Control Of Thrips Research Articles

Control of Western Flower Thrips on Gardenia, Summer 2004

Control of Western Flower Thrips on Gardenia, Summer 2004

English

This study was conducted in kewet district of Amhara region, Ethiopia. The experiment on seasonal thrips population dynamics and onion yield loss was conducted in 2003 and 2004. The treatments were five transplanting dates of two month interval with and without spray of insecticide in five replications. Thrips count per plant was low during the rainy and cool months of July to November and in April. Thrips population started increasing in December and reached the pick value of 159 thrips per plant in March. Thrips population on onion is high from six to ten leaves growth stages. Damage caused by thrips on onion significantly varies with growing season. More yield loss was observed in onion transplanted during dry seasons (October to February). The highest total bulb and marketable bulb yield loss of 16.9 and 17.7 tons/ha occurred on December transplanted onion. Onion from six to ten leaves growth stage is the most critical period for thrips control. These results are important for the management of onion thrips by growers. Key word: Onion thrips, population pick, bulb yield loss, insecticide, season.

Apple pollen as a supplemental food source for the control of western flower thrips by two predatory mites, Amblyseius swirskii and Neoseiulus cucumeris (Acari: Phytoseiidae), on potted chrysanthemum.

It has been shown that pollen as a dietary supplement may increase the establishment (development and reproduction) and survival of phytoseiid predatory mites, and therefore the pest control these mites can provide. In this study, the role of apple pollen as a supplemental food source was assessed as a means to increase the efficiency of two predatory mite species, Neoseiulus cucumeris and Amblyseius swirskii, for control of western flower thrips, Frankliniella occidentalis, under greenhouse conditions. The impact of apple pollen on thrips populations and predator establishment on a greenhouse chrysanthemum crop was determined over a 4-week period. The two mite species were released separately and in combination with and without pollen with two control treatments (thrips only and thrips + pollen). The introduction of A. swirskii together with pollen application provided the best control of thrips (adults and immatures). The establishment of N. cucumeris was very low in the crop during the greenhouse trial. This could be attributable, in part, to their response to extreme temperature ranges that were encountered during the greenhouse cage trials. The use of A. swirskii alone and the mixed population of the two predatory mite species without pollen resulted in the lowest frequencies of plants with heavy damage, followed by the same treatments with the addition of apple pollen.

Seasonal climatic variations influence the efficacy of predatory mites used for control of western flower thrips in greenhouse ornamental crops.

The influence of seasonal greenhouse climate on the efficacy of predatory mites for thrips control was determined for potted chrysanthemum. Trials in controlled environment chambers, small-scale greenhouses and commercial greenhouses were conducted to determine which biological control agent-that is, Amblyseius swirskii Athias-Henriot or Neoseiulus cucumeris (Oudemans)-is more efficacious for control of western flower thrips, Frankliniella occidentalis (Pergande), in different seasons. Under simulated summer conditions, no differences were observed in the predation and oviposition rates of both predatory mites in the laboratory trials. However, small-scale greenhouse trials showed that A. swirskii performed better than N. cucumeris in summer (i.e., more efficacious thrips control, higher predator abundance and less overall damage to the crop). Under simulated winter conditions, laboratory trials demonstrated variable differences in predation rates of the two predatory mites. The small-scale greenhouse trials in winter showed no differences in thrips control and predatory mite abundance between the two predatory mites, but plants with A. swirskii had less damage overall. The results from the small-scale trials were validated and confirmed in commercial greenhouse trials. Overall, A. swirskii performed better in the summer and equally good or better (less damage overall) under winter conditions, whereas N. cucumeris is a more cost effective biological control agent for winter months.

Effect of introductions of a predator complex on spider mites and thrips in a tunnel and an open field of pesticide-free everbearer strawberry

BACKGROUND: Chemical control of spider mites and thrips in everbearer strawberry is difficult as few efficient chemicals are available and residues represent a risk. In the north the success of biocontrol of mites and thrips in open fields compared with tunnels needs to be evaluated. OBJECTIVES: To investigate the need for control of spider mites and thrips and evaluate the effectiveness of biological control agents in everbearer strawberry. METHODS: Similar experimental plots, in a tunnel and an open field, planted with three everbearer strawberry varieties were arranged to compare the effect of introductions of the spider mite predator Phytoseiulus persimilis and releases of the generalist predatory mites Neoseiulus cucumeris and Neoseiulus barkeri and a predatory bug, Orius majusculus. Several sampling methods were used to evaluate mite and thrips populations. RESULTS: Phytoseiulus persimilis was successful against spider mites. Naturally occurring cecidomyiid and staphylinid predators affected control positively. Thrips damage remained mostly tolerable. The dominant thrips species were Thrips major, Thrips atratus, Thrips vulgatissimus and Frankliniella intonsa. Thrips numbers in the beating tray samples correlated with thrips damage to berries. CONCLUSIONS: Predatory mites were effective in controlling spider mites in an open field and a tunnel. The need for thrips control depended on the strawberry variety. Naturally occurring predators contributed to the control of spider mites and thrips.

