Functional response of Franklinothrips vespiformis (Thysanoptera: Aeolothripidae) to eggs and nymphs of Bemisia tabaci (Hemiptera: Aleyrodidae).

The Middle East Asia Minor 1 biotype of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a greenhouse and field crop pest of global significance. The objective of this study was to assess the potential of the generalist predatory thrips, Franklinothrips vespiformis Crawford (Thysanoptera: Aeolothripidae), as a biological control agent for B. tabaci. This was achieved by determining the functional responses of F. vespiformis larvae and adults to the egg and nymphal stages of B. tabaci under laboratory conditions. Analyses consisted of 10 replicates of each predator and prey stage combination on bean leaf discs for a 24-h period. Following logistic regression analyses to determine the functional response type exhibited, response parameters were estimated with nonlinear least squares regression using Roger's equation. Results showed that F. vespiformis larvae and adults exhibited a Type II functional response when feeding on immature B. tabaci. The handling times (Th) of F. vespiformis larvae and adults were magnitudes higher for B. tabaci nymphs than they were for eggs, which were in part driven by the higher attack rates (a) observed on eggs. The maximum attack rate (T/Th) for B. tabaci eggs and nymphs exhibited by first-stage larvae, second-stage larvae, and adult F. vespiformis increased with increasing predator age. Results from this study suggest that F. vespiformis larvae and particularly adults are promising biological control agents for B. tabaci and are efficient predators at both low and high prey densities.

Unravelling the synergistic interaction of Thrips tabaci and newly recorded, Thrips parvispinus with Alternaria porri (Ellis.) Cif., inciting onion purple blotch.

Onion purple blotch is the most indispensable foliar disease of crop and has become a major concern for farmers and research fraternity. An attempt to investigate the role of injury in parasitism by Alternaria porri indicated that disease incidence and severity enhance considerably with injury. Thrips injured plants inoculated with A. porri presented 100% incidence and 52-72% severity while mechanically injured plants inoculated with A. porri showed 60-70% incidence and 28-34% severity. The uninjured plants showed considerably less disease incidence (30-40%) and severity (10-16%). Injured inoculated plants presented reduced leaf length and leaf area while the leaf diameter remained unaffected. The lesion number, lesion length and size was substantially enhanced with concomitant infestation of pest and pathogen. Thrips tabaci injury led to more pronounced symptoms of purple blotch compared to Thrips parvispinus injury. There was substantial decrease in photosynthetic rate and chlorophyll content with stress imposed on plant whilst the relative stress injury was enhanced. The induction of injury and inoculation of A. porri had an impact on the concentration of total phenolics, total soluble sugars, total proteins and hydrogen peroxide in onion leaves. A. porri combined with injury caused a more pronounced decrease in total soluble sugars and total protein content while enhancement in total phenolics and hydrogen peroxide content compared to uninjured plants. The dynamic nature of morpho-physiological and biochemical changes owing to stress conditions imposed on onion plant adds an extra layer of complexity in understanding the onion plant physiology and their ability to work out in response to challenging environment conditions.

Distribution of Scirtothrips dorsalis (Thysanoptera: Thripidae) cryptic species complex in the United States and reproductive host assessment of its dominant member.

Chilli thrips, Scirtothrips dorsalis Hood, is a cryptic species complex of at least 9 species, 2 of which (South Asia 1 and East Asia 1) have been confirmed damaging >50 plant taxa in the United States. To develop a knowledge-based management program for this pest in the United States, the objectives of the study were to (i) survey for S. dorsalis species complex in the suspected regions and (ii) assess the reproductive hosts of the predominant member available. Thrips samples received from collaborators were subjected to morpholo-molecular characterization. Of the 101 thrips populations received across the United States between 2015 and 2021, 71 populations were confirmed as S. dorsalis, with ~25% further identified as East Asia 1, compared with ~41% identified as South Asia 1, suggesting the latter species is more prevalent in the US. East Asia 1 was primarily found in samples collected from Hydrangea sp. (95%) in Massachusetts, New York, and Pennsylvania, indicating geographic range expansion in the Northeast and successful overwintering in areas with hard freezes. While assessing the host range of South Asia 1 (dominant species), 62 plant taxa were evaluated under greenhouse conditions. Among these, 40 feeding and reproductive hosts were confirmed in Florida. We also found 18 new reproductive hosts and 3 feeding hosts of S. dorsalis, which were not previously reported in the literature. The results provide insight into the increasing host range and expanded geographical distribution of S. dorsalis species and will enable the development of a species-specific monitoring and management program.

