Western Flower Thrips Populations Research Articles

Life‐history parameters of the western flower thrips, Frankliniella occidentalis, are affected by host plant salinity stress

AbstractSalinization, as one of the foremost abiotic stresses, is an intensifying problem in many agroecosystems. Climatic changes, along with altering land use and also salinity of irrigation water all lead to enhanced soil salinity in agricultural lands. Changes in plant characteristics, as a result of raising soil salinity, may impose bottom‐up impact on plant‐feeding insects. We assessed the bottom‐up impact of salinity stress on demographic traits of the western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on cherry tomato, Solanum lycopersicum L. var. cerasiforme (Solanaceae) plants under greenhouse conditions (27 ± 2 °C, 65 ± 5% r.h., and L16:D8 photoperiod). Our results indicated that salinity stress interfered with the immature development period, adult longevity, and sex ratio of WFT. Salinity stress biased the sex ratio in favor of males. Significant concentration‐dependent differences were observed in the intrinsic (r) and finite (λ) increase rates and the net reproduction rate (R0) of WFT at different salinity levels. Salinity adversely influenced WFT development; nonetheless, population projection forecasted an ascending WFT population growth under moderate salinity stress of 100 mM (2.8 dS m−1 of NaCl), whereas severe salinity stress of 150 mM (4.7 dS m−1 of NaCl) resulted in remarkable fitness costs in WFT. This study demonstrates that WFT has the potential to become problematic in regions with moderate salinity. Therefore, it might exacerbate the detrimental impact of salinity on tomato production. The current survey provides information on the abundance of WFT on saline‐stressed tomato plants, thereby contributing to developing environmentally friendly measures to manage this notorious species in ecosystems under salinity stress.

An intelligent fuzzy system to manage western flower thrips population under biological treatment in roses yield

Experimentation centers in the French Riviera (SCRADH, Florisud, and others) are keen on informing growers about the propitious weather conditions relative to pest risk growth. The only existing method used nowadays is sending notifications to their mobile phones. In this study, we are interested in developing a system for Western Flower Thrips (WFT) risk assessment. We propose a fuzzy logic approach to build an intelligent system that supplies rose growers with an estimate of the next day’s risk in their greenhouses. The system relies on today’s data (data of the day) to predict the next day’s risk, under the presence of bio-control agents, in particular, harmless fungi called Beauveria Bassiana. We could recapitulate the study’s outcomes in the following elements. The most significant aspect is estimating a daily risk index that provokes premature detection of WFT. Besides, considering the utilization of biological treatment aids in reducing the pulverization of pesticides. In addition, the system incorporates a small number of sensors usually found in almost all greenhouses. Thanks to continuous monitoring of the weather conditions (real-time system), the system could help mitigate the percentage of yield loss. Finally, this is the first attempt to employ fuzzy logic to predict WFT subjected to biological treatment. We compared the obtained results to actual data. The model’s accuracy was determined by three statistical indicators (coefficient of determination (R2), root mean squared error (RMSE), and mean absolute error (MAE)) showing a noticeable performance. The fuzzy model showed satisfactory results (R2=0.9, RMSE= 10%, and MAE=7.3%) making it reliable and robust for pest monitoring.

Efficacy of Oil and Photosensitizer against Frankliniella occidentalis in Greenhouse Sweet Pepper.

Many common insect pests have developed resistance against the pesticides currently available, to the point where pest and disease management has become extremely difficult and expensive, increasing pressure on agriculture and food production. There is an urgent need to explore and utilize alternatives. Due to their unique mode of action, photosensitizers may be able to control insect pests effectively, especially in combination with oil-based products, without the risk of resistance build-up. In this study, the efficacy of a mineral oil-based horticultural spray oil, PureSpray™ Green (PSG), and a sodium magnesium chlorophyllin photosensitizer formulation, SUN-D-06 PS, were evaluated and compared to a registered cyantraniliprole insecticide (as positive control) and a negative control against western flower thrips (WFT), Frankliniella occidentalis. In detached leaf ingestion assays, PSG at high concentration was more effective than low concentration, causing >70% WFT mortality, whilst SUN-D-06 PS + PSG caused higher mortality than cyantraniliprole after five days of feeding. The same combination was as effective as cyantraniliprole in the contact assay. In greenhouse pepper, the photosensitizer decreased the WFT more than mineral oil applied alone, whilst a combination treatment of SUN-D-06 PS + PSG was most effective, decreasing the WFT population to fewer than four WFT per plant. SUN-D-06 PS + PSG shows promise as a sustainable, economical way of controlling WFT, with the potential to be incorporated into existing integrated pest (and disease) management (IPM) programs with ease.