Supplemental food that supports both predator and pest: a risk for biological control?

Supplemental food sources to support natural enemies in crops are increasingly being tested and used. This is particularly interesting for generalist predators that can reproduce on these food sources. However, a potential risk for pest control could occur when herbivores also benefit from supplemental food sources. In order to optimize biological control, it may be important to select food sources that support predator populations more than herbivore populations. In this study we evaluated the nutritional quality of four types of supplemental food for the generalist predatory mites Amblyseius swirskii Athias-Henriot and Amblydromalus (Typhlodromalus) limonicus (Garman and McGregor), both important thrips predators, and for the herbivore western flower thrips Frankliniella occidentalis Pergande, by assessing oviposition rates. These tests showed that application of corn pollen, cattail pollen or sterilized eggs of Ephestia kuehniella Zeller to chrysanthemum leaves resulted in three times higher oviposition rates of thrips compared to leaves without additional food. None of the tested food sources promoted predatory mites or western flower thrips exclusively. Decapsulated cysts of Artemia franciscana Kellogg were not suitable, whereas cattail pollen was very suitable for both predatory mites and western flower thrips. In addition, we found that the rate of thrips predation by A. swirskii can be reduced by 50 %, when pollen is present. Nevertheless, application of pollen or Ephestia eggs to a chrysanthemum crop still strongly enhanced the biological control of thrips with A. swirskii, both at low and high release densities of predatory mites through the strong numerical response of the predators. Despite these positive results, application in a crop should be approached with caution, as the results may strongly depend on the initial predator-prey ratio, the nutritional quality of the supplemental food source, the species of predatory mites, the distribution of the food in the crop and the type of crop.

Low temperature phosphine fumigation for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) on oriental lily

Western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), widely distributed in the main Chinese cut flower production areas, present a problem because it is listed as a quarantine pest in some exporting countries. Phosphine (PH3), a potential alternative to methyl bromide (MB), was investigated to determine its effects on postharvest control of western flower thrips at low temperature on oriental lily. Toxicity tests showed that the 3-d-old egg was the most tolerant among all life stages. Phosphine concentrations from 0.31 to 1.88mgL−1 and exposure durations from 6 to 120h at 5°C were applied on the 3-d-old eggs, and results showed 24.34–09.55h were required to achieve 99% mortality with different phosphine concentrations. The expression of C0.85T=k was obtained. Synergistic effects of controlled atmosphere (CA) treatment with increased carbon dioxide (CO2) and reduced oxygen to PH3 fumigation were verified. Phosphine fumigation could achieve 100% mortality and had no adverse effects on vase life and damage indices of two oriental lily cultivars at 1.66mgL−1 PH3 and 12% CO2 for 16h, and at 2.29mgL−1 PH3 without CO2 gas for 2d at 5°C. All results suggested that low temperature phosphine fumigation with or without CO2 could be used as an alternative for postharvest control of western flower thrips on oriental lily.

Control of Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae) with acephate to exclude a biological control agent of Schinus terebinthifolia

Post-release monitoring of biological control agents to determine impact on the target weed has recently received increased priority. Several methods are available to measure the impact of a biological control agent by manipulating the agent population while measuring fitness of the weed. Brazilian peppertree, Schinus terebinthifolia is one of the most damaging weeds in subtropical areas of Florida and Hawaii. A biological control agent, the thrips, Pseudophilothrips ichini is a sap-feeder that shows high levels of specificity and causes severe distortion of leaf tips of the weed. Thrips populations of this species and a generalist thrips, the red banded thrips Selenothrips rubrocinctus were experimentally manipulated by applications of the systemic insecticide acephate by both foliar applications and by an inserted encapsulated formulation. Foliar applications protected plants against red banded thrips for 29 days and against the biological control thrips, P. ichini for 22 days after treatment. Control with inserts were initially low but was achieved after 60 days and this control continued for 182 days after treatment. Manipulation of these biological control thrips populations with foliar or inserted formulations will assist in the determination of biological control agent impact.

