Pantoea Bacteria Isolated from Three Thrips (Frankliniella occidentalis, Frankliniella intonsa, and Thrips tabaci) in Korea and Their Symbiotic Roles in Host Insect Development.

Gut symbionts play crucial roles in host development by producing nutrients and defending against pathogens. Phloem-feeding insects in particular lack essential nutrients in their diets, and thus, gut symbionts are required for their development. Gram-negative Pantoea spp. are known to be symbiotic to the western flower thrips (Frankliniella occidentalis). However, their bacterial characteristics have not been thoroughly investigated. In this study, we isolated three different bacteria (BFoK1, BFiK1, and BTtK1) from F. occidentalis, F. intonsa, and T. tabaci. The bacterial isolates of all three species contained Pantoea spp. Their 16S rRNA sequences indicated that BFoK1 and BTtK1 were similar to P. agglomerans, while BFiK1 was similar to P. dispersa. These predictions were supported by the biochemical characteristics assessed by fatty acid composition and organic carbon utilization. In the bacterial morphological analysis, BFoK1 and BTtK1 were distinct from BFiK1. All these bacteria were relatively resistant to tetracycline compared to ampicillin and kanamycin, in which BFoK1 and BTtK1 were different from BFiK1. Feeding ampicillin (100,000 ppm) reduced the bacterial density in thrips and retarded the development of F. occidentalis. The addition of BFoK1 bacteria, however, rescued the retarded development. These findings indicate that Pantoea bacteria are symbionts to different species of thrips.

Endosymbionts moderate constrained sex allocation in a haplodiploid thrips species in a temperature-sensitive way.

Maternally inherited bacterial endosymbionts that affect host fitness are common in nature. Some endosymbionts colonise host populations by reproductive manipulations (such as cytoplasmic incompatibility; CI) that increase the reproductive fitness of infected over uninfected females. Theory predicts that CI-inducing endosymbionts in haplodiploid hosts may also influence sex allocation, including in compatible crosses, however, empirical evidence for this is scarce. We examined the role of two common CI-inducing endosymbionts, Cardinium and Wolbachia, in the sex allocation of Pezothrips kellyanus, a haplodiploid thrips species with a split sex ratio. In this species, irrespective of infection status, some mated females are constrained to produce extremely male-biased broods, whereas other females produce extremely female-biased broods. We analysed brood sex ratio of females mated with males of the same infection status at two temperatures. We found that at 20 °C the frequency of constrained sex allocation in coinfected pairs was reduced by 27% when compared to uninfected pairs. However, at 25 °C the constrained sex allocation frequency increased and became similar between coinfected and uninfected pairs, resulting in more male-biased population sex ratios at the higher temperature. This temperature-dependent pattern occurred without changes in endosymbiont densities and compatibility. Our findings indicate that endosymbionts affect sex ratios of haplodiploid hosts beyond the commonly recognised reproductive manipulations by causing female-biased sex allocation in a temperature-dependent fashion. This may contribute to a higher transmission efficiency of CI-inducing endosymbionts and is consistent with previous models that predict that CI by itself is less efficient in driving endosymbiont invasions in haplodiploid hosts.

Field Evaluation of Native Fungus, Beauveria bassiana (Bals.) Vuillemin Against some Piercing-Sucking Insects on the Grapevine.

BACKGROUND AND OBJECTIVE: The Taify cultivar of grapevine (Vitis vinifera L.) is the second important economical fruit after pomegranate at high altitudes of the Taif region in Saudi Arabia. The grapevine trees are infested with different piercing-sucking insect pests especially aphids, whiteflies and thrips. The purpose of this study was to evaluate the ability of an indigenous endophytic entomopathogenic fungus, Beauveria bassiana to control the important piercing-sucking insect pests on grapevines. MATERIALS AND METHODS: This investigation was carried out through 5, 10 and 15 day intervals between sprays for controlling Aphis illinoisensis, Bemisia tabaci and Frankliniella occidentalis with a concentration of 6×106 conidia mL-1 under field conditions. RESULTS: The higher infestation in the untreated control was by aphids followed by whitefly and thrips. At the end of the experiment in the treated trees, aphid and whitefly reduction percentages with 5 day intervals of sprays (98.5 and 96.12%, respectively) were not significantly different from 10 day intervals (95.17 and 91.81%, respectively) while these reductions were significantly higher than the reduction occurred by 15 day intervals of sprays (65.93 and 44.51%, respectively). Meanwhile, the 3 intervals of sprays did not differ significantly in the thrips reduction occurred by them with a range from 93.62-96.46%. CONCLUSION: This indigenous B. bassiana as 6×106 conidia mL-1 with 10 day intervals of the spray-on grapevine can suppress the piercing-sucking insect pests. This also will participate in grapevine organic production and furthermore, it could replace the chemical treatment.

