Managing Western Flower Thrips (Thysanoptera: Thripidae) on Lettuce and Green Peach Aphid and Cabbage Aphid (Hemiptera: Aphididae) on Broccoli with Chemical Insecticides and the Entomopathogenic Fungus Beauveria bassiana (Hypocreales: Clavicipitaceae)

2017 ◽  
Vol 10 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Surendra K. Dara

Aims:Lettuce and broccoli are high value vegetable crops in California. The western flower thrips,Frankliniella occidentalison lettuce, and the cabbage aphid,Brevicoryne brassicaeand the green peach aphid,Myzus persicaeon broccoli are important insect pests that are frequently managed with chemical insecticides.Observation:Efficacy of various chemical insecticides and the entomopathogenic fungusBeauveria bassianawas evaluated against these pests in field studies in the Santa Maria area of California. Some insecticides varied in their efficacy againstF. occidentalisfrom year to year and against different aphid species.Conclusion:A new insecticide sulfoxaflor provided good control of aphids on broccoli.Beauveria bassianademonstrated a potential for broccoli and lettuce integrated pest management.

2020 ◽  
Author(s):  
Sihyeon Kim ◽  
Jong Cheol Kim ◽  
Se Jin Lee ◽  
Mi rong Lee ◽  
So Eun Park ◽  
...  

Abstract Background: Insect-killing fungal species, Beauveria bassiana, is as an environment-friendly pest management tool, and many isolates are on the track of industrialization. However, some of B. bassiana isolates show similar morphology and virulence against insect pests, and so it is hard to differentiate them. Herein we used two patented isolates, ERL836 and JEF-007, and investigated their virulence against western flower thrips, Frankliniella occidentalis, and further analyzed genome structures and transcriptional responses when infecting the thrips to see possible differences. Results: The two isolates showed no significant differences in fungal growth, conidial production, and virulence against thrips, and they were structurally similar in genome. But, in transcription level, ERL836 appeared to infect thrips easily, while JEF-007 appeared to have more difficulty. In the GO analysis of ERL836 DEGs (differentially expressed genes), the number of up-regulated genes was much larger than that of down-regulated genes, when compared to JEF-007 DEGs (more genes down-regulated). Interestingly, in the enrichment analysis using shared DEGs between two infecting isolates, plasma membrane-mediated transporter activity and fatty acid degradation pathway including cytochrome P450 were more active in infecting ERL836. Conclusion: The two B. bassiana isolates had similar morphology and virulence as well as genome structure, but in transcription level they differently infected western flower thrips. This comparative approach using shared DEG analysis could be easily applied to characterize the difference of the two B. bassiana isolates, JEF-007 and ERL836.


Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 93 ◽  
Author(s):  
Wenchao Ge ◽  
Guangzu Du ◽  
Limin Zhang ◽  
Zhengyue Li ◽  
Guanli Xiao ◽  
...  

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is a highly invasive pest which is harmful to many cash crops globally and resistant to various insecticides. Entomopathogenic fungi (EPF), as biological control agents, have demonstrated a good control effect on WFT. The aim of this study was to evaluate the synergistic and pathogenicity efficacy of the fungal strain Metarhizium flavoviride WSWL51721 when distributed with diatomaceous earth (DE) and the active ingredient imidacloprid using four bioassay methods against adult and second instar larvae of WFT. The data of the four bioassays have been fitted to the time–concentration–mortality (TCM) model. The corrected mortality ranges of WFT adults were 75–100%, 82.69–100%, 78.85–100%, and 92.31–100%, and the corrected mortality ranges of WFT second instar larvae were 72.22–100%, 85.19–100%, 77.77–100%, and 100% in the four bioassays at concentrations of 1.2 × 106 to 1.2 × 108 conidia/mL, respectively. At 1.2 × 108 conidia/mL, assays 2 (M. flavoviride with DE), 3 (M. flavoviride with imidacloprid), and 4 (M. flavoviride with DE and imidacloprid) had the shortest median lethal time (LT50), compared with that of assay 1 (M. flavoviride alone) for adults at 2.26 d, 2.06 d, and 1.53 d, and second instar larvae at 2.45 d, 1.70 d, and 1.41 d, respectively. The median lethal concentration (LC50) in the four bioassays decreased within 3–10 days of inoculation. On the third day, it was found that the lowest median lethal concentrations in assays 2, 3, and 4 were 1.58 × 107, 1.13 × 107, and 3.39 × 106 conidia/mL, respectively, which were significantly different from that in assay 1 for the adults. For the second instar larvae, assays 2, 3, and 4 also had the lowest lethal concentrations and were significantly different from those of assay 1. There were significant differences in sporulation between adults and second instar larvae under the four bioassays. Our results indicate that assays 2 (M. flavoviride with DE), 3 (M. flavoviride with imidacloprid), and 4 (M. flavoviride with DE and imidacloprid) demonstrate synergistic effects on the control of both adult and second instar larvae of WFT under laboratory conditions.