Preference of the vector thrips Frankliniella occidentalis for plants infected with thrips‐non‐transmissible Tomato spotted wilt virus

AbstractThe effect of a thrips‐non‐transmissible Tomato spotted wilt virus (TSWV) on insect–host interactions between thrips and Arabidopsis thaliana was analysed. A wild‐type TSWV virulent isolate and a TSWV isolate that induces mild symptoms on inoculated plants (TSWV‐Mo) were used in this study, and TSWV‐Mo isolate was obtained by single local lesion isolation using Petunia x hybrid after several passages on Nicotiana rustica plants. In transmission test, although wild‐type TSWV (TSWV‐wt) was transmitted by two thrips species (transmission ratio; Frankliniella occidentalis, 25%; Thrips tabaci, 10%; and T. palmi, 0%), none of the thrips transmitted TSWV‐Mo. Feeding damage by F. occidentalis in A. thaliana plants was more extensive on TSWV‐wt‐infected plants than on TSWV‐Mo‐infected plants, despite comparable preference. Among the markers of plant defences, salicylic acid‐regulated genes were upregulated threefold to sixfold by TSWV‐wt or TSWV‐Mo infection. In contrast, jasmonate‐regulated genes and jasmonate/ethylene‐regulated genes were not affected by the infections. Pull assays showed that adjacent TSWV‐Mo‐infected plants were preferred over uninfected plants. In conclusion, our results showed that the transmissibility by thrips of TSWV is not related to preference of vector thrips and suggested that TSWV‐Mo‐infected plants may be used as attractants for behaviour control of thrips.

Increased control of thrips and aphids in greenhouses with two species of generalist predatory bugs involved in intraguild predation

The combined release of species of generalist predators can enhance multiple pest control when the predators feed on different prey, but, in theory, predators may be excluded through predation on each other. This study evaluated the co-occurrence of the generalist predators Macrolophus pygmaeus Rambur and Orius laevigatus (Fieber) and their control of two pests in a sweet pepper crop. Both predators consume pollen and nectar in sweet pepper flowers, prey on thrips and aphids, and O. laevigatus is an intraguild predator of M. pygmaeus. Observations in a commercial sweet pepper crop in a greenhouse with low densities of pests showed that the two predator species coexisted for 8months. Moreover, their distributions in flowers suggested that they were neither attracted to each other, nor avoided or excluded each other. A greenhouse experiment showed that the predators together clearly controlled thrips and aphids better than each of them separately. Thrips control was significantly better in the presence of O. laevigatus and aphid control was significantly better in the presence of M. pygmaeus. Hence, combined inoculative releases of M. pygmaeus and O. laevigatus seem to be a good solution for controlling both thrips and aphids in greenhouse-grown sweet pepper. The predators are able to persist in one crop for a sufficiently long period and they complement each other in the control of both pests. This study also provides further evidence that intraguild predation does not necessarily have negative effects on biological control.

Evaluation of Stratiolaelaos scimitus and Neoseiulus barkeri for biological control of thrips on greenhouse cucumbers

Stratiolaelaos scimitus Berlese (Acari: Laelapidae) is an important soil-dwelling predatory mite used to control thrips and it is necessary to explore its potential predation capacity. In the present study, the functional response for S. scimitus on the pupae of Frankliniella occidentalis Pergande was examined. In addition, the effects of released S. scimitus for the control of Thrips tabaci Lindeman and F. occidentalis on greenhouse cucumber were evaluated, and compared with that of the common predator Neoseiulus barkeri Hughes (Acari: Phytoseiidae). The results showed that S. scimitus exhibited a Holling type II functional response on thrips pupae. The greenhouse study indicated that the release of N. barkeri and S. scimitus separately at the density of 250 mites/m2 suppressed the population growth of thrips. In comparison with control plots, N. barkeri and S. scimitus reduced the population of T. tabaci by 76% and 64% in six weeks, respectively. Releases of N. barkeri and S. scimitus led to a reduction in F. occidentalis by 41% and 43%, respectively. Significantly lower densities of both thrips species per leaf were recorded in treatments of individual releases of N. barkeri or S. scimitus than that in the control plots. The findings highlight the potential for utilising N. barkeri and S. scimitus as biological control agents of T. tabaci and F. occidentalis, respectively.