Temporal decline of genetic differentiation among populations of western flower thrips across an invaded range

Temporal decline of genetic differentiation among populations of western flower thrips across an invaded range

Molecular diagnostics for monitoring insecticide resistance in the western flower thrips Frankliniella occidentalis.

Insecticide resistance has emerged in various western flower thrips (WFT) populations across the world, threatening the efficiency of chemical control applications. Elucidation of insecticide resistance mechanisms at the molecular level provides markers for the development of diagnostics to monitor the trait and support evidence-based resistance management. TaqMan and Droplet Digital polymerase chain reaction (ddPCR) diagnostics were developed and validated, against Sanger sequencing, in individual and pooled WFT samples respectively, for the G275E mutation (nicotinic acetylcholine receptor α6 gene, nAChR α6) associated with resistance to nAChR allosteric modulators, site I (spinosyns); L1014F, T929I, T929C and T292V mutations (voltage-gated sodium channel gene, vgsc) linked with pyrethroid resistance; and I1017M (chitin synthase 1 gene, chs1) conferring resistance to growth inhibitors affecting CHS1 (benzoylureas). The detection limits of ddPCR assays for mutant allelic frequencies (MAF) were in the range of 0.1%-0.2%. The assays were applied in nine WFT field populations from Crete, Greece. The G275E (MAF=29.66%-100.0%), T929I and T929V (combined MAF=100%), L1014F (MAF=11.01%-37.29%), and I1017M (MAF=17.74%-51.07%) mutations were present in all populations. The molecular diagnostics panel that was developed in this study can facilitate the quick and sensitive resistance monitoring of WFT populations at the molecular level, to support evidence-based insecticide resistance management strategies. © 2022 Society of Chemical Industry.

Colour Response in Western Flower Thrips Varies Intraspecifically.

Simple SummaryThe western flower thrips (WFT) is a major glasshouse pest worldwide. Colour and odour are used to attract WFT to traps for monitoring in pest management. However, the use of colour attraction for surveillance, or its potential as a control tool for mass trapping, has not progressed due to ongoing debate about the optimal colour. Blue is commonly used for monitoring, but yellow can also be preferred over blue, confounding the implications for field application. As methodological differences amongst studies could cause this discrepancy, in the present study we evaluated populations from Germany (DE) and the Netherlands (NL) that had previously expressed different preferences for blue and yellow. Examining the behavioural response of WFT to blue or yellow LEDs in a wind tunnel by using the same methodology and facilities, the two populations maintained their original differential preferences. This remained after several generations under common conditions, although a significant increase in attraction to yellow was observed for both populations when reared on yellow-flowered chrysanthemum plants. This is the first report demonstrating that WFT populations can differ in their colour preferences even under the same experimental circumstances. Given that research is typically achieved with populations isolated from the wild for many generations, caution is still needed when extrapolating this to field situations.Discrepancies in the published research as to the attraction of the economically important pest western flower thrips (WFT) to different colours confounds the optimisation of field traps for pest management purposes. We considered whether the different experimental conditions of independent studies could have contributed to this. Therefore, the behavioural response (i.e., landings) to different colour cues of two WFT laboratory populations from Germany (DE) and The Netherlands (NL), which had previously been independently shown to have different colour preferences, were tested in the same place, and under the same experimental conditions. Single-choice wind tunnel bioassays supported previous independent findings, with more of a NL population landing on the yellow LED lamp (588 nm) than the blue (470 nm) (p = 0.022), and a not-statistically significant trend observed in a DE population landing more on blue compared to yellow (p = 0.104). To account for potential original host rearing influences, both populations were subsequently established on bean for ~20 weeks, then yellow chrysanthemum for 4–8 and 12–14 weeks and tested in wind tunnel choice bioassays. Laboratory of origin, irrespective of the host plant rearing regime, remained a significant effect (p < 0.001), with 65% of the NL WFT landing on yellow compared to blue (35%), while 66% of the DE WFT landed on blue compared to yellow (34%). There was also a significant host plant effect (p < 0.001), with increased response to yellow independent of laboratory of origin after rearing on chrysanthemum for 12–14 weeks. Results suggest that differing responses of WFT populations to colour is, in this case, independent of the experimental situation. Long-term separate isolation from the wild cannot be excluded as a cause, and the implications of this for optimising the trap colour is discussed.

