Dataset Information

Wavelength-Specific Behavior of the Western Flower Thrips (Frankliniella occidentalis): Evidence for a Blue-Green Chromatic Mechanism.

ABSTRACT: The western flower thrips (Frankliniella occidentalis) is a serious pest in horticulture, feeding on leaf tissue and floral resources. Blue and yellow sticky traps are commonly used for monitoring and control in greenhouses. The mechanisms underlying the color preferences are largely unknown. The use of light-emitting diodes (LEDs) is a promising approach to increase the attractiveness of visual traps and to study the color choice behavior in insects. The color preferences of F. occidentalis were systematically investigated in a series of choice experiments with several LEDs from the ultraviolet (UV) and visible spectral range. Blue LEDs were most attractive, followed by green, while only a moderate attractiveness of UV was observed. Blue and green were identified as two separate attractive ranges. When light from blue and green LEDs was mixed, the attractiveness decreased compared to its single components. In conclusion, F. occidentalis exhibits two different wavelength specific behaviors towards blue and green. Compelling indications are provided that these behaviors are controlled by two photoreceptors maximally sensitive in the blue and green range with an inhibitory chromatic interaction between both. Since the known UV sensitive photoreceptor could be confirmed, a trichromatic photoreceptor setup is suggested for F. occidentalis. For advanced plant protection strategies, the results offer several opportunities to optimize monitoring or even develop mass trapping devices.

SUBMITTER: Stukenberg N

PROVIDER: S-EPMC7411919 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Wavelength-Specific Behavior of the Western Flower Thrips (Frankliniella occidentalis): Evidence for a Blue-Green Chromatic Mechanism.

Stukenberg Niklas N Pietruska Markus M Waldherr Axel A Meyhöfer Rainer R

Insects 20200709 7

The western flower thrips (Frankliniella occidentalis) is a serious pest in horticulture, feeding on leaf tissue and floral resources. Blue and yellow sticky traps are commonly used for monitoring and control in greenhouses. The mechanisms underlying the color preferences are largely unknown. The use of light-emitting diodes (LEDs) is a promising approach to increase the attractiveness of visual traps and to study the color choice behavior in insects. The color preferences of F. occide ...[more]

PMID: 32659926

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Project description:Western flower thrips (WFT) is one of the most important pests of horticultural crops worldwide because it can damage many different crops and transmit various plant viruses. Given these significant impacts on plant production, novel methodologies are required to maximize regulation of WFT to minimize crop losses. One particular approach is to develop control strategies for the non-feeding, soil-dwelling stages of WFT. Control of these stages could be enhanced through the use of granules impregnated with entomopathogenic fungi mixed in the soil. The use of soil-applied fungi contrasts with existing approaches in which entomopathogenic fungi are formulated as oil-based suspensions or water-based wettable powders for foliar applications against the feeding stages of WFT. To examine the efficacy of this approach, we evaluated the effects of a granular formulation of Beauveria bassiana on the soil-dwelling, pupal phases of Frankliniella occidentalis in laboratory bioassays and greenhouse experiments. Based on micromorphological observations of fungal conidia during the infection process after treatment of WFT with a B. bassiana suspension, fungal conidia complete the process of surface attachment, germination, and penetration of the body wall of the WFT pupa and enter the host within 60 h of treatment. Given these results, we undertook a controlled greenhouse experiment and applied B. bassiana granules to soil used to cultivate eggplants. Populations of F. occidentalis on eggplants grown in treated soil were 70% lower than those on plants grown in the untreated soil after 8 weeks. Furthermore, when measuring the survival and growth of B. bassiana on granules under different soil moisture conditions, survival was greatest when the soil moisture content was kept at 20%. These results indicate that the application of B. bassiana-impregnated granules could prove to be an effective biological control strategy for use against F. occidentalis under greenhouse conditions.