Effects of Exposure to High Temperature onFrankliniella occidentalis(Thysanoptera: Thripidae), under Arrhenotoky and Sexual Reproduction Conditions

Temperature plays a critical role in the population dynamics of insects. This study was designed to estimate the effect of exposure of Frankliniella occidentalis (Pergande) in the parental generation to 41 °C for various durations (2, 6, 12, 24, and 36 h) on their reproduction and on the first generation progeny. The data indicated that, under both the arrhenotoky and the sexual reproduction pattern, the longevity of adult females and the numbers of larvae and adults in the first generation decreased significantly as the period of exposure to heat increased. When adults were exposed at least 24 hours under arrhenotoky and at least 6 hours under sexual reproduction, the total survival rate from larva to adult in the first progeny generation was significantly lower compared with control groups whose parents had not been exposed to heat treatments. Furthermore, high-temperature exposure of sexually reproducing adults significantly decreased the proportion of females in the first progeny generation: The sex ratio (♀:♂) changed from 2.69:1 in the control to 2.31:1 after 2 h to 2.14:1 after 36 h of heat treatment. These results support the hypothesis that heat stress could be of use in the control of the western flower thrips.

Impacts on Natural Enemies and Competitor Thrips of Insecticides against the Western Flower Thrips (Thysanoptera: Thripidae) in Fruiting Vegetables

Newer, selective insecticides with few negative impacts on natural enemies and competitor species are needed for effective, sustainable management of the western flower thrips, Frankliniella occidentalis (Pergande). The purpose of this study was to evaluate the impacts on natural enemies and competitor thrips species of insecticides used for control of western flower thrips in fruiting vegetables. Trials with tomato (Solanum lycopersicum L.) and with pepper (Capsicum annuum L.) were conducted to evaluate insecticide treatment effects on western flower thrips and natural enemies at the North Florida in 2008, 2009, 2010 and 2011. A number of insecticides from different classes showed moderate to high efficacy against western flower thrips. The broad-spectrum insecticides acetamiprid, methomyl, and tolfenpyrad demonstrated activity against the pest, while also reducing populations of the key predator of thrips in pepper, Orius insidiosus (Say) (Hemiptera: Anthocoridae). Insecticides that showed little impact on populations of O. insidiosus were cyantraniliprole, flonicamid, spirotetramat, and terpenes. Although only moderately active against the western flower thrips, they would be valuable additions to existing management programs for pepper. Insecticides with activity against western flower thrips also showed activity against Frankliniella tritici (Fitch). This non-damaging congener species is a beneficial because it out-competes the western flower thrips, especially in tomato where O. insidiosus is not a major factor in western flower thrips management. Numerous insecticides were identified with activity against the western flower thrips that are suitable for use in integrated pest management programs of fruiting vegetables.

시설재배 국화에서 꽃노랑총채벌레 방제를 위한 미끌애꽃노린재와 new banker plants의 혼합 적용 효과

시설국화에서 꽃노랑총채벌레를 친환경적으로 방제하기 위하여 미끌애꽃노린재와 미끌애꽃노린재 뱅커플랜트를 적용하여 7주 동안 천적의 분포 및 해충의 밀도변동을 조사하였다. 시설국화에서 천적의 방사방법 및 방사량에 따른 해충의 밀도 억제 효과를 검증하고자 천적 단독 처리, 뱅커플랜트 단독 처리 I, II, 천적과 뱅커플랜트 혼합 처리 I, II의 시험구를 설정하였다. 천적과 뱅커플랜트를 혼합 적용하여 처리한 곳이 국화 1주당 꽃노랑총채벌레 1마리 이하로 70마리까지 증가한 무처리구에 비해 밀도 억제 효과가 가장 뛰어났다. 이 처리구에서 91.8%의 꽃노랑총채벌레에 대한 방제가를 보였으며 친환경자재 처리구에 비해 5.8배, 천적 단독 처리구에 비해 1.4배의 해충 방제 효과가 있어 시설재배 국화에서 천적과 뱅커플랜트 혼합 적용의 꽃노랑총채벌레 방제 가능성을 확인하였다. This studies by treatment of 25 individual adults of O. laevigatus and Banker plant with different number of eggs of O. laevigatus were conducted to develop new biological control of the western flower thrips (WFT) in chrysanthemum house. In this work, a treatment of 25 individual adults of O. laevigatus, Banker plant with different number of eggs of O. laevigatus and mixed treatment were applied. Initial WFT density per plant were 5 individuals. WFT density was measured every 7days after treatment for 7 weeks. Biological control of WFT by 25 individual adults of O. laevigatus and Banker plant with 25 eggs of O. laevigatus were applied 1 time and resulted in the high control value of thrips 91.8%. The population of WFT was kept under the economic threshold level (1 individual per plant). For the last three years we developed new banker plant system. This system is being developed to improve biological control of WFT on chrysanthemums.