Increasing Frequency of G275E Mutation in the Nicotinic Acetylcholine Receptor α6 Subunit Conferring Spinetoram Resistance in Invading Populations of Western Flower Thrips in China.

Simple SummaryThe western flower thrips (WFT) Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is an important invasive pest in agriculture and forestry. It has developed resistance to a frequently used pesticide spinetoram world widely, including the invading area of China. However, the mechanism of resistance to spinetoram is unclear in China. In this study, we found the presence of the G275E mutation in the nicotinic acetylcholine receptor Foα6 in the early invading populations, which has now increased to a high frequency in China. There was a correlation between the frequency of the G275E mutation and resistance to spinetoram as characterized by median lethal concentration. Our results showed that G275E mutation is one of the mechanisms conferring spinetoram resistance in invading populations in China, as in many other countries. Our study highlights the rapid spread of the G275E mutation in China in the 2009–2021 period.The western flower thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is an important invasive pest worldwide. Field-evolved resistance to the pesticide spinetoram is an increasing problem in the chemical control of this pest. Here, we examined changes in the frequency of a genetic mutation associated with spinetoram resistance, the G275E mutation in the acetylcholine receptor Foα6, in 62 field populations collected from 2009 to 2021 across areas of China invaded by this pest. We found a low frequency of the G275E mutation in populations collected at the early invasion stage, in contrast to a high frequency in native USA populations. However, the frequency of the G275E mutation has increased to a high level in recently collected populations, with the mutation becoming fixed in some populations. There was a correlation between the frequency of the G275E mutation and resistance to spinetoram as characterized by median lethal concentration, although two populations were outliers. These results showed that G275E mutation is one of the mechanisms conferring spinetoram resistance in many invading populations in China. Ongoing dispersal of the WFT may have facilitated a rapid increase in the G275E mutation across China. Our study highlights the rapid evolution of pesticide resistance in an invasive species and points to a useful marker for molecular diagnostics of spinetoram resistance.

The generalist predatory mite Anystis baccarum (Acari: Anystidae) as a new biocontrol agent for western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae).

A generalist predatory mite, Anystis baccarum (L.), was evaluated as a biological control agent against western flower thrips (WFT), Frankliniella occidentalis (Pergande). Laboratory assays showed A. baccarum was able to kill a mean of five WFT adult females or nine WFT larvae in 24h, out-performing both Neoseiulus cucumeris (Oudemans) and Amblyseius swirskii Athias-Henriot. Next, a greenhouse assay was conducted to assess the performance of A. baccarum on potted chrysanthemums, comparing their efficacy to that provided by N. cucumeris slow-release sachets which represented the commercial standard in Canada. A combined treatment which incorporated both predatory mite species was also included to assess compatibility and potential additive effects of using both species together for WFT management. Introduction of two A. baccarum per pot was as efficacious as 125N. cucumeris in terms of WFT control; however, despite the lack of significance between the level of WFT control obtained in the single predatory species treatments and the combined treatment, only the combination treatment suppressed WFT populations to levels that were almost unchanged over 8 weeks. There was no significant difference between the number of N. cucumeris recovered from plants in the single-species and the combination treatments, demonstrating the functional compatibility of the two predators. Additionally, WFT feeding damage was significantly lower on the A. baccarum-treated plants than on the untreated control and the N. cucumeris treatment. This study, together with our development of a prototype mass rearing method, shows that A. baccarum could be successfully used as a biocontrol agent for WFT.

Insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), predation on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on Transvaal daisy, Gerbera jamesonii, cut flowers and chrysanthemum, Tanacetum × grandiflorum, plants under laboratory and greenhouse conditions

The insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), is a generalist predator that feeds on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), larvae and adults. Our study involved a series of experiments conducted under laboratory and greenhouse conditions from 2017 to 2020 to: 1) determine the number of insidious flower bug adults that should be released to manage western flower thrips populations below damaging levels, 2) assess if integrating the insidious flower bug with the insecticide spinosad (Conserve®) is a viable alternative plant protection strategy, and 3) determine if short (<12 h) or long (>12 h) day lengths/photoperiods affect insidious flower bug predation on western flower thrips under greenhouse conditions. We found that releasing three or four insidious flower bug adults was most effective in managing western flower thrips populations on chrysanthemum, Tanacetum × grandiflorum, plants with the mean number of western flower thrips adults and larvae per chrysanthemum plant < 10. We determined that spinosad can be used with the insidious flower bug to manage western flower thrips populations. Finally, we ascertained that insidious flower bug predation was not affected by short [10.5:13.5 (light:dark hours)] or long [14.5:9.5 (light:dark hours)] day lengths/photoperiods. Consequently, greenhouse producers can release the insidious flower bug anytime during the growing season, even from fall through winter, to manage populations of western flower thrips on chrysanthemum. In addition, greenhouse producers can integrate spray applications of spinosad with the insidious flower bug as long as the applications do not negatively affect insidious flower bugs.

Effects of Spray Volume and Application Frequency on Insecticide Efficacy Against Adult Western Flower Thrips (Frankliniella Occidentalis) under Greenhouse Conditions

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major insect pest of greenhouse-grown horticultural crops. Western flower thrips causes direct and indirect damage by feeding on plant leaves, flowers, and fruits, and by transmitting viruses that can result in greenhouse producers experiencing substantial economic losses. Consequently, insecticides are used to suppress western flower thrips populations. However, issues associated with applying insecticides may affect the suppression of western flower thrips populations. Therefore, experiments were conducted under greenhouse conditions to determine the effects of the spray volume applied and application frequency on insecticide efficacy against western flower thrips adults located in transvaal daisy, Gerbera jamesonii, cut flowers. Four spray volumes (5.0, 10.0, 12.5, and 25.0 mL), two application frequencies (one or two spray applications), and three insecticides [spinosad (Conserve), chlorfenapyr (Pylon), and flonicamid (Aria)], each with a different mode of action, were tested. The insecticide treatments had the greatest effects on the mean percent mortality of western flower thrips adults regardless of spray volume or application frequency. However, in Expt. 3, the 5.0- and 10.0-mL spray volumes resulted in a higher mean percent mortality of western flower thrips adults than the 2.5-mL spray volume. Spinosad and chlorfenapyr resulted in a mean percent mortality of more than 72% for western flower thrips adults, whereas flonicamid resulted in mean percent mortality between 40% and 91%. Our study demonstrates that certain insecticides are more effective against western flower thrips adults located in transvaal daisy flowers than others, which will help greenhouse producers effectively manage western flower thrips populations.

Identification of Thrips Species and Resistance of Frankliniella occidentalis (Thysanoptera: Thripidae) to Malathion, Spinosad, and Bifenthrin in Blackberry Crops

Mexico is among the most important blackberry producers in the world. In this crop, thrips damage is associated with poor fruit set. The objectives of this study were to identify the main thrips species associated with the flowers of cultivated blackberries, and to determine the resistance level of 13 field-collected populations of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), to the insecticides malathion, bifenthrin, and spinosad in the states of Michoacan and Jalisco, Mexico. Verification of F. occidentalis was conducted by morphology and PCR amplification of the cytochrome oxidase I (COI) partial gene using LCO and HCO primers The susceptibility of adult thrips to insecticides was determined using residual contact exposure on bean (Phaseolus vulgaris L.; Fabaceae) leaf sections dipped into aqueous solutions of 8 different concentrations of malathion, bifenthrin, and spinosad. The morphological identification of thrips from 8 different sampling zones confirmed that the main thrips species associated with blackberry flowers was F. occidentalis. However, Retanathrips funestus (Hood), Frankliniella insularis (Franklin), Frankliniella tolucensis Watson, Taenothrips frici (Uzel), and Isoneurothrips australis Bagnall (all Thysanoptera: Thripidae) also were found. Most of the evaluated populations of F. occidentalis showed significant differences from the susceptible population in terms of the level of resistance to bifenthrin, malathion, and spinosad. The resistance ratios (RR50) for malathion varied from 36 to 2,458, followed by 4 to 974, and 2 to 248 in bifenthrin and spinosad, respectively. These results suggest the need to establish insecticide resistance management programs, particularly in zones that resulted in the highest levels of insecticide resistance.