Frankliniella occidentalis facilitate Salmonella enterica survival in the phyllosphere.

The human enteric bacterial pathogen Salmonella enterica causes approximately 1.35 million cases of food borne illnesses annually in the United States. Of these salmonellosis cases, almost half are derived from the consumption of fresh, raw produce. Although epiphytic S. enterica populations naturally decline in the phyllosphere, a subset of phytophagous insects have recently been identified as biological multipliers, consequently facilitating the growth of bacterial populations. We investigated whether tomato leaves with macroscopic feeding damage, caused by infestation of adult Western flower thrips (Frankliniella occidentalis), support higher S. enterica populations. To explore this hypothesis, we assessed S. enterica populations in response to thrips feeding by varying insect density, plant age, and the gender of the insect. As a reference control, direct leaf damage analogous to thrips feeding was also evaluated using directed, hydraulic pressure. In a supplementary set series of experiments, groups of F. occidentalis infested tomato plants were later inoculated with S. enterica to determine how prior insect infestation might influence bacterial survival and persistence. Following an infestation period, leaves visibly damaged by adult F. occidentalis supported significantly higher S. enterica populations and resulted in greater amounts of electrolyte leakage (measured as electrical conductivity) than leaves lacking visible feeding damage. Plant age did not significantly influence S. enterica populations or estimates of electrolyte leakage, independent of initial infestation. Additionally, the gender of the insect did not uniquely influence S. enterica population dynamics. Finally, applications of aggressive water bombardment resulted in more electrolyte leakage than leaves damaged by F. occidentalis, yet supported comparable S. enterica populations. Together, this study indicates that F. occidentalis feeding is one of the many potential biological mechanisms creating a more habitable environment for S. enterica.

Characterization of plant growth-promoting bacteria associated with avocado trees (Persea americana Miller) and their potential use in the biocontrol of Scirtothrips perseae (avocado thrips).

Plants interact with a great variety of microorganisms that inhabit the rhizosphere or the epiphytic and endophytic phyllosphere and that play critical roles in plant growth as well as the biocontrol of phytopathogens and insect pests. Avocado fruit damage caused by the thrips species Scirtothrips perseae leads to economic losses of 12-51% in many countries. In this study, a screening of bacteria associated with the rhizosphere or endophytic phyllosphere of avocado roots was performed to identify bacterial isolates with plant growth-promoting activity in vitro assays with Arabidopsis seedlings and to assess the biocontrol activity of the isolates against Scirtothrips perseae. The isolates with beneficial, pathogenic and/or neutral effects on Arabidopsis seedlings were identified. The plant growth-promoting bacteria were clustered in two different groups (G1 and G3B) based on their effects on root architecture and auxin responses, particularly bacteria of the Pseudomonas genus (MRf4-2, MRf4-4 and TRf2-7) and one Serratia sp. (TS3-6). Twenty strains were selected based on their plant growth promotion characteristics to evaluate their potential as thrips biocontrol agents. Analyzing the biocontrol activity of S. perseae, it was identified that Chryseobacterium sp. shows an entomopathogenic effect on avocado thrips survival. Through the metabolic profiling of compounds produced by bacteria with plant growth promotion activity, bioactive cyclodipeptides (CDPs) that could be responsible for the plant growth-promoting activity in Arabidopsis were identified in Pseudomonas, Serratia and Stenotrophomonas. This study unravels the diversity of bacteria from the avocado rhizosphere and highlights the potential of a unique isolate to achieve the biocontrol of S. perseae.