Parasitoid-mediated horizontal transmission of Rickettsia between whiteflies.

Intracellular bacterial endosymbionts of arthropods are mainly transmitted vertically from mother to offspring, but phylogenetically distant insect hosts often harbor identical endosymbionts, indicating that horizontal transmission from one species to another occurs in nature. Here, we investigated the parasitoid Encarsia formosa-mediated horizontal transmission of the endosymbiont Rickettsia between different populations of whitefly Bemisia tabaci MEAM1. Rickettsia was successfully transmitted from the positive MEAM1 nymphs (R +) into E. formosa and retained at least for 48 h in E. formosa adults. Fluorescence in situ hybridization (FISH) visualization results revealed that the ovipositors, mouthparts, and digestive tract of parasitoid adults get contaminated with Rickettsia. Random non-lethal probing of Rickettisia-negative (R- ) MEAM1 nymphs by these Rickettsia-carrying E. formosa resulted in newly infected MEAM1 nymphs, and the vertical transmission of Rickettsia within the recipient females can remain at least up to F3 generation. Further phylogenetic analyses revealed that Rickettsia had high fidelity during the horizontal transmission in whiteflies and parasitoids. Our findings may help to explain why Rickettsia bacteria are so abundant in arthropods and suggest that, in some insect species that shared the same parasitoids, Rickettsia may be maintained in populations by horizontal transmission.

Parasitoid vectors a plant pathogen, potentially diminishing the benefits it confers as a biological control agent.

Huanglongbing (HLB) is a destructive disease of citrus primarily transmitted by the Asian citrus psyllid (ACP). Biocontrol of ACP is an environmentally sustainable alternative to chemicals. However, the risk of parasitoid rational application in ACP biocontrol has never been evaluated. Here we show, the dominant parasitoid of ACP, Tamarixia radiata, can acquire the HLB pathogen Candidatus Liberibacter asiaticus (CLas) and transmit it horizontally when probing ACP nymphs. If these ACP nymphs survive the probing, develop to adults and move to healthy plants, CLas can be transmitted to citrus leaves during feeding. We illustrate the formerly unrecognized risk that a parasitoid can potentially serve as a phoretic vector of the pathogen transmitted by its host, thus potentially diminishing some of the benefits it confers via biocontrol. Our findings present a significant caution to the strategy of using parasitoids in orchards with different infection status of insect-vectored pathogens.

Taxonomic and identification review of adventive Fiorinia Targioni Tozzetti (Hemiptera, Coccomorpha, Diaspididae) of the United States.

This work provides general descriptions, illustrations, molecular diagnostic data, taxonomic keys, slide mounting recommendations, and Florida distribution records for Fiorinia Targioni Tozzetti species occurring in the USA. Species treated are F.externa Ferris, F.fioriniae (Targioni Tozzetti), F.japonica Kuwana, F.pinicola Maskell, F.phantasma Cockerell & Robinson, F.proboscidaria Green, and F.theae Green. New descriptions of second-instar males and females of all seven species in addition to first-instar nymphs and adult females of F.phantasma and F.proboscidaria are presented. Taxonomic keys to second-instar males and females are developed for the first time and previously available taxonomic keys to first-instar nymphs and adult females are improved. DNA sequences were used to further evaluate the monophyly of Fiorinia and provide additional diagnostic tools for Fiorinia species. Multigene phylogenetic analyses, COI barcoding methods, and examination of type material indicate that F.yongxingensis Liu, Cai & Feng, 2020, syn. nov. is a junior synonym of F.phantasma. A morphological survey of the genus demonstrates, for the first time, the utility of second-instar males for diagnostics. This study will help inform regulatory and pest management decisions by facilitating morphological and molecular identification of adventive Fiorinia species occurring in the USA.

Comparison of the phytoseiid mites Amblyseius swirskii and Amblydromalus limonicus for biological control of chilli thrips, Scirtothrips dorsalis (Thysanoptera: Thripidae).

