Mortality Of Western Flower Thrips Research Articles

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.

Azadirachtin Efficacy in Colorado Potato Beetle and Western Flower Thrips Control

Colorado potato beetle (CPB) and western flower thrips (WFT) are agricultural pests which are difficult to control due to resistance developed to many classes of insecticides. A botanical insecticide azadirachtin could represent an ecologically acceptable alternative for their management. This research tested the efficacy of azadirachtin on CPB and WFT mortality and feeding intensity, as well as thrips oviposition. Azadirachtin was used in three doses in laboratory trials. The results showed that this botanical insecticide was effective on larval stages of CPB and reduced the damages on treated leaves, but did not cause significant mortality or reduction in feeding intensity of the adults. It was not sufficiently effective against the WFT adults either, but it reduced the feeding damage on leaves and prevented egg laying. The results indicated that, even though azadirachtin did not have a significant adverse effect on the adult CPB and WFT insects, it reduced the overall population by affecting the CPB larvae or feeding intensity and egg laying in WFT. Antifeedant and anti-ovipositional activities, as shown in the case of WFT, should also be considered when assessing azadirachtin efficacy on insect pests.

Efficacy of Binary Pesticide Mixtures Against Western Flower Thrips

This study was designed to determine the efficacy of binary pesticide mixtures against one of the most important insect pests of greenhouse-grown horticultural crops, western flower thrips (Frankliniella occidentalis). Two separate experiments were conducted under greenhouse conditions to simulate a greenhouse production cycle using yellow transvaal daisy (Gerbera jamesonii) cut flowers, which were artificially infested with a known number of western flower thrips. The pesticides used in the two experiments were spinosad, pymetrozine, abamectin, pyridalyl, fluvalinate, chlorfenapyr, bifenazate, azadirachtin, petroleum oil, tolfenpyrad, fenhexamid, azoxystrobin, and spirotetramat. Pesticide mixtures were evaluated at the recommended labeled rates (Expt. 1) and assessments were made to determine if adding didecyl dimethyl ammonium chloride enhanced the efficacy of the pesticide mixtures (Expt. 2). Results from Expt. 1 indicated that many of the binary pesticide mixtures provided ≥80% mortality of western flower thrips although this was a baseline population without previous exposure to pesticides. In Expt. 2, the addition of didecyl dimethyl ammonium chloride failed to increase the efficacy of most of the designated pesticide mixtures compared with the pesticides applied separately. Furthermore, none of the binary pesticide mixtures were phytotoxic to the transvaal daisy flowers. Although there are issues associated with using pesticide mixtures such as the potential for resistance developing to different pesticides in mixtures, greenhouse producers combine pesticides together to reduce labor costs and expand the spectrum of activity against insect and mite (Tetranychidae) pests. Therefore, the relevance of this information is that greenhouse producers now understand which pesticide mixtures may be used and those that should be avoided when suppressing populations of western flower thrips thus minimizing feeding damage to greenhouse-grown horticultural crops.

Efficacy of Pesticide Mixtures Against the Western Flower Thrips (Thysanoptera: Thripidae) Under Laboratory and Greenhouse Conditions

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 semifield bioassays demonstrated significantly reduced efficacy associated with mixtures containing azadirachtin, however, all binary mixtures provided approximately 80% western flower thrips mortality.

Ultralow oxygen treatment for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), on iceberg lettuce : I. Effects of temperature, time, and oxygen level on insect mortality and lettuce quality

Ultralow oxygen (ULO) treatments with different oxygen levels, treatment times, and temperatures were studied to determine effects on western flower thrips mortality and postharvest quality of iceberg lettuce. Thrips mortality increased with reduced oxygen level and increased treatment time and temperature. At 0.003% oxygen, over 99.6% mortality rates of thrips were achieved in three ULO treatments of 2, 3, and 4 d at 10, 5, and 1 °C, respectively. No treatments caused injury to lettuce surface leaves and there was no reduction in visual quality for treated lettuce. However, about 9–33% of lettuce heads sustained injury to heartleaves. The 2 d ULO treatment with 0.003% oxygen had the lowest injury rate to heartleaves and the injury increased with increased treatment duration. The amount of injured leaves was small (<2 g per head). There were also some variations among the lettuce cultivars in susceptibility to heartleaf injury by ULO treatments. Four out of eight cultivars tested tolerated the 2 d ULO treatment at 10 °C without any injury. Therefore, ULO treatment has potential to be developed as an alternative postharvest treatment for western flower thrips on iceberg lettuce.