Immunocompetence of Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae) populations from different latitudes against Beauveria bassiana (Hypocreales: Cordycipitaceae).

Gynaikothrips uzeli gall thrips are protected from insecticide exposure by their leaf gall habitat. A biocontrol strategy based on entomopathogenic fungi is an alternative approach for the control of G. uzeli. Higher temperatures can promote the reproduction and spread of pests; however, the impact of higher temperatures on biological control is unclear. We studied the immunocompetence of thrips from different latitudes and determined the effect of degree days on thrips immunity. We examined the potential impact of temperature on the biocontrol provided by entomopathogenic fungi. Beauveria bassiana pathogenicity against thrips increased with decreasing latitude, suggesting that immunity of thrips increased as latitude increased. The phenoloxidase activity of G. uzeli increased with increasing latitude but there was no significant change in hemocyte concentration. This indicated that the humoral immunity of thrips was significantly associated with degree days, and this was confirmed by transcriptome data. Transcriptome and RT-PCR results showed that the expression of key genes in eight toll pathways increased with increasing latitude. The relative expression of key genes in the Toll pathway of thrips and the activity of phenoloxidase decreased with increasing degree days that are characteristic of lower latitudes. These changes led to a decrease in humoral immunity. The immunity of G. uzeli against entomopathogenic fungi increased as degree days characteristic of lower latitudes decreased. Increased temperatures associated with lower latitude may therefore increase biocontrol efficacy. This study clarified immune level changes and molecular mechanisms of thrips under different degree days.

Phytoseiid predatory mites can disperse entomopathogenic fungi to prey patches.

Recent studies have shown that predatory mites used as biocontrol agents can be loaded with entomopathogenic fungal conidia to increase infection rates in pest populations. Under laboratory conditions, we determined the capacity of two phytoseiid mites, Amblyseius swirskii and Neoseiulus cucumeris to deliver the entomopathogenic fungus Beauveria bassiana to their prey, Frankliniella occidentalis. Predatory mites were loaded with conidia and released on plants that had been previously infested with first instar prey clustered on a bean leaf. We examined each plant section to characterize the spatial distribution of each interacting organism. Our results showed that A. swirskii delivered high numbers of conidia to thrips infested leaves, thereby increasing the proportion of thrips that came into contact with the fungus. The effect was larger when thrips infestation occurred on young leaves than on old leaves. Neoseiulus cucumeris delivered less conidia to the thrips infested leaves. These patterns result from differences in foraging activity between predatory mite species. Amblyseius swirskii stayed longer on plants, especially within thrips colonies, and had a stronger suppressing effect on thrips than N. cucumeris. Our study suggests that loading certain predatory mite species with fungal conidia can increase their capacity to suppress thrips populations by combining predation and dispersing pathogens.

Microbiome profiling of the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae).

The gut microbial community structure of adult Thrips tabaci collected from 10 different agro-climatically diverse locations of India was characterized by using the Illumina MiSeq platform to amplify the V3 region of the 16S rRNA gene of bacteria present in the sampled insects. Analyses were performed to study the bacterial communities associated with Thrips tabaci in India. The complete bacterial metagenome of T. tabaci was comprised of 1662 OTUs of which 62.25% belong to known and 37.7% of unidentified/unknown bacteria. These OTUs constituted 21 bacterial phyla of 276 identified genera. Phylum Proteobacteria was predominant, followed by Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Additionally, the occurrence of the reproductive endosymbiont, Wolbachia was detected at two locations (0.56%) of the total known OTUs. There is high variation in diversity and species richness among the different locations. Alpha-diversity metrics indicated the higher gut bacterial diversity at Bangalore and lowest at Rahuri whereas higher bacterial species richness at T. tabaci samples from Imphal and lowest at Jhalawar. Beta diversity analyses comparing bacterial communities between the samples showed distinct differences in bacterial community composition of T. tabaci samples from different locations. This paper also constitutes the first record of detailed bacterial communities associated with T. tabaci. The location-wise variation in microbial metagenome profile of T. tabaci suggests that bacterial diversity might be governed by its population genetic structure, environment and habitat.