Field evaluation of selected botanicals and commercial synthetic insecticides against Thrips tabaci Lindeman (Thysanoptera: Thripidae) populations and predators in onion field plots

The effectiveness of three botanical insecticides (neem, datura and bitter apple), and three new chemistry synthetic insecticides (acephate, spirotetramat and spinetoram) against onion thrips (Thrips tabaci) was evaluated in experimental field plots at university of Sargodha, Pakistan. The influence of these botanical and chemical insecticides on natural predators and crop yield was simultaneously investigated. All the botanicals and chemical insecticides tested caused significant reductions (45–70%) in thrips populations; the botanicals gave more than 60% control of thrips, while among chemical insecticides, acephate was found to be the most effective followed by spirotetramat and spinetoram, respectively, and these insecticides gave better control than the botanicals. The adverse effects of the botanicals on predator populations were negligible compared to the chemical insecticides. All chemical treatments resulted in a significantly higher yield compared to the untreated control. The botanicals and chemical insecticides became less effective by 7 days after treatment. Therefore, it is recommended that treatment with botanical or chemical insecticides should be repeated weekly consecutively at least three times to keep thrips populations below economic injury levels until crop maturity.

6-Pentyl-2H-pyran-2-one: A Potent Peach-Derived Kairomone for New Zealand Flower Thrips, Thrips obscuratus

New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae), are attracted to ripening fruits, especially peaches. Volatiles from unripe and ripe peach fruits were collected and analyzed by gas chromatography/mass spectrometry. Six lactones were found only in ripe peach volatiles: γ-heptalactone, γ-octalactone, γ-nonalactone, 6-pentyl-2H-pyran-2-one, γ-decalactone, and δ-decalactone. When these compounds were tested individually in field-trapping experiments, three of them (γ-octalactone, γ-nonalactone, and 6-pentyl-2H-pyran-2-one) attracted New Zealand flower thrips. In another field-trapping experiment, aimed at testing various combinations of the three active compounds, no synergistic effects were found among all combinations tested; no combination caught more thrips than 6-pentyl-2H-pyran-2-one, alone. A further field-trapping experiment was conducted to determine the dose (10, 100, and 500mg) of 6-pentyl-2H-pyran-2-one that gave the greatest catch of T. obscuratus, while also comparing it against another attractant, ethyl nicotinate, for T. obscuratus. The greatest catches in traps baited with either attractant were at loadings of 500mg. At both 10 and 500mg, traps baited with 6-pentyl-2H-pyran-2-one caught more T. obscuratus than those baited with the same amounts of ethyl nicotinate. 6-Pentyl-2H-pyran-2-one is a potent attractant for New Zealand flower thrips and, therefore, could be used for monitoring and control of New Zealand flower thrips. Work is underway developing monitoring and control options utilizing 6-pentyl-2H-pyran-2-one for this important pest.

Development of IPM practices for the control of flower thrips and pod borers in mungbean (Vigna radiata L.)

Development of IPM practices for the control of flower thrips and pod borers in mungbean (Vigna radiata L.)

甘長ピーマンの害虫アザミウマ類に対するアカメガシワクダアザミウマとヒメハナカメムシ類による防除

甘長ピーマンの害虫アザミウマ類に対するアカメガシワクダアザミウマとヒメハナカメムシ類による防除

キュウリに放飼したアカメガシワクダアザミウマの個体分布とミナミキイロアザミウマの防除

キュウリに放飼したアカメガシワクダアザミウマの個体分布とミナミキイロアザミウマの防除

The Importance and Management Option of Onion thrips, Thrips tabaci (L.) (Thysanoptera: Thripidae) in Ethiopia: A Review

Thrips attack a number of vegetable crops particularly onion thrips causing considerable economic damage on onion crops. Usually young leaves are preferred, but buds and flowers also get infested. Under severe infested conditions the leaves shed and hence plant growth is affected and their control is vital to the production and profitability of onion crop. Most onion fields need protection against onion thrips for two to three months depends on the varieties. If onion thrips are not controlled, damage can routinely reduce bulb yields. In addition to use integrated pest management, use of selective insecticides in rotation to be the most important tools for thrips control, but there are few labeled insecticides that registered in Ethiopia provide effective and consistent control. Therefore, the objective of this review was undertaken to evaluate previous work in the management of onion thrips.