The chilli thrips, Scirtothrips dorsalis Hood, is a recently established pest in the USA and poses a serious risk to many economically important ornamental and food crops. In this study the biological control potential of the phytoseiid mites Amblydromalus limonicus (Garman and McGregor) and Amblyseius swirskii (Athias-Henriot) was compared by examining their predation and oviposition rates when fed different developmental stages of S. dorsalis. Gravid females were offered 10 individuals of either first instar, second instar, or adult S. dorsalis using a no-choice leaf disc bioassay and oviposition and predation rates were assessed daily for 2 and 3 days, respectively. There was no significant difference in predation and oviposition rates between mite species fed specific S. dorsalis life stages. There was, however, a significant effect of S. dorsalis life stage on the oviposition and predation rates observed for each mite species. The larval stage was the most preferred stage for both mite species, with A. swirskii consuming 4.6-6.3 and A. limonicus 4.8-6.4 individuals/day compared to only 1.6-1.7 adults/day consumed by both species. Female A. swirskii and A. limonicus laid 0.55-0.75 and 0.73 eggs/day on the two larval stages, respectively, compared to only 0.25-0.30 eggs/day observed for individuals feeding on adults. Although the results showed that the biological control potential of both mite species was similar, having an additional predator available that may be as effective as A. swirskii, a proven control agent against S. dorsalis in the field, warrants additional research into its potential utility.

Compatibility of the Predatory Beetle, Delphastus catalinae, with an Entomopathogenic Fungus, Cordyceps fumosorosea, for Biocontrol of Invasive Pepper Whitefly, Aleurothrixus trachoides, in Florida.

Aleurothrixus (formerly known as Aleurotrachelus) trachoides Back (Hemiptera: Aleyrodidae), commonly known as pepper or solanum whitefly, is a new emerging whitefly pest of several horticultural crops in the United States. During the preliminary survey for pepper whitefly infestation in Florida, a whitefly-specific predatory beetle Delphastus catalinae Horn (Coleoptera: Coccinellidae) was observed associated with this pest in the natural ecosystem. The current study was undertaken to determine the efficacy of this naturally occurring predator, D. catalinae, and an entomopathogenic fungus, Cordyceps (formerly known as Isaria) fumosorosea (Cfr) (Wize) (Hypocreales: Cordycipitaceae), alone or in combination, under controlled laboratory conditions. Whitefly mortality for Cfr (88%), beetle (100%) and Cfr + beetle (100%) treatments were similar and significantly higher compared to control. In the combination treatment, Cfr did not impact D. catalinae longevity and daily food intake, indicating a neutral interaction between the two treatments. Results showed that both of these natural biological control agents could potentially offer an effective alternative in the battle against invasive whiteflies such as pepper whitefly in U.S. horticulture production, either as a stand-alone strategy or in an integrated approach. Although these findings are promising, compatibility of the two treatments needs to be evaluated further under greenhouse and semi-field conditions before recommending to commercial growers.

An Ecological Assessment of Isaria fumosorosea Applications Compared to a Neonicotinoid Treatment for Regulating Invasive Ficus Whitefly.

A pilot study was conducted on a weeping fig, Ficus benjamina shrub hedge in a Florida urban landscape to determine the efficacy of a fungal biopesticide, PFR-97™ which contains blastospores of Isaria fumosorosea, and a neonicotinoid treatment (Admire Pro™) applied against the invasive ficus whitefly pest, Singhiella simplex (Singh). Post treatment, an ecological assessment of the study was conducted by observing the impact of the fungal biopesticide and neonicotinoid treatment on natural enemies, e.g., predators, parasitoids and enzootic fungal pathogens occurring in the whitefly-infested hedge. Both treatments provided a significant reduction in the whitefly population compared to control and were compatible with the natural enemies present. Various natural enemies including fungal entomopathogens were identified associated with the whitefly population infesting the weeping fig hedge. The parasitoids, Encarsia protransvena Viggiani and Amitus bennetti Viggiani & Evans combined parasitized a similar mean number of whitefly nymphs in both treatments and control; however, the number parasitized decreased over time. Natural enzootic fungi isolated from the ficus whitefly nymphs were I. fumosorosea, Purpureocillium lilacinum and Lecanicillium, Aspergillus and Fusarium species. Results from this pilot study suggest there is much potential for using repeated applications of the fungal biopesticide, PFR-97™ as a foliar spray compared to a neonicitionid as a soil drench for managing S. simplex on Ficus species for ≥28 days.