Controlling the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) by releasing the predatory phytoseiid mites and pesticides on pepper in a greenhouse

Two programs for controlling the western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were evaluated. Greenhouse experiments were conducted for reducing F. occidentalis populations on pepper plants. The first program was by releasing four phytoseiid predacious mite species namely Neoseiulus arundonaxi (Metwally and Sanad), N. barkeri (Hughes), N. bicaudus (Wainstein), and Cydnoseius negevi (Swirski and Amitai) in the presence of blue sticky traps. The second one was by applying four sequential applications of different pesticides. Results showed that two releases of N. bicaudus, N. barkeri, and N. arundonaxi in the presence of the blue sticky traps reduced WFT population by 45 to 56%. The best control management of the WFT was by the following insecticides: chlorfenapyr, imidacloprid, azadirachtin, and agricultural potassium soap (third program).

Management of Frankliniella occidentalis (Western Flower Thrips), and the Potential use of Entomopathogenic Nematodes: A South African Perspective

Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) or western flower thrips (WFT), has become a global pest of economic importance. WFT is extremely polyphagous, attacking a wide range of host plants in both field and greenhouse production systems. Chemical control is the most frequently used method for the control of WFT, but their cryptic nature, which protects them from contact with insecticides, and their resistance to many insecticides, have become critical limiting factors in terms of control. This has led to heightened emphasis on biological control in integrated pest management (IPM) programmes for WFT. Most commonly used predators are relatively large and unable to enter the cryptic spaces inhabited by WFT, thus limiting their ability to reduce WFT populations. Entomopathogenic nematodes (EPNs) and fungi offer alternative biocontrol options that suit IPM programmes well. This review focuses on WFT and its management, with an emphasis on crops being grown under cover, and on the use of EPNs for biocontrol, from a South African perspective.

The maternal effects of heat shock on biological parameters and ovaries of Frankliniella occidentalis (Thysanoptera: Thripidae)

Maternal effects of heat shock are reported for some species of insects, but little is known about such effects in the western flower thrips (WFT) Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). WFT is a pest of vegetables in greenhouses worldwide. It is susceptible to high temperatures in its natural environment and is controlled using heat treatment in China. WFT population growth is suppressed by a brief exposure to a high temperature of 40°C or 45°C in the laboratory. To explore the mechanism by which high temperatures suppress the growth of WFT populations, as well as the effects of multiple heat treatments on WFT, we recorded the duration of development and survival of immature WFT, and the sex ratio (female/male) and fecundity of F1, F2, F3 and F4 adult females that developed after a single heat shock, and those of F2 offspring after a double heat shock. We also recorded the longevity and ovarian structure of adult females of the treated generation (P) and their F1, F2 and F3 offspring after a single heat shock. In addition, we determined whether the effects of a heat shock on second instar nymphs and adults differed. The results indicate that exposure of the parental generation to 41°C or 45°C for 2 h significantly prolonged the duration of development, reduced survival of immature WFT and altered the sex ratio (female/male), longevity and fertility of their adult female offspring. The effects of a heat shock of 41°C persisted for two generations, whilst the effect of heat shock of 45°C persisted for three generations. In addition, double heat shocks had more pronounced effects than a single heat shock. Heat shock administered to second instar nymphs resulted in a decrease in the number of ovarioles, whilst a heat shock administered to adults resulted in ovariole deformity. The maternal effects of heat shock in terms of the biological parameters of WFT, structure and number of ovarioles, are critical in determining the suppression of the growth at high temperatures of WFT populations.