Mode of Action of a Novel Nonchemical Method of Insect Control: Atmospheric Pressure Plasma Discharge

Atmospheric pressure plasma discharge (APPD) has been applied to a number of industrial applications, including the bacterial sterilization of medical equipment of bacteria. APPD may also have applications in insect control. A positive correlation was found between exposure time to APPD and mortality of western flower thrips, Frankliniella occidentalis (Pergande); tobacco thrips, Frankliniella fusca (Hinds); Asian tiger mosquito, Aedes albopictus (Skuse); twospotted spider mite, Tetranychus urticae Koch; and German cockroach, Blattella germanica (L.), with the level of mortality also increasing with time after treatment. Cockroaches exposed to APPD for 60, 90, 120, and 180 s lost on average 7.5 +/- 0.8, 8.1 +/- 0.6, 8.7 +/- 0.4, and 10.1 +/- 1.1 (+/-1 SEM) mg of water weight, respectively, which was an increase over that of the controls. The metabolic rate of cockroaches exposed to plasma for 180 s increased from 0.79 +/- 0.03 to 1.07 +/- 0.04 ml of oxygen consumed mg-cockroach(-1) h(-1) at standard temperature and pressure. The level of cuticular hydrocarbons identified by electron impact gas chromatography-mass spectrometry were not significantly affected by plasma exposure in the green peach aphid, Myzus persicae (Sulzer), German cockroach, and citrus mealybug, Planococcus citri (Risso), except for a reduction in n-tritriacontane in the latter. However, changes in the behavior of cockroaches after plasma exposure, including the loss of photo-, vibro-, and thigmotropic responses, inability to right themselves, and hyperexcitatory symptoms, suggest that the site of action of APPD in insects is the nervous and/or neuromuscular system.

Effect of Pesticide Mixtures in Controlling Western Flower Thrips (Thysanoptera: Thripidae)

Greenhouse managers mix together pesticides to broaden the spectrum of pest control and to reduce pesticide and labor costs. However, the efficacy of pesticide mixtures has not been well-documented. This study assesses how mixtures of commercially available insecticides and miticides in two, three, and four-way combinations affected the control of western flower thrips, Frankliniella occidentalis Pergande, in greenhouse experiments and in a laboratory bioassay. The pesticides screened in the greenhouse experiments and laboratory bioassay were spinosad, abamectin, bifenazate, azadirachtin and imidacloprid. Each pesticide was applied at the maximum label-recommended rate. In the greenhouse experiments, transvaal daisy (Gerbera jamesonii H. Bolus ex Hook. f) and lisianthus (Eustoma grandiflorum G. Don ex Sweet) flowers were infested with 25 adult western flower thrips (mixture of females and males). Flowers were then sprayed with the designated treatments. After 72 h, flowers were dissected to assess the numbers of live and dead western flower thrips. In the laboratory bioassay, chrysanthemum (Dendranthema grandiflora Tzvelev) leaf sections, treated with solutions of each pesticide and all possible combinations, were exposed to 15 adult western flower thrips. The numbers of live and dead western flower thrips were assessed after 48 h. For all three experiments, we were not able to identify any antagonistic pesticide combinations. All treatments with spinosad, including the individual application and pesticide mixtures, resulted in high mortality of western flower thrips. Our data suggest that combinations of spinosad with the other pesticides tested do not affect the efficacy of spinosad in controlling western flower thrips. This information is important to greenhouse managers who wish to mix pesticides and still control western flower thrips in addition to the other plant-feeding arthropods found in greenhouses.

Effect of Tank Mixing Pesticides in Controlling Western Flower Thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

Greenhouse managers tank mix pesticides to broaden the spectrum of pest control, and reduce pesticide and labor costs. However, the effect of tank mixing an assortment of pesticides on efficacy to control pests has not been documented. This study assessed how tank mixing commercially available insecticides and miticides in two-, three-, and four-way combinations impacts the control of western flower thrips (WFT), Frankliniella occidentalis in greenhouse experiments and a laboratory bioassay. The pesticides screened were spinosad, abamectin, bifenazate, azadirachtin, and imidacloprid. Each pesticide was applied at the label-recommended rate. In the greenhouse experiments, transvaal daisy (Gerbera jamesonii) and lisianthus (Eustoma grandiflorum) flowers were inoculated with 25 adult WFT, and then flowers were sprayed with the designated treatments. After 72 hours, flowers were emasculated to assess the numbers of live and dead WFT. In the laboratory bioassay, chrysanthemum (Dendranthema grandiflora) leaf disks, treated with each pesticide and all tank mixes, were exposed to 15 adult WFT. The numbers of live and dead WFT were assessed after 48 hours. For all three experiments, no antagonistic tank mixes were identified. All treatments with spinosad, including the individual application and tank mixes, resulted in high mortality of WFT based on the numbers of live and dead WFT recovered. Our data suggest that tank mixes of spinosad with the other pesticides tested do not affect the efficacy of spinosad in controlling WFT. This information is important to greenhouse managers who want to tank mix pesticides and still control WFT in addition to the other plant-feeding arthropods found in greenhouses.