Lethal and Sublethal Effects of Selected Systemic and Contact Insecticides on Nephaspis oculata (Coleoptera: Coccinellidae), in a Tri-Trophic System.

Nephaspis oculata (Blatchley, 1917) is a whitefly predator which has been reported feeding on several whitefly species. In South Florida, it attacks rugose spiraling whitefly, an invasive pest of urban trees which was first reported in the United States in 2009. The management of rugose spiraling whitefly relies heavily on the use of insecticides which may negatively impact biological control agents. We studied the effect of bifenthrin (spray) and imidacloprid (drench) application on survival, fecundity, and behavior of N. oculata in the laboratory. Adult beetles survived significantly longer in control and systemic imidacloprid compared to bifenthrin treatment, but there was no significant difference between control and systemic imidacloprid applications. However, the fecundity of beetles in the imidacloprid treatment was significantly lower than the control. There was no significant difference between the survival of beetles in bifenthrin and control treatments 3 mo post application. Beetles avoided bifenthrin-treated leaves but did not avoid systemic imidacloprid-treated in a no-choice test. Also, beetles' feeding rate on bifenthrin-treated rugose spiraling whitefly nymphs was significantly lower in a no-choice test. In the choice test, there was a significant difference in feeding rates on whiteflies between choices of bifenthrin/control but no significant difference in the control/control or in imidacloprid/control treatments. The results from this study shows that while systemic imidacloprid has sublethal effects on N. oculata, it does not significantly affect mortality of adult beetles in the tri-trophic system tested. Therefore, using systemic imidacloprid and N. oculata for controlling rugose spiraling whitefly might be compatible or at least not significantly incompatible.

Lethal and Sublethal Effects of Three Microbial Biocontrol Agents on Spodoptera litura and Its Natural Predator Rhynocoris kumarii.

Entomopathogenic microbes such as Spodoptera litura nucleopolyhedrovirus (SpltNPV), Metarhizium anisopliae, and Pseudomonas fluorescens are biological agents used for the control of multiple arthropod pests. The objective of this study was to assess their effects on the biological parameters of Spodoptera litura (Lepidoptera: Noctuidae) larvae, and its natural reduviid predator Rhynocoris kumarii (Hemiptera: Reduviidae) under laboratory conditions. Results suggested that P. fluorescens reduced the food consumption index, relative growth rate, approximate digestibility, the efficiency of conversion of ingested food, and the efficiency of conversion of digested food of S. litura third instar larvae compared to prey infected with M. anisopliae and SpltNPV. Both SpltNPV and M. anisopliae caused similar mortality of S. litura life stages after 96 h of observation. To observe the effect of an infected prey diet on predator behavior, infected S. litura larvae were offered to the third, fourth, and fifth instar nymphs of R. kumarii, and their prey handling time, predation rate (number/day/predator), developmental period, and the survival rate was recorded. When the life stages of R. kumarii were offered entomopathogen-infected S. litura larvae, their predation rate was comparable to or higher than the untreated control. The juvenile predator, after feeding on P. fluorescens-infected S. litura larvae, had a significantly longer developmental period (2⁻4 days) compared to those fed on larvae infected with other microbial control agents. However, feeding on P. fluorescens alone did not affect the predator nymphal survival rate or the adult sex ratio. Although three entomopathogens had some degree of effect on the biological parameters of R. kumarii, the outcome of this study suggests that integration of reduviids with the tested entomopathogens are a compatible and potentially effective strategy for the management of S. litura populations. However promising, this combined strategy needs to be tested under field conditions to confirm the laboratory findings.

Assessing Compatibility of Isaria fumosorosea and Buprofezin for Mitigation of Aleurodicus rugioperculatus (Hemiptera: Aleyrodidae): An Invasive Pest in the Florida Landscape.

Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) is a new invasive whitefly pest in the Florida landscape, known to feed on a wide range of plants including palms, woody ornamentals, shrubs, and fruits. With the objective to find an alternative to neonicotinoid insecticides, and develop an ecofriendly management program for RSW, in the current study we evaluated the efficacy of a biopesticide containing the entomopathogenic fungi, Isaria fumosorosea Wize (Hypocreales: Clavicipitaceae), and an insect growth regulator buprofezin applied alone and in combination under laboratory and field conditions. Before assessing the two products, their compatibility was studied at six different concentrations of buprofezin. No significant inhibitive effect of buprofezin was observed on I. fumosorosea spore germination, and the average linear growth of the colony measured 14 d postinoculation. Under laboratory conditions, I. fumosorosea treatments (alone or mixed with buprofezin) provided higher RSW mortality than buprofezin alone. However, in both outdoor cage studies, the efficacy of buprofezin treatments (alone or mixed with I. fumosorosea) was higher than I. fumosorosea alone. A significant reduction in RSW population was reported for more than 5 wk in buprofezin alone and more than 7 wk in the combination treatments. In fall of 2014 and summer of 2015, the mean whitefly mortality observed during the 10-wk assessment period was 52.4 and 42.1% for I. fumosorosea, 79.6 and 79.0% for buprofezin, and 87.6 and 84.3% in mixed treatments, respectively. Results suggest that buprofezin can offer an effective alternate in the battle against invasive whiteflies such as RSW in Florida ecosystems, either as a stand-alone strategy or in an integrated approach.

Compatibility and Efficacy of Isaria fumosorosea with Horticultural Oils for Mitigation of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae).

Horticultural oils are an important component of integrated management programs of several phytophagous arthropods and pathogens affecting fruit, ornamentals and vegetables in greenhouse and field production systems. Although effective against the target pest, their incompatibility with biological control agents can compromise efforts to develop eco-friendly management programs for important agricultural pests. In this study, we assessed the in vitro effect of selected refined petroleum oils used in citrus and other horticultural crops with a biopesticide containing the entomopathogenic fungi, Isaria fumosorosea (PFR-97) under laboratory conditions. Further, we used leaf disk bioassays to evaluate the combined efficacy of petroleum oils and I. fumosorosea against the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), a major pest of citrus in the United States. All five petroleum oil treatments (Orchex, Sun Pure, Conoco Blend -1, Conoco Blend -2, and JMS) were compatible with I. fumosorosea blastospores, as none of them were found to affect I. fumosorosea colony-forming units and radial fungal growth measured at 3, 6, 9, and 12 days post-inoculation. All mixed treatments performed better than I. fumosorosea alone against D. citri, where the highest mean survival time of D. citri was 12.5 ± 0.7 days. No significant differences in D. citri survival time and I. fumosorosea growth (fungal development index) on dead cadavers, which is important for determining their horizontal transmission, were observed when mixed with Orchex, Sun Pure, Conoco Blend -2, and JMS. Results indicated that horticultural oils in combination with I. fumosorosea could offer citrus growers an alternative treatment for integrating into their current management programs while battling against D. citri in citrus production systems. Due to their eco-friendly, broad-spectrum effect, it could provide control against various citrus pests, while also encouraging the retention of effective chemistries for a longer period in the marketplace. However promising, these combination treatments need to be tested further with I. fumosorosea under grove conditions to confirm their field efficacy.

Unexpected High Intragenomic Variation in Two of Three Major Pest Thrips Species Does Not Affect Ribosomal Internal Transcribed Spacer 2 (ITS2) Utility for Thrips Identification.

The mitochondrial cytochrome oxidase I gene (mtCO1) and the ribosomal internal transcribed spacer 2 region (ITS2) are among the most widely used molecular markers for insect taxonomic characterization. Three economically important species of thrips, Scirtothripsdorsalis, Thripspalmi, and Frankliniellaoccidentalis were selected to examine the extent of intragenomic variation within these two marker regions in the family Thripidae, and determine if this variation would affect the utility of markers in thrips molecular diagnostics. For each species, intragenomic (within individual) variation and intergenomic (among individuals) variation was assessed by cloning and sequencing PCR-amplified copies. Intergenomic variation was generally higher than intragenomic variation except in cases where intergenomic variation was very low, as in mtCO1 from S.dorsalis and F.occidentalis. Intragenomic variation was detected in both markers in all three of the thrips species, however, 2-3 times more intragenomic variation was observed for ITS2 than mtCO1 in both S.dorsalis and T.palmi. Furthermore, levels of intragenomic variation were low for both of the genes in F.occidentalis. In all of the three thrips species, no sex-based clustering of haplotypes was observed in either marker. Unexpected high intragenomic variation in ITS2 for two of three thrips species did not interfere with thrips diagnostics. However, caution should be taken in applying ITS2 to certain studies of S.dorsalis and T.palmi when high levels of intragenomic variation could be problematic or confounding. In such studies, mtCO1 may be a preferable marker. Possible reasons for discrepancies in intragenomic variation among genomic regions are discussed.