Effect of Two Oviposition Feeding Substrates on Orius insidiosus and Orius tristicolor (Hemiptera: Anthocoridae)

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is one of the most significant pests of commercial vegetables, fruits, and ornamental crops worldwide, causing both direct and indirect damage. Chemical control is the most common methodology for dealing with F. occidentalis, but this pest lays its eggs inside plant tissues, and adults and larvae feed in concealed locations, which can make chemical control of this pest difficult. As an alternative to chemical control, research attention has been focused on biological control through inoculative augmentation using anthocorid flower bugs of the genus Orius (Hemiptera: Anthocoridae). Although Orius insidiosus (Say) (Hemiptera: Anthocoridae) is an effective predator used worldwide for suppressing populations of western flower thrips, its use on pepper crops in Uruguay (Salto) has not achieved favorable results to date. Taking into account that O. insidiosus can supplement its diet by feeding on pollen and plant tissues, the aim of this study was to assess the effects of pepper fruits compared to bean pods, a vegetable substrate widely used for multiplying this predator, on the duration of the embryonic and nymph developmental stages, survival, fertility, and longevity of this species. Since Orius tristicolor (White) (Hemiptera: Anthocoridae) is present also in the horticultural region of Salto, this species was incorporated into the study in order to evaluate if significant differences exist between these 2 species. When biological parameters were measured, pepper fruits proved to be a more appropriate substrate than bean for the 2 Orius species studied. We reject the hypothesis that an antibiosis effect would explain the difficulties for the establishment of O. insidiosus in the greenhouses of Salto. These results show the need to examine other factors contributing to low establishment of these predatory bugs in greenhouses in Uruguay. Resumen El trips occidental de las flores, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), es una de las plagas mas importantes de hortalizas comerciales, frutas y cultivos ornamentales en todo el mundo, causando dano tanto directo como indirecto. El control quimico es la metodologia mas comun para el control de F. occidentalis, pero esta plaga pone sus huevos dentro de los tejidos vegetales y los adultos y las larvas se alimentan en lugares ocultos, lo que puede dificultar el control quimico de esta plaga. Como una alternativa al control quimico, mucha de la atencion de la investigacion se ha enfocado en el control biologico a traves del aumento inoculativo usando insectos antocoridos del genero Orius (Hemiptera: Anthocoridae). Aunque Orius insidiosus (Say) (Hemiptera: Anthocoridae) es un depredador eficaz utilizado en todo el mundo para suprimir poblaciones de trips occidental de las flores, su uso en cultivos de pimiento en Uruguay (Salto) no ha dado buenos resultados hasta la fecha. Teniendo en cuenta que O. insidiosus puede complementar su dieta alimentandose de polen y de tejidos vegetales, el objetivo de este estudio fue evaluar los efectos de los frutos de pimiento, en comparacion con las vainas de frijol (un sustrato vegetal ampliamente utilizado para multiplicar este depredador), en la duracion de las etapas de desarrollo embrionario y ninfal, supervivencia, fertilidad y longevidad de esta especie. Como Orius tristicolor (White) (Hemiptera: Anthocoridae) esta presente tambien en la region horticola de Salto, esta especie se incorporo al estudio para evaluar si existian diferencias significativas entre estas dos especies. Cuando se midieron los parametros biologicos, los frutos de pimiento probaron ser un sustrato mas apropiado para las dos especies de Orius estudiadas que las vainas de frijol. Rechazamos la hipotesis de que un efecto de antibiosis explicaria las dificultades para el establecimiento de O. insidiosus en los invernaderos de Salto. Estos resultados muestran la necesidad de examinar otros factores que contribuyen al bajo establecimiento de estos insectos depredadores dentro de los invernaderos en Uruguay. Key Words: biological control; omnivory; plant-feeding predators; pepper; Frankliniella occidentalis; oviposition substrates View this article in BioOne https://doi.org/10.1653/024.102.0216

Effect of Integrating the Entomopathogenic Fungus (Hypocreales: Cordycipitaceae) and the Rove Beetle (Coleoptera: Staphylinidae) in Suppressing Western Flower Thrips (Thysanoptera: Thripidae) Populations Under Greenhouse Conditions.

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.