Managing Onion Thrips can Limit Bacterial Stalk and Leaf Necrosis in Michigan Onion Fields.

Onion thrips (Thrips tabaci) is a major insect pest of onion and it has been identified as a likely vector of Pantoea agglomerans (bacterial stalk and leaf necrosis), a relatively new pathogen to Michigan's onion industry. Our objective was to develop an integrated insect and disease management program by examining the efficacy of bactericides and insecticides alone and in combination to limit bacterial stalk and leaf necrosis caused by P. agglomerans. We also examined the association of onion thrips and disease incidence in the field, because thrips are known to transmit this pathogen. In the pesticide trial, insecticides reduced both thrips abundance and bacterial stalk and leaf necrosis incidence whereas bactericides alone did not reduce disease severity. Positive correlations among thrips population density, numbers of thrips positive for P. agglomerans, and bacterial stalk and leaf necrosis incidence in onion fields were determined. This study suggests that onion thrips feeding can facilitate the development of bacterial stalk and leaf necrosis in Michigan's commercial onion fields, and results from the pesticide trials indicate that thrips feeding damage is positively correlated with disease incidence. Therefore, in order to reduce bacterial stalk and leaf necrosis incidence in onion, management efforts should include reducing onion thrips populations through the use of insecticides and other cultural practices.

Integration of microbial biopesticides in greenhouse floriculture: The Canadian experience.

Historically, greenhouse floriculture has relied on synthetic insecticides to meet its pest control needs. But, growers are increasingly faced with the loss or failure of synthetic chemical pesticides, declining access to new chemistries, stricter environmental/health and safety regulations, and the need to produce plants in a manner that meets the 'sustainability' demands of a consumer driven market. In Canada, reports of thrips resistance to spinosad (Success™) within 6-12 months of its registration prompted a radical change in pest management philosophy and approach. Faced with a lack of registered chemical alternatives, growers turned to biological control out of necessity. Biological control now forms the foundation for pest management programs in Canadian floriculture greenhouses. Success in a biocontrol program is rarely achieved through the use of a single agent, though. Rather, it is realized through the concurrent use of biological, cultural and other strategies within an integrated plant production system. Microbial insecticides can play a critical supporting role in biologically-based integrated pest management (IPM) programs. They have unique modes of action and are active against a range of challenging pests. As commercial microbial insecticides have come to market, research to generate efficacy data has assisted their registration in Canada, and the development and adaptation of integrated programs has promoted uptake by floriculture growers. This review documents some of the work done to integrate microbial insecticides into chrysanthemum and poinsettia production systems, outlines current use practices, and identifies opportunities to improve efficacy in Canadian floriculture crops.

First insight into microbiome profile of fungivorous thrips Hoplothrips carpathicus (Insecta: Thysanoptera) at different developmental stages: molecular evidence of Wolbachia endosymbiosis.

Insects' exoskeleton, gut, hemocoel, and cells are colonized by various microorganisms that often play important roles in their host life. Moreover, insects are frequently infected by vertically transmitted symbionts that can manipulate their reproduction. The aims of this study were the characterization of bacterial communities of four developmental stages of the fungivorous species Hoplothrips carpathicus (Thysanoptera: Phlaeothripidae), verification of the presence of Wolbachia, in silico prediction of metabolic potentials of the microorganisms, and sequencing its mitochondrial COI barcode. Taxonomy-based analysis indicated that the bacterial community of H. carpathicus contained 21 bacterial phyla. The most abundant phyla were Proteobacteria, Actinobacteria, Bacterioidetes and Firmicutes, and the most abundant classes were Alphaproteobacteria, Actinobacteria, Gammaproteobacteria and Betaproteobacteria, with different proportions in the total share. For pupa and imago (adult) the most abundant genus was Wolbachia, which comprised 69.95% and 56.11% of total bacterial population respectively. Moreover, similarity analysis of bacterial communities showed that changes in microbiome composition are congruent with the successive stages of H. carpathicus development. PICRUSt analysis predicted that each bacterial community should be rich in genes involved in membrane transport, amino acid metabolism, carbohydrate metabolism, replication and repair processes.

AAI-profiler: fast proteome-wide exploratory analysis reveals taxonomic identity, misclassification and contamination.

