultural crops. In this study, we investigated the variations in the population density of these 2 thrips species in 2 sites (Dabai and Heilongtan) with different insecticide application levels. Bioassays were performed to determine the susceptibility of both thrips species to imidacloprid, abamectin, and high-bromine cyhalothrin in summer. The results showed that the F. occidentalis species were more abundant in Dabai than in Heilongtan during both winter and summer. The proportions of F. occidentalis in winter and summer were 28.32–43.35% and 61.79–76.02%, respectively. Moreover, F. occidentalis resistance against the 3 insecticides was significantly higher than that of T. flavus in both 2017 and 2019. Compared with 2017, the LC50 values of F. occidentalis populations in Dabai to imidacloprid, abamectin, and lambda-cyhalothrin increased to 100.076, 16.52, and 130.44 mg/liter, respectively. The number of F. occidentalis, reaching the proportion of 91.63% in 90 days, was significantly higher than that of the control after imidacloprid treatment. In conclusion, thrips interspecies competition is affected by the irrational use of insecticides, which may cause the replacement of native species by invasive species, thereby leading to an outbreak. [ABSTRACT FROM AUTHOR]

Western flower thrips (WFTs), Frankliniella occidentalis (Thysanoptera, Thripidae), is one of the most serious pests that attack rose flowers. Little is known about the effect of different parts of the rose flower on nutritional contents and digestive enzyme activities in thrips. This study assessed variations in the nutritional contents and digestive enzyme activities in the second-instar larvae and adults WFTs fed on 3 food types (rose petals, rose flowers, and honey solution + kidney bean pods) for multiple generations. The highest contents of soluble sugar (in 10% honey solution + kidney bean pods), amino acid (in rose flowers), and protein (in rose flowers) were observed, respectively. Soluble sugar and protein contents in the second-instar larvae and adults fed on rose petals decreased in the F1 generation but increased in the F2 generation and remained at higher levels until the F7 generation. Feeding of thrips with 3 food types increased the lipid content in the F1 generation, which peaked in the F2 generation and remained high until the F7 generation. In most cases, α-amylase and trypsin activities significantly decreased in the F1 generation after feeding on rose petals and then prominently increased in the F2 generation. In contrast, chymotrypsin activity remarkably increased and peaked in the F1 generation after second-instar larvae thrips fed on rose petals. There were correlations among the contents of 3 nutrient related positively with the activities of α-amylase and trypsin in WFTs second-instar larvae and adults, respectively. Overall, variations in the nutrient properties of the 3 food types caused changes in nutrient contents and digestive enzyme activities in thrips. [ABSTRACT FROM AUTHOR]

Currently, there are a total of 15 thrips species in the genus Megalurothrips (Thysanoptera: Thripidae). Megalurothrips sjostedti Trybom and Megalurothrips usitatus (Bagnall) are the most economically important pest species because of the serious damage they can do to leguminous crops, especially cowpea, which is an important grain crop for Africa and a vegetable crop for the rest of the world. Megalurothrips sjostedti is only distributed in Africa, while M. usitatus is widely spread in subtropical and tropical regions of the world and is more invasive. Nigeria is the only area where both thrips species are shared. Inexplicably, M. usitatus does not seriously damage cowpea in Africa. Bioecological characteristics indicated that M. usitatus adapts to a wider temperature and humidity range, which may result in its current geographic distribution. Since the 2010s, M. usitatus has received more attention and research. The integrated pest management (IPM) strategy of both thrips as case studies was reviewed in this paper, along with multiple complementary tactics, including agronomic measures, physical-chemical lure control, biological control, and chemical control, and insecticide resistance. Lessons have been learned from both M. sjostedti and M. usitatus , as well as from another widespread invasive thrips species, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), thus enhancing our overall understanding of the biology, ecology, and IPM practices of M. sjostedti and M. usitatus. [ABSTRACT FROM AUTHOR]

Host plant species will influence the population and physiological performance of insects. Frankliniella occidentalis is a well-known invasive pest commonly found on flowering plants. Herein, the population development of F. occidentalis was investigated on the flowers of different Rosa chinensis cultivars (Ruby, Love, Parade, Pink Peace, and Mohana), and the digestive enzyme activities in thrips were measured after feeding on these flowers. The developmental times of F. occidentalis from egg to adult were 10.07, 10.37, 11.64, 10.66, and 10.90 d on Ruby, Love, Parade, Pink Peace, and Mohana, respectively. Significant differences in fecundity were also observed, with the greatest fecundity levels of F. occidentalis on Ruby (82.96) and the lowest on Mohana (63.40). F. occidentalis showed the greatest R 0 on Ruby (43.57), followed by Love (36.46), Parade (33.00), Pink Peace (27.97), and Mohana (23.21). The r m showed a similar trend, with values of 0.156, 0.145, 0.141, 0.134, and 0.130, respectively. There were significant differences in digestive enzyme activities in F. occidentalis on different flowers, and different digestive enzymes showed different performance among these plants. The highest amylase and lipase activities in F. occidentalis were on Ruby, on which F. occidentalis had the fastest development rate and the highest R 0, whereas the highest trypsin activity was on Pink Peace. All three digestive enzymes in thrips showed the lowest activities on Mohana. The varied population development of F. occidentalis associated with R. chinensis cultivars may be related to their digestive enzyme performance, which plays important roles in nutrient metabolism and insect growth. [ABSTRACT FROM AUTHOR]

The western flower thrip (WFT) Frankliniella occidentalis (Pergande) is a serious agricultural pest with a wide host range which has developed resistance to several groups of insecticides. In this study, the effect of insecticide resistance on WFT host adaptability was explored by examining changes in detoxification enzyme activities and thrip development, and reproduction on preferred and less preferred host plants, eggplant Solanum melongena L. and broad bean Vicia faba L. respectively. Thrips were screened with spinetoram on kidney bean for six generations. Activities of glutathione S-transferase (GST), mixed function oxidases (MFOs), and cytochrome P450 enzyme (P450) in a resistant strain (RS) reared on broad bean were significantly higher than those in a sensitive strain (SS), and only carboxylesterase (CarE) increased in the RS when reared on eggplant, compared with the SS. Activities of the four detoxification enzymes in the RS reared on broad bean were significantly higher than in those reared-on eggplant. On broad bean, RS adult longevity was lower and developmental duration of offspring was shorter than those of the SS, but fecundity increased. On eggplant, RS fecundity was lower and developmental duration of offspring was shorter than those of the SS. In addition, fecundity was higher and developmental duration was longer in the RS reared on broad bean than in those reared-on eggplant. The results indicated that spinetoram resistance could change WFT host preference and that those changes might be associated with detoxification enzyme activities. Thus, it was hypothesized that adaptability of the RS to the less preferred host broad bean increased, whereas adaptability to the preferred host eggplant decreased. [ABSTRACT FROM AUTHOR]

Phytoseiid predatory mites are efficient biocontrol agents of important thrips pests, such as the western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae). Until recently, it was believed that first instars, and to a lesser extent second instars, were the most vulnerable developmental stages of thrips to be attacked by phytoseiids. However, recent evidence showed that some phytoseiids can detect and prey upon thrips eggs inserted in the leaf tissue. As phytoseiid predatory mites often co-occur with other beneficial insects, such as mirid and anthocorid predatory bugs which also insert their eggs inside leaf material, this raises the question whether phytoseiid predatory mites may also feed on predatory bug eggs. Here we first tested the potential of Amblyseius swirskii Athias-Henriot, Transeius montdorensis Schicha, and Amblydromalus limonicus Garman and McGregor (Acari: Phytoseiidae) to kill eggs of F. occidentalis in leaf tissue. Secondly, we tested whether those phytoseiids were capable of killing eggs of Orius laevigatus Fieber (Hemiptera: Anthocoridae), Macrolophus pygmaeus Rambur and Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), three biocontrol agents that also insert their eggs inside plant tissue. Our results showed that A. swirskii and A. limonicus could kill thrips eggs, whereas T. montdorensis could not. Furthermore, we show that the presence of phytoseiid predatory mites does not affect the hatch rate of predatory bugs that insert their eggs inside leaves. [ABSTRACT FROM AUTHOR]