Effect of Insecticide Drench Applications on Western Flower Thrips, Frankliniella occidentalis, Pupae in Growing Media

Western flower thrips, Frankliniella occidentalis, is one of the most destructive insect pests of greenhouse-grown horticultural crops. The primary method of managing western flower thrips populations involves applications of insecticides; however, there is no information associated with the effect of the insect growth regulator, pyriproxyfen, or the entomopathogenic fungus, Isaria fumosorosea, on western flower thrips pupae in growing media. Therefore, four laboratory experiments were conducted to determine the effect of pyriproxyfen and I. fumosorosea applied as a drench to growing media on western flower thrips pupae. Expt. 1 evaluated the efficacy of pyriproxyfen and I. fumosorosea on western flower thrips pupae. Based on the results from Expt. 1, Expt. 2 assessed the effect of pyriproxyfen in two growing media (LC1 and BM1) on western flower thrips pupae. Expts. 3 and 4 determined the residual activity of pyriproxyfen in growing media on western flower thrips pupae 3, 5, 7, and 14 days after treatments were applied. The pyriproxyfen treatment resulted in a significantly lower estimated mean probability of western flower thrips adults captured on yellow sticky cards (17%) compared with the water control (59%), untreated check (88%), and two I. fumosorosea treatments (46% for 1.0 g and 41% for 2.0 g of Ancora) in Expt. 1. However, for the two growing media in Expt. 2, the estimated mean probability of western flower thrips adults captured on yellow sticky cards was not significantly different between the pyriproxyfen treatment (LC1 = 15%; BM1 = 12%) and the water control (LC1 = 41%; BM1 = 24%). For either the pyriproxyfen treatment or the untreated check, there was no evidence of a significant difference between the two growing media on the estimated mean probability of western flower thrips adults captured on yellow sticky cards. Furthermore, there was no evidence of any residual activity 3 days after drench applications of pyriproxyfen. The results of the study have demonstrated that drench applications of pyriproxyfen are not affecting survival of western flower thrips pupae.

Effects of Predators on the Belowground Life Stages (Prepupae and Pupae) of the Western Flower Thrips, &amp;lt;i&amp;gt;Frankliniella occidentalis&amp;lt;/i&amp;gt; (Thripidae: Thysanoptera): A Review

Western flower thrips, Frankliniella occidentalis, is a major cosmopolitan insect pest causing direct and indirect damage to greenhouse-grown horticultural crops. The primary way of managing western flower thrips populations is by routinely applying insecticides, which target the aboveground life stages: larvae and adult. However, insecticides are minimally effective against the pupal stages (prepupae and pupae) that reside in the growing medium or soil. Therefore, soil-dwelling biological control agents including: predatory mites [Stratiolaelaps scimitus and Hypoaspis = (Geolaelaps) aculeifer], and a rove beetle, Dalotia coriaria may be a viable option to induce mortality on the pupal stages. These predators will feed on the pupal stages of the western flower thrips and can provide mortality on a life stage that is tolerant of insecticide applications. However, these biological control agents need to be used in conjunction with other plant protection strategies, such as insecticides and/or biological control agents that target the aboveground life stages (larvae and adult) to effectively manage western flower thrips populations in greenhouse production systems.

Occurrence of Thrips in Greenhouse Cucumber and Insecticidal Activity of Five Local Western Flower Thrips Populations

Occurrence of Thrips in Greenhouse Cucumber and Insecticidal Activity of Five Local Western Flower Thrips Populations

Western Flower Thrips (Thysanoptera: Thripidae) and Insecticide Resistance: An Overview and Strategies to Mitigate Insecticide Resistance Development

Abstract Western flower thrips, Frankliniella occidentalis (Pergande), are one of the most-destructive insect pests of greenhouse-grown horticultural crops worldwide due to the direct and indirect damage they cause to plants. Western flower thrips induce direct damage by feeding on leaves and flowers and also cause indirect damage by vectoring certain tospoviruses including Impatiens necrotic spot and Tomato spotted wilt viruses. As a result, the threshold for this insect pest is near zero. Consequently, the primary means of suppressing populations of western flower thrips in greenhouse production systems is the application of insecticides. In general, insecticides are inexpensive, easy to apply, and relatively effective. However, the selection pressure placed on western flower thrips populations due to intensive applications of insecticides has resulted in severe problems associated with the development of resistance. Therefore, in order to avoid the prospect of insecticide resistance developing in west...