We present AAI-profiler, a web server for exploratory analysis and quality control in comparative genomics. AAI-profiler summarizes proteome-wide sequence search results to identify novel species, assess the need for taxonomic reclassification and detect multi-isolate and contaminated samples. AAI-profiler visualises results using a scatterplot that shows the Average Amino-acid Identity (AAI) from the query proteome to all similar species in the sequence database. Taxonomic groups are indicated by colour and marker styles, making outliers easy to spot. AAI-profiler uses SANSparallel to perform high-performance homology searches, making proteome-wide analysis possible. We demonstrate the efficacy of AAI-profiler in the discovery of a close relationship between two bacterial symbionts of an omnivorous pirate bug (Orius) and a thrip (Frankliniella occidentalis), an important pest in agriculture. The symbionts represent novel species within the genus Rosenbergiella so far described only in floral nectar. AAI-profiler is easy to use, the analysis presented only required two mouse clicks and was completed in a few minutes. AAI-profiler is available at http://ekhidna2.biocenter.helsinki.fi/AAI.

Multifarious plant growth promotion by an entomopathogenic fungus Lecanicillium psalliotae.

An entomopathogenic fungus, Lecanicillium psalliotae strain IISR-EPF-02 previously found infectious to cardamom thrips, Sciothrips cardamomi promoted plant growth in cardamom, Elettaria cardamomum. The isolate exhibited direct plant growth promoting traits by production of indole-3-acetic acid and ammonia and by solubilizing inorganic phosphate and zinc. It also showed indirect plant growth promoting traits by producing siderophores and cell wall-degrading enzymes like, α-amylases, cellulases and proteases. In pot culture experiments, application of the fungus at the root zone of cardamom seedlings significantly increased shoot and root length, shoot and root biomass, number of secondary roots and leaves and leaf chlorophyll content compared to untreated plants. This is the first report on the plant growth promoting traits of this fungus. The entomopathogenic and multifarious growth promoting traits of L. psalliotae strain IISR-EPF-02 suggest that it has great potential for exploitation in sustainable agriculture.

Independent cytoplasmic incompatibility induced by Cardinium and Wolbachia maintains endosymbiont coinfections in haplodiploid thrips populations.

Cardinium and Wolbachia are common maternally inherited reproductive parasites that can coinfect arthropods, yet interactions between both bacterial endosymbionts are rarely studied. For the first time, we report their independent expression of complete cytoplasmic incompatibility (CI) in a coinfected host, and CI in a species of the haplodiploid insect order Thysanoptera. In Pezothrips kellyanus, Cardinium-induced CI resulted in a combination of male development (MD) and embryonic female mortality (FM) of fertilized eggs. In contrast, Wolbachia-induced CI resulted in FM together with postembryonic mortality not previously reported as a CI outcome. Both endosymbionts appeared to not influence fecundity but virgins produced more offspring than mated females. In coinfected individuals, Wolbachia density was higher than Cardinium. Wolbachia removal did not impact Cardinium density, suggesting a lack of competition within hosts. Maternal transmission was complete for Wolbachia and high for Cardinium. Our data support theoretical predictions and empirical detection of high endosymbiont prevalence in field populations of the native range of this pest thrips. However, previous findings of more frequent loss of Wolbachia than Cardinium, particularly in field populations of the host's invasive range, suggest that genetic diversity or varying environmental factors between field populations also play a role in shaping host-endosymbiont dynamics.

Tomato spotted wilt virus Can Infect Resistant Tomato when Western Flower Thrips Inoculate Blossoms.