Proteus, matrine, and pyridalyl were tested in the laboratory for their effects upon Orius laevigatus (Fieber), which is a polyphagous predator used for IPM programs of Frankliniella occidentalis (Pergande). Against female adults, the most toxic insecticide was Proteus (LC50 = 44.3 µl L–1), followed by pyridalyl (LC50 = 83.8 µl L–1) and matrine (LC50 = 102.7 µl L–1). The mortality of female adults was checked 24, 48, 72, and 96 h after exposure to 14-d residues of the treatments on strawberry leaves. The residual of Proteus was less toxic; the remaining products caused the lowest mortality at different times after exposure. Sublethal treatments (LC25) significantly prolonged the developmental duration of total immature stages from 17.6 d in control to 21.6 and 20.0 d in Proteus and pyridalyl treatments, respectively. Also, the fecundity of O. laevigatus treated with Proteus, pyridalyl, and matrine decreased to 58.8%, 75.6%, and 96.7%, respectively, in comparison to the control. Compared with the control population (0.118 d–1), the intrinsic rate of increase (r) of F1 generation decreased by 0.053, 0.095, and 0.110 d–1 in Proteus, pyridalyl, and matrine treatments, respectively. The consumption rate of control bugs reached 14.0 thrips during 24 h. The adults fed on Proteus treatment had the lowest consumption rate in this period (9.4 preys). Overall, matrine proved to be harmless with reproductive capacity and r similar to what was recorded in control bugs. We concluded that matrine can be used as an alternative for the synthetic insecticide to integrate with O. laevigatus. [ABSTRACT FROM AUTHOR]

The western flower thrips (WFT), Frankliniella occidentalis (Pergande) is one of the most harmful pests of crops in greenhouses and fields. Considering the need for studies that introduce new insecticides for control of the WFT, the leaf dip method was carried out to study the acute toxicity of Proteus, matrine, and pyridalyl to adult thrips, and life tables were constructed to assess the impacts of sublethal concentrations (LC25) of these insecticides on the development and reproduction of the F1 generation. Bioassays showed that the toxicity of matrine (LC50: 45.9 µl ml–1) and Proteus (LC50: 54.5 µl ml–1) was higher than pyridalyl (LC50: 176.5 µl ml–1). At LC25 concentration, both Proteus and matrine prolonged the development period and reduced the survival rate of eggs, larval stages, and pupae in the F1 generation. Also, the adults' longevity, oviposition duration, and the cumulative number of eggs laid per female (fecundity) were decreased significantly. Sublethal concentrations of Proteus and matrine inhibited the population growth rate relative to the control based on the predicted number of offspring. The lowest net reproductive rate (R 0), intrinsic rate of increase (r), and finite rate of increase (λ) were estimated for Proteus (7.02 offspring/individual, 0. 0838 d–1, and 1. 08 d–1, respectively). In contrast, the WFT F1 generation that resulted from parent adults treated with pyridalyl was neither affected in their developmental time, nor fecundity, or the intrinsic rate of increase. According to our findings, all tested insecticides, especially Proteus, showed good potential for use in integrated pest management strategies against F. occidentalis. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important, worldwide vector of two tospoviruses (Family Bunyaviridae; Genus Tospovirus), Impatiens necrotic spot virus (INSV) and Tomato spotted wilt virus (TSWV). In the Salinas Valley of California, INSV causes severe necrosis, stunting, and crop losses to lettuce (Lactuca sativa L.). Because broccoli (Brassica oleracea var. italica L.) and cauliflower (Brassica oleracea var. botrytis L.) are major rotation crops with lettuce in the Salinas Valley, it is critical to understand if these Brassicas influence the dispersal dynamics of F. occidentalis. In 2013 and 2014, surveys were conducted evaluating yellow sticky cards and plant samples in lettuce, broccoli, and cauliflower fields in three regions of the Salinas Valley. F. occidentalis were collected on sticky cards from April to November and on foliage in all three regions. Two-choice oviposition assays as well as no-choice and two-choice feeding assays were conducted where F. occidentalis adults were exposed to leaves of lettuce, broccoli, and cauliflower. A significantly greater number of eggs was found on lettuce than on broccoli or cauliflower leaves in the choice assay, whereas for the broccoli and cauliflower choice assay, the number of eggs retrieved was low and not significantly different between hosts. The number of F. occidentalis feeding spots and leaf area injury ratings were similar on broccoli and lettuce leaves but were significantly lower on cauliflower than on lettuce and broccoli leaves. The implications of these results on thrips and plant virus management are discussed. [ABSTRACT FROM AUTHOR]

Frankliniella flower thrips are pests of numerous fruit and vegetable crops as they feed and reproduce in the flowers and fruits. The invasive Frankliniella occidentalis (Pergande) from the Southwestern United States, an economic pest in Florida since 2005, and the native Frankliniella bispinosa Morgan are both found in Florida strawberries. The objective of this research was to characterize injury to strawberry fruit from these species. Densities of 0, 2, 4, 8, 16, or 32 adult females of each species were caged on a strawberry plant with one flower. The cages were removed after 2, 5, or 10 d, and the number of surviving adults and the number of larvae determined. Injury was quantified on the mature fruit 21 d after thrips were introduced onto the experimental plant. Initial densities as low as two adult F. occidentalis females per flower decreased fruit set and increased cat-facing on the fruits that developed. There were no significant effects on fruit set and cat-facing by any initial density of F. bispinosa. Feeding by thrips on the small, green fruit affected the size and shape of the mature fruit: the diameters were decreased as a linear function of increased feeding by F. bispinosa , and the weights were decreased as a linear function of increased feeding by F. occidentalis. Overall, results showed that F. occidentalis was more damaging to strawberry than F. bispinosa. The differences in pest status between these common flower thrips species in Florida presents challenges to management programs. [ABSTRACT FROM AUTHOR]

A number of thrips species are among the most significant agricultural pests globally. Use of repellent intercrop plants is one of the key components in plant-based 'push–pull' strategies to manage pest populations. In this study, the behavioral responses of three thrips species, Frankliniella occidentalis (Pergande), Frankliniella intonsa (Trybom), and Thrips palmi Karny (Thysanoptera: Thripidae) to Rosmarinus officinalis were investigated in Y-tube olfactometer bioassays and cage experiments. In addition, the major volatile compounds from rosemary were identified and the effect of the individual compounds on thrips behavior was evaluated. Females and males of the three thrips species were significantly repelled by the volatiles from cut rosemary leaves. The presence of rosemary plants significantly reduced settlement of females of the three thrips species and eggs laid by F. occidentalis females on target host plants. In total, 47 compounds were identified in the volatiles collected from the cut leaves of rosemary plants. The responses of the three thrips species to 10 major volatile compounds showed significant differences. However, α-pinene, the most abundant volatile, was repellent to F. occidentalis and F. intonsa. Eucalyptol, the second most abundant volatile, showed significant repellent activity to all the three thrips species. Our findings showed that rosemary is a promising repellent plant against the three thrips pests we tested, which could be a good candidate for 'push' plants in plant-based 'push–pull' strategies. The identified volatile compounds that accounted for the repellent activity could be developed as repellents for sustainable thrips management. [ABSTRACT FROM AUTHOR]

This study was conducted at the Oregon State University Hermiston Agricultural Research and Extension Center, Hermiston, Umatilla County, OR, during the 2016 and 2017 potato, Solanum tuberosum L. (Solanales: Solanaceae), growing seasons. The objective was to determine the vertical distribution of hemipteran (Bactericera cockerelli Šulc, Circulifer tenellus Baker, Myzus persicae Sulzer, Macrosiphum euphorbiae Thomas, and Lygus spp.) and thysanopteran (Frankliniella occidentalis Pergande and Thrips tabaci Lindeman) potato pests using insect towers placed near potato fields. Towers were 8 m tall and secured to the ground with metal cables. In each tower, yellow sticky cards were mounted at 1.5 m intervals up to 7.6 m aboveground. Data were collected at 7-d intervals from mid-April until mid or end of August. This study showed that B. cockerelli , C. tenellus , M. persicae , Lygus spp. and both species of thrips were captured on sticky cards placed closest to the ground; in both years, as sticky card height increased, abundances decreased. In contrast, trapped M. euphorbiae numbers were not affected by sticky card height. To our knowledge, this is the first study in the lower Columbia Basin of Oregon that evaluated the vertical distribution of major potato pests. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis, is a major invasive pest of commercially important crops worldwide. We compared the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and the expressions of two putative SOD and two putative POD sequences in second instar larvae and adults after three generations of adaptation to kidney bean and broad bean plants. The results showed that the SOD, POD, and CAT activities in adults were significantly higher than those in the second instar larvae. The SOD activities were significantly higher in both the second instar larvae and the adults fed on kidney bean (Phaseolus vulgaris) plants versus broad bean (Vicia faba) plants, whereas the POD and CAT activities showed the opposite trend. The gene expression data showed that the FoPOD-2 expression levels were lower in the second instar larvae after three generations of feeding on broad bean plants versus kidney bean plants. The expression levels of FoSOD-1 and FoSOD-2, and FoPOD-1 under broad bean plant treatment were higher than those under kidney bean plant treatment. Additionally, gene expression fluctuated among the different generations. Our results indicated that western flower thrips demonstrated plasticity in gene expression and activity of protective enzymes, which is related to their adaptability to the host plants. Western flower thrips can change the expression of protective enzyme genes and enzyme activity in vivo to better adapt to kidney bean and broad bean plants. [ABSTRACT FROM AUTHOR]