2020 ◽  
Vol 55 (3) ◽  
pp. 350-365
Author(s):  
Yinping Li ◽  
Raymond A. Cloyd ◽  
Nora M. Bello

Abstract The rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), is a soil-dwelling predator that preys upon insect pests residing in growing media. Minimal information exists addressing its predation on western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), below-ground life stages. Two laboratory experiments were conducted to assess the effects of western flower thrips pupal stage, predator–prey ratio, and searchable area on predation efficacy of rove beetle adults. In Experiment 1, predation was recorded in response to two thrips pupal stages (prepupae and pupae); three predator–prey ratios (1:5, 1:10, 1:15) and predator–prey ratios that were 2, 3, and 4 times greater. Experiment 2 was designed to assess predation in response to those predator–prey ratios along with searchable areas in 15.2- and 11.5-cm-diameter containers. Response was measured by capturing thrips adults on yellow sticky cards (YSC) as they emerged from pupation. The estimated mean probability of thrips adults captured on the cards was significantly higher for the 1:5 (61.1%) than for the 1:10 (39%) and 1:15 (34.7%) predator–prey ratios. The estimated mean probability of thrips adults captured on the cards for 2 times the predator–prey ratio (57%) was significantly higher than 3 times (37.2%) and 4 times (40.6%) the ratios. A significantly higher estimated mean probability of thrips adults was captured on the cards in the 15.2-cm-diameter containers than in the 11.5-cm-diameter containers. We conclude that a predator–prey ratio of 1:15 would result in fewer rove beetle adults needed to reduce western flower thrips prepupae/pupae stages and subsequent adult populations.


Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1910
Author(s):  
Zhijian Zhang ◽  
Changying Zheng ◽  
Nemat O. Keyhani ◽  
Yulin Gao ◽  
Junping Wang

The western flower thrips, Frankliniella occidentalis, is an aggressive agricultural insect pest causing significant damage to a wide range of fruit, vegetable, and ornamental crops. Beauveria bassiana is a broad-host-range entomopathogenic fungus capable of infecting and killing F. occidentalis. Infection of thrips by B. bassiana strain BbYT12 using a concentration of 1 × 108 conidia/mL resulted in 81.48% mortality in adults in 6 d (LT50 = 90 ± 15.1 h). Scanning electron microscopy of the infection process revealed preferential adhesion and germination of fungal spores to inter-segmental folds or grooves on the insect body surface with penetrating germlings and extended hyphae visualized during the initial stages of infection (6–24 h). Histological analyses showed the appearance of in vivo hyphal bodies in sagittal sections and the fat body as early as 24 h post-infection. Within 72 h, hyphal bodies and hyphae could be found throughout the infected organism including in the midgut, Malphigian tubules, alimentary canal, ovarioles (in females), and an extended hyphal network could be seen on insect cadavers (>72 h post-infection). Real-time RT-PCR analyses of the expression of select genes implicated in virulence including the Pr1 protease, beauvericin synthase, involved in the production of the secondary metabolite beauvericin, two cytochrome P450 monooxygenases implicated in cuticular hydrocarbon degradation, two multidrug efflux proteins, a perilipin involved in lipid storage, and the Hog1 MAP kinase and protein kinase A signaling factors revealed discrete patterns of infection-time dependent expression. These data provide basic insights into the process of B. bassiana infection of F. occidentalis.