Tomato spotted wilt is a major disease of crops worldwide. Resistant cultivars carrying the Sw-5 allele for resistance to tomato spotted wilt disease (TSW) provide the most effective control method in tomato (Solanum lycopersicum). However, infections of fruit on Sw-5+ tomato plants suggest the virus resistance may not be fully expressed in blossoms or developing fruit. The objective of this study was to determine if the thrips vector, the western flower thrips (Frankliniella occidentalis), can transmit non-resistance breaking Tomato spotted wilt virus (TSWV) isolates when confined to blossoms on plants with and without the Sw-5 resistance allele. Twenty-one percent of 33 Sw-5+ plants inoculated by adult thrips feeding on blossom clusters or small fruit developed infections in the reproductive tissue, whereas 68% of 25 Sw-5- plants developed infections. Systemic infections also occurred following inoculation of blossoms in host genotypes with and without Sw-5. These results were further supported by field experiments that showed high proportions of infected fruit as well as a limited infection of foliage on the same stem as the infected fruit in Sw-5+ plants when F. occidentalis were abundant in blossoms. These findings help to explain observations of abundant late season infections of Sw-5 cultivars in commercial plantings and suggest that management of F. occidentalis infestations during the bloom period may be important for effective management of TSWV in susceptible tomato cultivars as well as cultivars expressing the Sw-5 allele for TSW resistance.

Interactions Between Frankliniella fusca and Pantoea ananatis in the Center Rot Epidemic of Onion (Allium cepa).

An Enterobacteriaceae bacterium, Pantoea ananatis (Serrano) Mergaert, is the causal agent of an economically important disease of onion, center rot. P. ananatis is transmitted by an onion-infesting thrips, Frankliniella fusca (Hinds). However, interactions between F. fusca and P. ananatis as well as transmission mechanisms largely remain uncharacterized. This study investigated P. ananatis acquisition by thrips and transstadial persistence. Furthermore, the effects of bacterial acquisition on thrips fitness were also evaluated. When thrips larvae and adults were provided with acquisition access periods (AAP) on peanut leaflets contaminated with the bacterium, an exponentially positive relationship was observed between AAP and P. ananatis acquisition (R(2) ≥ 0.77, P = 0.01). P. ananatis persisted in thrips through several life stages (larvae, pupae, and adult). Despite the bacterial persistence, no significant effects on thrips fitness parameters such as fecundity and development were observed. Immunofluorescence microscopy of adult thrips with P. ananatis-specific antibody after 48 h AAP on contaminated food revealed that the bacterium was localized only in the gut. These results suggested that the pathogen is not circulative and could be transmitted through feces. Mechanical inoculation of onion seedlings with fecal rinsates produced center rot symptoms, whereas inoculation with rinsates potentially containing salivary secretions did not. These results provide evidence for stercorarian transmission (transmission through feces) of P. ananatis by F. fusca.

Symbiont-mediated RNA interference in insects.

RNA interference (RNAi) methods for insects are often limited by problems with double-stranded (ds) RNA delivery, which restricts reverse genetics studies and the development of RNAi-based biocides. We therefore delegated to insect symbiotic bacteria the task of: (i) constitutive dsRNA synthesis and (ii) trauma-free delivery. RNaseIII-deficient, dsRNA-expressing bacterial strains were created from the symbionts of two very diverse pest species: a long-lived blood-sucking bug, Rhodnius prolixus, and a short-lived globally invasive polyphagous agricultural pest, western flower thrips (Frankliniella occidentalis). When ingested, the manipulated bacteria colonized the insects, successfully competed with the wild-type microflora, and sustainably mediated systemic knockdown phenotypes that were horizontally transmissible. This represents a significant advance in the ability to deliver RNAi, potentially to a large range of non-model insects.

Insecticide Rotation Programs with Entomopathogenic Organisms for Suppression of Western Flower Thrips (Thysanoptera: Thripidae) Adult Populations under Greenhouse Conditions.