Tomato chlorotic spot virus (TCSV) is an orthotospovirus that causes a devastating disease in tomato (Lycopersicon esculentum Miller). TCSV emerged recently in South Florida. Studies were conducted in three commercial tomato fields in Miami-Dade County, Florida during the vegetable-growing seasons from October to April in 2015 through 2017. Each year, data were collected at 3, 6, and 9 wk after transplanting at various distances from the edges of each fields. Based on 3 yr total samples, three species of thrips were commonly observed melon thrips, Thrips palmi Karny (62.16 ± 0.79%), being the most abundant species followed by common blossom thrips, Frankliniella schultzei Trybom (21.55 ± 0.66%), and western flower thrips, Frankliniella occidentalis (Pergande) (16.26 ± 0.61%). Abundance of all thrips and TCSV infected plants was high at the edge of a tomato field 3 wk after transplanting with significantly fewer infected plants toward the center of the field. The distribution patterns of thrips and TCSV in various fields were mostly regular and aggregated across the sampling dates during the study period. Abundance of TCSV symptomatic plants and thrips species was high at the edge of the field and increased over time. The number of samples required to accurately determine population density of thrips was calculated by using three precision levels (0.10, 0.20, 0.30) at three predetermined densities of thrips (0.10, 0.20, and 0.40 per sample). This information will provide guidelines to growers, crop protection personnel, agricultural scouts, and researchers to develop a sustainable thrips and tospovirus management program. [ABSTRACT FROM AUTHOR]

Western flower thrips, Frankliniella occidentalis (Pergande), is a destructive insect pest in greenhouse production systems. Therefore, integrating the entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin, with the soil-dwelling rove beetle, Dalotia coriaria (Kraatz), targeting different aboveground and belowground life stages may help effectively manage western flower thrips populations. Two greenhouse experiments were conducted evaluating five treatments: 1) insecticides (spinosad, pyridalyl, chlorfenapyr, and abamectin), 2) B. bassiana , 3) D. coriaria , 4) B. bassiana and D. coriaria combination, and 5) water control. The estimated mean number of western flower thrips adults captured on yellow sticky cards was significantly lower for the insecticide treatment (mean range: 0–46 western flower thrips adults per yellow sticky card) than the B. bassiana and D. coriaria combination (0.3–105.1 western flower thrips per yellow card) over 8 wk. There were no significant differences in the final foliar damage ratings of chrysanthemum, Dendranthema × grandiflorum (Ramat.) Kitam. plants among the five treatments in experiment 1, but there were significant differences in experiment 2. In experiment 2, chrysanthemum plants across all treatments were not marketable due to western flower thrips feeding damage. Therefore, using B. bassiana and D. coriaria early in production should suppress population growth by targeting both foliar-feeding and soil-dwelling life stages of western flower thrips simultaneously. [ABSTRACT FROM AUTHOR]

Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) is an early-season cotton pest. Seedlings are injured by larvae, which hatch from eggs oviposited into seedlings and feed on developing plant tissue. Better understanding F. fusca oviposition in cotton may improve their management and address new challenges such as resistance to neonicotinoid seed treatments (NSTs). Cotton seedlings exposed to F. fusca were either cleared and stained to determine egg density and location, or dissected and washed to determine larval distribution. Experiments were conducted in the greenhouse with a susceptible population and field with a NST-resistant population. Eggs of both populations were recovered predominantly in cotyledons. Larvae were more uniformly distributed on seedlings. On NST seedlings, oviposition by the susceptible population was reduced and preference shifted to true leaves. NSTs did not alter egg placement by the resistant population. These findings suggest that injury to cotton seedlings is primarily caused by F. fusca emerging on the cotyledons, and then moving to developing leaves. The oviposition shift in NST plants correlates with how systemic NSTs have been reported to concentrate in cotyledons. This can better inform management tactics in cotton, such as well-timed foliar sprays, which, given the current resistance issue, are needed to maintain effective thrips management. [ABSTRACT FROM AUTHOR]

In cultivated tomato (Solanum lycopersicum), increases in photosynthetically active radiation (PAR) induce type VI leaf glandular trichomes, which are important defensive structures against arthropod herbivores. Yet, how PAR affects the type VI trichome-associated leaf chemistry and its biological significance with respect to other photomorphogenic responses in this agronomically important plant species is unknown. We used the type VI trichome-deficient tomato mutant odorless-2 (od-2) and its wild type to investigate the influence of PAR on trichome-associated chemical defenses against thrips (Frankliniella occidentalis). High PAR increased thrips resistance in wild-type plants, but not in od-2. Furthermore, under high PAR, thrips preferred od- 2 over the wild type. Both genotypes increased type VI trichome densities under high PAR. Wild-type plants, however, produced more trichome-associated allelochemicals, i.e. terpenes and phenolics, these being undetectable or barely altered in od-2. High PAR increased leaf number and thickness, and induced profound but similar metabolomic changes in wild-type and od-2 leaves. Enhanced PAR also increased levels of ABA in wild-type and od-2 plants, and of auxin in od-2, while the salicylic acid and jasmonate concentrations were unaltered. However, in both genotypes, high PAR induced the expression of jasmonic acid-responsive defense-related genes. Taken together, our results demonstrate that high PAR-mediated induction of trichome-associated chemical defenses plays a prominent role in tomato–thrips interactions. [ABSTRACT FROM AUTHOR]

The insecticidal activity of phosphine (PH3) and ethyl formate (EF) toward Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and their phytotoxicity to asparagus were evaluated. Both the PH3 and EF fumigants showed higher lethal concentration and time (LCT) values at lower temperatures. The LCT99 values of PH3 and EF at 5°C in a 12 liters desiccator for 4 h showed the following ranking: eggs (64.69 mg·h/liter for PH3 and EF indicating phytotoxicity to asparagus), nymphs (5.54 and 17.48 mg·h/liter, respectively), and adults (3.83 and 14.67 mg·h/liter, respectively). The adsorption of PH3 was approximately 11% at 2°C and 13% at 5°C, whereas the adsorption of EF increased sharply to 88% at 2°C and 97% at 5°C. The hatching rate of F. occidentalis eggs was approximately 95% at all locations (top, middle, and bottom) in the presence of 4 mg/liter PH3 at 5°C in a 0.65-m3 fumigation chamber for 24 h. However, extension of the treatment to 48 h resulted in 100% inhibition of egg hatching. The atmospheric level of PH3 decreased below the threshold limit value after 80 min, and phytotoxicity was not observed. The results revealed that EF is highly absorbed by asparagus and is not suitable as a fumigant, but PH3 is a suitable alternative to the fumigant methyl bromide for the control of western flower thrips in asparagus. [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to optimize the potential of Beauveria bassiana through cell electrofusion technique with emphasis on improving its thermotolerance and virulence against western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) (WFT). Methods and Results: Nine B. bassiana isolates were tested against western flower thrips, F. occidentalis (Thysanoptera: Thripidae) (WFT) to estimate their pathogenicity and speed of infection under laboratory conditions. The isolates were also exposed to 25, 36, 38 and 40°C, for 24, 48, 72 and 120 h. Two isolates with the highest virulence against WFT and highest thermotolerance were selected and paired using a cell electrofusion technique to obtain a single strain that was both highly virulent and thermotolerant. To determine the hybrid conidia among the fusion cells, each selected isolate was loaded with a different nuclei‐staining fluorescent dye before the fusion process. Hybridized fungal strains were acquired by a series of sequential dilutions and were tested for thermotolerance and virulence against WFT. Those that demonstrated both characteristics (high thermotolerance and virulence) similar to or greater than the parental isolates were considered hybrids. Conclusions: The results demonstrated that genetic transformation using cell electrofusion can be used to obtain hybrid isolates of fungal pathogens that contain the desired genes from selected isolates. Further DNA‐based analysis is required to determine the genetic variation between hybrids and the parental isolates. Significance and Impact of the Study: This is the first study to demonstrate genetic transformation in B. bassiana by use of cell electrofusion and it could be developed to create superior hybrid isolates with various desired properties for integrated pest management and industrial uses in the future. [ABSTRACT FROM AUTHOR]