Project description:Using RT-PCR and RACE-PCR strategies, we cloned and identified a new chemosensory protein (FoccCSP) from the Western flower thrips, Frankliniella occidentalis, a species for which no chemosensory protein (CSP) has yet been identified. The FoccCSP gene contains a 387 bp open-reading frame encoding a putative protein of 128 amino acids with a molecular weight of 14.51 kDa and an isoelectric point of 5.41. The deduced amino acid sequence contains a putative signal peptide of 19 amino acid residues at the N-terminus, as well as the typical four-cysteine signature found in other insect CSPs. As FoccCSP is from a different order of insect than other known CSPs, the GenBank FoccCSP homolog showed only 31-50% sequence identity with them. A neighbor-joining tree was constructed and revealed that FoccCSP is in a group with CSPs from Homopteran insects (e.g., AgosCSP4, AgosCSP10, ApisCSP, and NlugCSP9), suggesting that these genes likely developed from a common ancestral gene. The FoccCSP gene expression profile of different tissues and development stages was measured by quantitative real-time PCR. The results of this analysis revealed this gene is predominantly expressed in the antennae and also highly expressed in the first instar nymph, suggesting a function for FoccCSP in olfactory reception and in particular life activities during the first instar nymph stage. We expressed recombinant FoccCSP protein in a prokaryotic expression system and purified FoccCSP protein by affinity chromatography using a Ni-NTA-Sepharose column. Using N-phenyl-1-naphthylamine (1-NPN) as a fluorescent probe in fluorescence-based competitive binding assay, we determined the binding affinities of 19 volatile substances for FoccCSP protein. This analysis revealed that anisic aldehyde, geraniol and methyl salicylate have high binding affinities for FoccCSP, with KD values of 10.50, 15.35 and 35.24 ?M, respectively. Thus, our study indicates that FoccCSP may play an important role in regulating the development of the first instar nymph and mediate F. occidentalis host recognition.

Project description:Tomatoes (Solanum lycopersicum L.) have been bred to exude higher amounts or different types of the specialized plant metabolites, acylsugars, from type IV trichomes. Acylsugars are known to deter several herbivorous insect pests, including the western flower thrips (WFT), Frankliniella occidentalis (Pergande); however, all previous studies investigated the effect of acylsugars on leaves, or acylsugar extracts obtained from leaves. In spite of the WFT predilection for flowers, there is a gap in knowledge about flower defenses against thrips damage. This is especially important in light of their capacity to acquire and inoculate viruses in the genus Orthotospovirus, such as Tomato spotted wilt orthotospovirus (TSWV), in flowers. Therefore, we turned our attention to assessing thrips oviposition differences on flowers of 14 entries, including 8 interspecific hybrids, 5 tomato lines bred for specific acylsugar-related characteristics (type IV trichome densities, acylsugar amount, sugar moiety and fatty acid profile), and a fresh market tomato hybrid, Mt. Spring, which only produces trace amounts of acylsugars. Our results show that the density of the acylsugar droplet bearing type IV trichomes is greatest on sepals, relative to other flower structures, and accordingly, WFT avoids oviposition on sepals in favor of trichome-sparse petals. In concordance with past studies, acylsugar amount was the most important acylsugar-related characteristic suppressing WFT oviposition. Certain acylsugar fatty acids, specifically i-C5, i-C9 and i-C11, were also significantly associated with changes in WFT oviposition. These results support continued breeding efforts to increase acylsugar amounts and explore modifications of fatty acid profile and their roles in deterring thrips oviposition. The finding that acylsugar production occurs and reduces thrips oviposition in tomato flowers will be important in efforts to use acylsugar-mediated resistance to reduce incidence of orthotospoviruses such as TSWV in tomato by deterring virus transmission and development of thrips vector populations in the crop.

Project description: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.

Dataset Information

Wavelength-Specific Behavior of the Western Flower Thrips (Frankliniella occidentalis): Evidence for a Blue-Green Chromatic Mechanism.

Publications

Wavelength-Specific Behavior of the Western Flower Thrips (<i>Frankliniella occidentalis</i>): Evidence for a Blue-Green Chromatic Mechanism.

Similar Datasets

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