Western flower thrips, Frankliniella occidentalis (Pergande), is one of the most destructive insect pests of greenhouse production systems with the ability to develop resistance to a wide variety of insecticides. A common resistance management strategy is rotating insecticides with different modes of action. By incorporating entomopathogenic organisms (fungi and bacteria), which have discrete modes of action compared to standard insecticides, greenhouse producers may preserve the effectiveness of insecticides used for suppression of western flower thrips populations. The objective of this study was to determine how different rotation programs that include entomopathogenic organisms (Beauveria bassiana, Isaria fumosoroseus, Metarhizium anisopliae, and Chromobacterium subtsugae) and commonly used standard insecticides (spinosad, chlorfenapyr, abamectin, and pyridalyl) may impact the population dynamics of western flower thrips adult populations by means of suppression. Eight-week rotation programs were applied to chrysanthemum, Dendranthema x morifolium plants and weekly counts of western flower thrips adults captured on yellow sticky cards were recorded as a means to evaluate the impact of the rotation programs. A final quality assessment of damage caused by western flower thrips feeding on foliage and flowers was also recorded. Furthermore, a cost comparison of each rotation program was conducted. Overall, insecticide rotation programs that incorporated entomopathogenic organisms were not significantly different than the standard insecticide rotation programs without entomopathogenic organisms in suppressing western flower thrips adult populations. However, there were no significant differences among any of the rotation programs compared to the water control. Moreover, there was no differential effect of the rotation programs on foliage and flower quality. Cost savings of up to 34% (in US dollars) are possible when including entomopathogenic organisms in the rotation program. Therefore, by incorporating entomopathogenic organisms into insecticide rotation programs, greenhouse producers can decrease costs without affecting suppression, as well as diminish selection pressure on western flower thrips adult populations, which may avoid or delay resistance development.

Draft Genomes, Phylogenetic Reconstruction, and Comparative Genomics of Two Novel Cohabiting Bacterial Symbionts Isolated from Frankliniella occidentalis.

Obligate bacterial symbionts are widespread in many invertebrates, where they are often confined to specialized host cells and are transmitted directly from mother to progeny. Increasing numbers of these bacteria are being characterized but questions remain about their population structure and evolution. Here we take a comparative genomics approach to investigate two prominent bacterial symbionts (BFo1 and BFo2) isolated from geographically separated populations of western flower thrips, Frankliniella occidentalis. Our multifaceted approach to classifying these symbionts includes concatenated multilocus sequence analysis (MLSA) phylogenies, ribosomal multilocus sequence typing (rMLST), construction of whole-genome phylogenies, and in-depth genomic comparisons. We showed that the BFo1 genome clusters more closely to species in the genus Erwinia, and is a putative close relative to Erwinia aphidicola. BFo1 is also likely to have shared a common ancestor with Erwinia pyrifoliae/Erwinia amylovora and the nonpathogenic Erwinia tasmaniensis and genetic traits similar to Erwinia billingiae. The BFo1 genome contained virulence factors found in the genus Erwinia but represented a divergent lineage. In contrast, we showed that BFo2 belongs within the Enterobacteriales but does not group closely with any currently known bacterial species. Concatenated MLSA phylogenies indicate that it may have shared a common ancestor to the Erwinia and Pantoea genera, and based on the clustering of rMLST genes, it was most closely related to Pantoea ananatis but represented a divergent lineage. We reconstructed a core genome of a putative common ancestor of Erwinia and Pantoea and compared this with the genomes of BFo bacteria. BFo2 possessed none of the virulence determinants that were omnipresent in the Erwinia and Pantoea genera. Taken together, these data are consistent with BFo2 representing a highly novel species that maybe related to known Pantoea.

Feeding on Beauveria bassiana-treated Frankliniella occidentalis causes negative effects on the predatory mite Neoseiulus barkeri.

The entomopathogenic fungus Beauveria bassiana and the predatory mite Neoseiulus barkeri are both potential biocontrol agents for their shared host/prey Frankliniella occidentalis. The combination of the two agents may enhance biological control of F. occidentalis if the fungus does not negatively affect N. barkeri. This study evaluated the indirect effects of B. bassiana strain SZ-26 on N. barkeri mediated by F. occidentalis using the age-stage, two-sex life table. When fed on the first instar larvae of F. occidentalis that had been exposed for 12 h to the SZ-26 suspension, the developmental time of preadult N. barkeri was significantly longer, and the longevity and fecundity were significantly lower than that of N. barkeri fed on untreated F. occidentalis. The mean generation time (T), net reproductive rate (R0), finite rate of increase (λ), intrinsic rate of natural increase (rm) and predation rates were correspondingly affected. The data showed that B. bassiana has indirect negative effects on N. barkeri population dynamics via influencing their prey F. occidentalis larvae, which indicates that there is a risk in combining B. bassiana with N. barkeri simultaneously for the biocontrol of F. occidentalis. The probable mechanism for the negative effects is discussed.