Tomato spotted wilt orthotospovirus (TSWV) is a major disease in peanut, Arachis hypogaea L. across peanut producing regions of the United States and elsewhere. Two thrips, Frankliniella fusca Hinds and Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), are considered important vectors of TSWV in peanut in the Southeast. We compared the efficiency of acquisition (by larvae) and transmission (adults) of both thrips species for TSWV (Texas peanut-strain) to leaf disks of peanut (Florunner), as well as to Impatiens walleriana Hook. f. (Dwarf White Baby) and Petunia hybrida Juss. 'Fire Chief' using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Both species were competent TSWV vectors in peanut and Impatiens, although F. fusca was the more efficient vector overall, i.e. virus acquisition and transmission rates for F. fusca averaged over several bioassays were 51.7 and 26.6%, respectively, compared with 20.0 and 15.3% for F. occidentalis. Neither species effectively transmitted this TSWV strain to Petunia (i.e. ≤3.6% transmission). We found statistically similar virus acquisition and transmission rates between both sexes for each species. We also detected no differences in TSWV-acquisition and transmission frequency between macropterous and brachypterous (short-wing) forms of F. fusca collected from a field population in south Texas. DAS-ELISA failed to detect low levels of TSWV in a few thrips that subsequently proved to be competent vectors. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important pest of fresh horticultural produce and as such is considered a biosecurity risk in many countries from which it is absent. Information is needed on the radiation tolerance of important surface pests of quarantine importance such as F. occidentalis so that phytosanitary irradiation treatments for exported fresh commodities can be lowered to below the 400 Gy generic treatment currently approved for most insects in the United States and Australia. Lowering the dose will help minimize any product quality problems, reduce costs, and shorten treatment time. In large-scale confirmatory trials conducted in two independent laboratories in Hawaii and Australia, a dose of 250 Gy (measured doses 222–279 Gy) applied to adult F. occidentalis on green beans resulted in no reproduction in 5,050 treated individuals. At 250 Gy, the effective dose is significantly below the 400 Gy generic dose, demonstrating that irradiation at this lowered level is an effective method for the disinfestation of F. occidentalis from fresh horticultural produce. [ABSTRACT FROM AUTHOR]

A research-scale phosphine generator, QuickPHlo-R, from United Phosphorus Ltd. (Mumbai, India) was tested to determine whether it was suitable for low-temperature fumigation and oxygenated phosphine fumigation of harvested lettuce. Vacuum cooled Iceberg and Romaine lettuce (Lactuca sativa) were fumigated in 442-liter chambers at 2°C for 24 and 72 h for control of western flower thrips [Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)] and lettuce aphid [Nasonovia ribisnigri (Mosely) (Homoptera: Aphididae)]. Oxygenated phosphine fumigation for 48 h under 60% O2 was also conducted at 2°C with Iceberg and Romaine lettuce for control of lettuce aphid. The generator completed phosphine generation in 60–90 min. Complete control of western flower thrips was achieved in 24-h treatment, and the 48-h oxygenated fumigation, and 72-h regular fumigation treatments completely controlled lettuce aphid. Lettuce quality was evaluated 14 d after fumigation. There was increased incidence of brown stains on fumigated Iceberg lettuce, and the increases were more obvious in longer (≥48 h) treatments. Both Iceberg and Romaine lettuce from all treatments and controls had good visual quality even though there was significantly higher brown stain incidence on fumigated Iceberg lettuce in ≥48-h treatment and significant differences in quality score for both Iceberg and Romaine lettuce in the 72-h treatment.The brown stains were likely due to the high sensitivity of lettuce to carbon dioxide.The study indicated that QuiPHlo-R phosphine generator has potential in low-temperature phosphine fumigation due to the quick establishment of desired phosphine levels, efficacy in pest control, and reasonable safety to product quality. [ABSTRACT FROM AUTHOR]

Herbivore natural enemies base their foraging decision on information cues from different trophic levels but mainly from plant odors. However, the second trophic level (i.e., the herbivorous prey) may also provide reliable infochemical cues for their natural enemies. We have evaluated the role of the aggregation pheromone from Frankliniella occidentalis (Pergande) as a potential kairomone for its natural enemy, the predatory bug Orius laevigatus (Fieber). For this purpose, we have analyzed the response of O. laevigatus to (R)-lavandulyl acetate and neryl (S)-2-methylbutanoate, the two major components of the thrips aggregation pheromone. These compounds have been offered to O. laevigatus adult females and nymphs of the predatory bugs both in separate and as specific (1:1 or 1:2.3) blends, in experiments involving a dual choice Y-tube olfactometer. None of the compounds attracted adults or nymphs when they were individually supplied. Conversely, they were significantly attracted to both adults and nymphs when offered as a blend. A 1:2.3 (R)-lavandulyl acetate:neryl (S)-2-methylbutanoate blend was attractive to both nymphs and adults, while a 1:1 blend elicited response only in nymphs. These results suggest that specific blends of these compounds from the aggregation pheromone may be used as an attractant to O. laevigatus. The results of this work highlight the importance of studying olfactory responses of natural enemies for a better understanding of their foraging behavior. Potential uses of these results in future studies are discussed. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis (Pergande) is an economically important pest of agricultural crops. High resistance has been detected in field populations of F. occidentalis against the insecticide spinosad. In this study, we compared life history traits, body sizes, and feeding behaviors (recorded via an electrical penetration graph) of spinosad-susceptible (Ivf03) and spinosad-resistant (NIL-R) near-isogenic lines of F. occidentalis. Life table analysis showed that NIL-R had reduced female longevity and reduced fecundity. The relative fitness of NIL-R (0.43) was less than half that of Ivf03. NIL-R individuals were smaller than Ivf03 individuals, both in body length and body width at every stage. The number and duration of feeding activities were significantly reduced in NIL-R, with the exception of total duration of long-ingestion probes. These results suggest that there is a fitness trade-off associated with spinosad resistance in F. occidentalis, and that the development of resistance in this pest species may be reduced by rotating spinosad with other pesticides lacking cross-resistance. [ABSTRACT FROM AUTHOR]

Development and fecundity were investigated in an invasive alien thrips species, Frankliniella occidentalis (Pergande), and a related native species, Frankliniella intonsa (Trybom), under high CO2 concentration. Results show that the two thrips species reacted differently toward elevated CO2 concentration. Developmental duration decreased significantly (11.93%) in F. occidentalis at the CO2 concentration of 800 ml/liter; survival rate of all stages also significantly increased (e.g., survival rate of first instar increased 17.80%), adult longevity of both female and male extended (e.g., female increased 2.02 d on average), and both fecundity and daily eggs laid per female were higher at a CO2 concentration of 800 ml/liter than at 400 ml/liter. Developmental duration of F. intonsa decreased, insignificantly, at a CO2 concentration of 800 ml/liter. Unlike F. occidentalis, survival rate of F. intonsa declined considerably at higher CO2 concentration level (e.g., survival rate of first instar decreased 19.70%), adult longevity of both female and male curtailed (e.g., female reduced 3.82 d on average), and both fecundity and daily eggs laid per female were reduced to 24.86 and 0.83, respectively, indicating that there exist significant differences between the two CO2 levels. Results suggest that the population fitness of invasive thrips species might be enhanced with increase in CO2 concentration, and accordingly change the local thrips population composition with their invasion. [ABSTRACT FROM AUTHOR]