Mass rearing and augmentative biological control evaluation of Rhynocoris fuscipes (Hemiptera: Reduviidae) against multiple pests of cotton.

BACKGROUND: Rhynocoris fuscipes (Fab.) (Hemiptera: Reduviidae) is a generalist predator of cotton pests and is commonly found inhabiting cotton-growing regions in southern India. With the goal of integrating this predator in standard management practices used against cotton pests on a commercial scale, (1) we developed a protocol for adult group rearing of this predator inside micro-environmental cages (MECs), and (2) we evaluated the biocontrol potential of mass-produced predators against cotton pests under potted and field conditions. RESULTS: Higher fecundity and adult longevity of R. fuscipes was recorded in the MECs than under natural growing conditions. The reduviid predator preferred stones and fallen leaves as hiding places in the MECs. The predator showed a higher biocontrol potential during the night hours against two pests, Phenacoccus solenopsis Tinsley and Dysdercus cingulatus (Fab.), than during the day under potted conditions. Under field conditions, R. fuscipes significantly reduced the population of Aphis gossypii Glover, P. solenopsis, D. cingulatus and Helicoverpa armigera (Hübner) by 28, 70, 29 and 50%, respectively. No negative impact of R. fuscipes was reported on other natural enemies present in the cotton agroecosystem. CONCLUSION: Significantly higher crop yield and cost benefit ratio were observed in R. fuscipes-released plots than in the control plots. The results suggest that R. fuscipes can be mass produced efficiently under controlled conditions in MECs, and used in an integrated management program for multiple cotton pests. © 2017 Society of Chemical Industry.

Susceptibility of Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae) to Imidacloprid, Thiamethoxam, Dinotefuran and Flupyradifurone in South Florida.

Populations of Bemisa tabaci MEAM1 were established from nineteen locations in south Florida, primarily from commercial tomato fields, and were tested using a cotton leaf petiole systemic uptake method for susceptibility to the nicotinic acetylcholine agonist insecticides imidacloprid, thiamethoxam, dinotefuran and flupyradifurone. Eleven populations produced LC50s for one or more chemicals that were not significantly different from the susceptible laboratory colony based on overlapping fiducial limits, indicating some degree of susceptibility. LC50s more than a 100-fold the laboratory colony were measured in at least one population for each material tested, indicating tolerance. LC50s (ppm) from field populations ranged from 0.901-24.952 for imidacloprid, 0.965-24.430 for thiamethoxam, 0.043-3.350 for dinotefuran and 0.011-1.471 for flupyradifurone. Based on overlapping fiducial limits, there were no significant differences in relative mean potency estimates for flupyradifurone and dinotefuran in relation to imidacloprid and thiamethoxam.

A novel mitochondrial genome architecture in thrips (Insecta: Thysanoptera): extreme size asymmetry among chromosomes and possible recent control region duplication.

BACKGROUND: Multipartite mitochondrial genomes are very rare in animals but have been found previously in two insect orders with highly rearranged genomes, the Phthiraptera (parasitic lice), and the Psocoptera (booklice/barklice). RESULTS: We provide the first report of a multipartite mitochondrial genome architecture in a third order with highly rearranged genomes: Thysanoptera (thrips). We sequenced the complete mitochondrial genomes of two divergent members of the Scirtothrips dorsalis cryptic species complex. The East Asia 1 species has the single circular chromosome common to animals while the South Asia 1 species has a genome consisting of two circular chromosomes. The fragmented South Asia 1 genome exhibits extreme chromosome size asymmetry with the majority of genes on the large, 14.28 kb, chromosome and only nad6 and trnC on the 0.92 kb mini-circle chromosome. This genome also features paralogous control regions with high similarity suggesting a very recent origin of the nad6 mini-circle chromosome in the South Asia 1 cryptic species. CONCLUSIONS: Thysanoptera, along with the other minor paraenopteran insect orders should be considered models for rapid mitochondrial genome evolution, including fragmentation. Continued use of these models will facilitate a greater understanding of recombination and other mitochondrial genome evolutionary processes across eukaryotes.