Efficacy of entomopathogenic nematodes against western flower thrips Frankliniella occidentalis at different pupation depths

Abstract To study the effects of the pupation depth of western flower thrips (WFT), Frankliniella occidentalis (Pergande), on the efficacy of entomopathogenic nematodes (EPN), Heterorhabditis indica strain LN2 and Steinernema bicornutum were applied at dose rates of 100 and 400 infective juveniles (IJ) cm–2to WFT that had pupated at different depths. Additionally, the effects of EPN concentrations and thrips densities were tested on the pupation depth of WFT. A higher concentration of H. indica was required when the thrips pupated deeper. Yet applications of S. bicornutum even at a high concentration resulted in a significantly lower WFT mortality at greater rather than at shallower depths. Generally, WFT control levels of 5-57% were obtained depending on depth of pupation, EPN species, and concentrations. The results clearly indicate that WFT at high EPN concentrations seem to remain at a certain soil depth in order to avoid EPN attraction by moving around. Without or at low EPN concentrations, up to 80% of WFT pupated at the deepest depth of 3-5 cm. However, at higher thrips densities and EPN concentrations, 45-48% of WFT pupated in the medium depth of 1-3 cm. Thus, depth of pupation is an important factor in WFT control using EPN.

Effects of acetaldehyde on fruit quality and target pest mortality for harvested strawberries

Strawberry fruit and western flower thrips were exposed to 1, 2, 3, or 4% acetaldehyde (Aa) for 2 h in air or in 20 kPa CO2. Following treatment, fruit were stored at 0 or 20 8C for 4 or 2 days, respectively. Aa treatment did not significantly impact fruit firmness, color, or soluble solids content; however, calyx damage increased with increasing concentration of Aa. Strawberry fruit tolerated exposure to 1 or 2% Aa with little or no damage to the fruit calyx. Fruit Aa, ethanol, and ethyl acetate concentrations increased initially, but decreased over time; the decrease being greater in fruit stored at 20 8C as compared with 0 8C. Methanol and acetone levels were lower in treated than untreated fruit. Western flower thrips were not completely controlled by any of the treatments, but � /95% mortality was achieved by a 2 h exposure to 3 or 4% Aa. The presence of 20 kPa CO2 enhanced mortality of western flower thrips at lower concentrations of Aa. Strawberry fruit, western flower thrips and two-spotted spider mites were also exposed to multiple applications of Aa over time. Strawberry fruit exposed to low concentrations of Aa in repeated doses showed higher tolerance than fruit exposed to the same dose as a single exposure. While repeated exposure to 1 or 2% Aa resulted in greater pest mortality than a single exposure to 1 or 2% Aa, mortality was significantly lower with repeated applications of low doses as compared with a single application of the accumulated dose (1, 1, 1 Aa vs. 3% Aa). None of the treatments resulted in complete control of either target pest. # 2002 Elsevier Science B.V. All rights reserved.

Pest response in packed table grapes to low temperature storage combined with slow-release sulfur dioxide pads in basic and large-scale tests.

The effect of low temperature storage combined with slow release sulfur dioxide pads was determined in basic laboratory and large-scale commercial tests on western flower thrips, Frankliniella occidentalis Pergande; grape mealybug, Pseudococcus maritimus (Ehrhorn); Pacific spider mite, Tetranychus pacificus McGregor; twospotted spider mite, Tetranychus urticae Koch; and omnivorous leafroller, Platynota stultana Walshingham. Temperatures within the foam containers among the packed clusters decreased from ambient to 2 degrees C within approximately 1 d and ranged from 0.4 to 1.7 degrees C in all tests. Sulfur dioxide concentrations in the foam containers ranged between 0.2 and 1.6 ppm during the 1- to 6-wk storage period in basic tests and 0.5-1.1 ppm during the 1- to 8-wk storage period in the large-scale test. Western flower thrips was completely controlled by a > or =1-wk exposure. Grape mealybug mortality was > or =93% after 2-5 wk exposures and 100% after a 6-wk exposure in basic tests. Pacific spider mite and twospotted spider mite mortality was 98.0 and 99.6%, respectively, after a 6-wk exposure. Mortality of grape mealybug and twospotted spider mite increased significantly at > or =3-wk exposures and Pacific spider mite mortality increased significantly at > or =4-wk exposures. Mortality of the spider mites in general was directly related to the duration of exposure. An 8-wk exposure to low temperature storage combined with slow release sulfur dioxide pads in the large-scale test resulted in 100% mortality of western flower thrips, twospotted spider mite, and omnivorous leafroller. The treatment resulted in <8% survival of grape mealybug and <1% survival of Pacific spider mite in the large-scale test. The combination treatment offers an economical method to attain quarantine control of certain insects and mites.

The Effects of Refrigerated, Controlled-atmosphere Storage during Marine Shipment on Insect Mortality and Cut-flower Vase Life

Refrigerated (2 °C) controlled atmospheres significantly increased the mortality of green peach aphids [Myzus persicae (Sulzer)] and western flower thrips [Frankliniella occidentalis (Pergande)] in laboratory experiments. However, insect mortality during marine shipment in mixedload containers at 0.5 °C did not significantly increase in a controlled atmosphere. In laboratory experiments, mortality of green peach aphids ranged from 32.8% in the refrigerated control to 96.8% after storage in 0.10% O2 for 4 d followed by 7 d in 3% O2 with 5% CO2. When stored under these same conditions, western flower thrips mortality was 71% compared to 16% mortality in the refrigerated control. Following an 11-day marine shipment from California to Guam in a controlled atmosphere, vase life was extended for most of the 20 California cut-flower and foliage products compared to those shipped in the refrigerated air control.