Greenhouse producers are interested in integrating natural enemies along with pesticides to suppress western flower thrips, Frankliniella occidentalis (Pergande), populations. The insidious flower bug, Orius insidiosus (Say), is a commercially available natural enemy of western flower thrips. We conducted a series of laboratory experiments to determine the direct and indirect effects of 28 pesticides (insecticides, miticides, and fungicides), 4 pesticide mixtures, and 4 surfactants (36 total treatments plus a water control) on the adult O. insidiosus survival and predation on western flower thrips adults under laboratory conditions. The number of live and dead O. insidiosus adults was recorded after 24, 48, 72, and 96 h. The results of the study indicate that the fungicides (aluminum tris, azoxystrobin, fenhexamid, and kresoxim-methyl), insect growth regulators (azadirachtin, buprofezin, kinoprene, and pyriproxyfen), botanicals (Capsicum oleoresin extract, garlic oil, soybean oil; and rosemary, rosemary oil, peppermint oil, and cottonseed oil), and entomopathogenic fungi (Beauveria bassiana and Metarhizium anisopliae) were minimally directly harmful to adult O. insidiosus, with 80% to 100% adult survival. However, abamectin, spinosad, pyridalyl, chlorfenapyr, tau-fluvalinate, imidacloprid, dinotefuran, acetamiprid, and thiamethoxam directly affected O. insidiosus survival after 96 h (0-60% adult survival). The pesticide mixtures of abamectin+spinosad and chlorfenapyr+dinotefuran reduced adult survival (20% and 0%, respectively, after 48 h). Furthermore, the surfactants were not directly harmful to O. insidiosus adults. All western flower thrips adults were killed by the surviving adult O. insidiosus after 48 h, indicating no indirect effects of the pesticides on predation. [ABSTRACT FROM AUTHOR]

Lily (Lilium longiflorum Thunb.) is the most representative bulb flower, and it is the third most important flower in the flower industry of South Korea after rose and chrysanthemum. To determine the efficacy of X-ray irradiation for use in quarantine processing, two species of flower thrips (Frankliniella intonsa (Trybom) and Frankliniella occidentalis (Pergande)) were placed in the top, middle, and bottom locations of lily boxes and irradiated with different X-ray doses. After irradiation with an X-ray dose of 150 Gy, the egg hatching of the two flower thrips was completely inhibited at every location in the lily boxes, and the irradiated F. intonsa and F. occidentalis nymphs failed to emerge as adult in every location of the lily boxes. When the adults were irradiated at 150 Gy, the fecundity of the two flower thrips was markedly lower than that of the untreated control groups. The F1 generation failed to hatch at the top and middle locations, whereas the F1 generation of both F. intonsa and F. occidentalis was not suppressed at the bottom locations, even at 200 Gy. However, hatching was perfectly inhibited at 300Gy of X-ray irradiation. Also, X-rays did not affect the postharvest physiology of cut lilies. Therefore, a minimum dose of 300Gy is recommended for the control of F. intonsa and F. occidentalis for the exportation of lily. [ABSTRACT FROM AUTHOR]

Catalase is an important antioxidant enzyme that protects aerobic organisms from oxidative damage by degrading hydrogen peroxide to oxygen and water. In order to indicate the role of catalase in the thermotolerance of the western flower thrips, Frankliniella occidentalis (Pergande), a major pest of agricultural and horticultural crops, we cloned the cDNA encoding catalase from F. occidentalis in this study. Sequence analyses indicated that the catalase gene from F. occidentalis (FoCAT) encoded a protein containing 506 amino acids, including three catalytic amino acid residues (His-73, Asn-146, and Tyr-356), the proximal heme-ligand signature sequence, 62FDRERIQERVVHAKGAG78, and the proximal active site, 352RIFSYADTH360. Phylogenetic analysis indicated that CAT from different insect species could be grouped into a well-supported cluster that included Diptera, Lepidoptera, and Hemiptera. qRT-PCR analyses initially indicated that FoCAT expression was significantly up-regulated under heat and cold stress. When F. occidentalis nymphs were incubated at 37 or-6°C, FoCAT expression showed a significant increase at 2h for both temperatures and then declined when the temperature duration was 4 or 8h. The enzymatic activity of FoCAT was significantly elevated at moderate heat stress (33 °C), but showed a significant decrease at-6 °C. When F. occidentalis nymphs were incubated at 37 or-6 °C, FoCAT activity showed a gradual decline for both temperatures and was lowest at the 8-h exposure time. In conclusion, FoCAT plays an important role in the thermotolerance of F. occidentalis, whichmay partially explain the widespread distribution of this important pest. [ABSTRACT FROM AUTHOR]

Plant defenses inducible by herbivorous arthropods can determine performance of subsequent feeding herbivores. We investigated how infestation of tomato (Solanum lycopersicum) plants with the Western flower thrips (Frankliniella occidentalis) alters host plant suitability and foraging decisions of their conspecifics. We explored the role of delayedinduced jasmonic acid (JA)-mediated plant defense responses in thrips preference by using the tomato mutant def-1, impaired in JA biosynthesis. In particular, we investigated the effect of thrips infestation on trichome-associated tomato defenses. The results showed that when offered a choice, thrips preferred non-infested plants over infested wild-type plants, while no differences were observed in def-1. Exogenous application of methyl jasmonate restored the repellency effect in def-1. Gene expression analysis showed induction of the JA defense signaling pathway in wild-type plants, while activating the ethylene signaling pathway in both genotypes. Activation of JA defenses led to increases in type-VI leaf glandular trichome densities in the wild type, augmenting the production of trichome-associated volatiles, i.e. terpenes. Our study revealed that plantmediated intraspecific interactions between thrips are determined by JA-mediated defenses in tomato. We report that insects can alter not only trichome densities but also the allelochemicals produced therein, and that this response might depend on the magnitude and/or type of the induction. [ABSTRACT FROM AUTHOR]

Earlier studies have shown that Tomato spotted wilt virus (TSWV) influences the biology, performance, and behavioral patterns of its vector Frankliniella occidentalis Pergande. In this study, using Capsicum annuum L. as the host plant, we aimed to determine the manipulation of F. occidentalis by TSWV through switching of the diet (+ or -TSWV) during vector's development. Behavioral patterns, fitness, as well as vector performance were evaluated. The specific parameters investigated included longevity/survival, fecundity, development time, feeding, and preferential behavior. F. occidentalis were reared on either TSWV-infected (exposed) or healthy leaves (non-exposed) throughout their larval stages. The emerging adults were then individually transferred to either healthy or TSWV-infected leaf disks. This resulted into four treatments, consisting of exposed or non-exposed thrips reared on either infected or healthy leaf disks as adults. All F. occidentalis exposed to TSWV in their larval stages had shorter development time regardless of the adults' diet. Whereas, the ones that were later reared on healthy leaf disks as adults recorded the highest longevity and reproduction rate. Furthermore, adults of F. occidentalis that were exposed to TSWV in their larval stages showed preference toward healthy leaf disks (-TSWV), whereas the non-exposed significantly preferred the infected leaf disks (+TSWV). These are further indications that TSWV modifies the nutritional content of its host plants, which influences vector's biology and preferential behavior, in favor of its multiplication and dispersal. The findings offer additional explanation to the often aggressive spread of the virus in crop stands. [ABSTRACT FROM AUTHOR]

Animals often respond to danger by raising alarm to inform others. Alarm signals come in many different forms, such as visual or mechanical display, sound or odour. Some animals produce vocal alarm signals that vary with the level of danger. For chemical alarm signals, virtually nothing is known about such context-dependent signalling due to a general notion that alarm pheromones have fixed compositions. Here, we show that larvae of the Western Flower Thrips ( Frankliniella occidentalis) produce an alarm pheromone whose composition varies with the level of danger they face: the presence of a relatively harmless predator or a very dangerous predator, that is either actually attacking or not. The frequency of alarm pheromone excretion increases with the level of danger. Moreover, the composition of excreted alarm pheromone varies in the relationship between total and relative amount of the putative two components, decyl acetate ( DAc) and dodecyl acetate ( DDAc). When pheromone is excreted with a predator present but not attacking, the percentage DDAc increases with the total amount of pheromone. When a predator does attack, however, the relationship between percentage DDAc and total amount of pheromone is reversed. Taken together, the alarm signal of thrips larvae appears to be context dependent, which to our knowledge is the first report of context-dependent composition of an alarm pheromone. [ABSTRACT FROM AUTHOR]