HortScience ◽  
2020 ◽  
Vol 55 (8) ◽  
pp. 1323-1326
Author(s):  
Nathan J. Herrick ◽  
Raymond A. Cloyd

Western flower thrips, Frankliniella occidentalis, and fungus gnats (Bradysia spp.) are major insect pests of greenhouse production systems. Both insect pests have life stages that reside in the soil or plant-growing medium: prepupae and pupae of western flower thrips and fungus gnat larvae. There are unsubstantiated allegations made by a manufacturer that certain plant-growing media that contain a bacterium, Bacillus pumilus, and arbuscular mycorrhizal fungus, Glomus intraradices, negatively affect the survival of western flower thrips pupae and fungus gnat larvae. Therefore, we conducted a study involving laboratory experiments replicated over time (2019 and 2020) to investigate the influence of the plant-growing media Pro-Mix BX + Mycorrhizae and Pro-Mix BX + Biofungicide + Mycorrhizae on western flower thrips pupae and fungus gnat larvae. All experiments involved placing western flower thrips pupae or fungus gnat larvae (second and third instar) into 473-mL deli containers with the different treatments (plant-growing media). A 5 × 4-cm section of a yellow sticky card was affixed to the lid of each deli container. After 21 days, the number of western flower thrips or fungus gnat adults that emerged from the growing media and were captured on the yellow sticky cards was recorded. The use of the yellow sticky card was an indirect assessment of western flower thrips pupal or fungus gnat larval mortality. We found none of the plant-growing media tested that contained a bacterium and/or arbuscular mycorrhizal fungus affected the survival of western flower thrips pupae or fungus gnat larvae. Therefore, greenhouse producers should be leery of information provided by manufacturers that does not contain valid, scientifically based data.


2019 ◽  
Author(s):  
Yanran Wan ◽  
Sabir Hussain ◽  
Baoyun Xu ◽  
Wen Xie ◽  
Shaoli Wang ◽  
...  

ABSTRACTBACKGROUNDTomato spotted wilt virus(TSWV), one of the most devastating viruses of ornamental plants and vegetable crops worldwide, is transmitted by the western flower thrips,Frankliniella occidentalis(Pergande), in a persistent-propagative manner. How TSWV manipulates the reproduction of its vector to enhance transmission and whether infection with TSWV changes the mating behaviour of this thrips vector are not fully understood.RESULTSIn this study, we found that TSWV-exposed thrips, in general, had a significantly longer developmental time than did non-exposed individuals. Such an increase was predominantly seen in adults, a stage associated with dispersal and virus transmission. TSWV-exposedF. occidentalis produced substantially more progeny than did non-exposed thrips. Interestingly, most of the increase in progeny came from an increase in males, a sex with a greater dispersal and virus transmission capability. Specifically, the sex ratio of progeny shifted from female biased (2-7:1) to evenly split or male biased. Regarding mating behaviour, compared to virus-free controls, TSWV-exposedF. occidentalis had significantly longer copulation duration, were more active in males, and remated less often in females.CONCLUSIONThese combined results suggest that TSWV alters the reproductive behaviour of its insect vector,F. occidentalis, to promote virus transmission. Consequently, a monitoring program capable of earlier detection of the virus and a reduced economic threshold for vector (thrips) control should be in consideration for the long-term, sustainable management of TSWV.


2020 ◽  
Author(s):  
Sihyeon Kim ◽  
Jong Cheol Kim ◽  
Se Jin Lee ◽  
Mi rong Lee ◽  
So Eun Park ◽  
...  

Abstract Background: Insect-killing fungal species, Beauveria bassiana, is as an environment-friendly pest management tool, and many isolates are on the track of industrialization. However, some of B. bassiana isolates show similar morphology and virulence against insect pests, and so it is hard to differentiate them. Herein we used two patented isolates, ERL836 and JEF-007, and investigated their virulence against western flower thrips, Frankliniella occidentalis, and further analyzed genome structures and transcriptional responses when interacting with cuticles of thrips to see possible differences on the initial step of fungal infection.Results: The two isolates showed no significant differences in fungal growth, conidial production, and virulence against thrips, and they were structurally similar in genome. But, in transcription level, ERL836 appeared to infect thrips easily, while JEF-007 appeared to have more difficulty. In the GO analysis of ERL836 DEGs (differentially expressed genes), the number of up-regulated genes was much larger than that of down-regulated genes, when compared to JEF-007 DEGs (more genes down-regulated). Interestingly, in the enrichment analysis using shared DEGs between two infecting isolates, plasma membrane-mediated transporter activity and fatty acid degradation pathway including cytochrome P450 were more active in infecting ERL836.Conclusion: The two B. bassiana isolates had similar morphology and virulence as well as genome structure, but in transcription level they differently interacted with the cuticle of western flower thrips. This comparative approach using shared DEG analysis could be easily applied to characterize the difference of the two B. bassiana isolates, JEF-007 and ERL836.


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