The Scirtothrips dorsalis Species Complex: Endemism and Invasion in a Global Pest.

Invasive arthropods pose unique management challenges in various environments, the first of which is correct identification. This apparently mundane task is particularly difficult if multiple species are morphologically indistinguishable but accurate identification can be determined with DNA barcoding provided an adequate reference set is available. Scirtothrips dorsalis is a highly polyphagous plant pest with a rapidly expanding global distribution and this species, as currently recognized, may be comprised of cryptic species. Here we report the development of a comprehensive DNA barcode library for S. dorsalis and seven nuclear markers via next-generation sequencing for identification use within the complex. We also report the delimitation of nine cryptic species and two morphologically distinguishable species comprising the S. dorsalis species complex using histogram analysis of DNA barcodes, Bayesian phylogenetics, and the multi-species coalescent. One member of the complex, here designated the South Asia 1 cryptic species, is highly invasive, polyphagous, and likely the species implicated in tospovirus transmission. Two other species, South Asia 2, and East Asia 1 are also highly polyphagous and appear to be at an earlier stage of global invasion. The remaining members of the complex are regionally endemic, varying in their pest status and degree of polyphagy. In addition to patterns of invasion and endemism, our results provide a framework both for identifying members of the complex based on their DNA barcode, and for future species delimiting efforts.

Early establishment of the phytoseiid mite Amblyseius swirskii (Acari: Phytoseiidae) on pepper seedlings in a Predator-in-First approach.

The establishment of biocontrol agents is critical for success of biological control strategies. Predator-in-First (PIF) is a prophylactic control strategy that aims to establish predators before the appearance of pests in an agro-ecosystem. PIF uses the ability of generalist phytoseiid mites to survive, develop and reproduce on pollen and thus establish in the absence of prey. The early establishment of populations of natural enemies helps control the pests at their incipient stage of infestation. The current study was undertaken to screen pepper cultivars for their ability to support populations of the predatory mite Amblyseius swirskii Athias-Henriot in the absence of prey. Twenty-nine pepper cultivars (11 hot and 18 sweet) were tested through a series of experiments, and four cultivars (7141, 992-7141, FPP7039 and FPP9048) were found to sustain A. swirskii populations throughout the study period. The initial application of pollen was important for establishment and maintenance of the predatory mites within the greenhouse system. Among the three screening experiments, high densities of mites were obtained in the experiment where 20 mites were released per plant, even reaching densities of >100 mites/plant. Recovery of predatory mites was significantly higher (ca. 2-3 fold) on the four pepper cultivars when predatory mites were mass released using an indirect method (banker plants) than when they were released directly on the seedlings, suggesting an advantage of passive continuous release. Future work will evaluate the selected pepper cultivars with the PIF strategy under greenhouse and field production conditions.

ESTIMATING BACTERIAL DIVERSITY IN SCIRTOTHRIPS DORSALIS (THYSANOPTERA: THRIPIDAE) VIA NEXT GENERATION SEQUENCING.

The last 2 decades have produced a better understanding of insect-microbial associations and yielded some important opportunities for insect control. However, most of our knowledge comes from model systems. Thrips (Thysanoptera: Thripidae) have been understudied despite their global importance as invasive species, plant pests and disease vectors. Using a culture and primer independent next-generation sequencing and metagenomics pipeline, we surveyed the bacteria of the globally important pest, Scirtothrips dorsalis Hood. The most abundant bacterial phyla identified were Actinobacteria and Proteobacteria and the most abundant genera were Propionibacterium, Stenotrophomonas, and Pseudomonas. A total of 189 genera of bacteria were identified. The absence of any vertically transferred symbiont taxa commonly found in insects is consistent with other studies suggesting that thrips primarilly acquire resident microbes from their environment. This does not preclude a possible beneficial/intimate association between S. dorsalis and the dominant taxa identified and future work should determine the nature of these associations.