Tomato spotted wilt virus (TSWV) is transmitted by Frankliniella occidentalis (Pergande) in a persistent-propagative manner. We previously observed significant results in terms of feeding behavior of spinosad-susceptible (Ivf03) and -resistant (Spin-R) strains of F. occidentalis using electrical penetration graph. TSWV transmission by the two strains was compared in the present study. The results showed that the titer of TSWV-N RNA (a part of S RNA of TSWV and encoding the nucleocapsid protein) in Ivf03 and Spin-R strains was not significantly different after a 48-h inoculation access period. The TSWV transmission rate did not significantly differ between the two strains and was 51.0% for Ivf03 and 44.4% for Spin-R. The virus transmission rate was significantly higher for males than females of both strains. The virus transmission rate for males and females of Ivf03 was 68.1 and 33.8%, respectively; however, in case of Spin-R, it was 60 and 28.8% for males and females, respectively. Additionally, number of probes and duration of probes were generally greater for viruliferous females of Ivf03 than for viruliferous females of Spin-R but the total number and duration of noningestion probes did not significantly differ between males of the two strains. The latter finding behavior may help explain the similar transmission rates for the susceptible and resistant strains. [ABSTRACT FROM AUTHOR]

Above- and belowground plant parts are simultaneously attacked by different pests and pathogens. The host mediates these interactions and physiologically reacts, e.g. with local and systemic alterations of endogenous hormone levels coupled with coordinated transcriptional changes. This in turn affects attractiveness and susceptibility of the plant to subsequent attackers. Here, the model plant Arabidopsis thaliana is used to study stress hormone-based systemic responses triggered by simultaneous root parasitism by the cyst nematode Heterodera schachtii and shoot herbivory by the thrips Frankliniella occidentalis and the spider mite Tetranychus urticae. First, HPLC/MS and quantitative reverse transcriptase PCR are used to show that nematode parasitism strongly affects stress hormone levels and expression of hormone marker genes in shoots. Previous nematode infection is then demonstrated to affect the behavioural and life history performance of both arthropods. While thrips explicitly avoid nematode-infected plants, spider mites prefer them. In addition, the life history performance of T. urticae is significantly enhanced by nematode infection. Finally, systemic changes triggered by shoot-feeding F. occidentalis but not T. urticae are shown to make the roots more attractive for H. schachtii. This work emphasises the importance of above- and belowground signalling and contributes to a better understanding of plant systemic defence mechanisms against plant-parasitic nematodes. [ABSTRACT FROM AUTHOR]

Obligate bacterial symbionts are widespread in many invertebrates, where they are often confined to specialized host cells and are transmitted directly from mother to progeny. Increasing numbers of these bacteria are being characterized but questions remain about their population structure and evolution. Here we take a comparative genomics approach to investigate two prominent bacterial symbionts (BFo1 and BFo2) isolated from geographically separated populations of western flower thrips, Frankliniella occidentalis. Our multifaceted approach to classifying these symbionts includes concatenated multilocus sequence analysis (MLSA) phylogenies, ribosomal multilocus sequence typing (rMLST), construction of whole-genome phylogenies, and in-depth genomic comparisons. We showed that the BFo1 genome clusters more closely to species in the genus Erwinia, and is a putative close relative to Erwinia aphidicola. BFo1 is also likely to have shared a common ancestor with Erwiniapyrifoliae/Erwinia amylovora and the nonpathogenic Erwinia tasmaniensis and genetic traits similar to Erwinia billingiae. The BFo1 genome contained virulence factors found in the genus Erwinia but represented a divergent lineage. In contrast, we showed that BFo2 belongs within the Enterobacteriales but does not group closely with any currently known bacterial species. Concatenated MLSA phylogenies indicate that it may have shared a common ancestor to the Erwinia and Pantoea genera, and based on the clustering of rMLST genes, it was most closely relatedtoPantoea ananatis but represented adivergent lineage. We reconstructed a core genome of a putative common ancestor of Erwinia and Pantoea and compared this with the genomes of BFo bacteria. BFo2 possessed none of the virulence determinants that were omni present in the Erwinia and Pantoea genera. Taken together, these data are consistent with BFo2 representing a highly novel species that maybe related to known Pantoea. [ABSTRACT FROM AUTHOR]

The western flower thrips is an economically important worldwide pest of many crops, and chlorpyrifos has been used to control western flower thrips for many years. To develop a better resistance- management strategy, a chlorpyrifos-resistant strain of western flower thrips (WFT-chl) was selected in the laboratory. More than 39-fold resistance was achieved after selected by chlorpyrifos for 19 generations in comparison with the susceptible strain (WFT-S). Proteome of western flower thrips (WFT-S and WFT-chl) was investigated using a quantitative proteomics approach with isobaric tag for relative and absolute quantification technique and liquid chromatography-tandem mass spectrometry technologies. According to the functional analysis, 773 proteins identified were grouped into 10 categories of molecular functions and 706 proteins were presented in 213 kinds of pathways. Comparing the proteome of WFT-chl with that of WFT-S, a total of eight proteins were found up-regulated and three down-regulated. The results from functional annotation and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses indicated that the differentially expressed protein functions in binding, catalyzing, transporting, and enzyme regulation were most important in resistance development. A list of proteins functioning in biological processes of metabolism, biological regulation, and response to stimulus was found in WFT-chl, suggesting that they are possibly the major components of the resistance mechanism to chlorpyrifos in western flower thrips. Notably, several novel potential resistance-related proteins were identified such as ribosomal protein, Vg (vitellogenin), and MACT (muscle actin), which can be used to improve our understanding of the resistance mechanisms in western flower thrips. This study provided the first comprehensive view of the complicated resistance mechanism employed by WFT-S and WFT-chl through the isobaric tag for relative and absolute quantification coupled with liquid chromatography-tandem mass spectrometry technologies. . [ABSTRACT FROM AUTHOR]

Western flower thrips, Frankliniella occidentalis (Pergande), is one of the most destructive insect pests of greenhouse production systems with the ability to develop resistance to a wide variety of insecticides. A common resistance management strategy is rotating insecticides with different modes of action. By incorporating entomopathogenic organisms (fungi and bacteria), which have discrete modes of action compared to standard insecticides, greenhouse producers may preserve the effectiveness of insecticides used for suppression of western flower thrips populations. The objective of this study was to determine how different rotation programs that include entomopathogenic organisms (Beauveria bassiana, Isaria fumosoroseus, Metarhizium anisopliae, and Chromobacterium subtsugae) and commonly used standard insecticides (spinosad, chlorfenapyr, abamectin, and pyridalyl) may impact the population dynamics of western flower thrips adult populations by means of suppression. Eight-week rotation programs were applied to chrysanthemum, Dendranthema x morifolium plants and weekly counts of western flower thrips adults captured on yellow sticky cards were recorded as a means to evaluate the impact of the rotation programs. A final quality assessment of damage caused by western flower thrips feeding on foliage and flowers was also recorded. Furthermore, a cost comparison of each rotation program was conducted. Overall, insecticide rotation programs that incorporated entomopathogenic organisms were not significantly different than the standard insecticide rotation programs without entomopathogenic organisms in suppressing western flower thrips adult populations. However, there were no significant differences among any of the rotation programs compared to the water control. Moreover, there was no differential effect of the rotation programs on foliage and flower quality. Cost savings of up to 34% (in US dollars) are possible when including entomopathogenic organisms in the rotation program. Therefore, by incorporating entomopathogenic organisms into insecticide rotation programs, greenhouse producers can decrease costs without affecting suppression, as well as diminish selection pressure on western flower thrips adult populations, which may avoid or delay resistance development. [ABSTRACT FROM AUTHOR]

We assessed effects of parental exposure to Beauveria bassiana on life history traits of subsequent generations of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Progeny from individuals that survived fungal exposure as second instars had significantly shorter egg stages, but longer prepupal development times than corresponding untreated controls. However, survivorship to adulthood of these progeny groups did not differ. Although fecundities of the parental types did not differ, the sex ratio of progeny from fungal-treated parents was male-biased, whereas sex ratio of progeny from untreated control parents was even. We calculated life table parameters for the progeny and found that all parameters, except for generation time, were significantly less for the progeny of fungal-treated parents than for progeny of untreated parents. The intrinsic rate of increase, finite rate of increase, net reproductive rate, mean generation time, and gross reproductive rate were 0.199 d-1, 1.229 d-1, 21.84, 15.48 d, and 27.273, respectively, for progeny of treated thrips, and 0.266 d-1, 1.316 d-1, 52.540, 14.92 d, and 70.64, respectively, for progeny of control thrips. Consequently, population projections demonstrated that offspring of parents exposed to B. bassiana would increase their population more slowly than those from untreated parents. These results demonstrate that B. bassiana has sublethal effects that reduce the reproductive success of F. occidentalis and these effects should be taken into account when evaluating its use in management programs for F. occidentalis. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis (Pergande) and Frankliniella intonsa (Trybom) are sympatric pests of many greenhouse and field crops in Korea. We compared the influence of constant (27.3°C) and fluctuating temperatures (23.8-31.5°C, with an average of 27.3°C) on the life table characteristics of F. occidentalis and F. intonsa held at a photoperiod of 16:8 (L:D) h and 45 ± 5% relative humidity. The development times of both F. occidentalis and F. intonsa were significantly affected by temperature fluctuation, species, and sex. The development time from egg to adult of F. intonsa was shorter than that for F. occidentalis at both constant and fluctuating temperatures. Survival of immature life stages was higher under fluctuating than constant temperature for both thrips species. The total and daily production of first instars was higher in F. intonsa (90.4 and 4.2 at constant temperature, and 95.7 and 3.9 at fluctuating temperatures) than that of F. occidentalis (58.7 and 3.3 at constant temperature, and 60.5 and 3.1 at fluctuating temperatures) under both constant and fluctuating temperatures. The percentage of female offspring was greater in F. intonsa (72.1-75.7%) than in F. occidentalis (57.4-58.7%) under both temperature regimes. The intrinsic rate of natural increase (rm) was higher at constant temperature than at fluctuating temperature for both thrips species. F. intonsa had a higher rm value (0.2146 and 0.2004) than did F. occidentalis (0.1808 and 0.1733), under both constant and fluctuating temperatures, respectively. The biological response of F. occidentalis and F. intonsa to constant and fluctuating temperature was found to be interspecifically different, and F. intonsa may have higher pest potential than F. occidentalis based on the life table parameters we are reporting first here. [ABSTRACT FROM AUTHOR]

To compare the performance of Frankliniella occidentalis (Pergande) and native Frankliniella intonsa (Trybom) on cucumber and tomato leaves in laboratory, life history characters were investigated, and life tables were constructed using the method of age-stage, two-sex table life. Compared with tomato leaf, there were shorter total preoviposition period (TPOP), higher fecundity, longer female longevity, and higher intrinsic rate of increase ( r) of both F. occidentalis and F. intonsa on cucumber leaf. Meanwhile, on cucumber leaf, the shorter TPOP, higher fecundity, longer female longevity, and higher value of r were found on population of F. intonsa but on tomato leaf which were found on population of F. occidentalis. From above, cucumber leaf was the preference to population development of both F. occidentalis and F. intonsa compared with tomato leaf. Nevertheless, on cucumber leaf, population of F. intonsa would grow faster than that of F. occidentalis, which was the opposite on tomato leaf. As to the population development in fields, much more factors would be taken into account, such as pollen, insecticide resistance, and effects of natural enemies etc. [ABSTRACT FROM AUTHOR]

Temperature is known to play a crucial role in the population dynamics of insects. Insects have evolved different mechanisms to resist unfavorable extreme temperatures. In recent years, western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), have caused significant damage to vegetable crops. Because of global warming and expanding areas of vegetable cultivation, a study of the effects of heat stress on these thrips species is warranted. We exposed the various developmental stages of western flower thrips and onion thrips to temperatures of 41, 43, or 45°C for 2, 6, 12, 24, or 36 h to determine the effects of heat stress on survival. Our results showed that the heat resistance of nonadult western flower thrips was greater than that of the nonadult onion thrips, and that the natural heat resistant ability was the primary factor in heat resistance in western flower thrips. In contrast, the heat resistance of adult onion thrips was greater than that of the adult western flower thrips, which was primarily the result of the ability of searching suitable microenvironment that enabled the onion thrips to mitigate the effects of high temperatures more efficiently than the western flower thrips. Our analysis of the differences in heat resistance between western flower thrips and onion thrips provides important information for the development of thermal treatments for controlling western flower thrips and onion thrips. [ABSTRACT FROM AUTHOR]

Western flower thrips, Frankliniella occidentalis (Pergande), is an economically important pest all over the world. New products against thrips are necessary, as there are few effective compounds exhibiting cross-resistance among them. Lethal effects, cross-resistance, and baseline susceptibility to spirotetramat were evaluated in this study. A new bioassay method for testing thrips against spirotetramat was developed. Spirotetramat showed a significant mortality effect on larvae after 7 d of exposure, but a low effect was observed on adults. Baseline results for larval instars showed LC50 values ranging from 11.59 to 49.81 mg AI/liter, with a low natural variability (3.2-fold). Cross-resistance studies showed overlapping confidence limits of the LC50 values for laboratory-selected (against acrinathrin, methiocarb, formetanate, and spinosad) resistant and susceptible strains, and low resistance factors, from 0.5 to 1.9, suggesting no cross-resistance to conventional insecticides previously used. A slight ovicidal effect (21-40% reduction) was also detected. Despite presenting low effects on adults, spirotetramat showed high but slow efficacy on F. occidentalis larvae. Field populations in southeast Spain showed a consistent susceptibility to spirotetramat. Given the scarcity of effective products and the lack of cross-resistance to other insecticides, spirotetramat can be considered as a good chemical tool to control F. occidentalis. [ABSTRACT FROM AUTHOR]

Thrips-transmitted Tomato spotted wilt virus (TSWV) has a broad host range including crops and weeds. In Georgia, TSWV is known to consistently affect peanut, tomato, pepper, and tobacco production. These crops are grown from March through November. In the crop-free period, weeds are presumed to serve as a green bridge for thrips and TSWV. Previous studies have identified several winter weeds as TSWV and thrips hosts. However, their ability to influence TSWV transmission in crops is still not completely understood. To further understand these interactions, population dynamics of two prevalent vectors, viz., Frankliniella fusca (Hinds) and Frankliniella occidentalis (Pergande), on selected winter weeds were monitored from October through April in four counties from 2004 to 2008. Peak populations were typically recorded in March. E fusca and F. occidentalis adults were found on winter weeds and their percentages ranged from 0 to 68% in comparison with other adults. Immatures outnumbered all adults. Microcosm experiments indicated that the selected winter weeds differentially supported F. fusca reproduction and development. The time required to complete one generation (adult to adult) ranged from 11 to 16 d. Adult recovery ranged from 0.97 to 2.2 per female released. In addition, transmission assays revealed that thrips efficiently transmitted TSWV from peanut to weeds, the incidence of infection ranged from 10 to 55%. Back transmission assays with thrips from TSWV-infected weeds resulted in up to 75% TSWV infection in peanut. These whole-plant transmission and back transmission assays provide the basis for TSWV persistence in farmscapes year round. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis (Pergande), and the sweetpotato whitefly, Bemisia tabaci (Gennadius), are both invasive insect pests and are present in most of the same agricultural crops without a clear dominance of either species. Here, intra- and interspecific competition in B. tabaci and F. occidentalis was determined under controlled experiments. The results showed that intraspecific competition was distinct in F. occidentalis and that the co-occurrence of B. tabaci had a strong effect on F. occidentalis, resulting in a decrease in oviposition. Significant intraspecific competition was found in B. tabaci, and the coexistence of F. occidentalis had limited effect on the oviposition of B. tabaci. In a selective host plant preference experiment, both F. occidentalis and B. tabaci preferred eggplants most, followed by cucumbers and tomatoes. On cucumber plants, B. tabaci was predominant, whereas on eggplant and tomato plants, F. occidentalis and B. tabaci exhibited comparative competitive abilities during the initial stage. However, over time, higher numbers of B. tabaci than that of F. occidentalis were found on the two host plants. Our in vitro and potted plant experiments indicate that B. tabaci is competitively superior to F. occidentalis, which might help to explain their differential distribution patterns in China. [ABSTRACT FROM AUTHOR]

There is a great demand for safe and effective alternative fumigants to replace methyl bromide and other toxic fumigants for postharvest pest control. Nitric oxide, acommonsignal molecule in biological systems, was found to be effective and safe to control insects under ultralow oxygen conditions. Four insect species including western ßower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae); aphid, Nasonovia ribisnigri (Mosley) (Homoptera: Aphididae); confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae); and rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), at various life stages were fumigated with 0.1-2.0% nitric oxide under ultralow oxygen levels of ≤50 ppm in 1.9-liter glass jars at 2-25°C depending on insect species. Fumigations were effective against all four insect species. EfÞcacy of nitric oxide fumigation increased with nitric oxide concentration, treatment time, and temperature. There were also considerable variations among insect species as well as life stages in susceptibility to nitric oxide fumigation. Complete control of thrips was achieved in 2 and 8 h with 2.0 and 0.2% nitric oxide, respectively, at 2°C. At the same temperature, complete control of the aphid was achieved in 3, 9, and 12 h with 1.0, 0.5, and 0.2% nitric oxide, respectively. Larvae, pupae, and adults of confused flour beetle were effectively controlled in 24 h with 0.5% nitric oxide at 20°C. Complete mortality of confused flour beetle eggs was achieved in 24 h with 2.0% nitric oxide at 10°C. Rice weevil adults and eggs were effectively controlled with 1.0% nitric oxide in 24 and 48 h, respectively, at 25°C. These results indicate that nitric oxide has potential as a fumigant for postharvest pest control. [ABSTRACT FROM AUTHOR]

Western flower thrips, Frankliniella occidentalis Pergande is a commonly encountered and economically important insect pest of greenhouses. Greenhouse producers typically apply pesticides as mixtures to mitigate western flower thrips populations; however, there is limited information available on the compatibility and efficacy of commonly used pesticide mixtures. This study assessed nine binary and three tertiary pesticide mixtures used in greenhouses which included pesticides containing abamectin, acephate, azadirachtin, bifenazate, bifenthrin, fenpropathrin, imidacloprid, novaluron, pymetrozine, and spinosad. Compatibility was determined for the binary pesticide mixtures using jar tests. In addition, the binary mixtures were applied to nine horticultural plant species to determine phytotoxicity based on visual appearance assessed 7 d after treatment. Bean-dip bioassays were performed in a laboratory using green bean (Phaseolus vulgaris L.) to determine LC50 values for each individual pesticide and the mixtures to establish whether the mixtures were synergistic, antagonistic, or there was no effect. The mortality of western flower thrips was assessed after 24 h, and LC50 values were calculated. Furthermore, semifield bioassays were performed in greenhouses for binary and tertiary mixtures to evaluate the efficacy (based on percent mortality) of the pesticide mixtures against western flower thrips. Results indicated that all binary mixtures were visibly compatible, and not phytotoxic to any of the plant species evaluated. Combination index calculations based on laboratory results indicated most of the binary mixtures were synergistic; however, the mixture containing spinosad + bifenazate appeared to be antagonistic against western flower thrips. The semi field bioassays demonstrated significantly reduced efficacy associated with mixtures containing azadirachtin, however, all binary mixtures provided ≈80% western flower thrips mortality. [ABSTRACT FROM AUTHOR]

Invasion of pests may result in local adaptation and the development of biotypes specialized in different hosts. In this study, we investigated western flower thrips, Frankliniella octidentalis (Pergande), an invasive pest in Europe. Thrips from different commercial glasshouse crops within the Dutch Westland and a lab culture kept on chrysanthemum were compared. Genetic barcoding was applied for the identification of potential western flower thrips cryptic species in the Netherlands revealing that all western flower thrips populations studied belonged to the "glasshouse" strain reported in California as the only existing species in the Netherlands. Feeding and reproduction parameters in leaf disc and whole plant bioassays were scored. We detected significant differences in thrips feeding among host plants and thrips origin. Host plants differed in average thrips damage while thrips from different origins caused similar amounts of damage across host plants. In contrast, reproductive success of thrips on all plant species depended strongly on thrips origin. The thrips lab culture maintained on chrysanthemum obtained the highest levels of reproduction on chrysanthemum. Differences among the other thrips populations were relatively small. Amplified fragment length polymorphisms analyses were used to study genetic differences between western flower thrips populations and confirmed that the lab culture population was also genetically the most different of all studied populations. The results of the amplified fragment length polymorphisms analyses together with the better reproductive performance of thrips on the host plant on which they were maintained demonstrate the evolution of a lab biotype specialized in a particular host. This finding has potential relevance for future crop control and breeding programs. [ABSTRACT FROM AUTHOR]

Eight essential oils [0.125-1.0% (vol:vol) in acetone] were separately deposited on leaf disks to evaluate their potential to repel western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), adult females. Two of the best-performing essential oils were incorporated into polymer matrices of methyl cellulose or alginate [0.5 or 1% (wt:vol) ] to verify the potential o the polymer to extend repellency of oils over time (24-120 h). Results showed that at a concentration of 0.5%, Thymus vulgaris L. (common thyme) and Satureja montana L. (winter savory) were the mos repellent essential oils. For these two treatments, no western flower thrips were counted on treated leaf disks 60 min after the start of the test. T. serpyllum and O. compactum also showed repellency v ≥ 90% at this concentration. With both the alginate and methyl cellulose polymers, the incorporation of polymers into treatment solutions containing 0.5% concentrations of S. montana and T. serpyllum resulted in higher repellency compared with treatment solutions lacking these polymers for a minimum of 3 d. For the alginate polymer, differences associated with polymer concentrations were most dramatic. High repellency was maintained for 4 d when a 0.5% concentration of the alginate was used in combination with a 0.5% concentration of S. montana. The use of repellent oils with polymers that extend their repellency may prove useful for both pre- and postharvest applications in flower crops. [ABSTRACT FROM AUTHOR]

Aims: Larval stages of Frankliniella occidentalis are known to be refractory to fungal infection compared with the adult stage. The objective of this study was to identify promising fungal isolate(s) for the control of larval stages of F. occidentalis. Methods and Results: Ten isolates of Metarhizium anisopliae and eight of Beauveria bassiana were screened for virulence against second-instar larvae of F. occidentalis. Conidial production and genetic polymorphism were also investigated. Metarhizium anisopliae isolates ICIPE 7, ICIPE 20, ICIPE 69 and ICIPE 665 had the shortest LT50 values of 8·0-8·9 days. ICIPE 69, ICIPE 7 and ICIPE 20 had the lowest LC50 values of 1·1 × 107, 2·0 × 107 and 3·0 × 107 conidia ml−1, respectively. Metarhizium anisopliae isolate ICIPE 69 produced significantly more conidia than M. anisopliae isolates ICIPE 7 and ICIPE 20. Internally transcribed spacers sequences alignment showed differences in nucleotides composition, which can partly explain differences in virulence. Conclusion: These results coupled with the previous ones on virulence and field efficacy against other species of thrips make M. anisopliae isolate ICIPE 69 a good candidate. Significance and Impact of the Study: Metarhizium anisopliae isolate ICIPE 69 can be suggested for development as fungus-based biopesticide for thrips management. [ABSTRACT FROM AUTHOR]

Control of Frankliniella occidentalis (Pergande) is a serious problem for agriculture all over the world because of the limited range of insecticides that are available. Insecticide resistance in F. occidentalis has been reported for all major insecticide groups. Our previous studies showed that cytochrome P450-mediated detoxification is a major mechanism responsible for insecticide resistance in this pest. Degenerate polymerase chain reaction was used to identify P450 genes that might be involved in acrinathrin resistance, in a laboratory population of F. occidentalis. Associated sequences were classified as belonging to the CYP4 and CYP6 families. Real-time quantitative polymerase chain reaction analyses revealed that two genes, CYP6EB1 and CYP6EC1, were over-expressed in adults and L2 larvae of the resistant population, when compared with the susceptible population, suggesting their possible involvement in resistance to acrinathrin. [ABSTRACT FROM AUTHOR]

The western flower thrips (Frankliniella occidentalis) is a polyphagous herbivore that causes serious damage to many agricultural plants. In addition to causing feeding damage, it is also a vector insect that transmits tospoviruses such as Tomato spotted wilt virus (TSWV). We previously reported that thrips feeding on plants induces a jasmonate (JA)-regulated plant defense, which negatively affects both the performance and preference (i.e. host plant attractiveness) of the thrips. The antagonistic interaction between a JA-regulated plant defense and a salicylic acid (SA)-regulated plant defense is well known. Here we report that TSWV infection allows thrips to feed heavily and multiply on Arabidopsis plants. TSWV infection elevated SA contents and induced SA-regulated gene expression in the plants. On the other hand, TSWV infection decreased the level of JA-regulated gene expression induced by thrips feeding. Importantly, we also demonstrated that thrips significantly preferred TSWV-infected plants to uninfected plants. In JA-insensitive coi1-1 mutants, however, thrips did not show a preference for TSWV-infected plants. In addition, SA application to wild-type plants increased their attractiveness to thrips. Our results suggest the following mechanism: TSWV infection suppresses the anti-herbivore response in plants and attracts its vector, thrips, to virus-infected plants by exploiting the antagonistic SA–JA plant defense systems. [ABSTRACT FROM PUBLISHER]