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Palm-infecting phytoplasmas have been a persistent threat to sustainable palm production in Florida, U.S.A., for nearly a century. First, lethal yellowing (LY) was introduced in the early 1900s, then lethal bronzing (LB) was introduced around 2006. While LY is currently rare in Florida, LB is actively spreading throughout the state and as it becomes more established, has begun infecting new host species. Continual monitoring efforts throughout the state seeks to catch infections and remove palms before further spread. As a result of this effort, many palms displaying a variety of symptoms are sampled and submitted to the University of Florida – Fort Lauderdale Research and Education Center (FLREC) for confirmation of phytoplasma infection status. Over the course of 3 years, multiple samples of Washingtonia robusta and Roystonea regia were submitted. All of these samples were negative for phytoplasma upon the initial qPCR screening and were tested with universal primers and confirmed as negative. Specimens of Arenga engleri, Rhapidophyllum hystrix, and Sabal palmetto were received and tested positive for LB, LB, and LY, respectively, tentatively representing new host records for these species and respective phytoplasma. Multilocus sequence analyses utilizing the 16S rRNA, 16S-23S intergenic spacer region, secA, secY, and groEL further confirmed the identity of LB and LY in the respective new hosts. These results highlight the need for continued monitoring of palms in Florida so that infected palms can be removed quickly. Also, the novel molecular data ( secY) help better understand and identify phytoplasmas in palms.

Lethal bronzing (LB) is a fatal palm disease caused by the phytoplasma ‘ Candidatus Phytoplasma aculeata’. This disease causes significant economic losses in palm industries and landscapes. The American palm cixiid, Haplaxius crudus, recently was identified as the vector of the phytoplasma. However, knowledge about LB phytoplasma transmission is limited due to the lack of a method to generate phytoplasma-infected insects in the laboratory. In this study, the acquisition and transmission of the LB phytoplasma by H. crudus were investigated. Successful acquisitions of the phytoplasma by H. crudus were observed at 2 days acquisition access period on LB-infected palm spear leaves. Analyses revealed increased phytoplasma infection rates of H. crudus with longer acquisition access periods and latent periods. A significantly higher phytoplasma infection rate was shown after various acquisition access periods and latent periods than the infection rate of the field-collected H. crudus population. Transmission of the phytoplasma from LB-infected spear leaves to sucrose media by H. crudus also was observed using digital PCR assays. These results further support the vector status of H. crudus and offer valuable information to understand LB phytoplasma transmission. Additionally, these results generate a critical baseline for future LB phytoplasma−vector research by providing a way to generate vectors with high phytoplasma infection rates in the laboratory setting.

Persimmon is a hardwood tree in the genus Diospyros that is commonly cultivated for its fruit in Eurasia and North America. Recent advances in metagenomics have resulted in the discovery of multiple novel viruses and viroids infecting persimmon trees in Asia and Europe. Recent survey work revealed the presence of viral pathogens in North America in Diospyros kaki, the Japanese persimmon, which is the most widely cultivated species globally. In this study, a survey of both D. kaki and D. virginiana, a native to the southeastern United States, was conducted to evaluate the viral infection status of these species in Florida. It was determined that out of the eight viral pathogens known from persimmon, six are present in Florida: apple fruit crinkle viroid (AFCVd), persimmon cryptic virus (PeCV), persimmon viroid (PeVd), persimmon virus A (PeVA), persimmon virus B (PeVB), and persimmon viroid 2 (PeVd2). In D. kaki, the most common viroid was PeVd and the most common virus was PeVA. In D. virginiana, PeVd2 was the most common viroid and PeVA was the most common virus. Most of the infections in D. kaki were mixed infections, while most infections in D. virginiana were single infections. The findings of this study are the first evidence of viral pathogens in Florida in D. kaki and the first evidence of these pathogens in native D. virginiana in North America. Future efforts should focus on vector surveys and transmission experiments.

A survey of weeds was undertaken in a palm nursery affected by lethal bronzing (LB) to identify a reservoir host of the causal phytoplasma. Three common species were identified; Urochloa maxima (Guineagrass), Sporobolus indicus (smut grass), and Cyperus esculentus (yellow nutsedge) and sampled over a period of 2 years. Each species was sampled 36 times and all three species were negative for the LB phytoplasma. However, three specimens of C. esculentus tested positive for the phytoplasma species ‘Candidatus Phytoplasma brasiliense’. These findings represent the first documented case of ‘Ca. P. brasiliense’ in North America, specifically in Florida, U.S.A., as well as a new host record for the phytoplasma and the first monocot host documented. Because of the impact this phytoplasma has on papaya and hibiscus in South America, it presents a unique threat to ornamental and agricultural sectors in south Florida. An area-wide survey for the phytoplasma and potential vectors is recommended.

Lethal bronzing (LB) is a phytoplasma disease of palms in Florida, U.S.A. Historically, the use of the antibiotic oxytetracycline-hydrochloride (OTC-HCl) was optimized to treat for LY, and currently label rates for OTC-HCl developed for LY are being used to treat palms preventatively against LB. Because of the economic impact of LB, assessing OTC-HCl against LB is essential for developing and optimizing management options for this disease. In this study, Sabal palmetto palms declining from LB were injected with OTC-HCl to assess efficacy on LB. Four groups of palms were selected that represented healthy palms, early symptomatic palms, palms with moderate symptoms, and palms with late-stage symptoms. Within each group, treatment palms injected with OTC-HCl and a control group with no antibiotics were tested weekly by quantitative PCR for 1 year. For asymptomatic palms, treated palms never developed symptoms or tested positive, whereas one of the control palms did. The early symptomatic palms that were treated had similar levels of phytoplasma to the control group but had much slower symptom development. Palms with moderate symptoms had no difference in titer between the treatment and the control group, but treated palms had much slower symptom development. Palms with late-stage symptoms showed no difference in phytoplasma titer or symptom progression between treated and control palms. These results suggest that label rates of OTC-HCl appear useful as a preventative against LB, but once symptoms develop, label rates cannot cure palms. In the meantime, removal of symptomatic palms is recommended.

Lethal bronzing disease (LBD) is a fatal infection in a variety of ornamental palms in Florida caused by the 16SrIV-D phytoplasma. The disease was first found in 2006 in Florida and has since spread to 31 different counties, reaching as far north as Jacksonville and as far south as Key Largo. Stakeholders (nursery personnel, landscaping personnel, and extension agents) from across the state take and send samples for analysis. To provide better sampling recommendations and reduce the time associated with the sampling process, the distribution of the 16SrIV-D phytoplasma was examined by quantitative PCR analysis in various Phoenix sylvestris that displayed different stages of decline, including early symptoms, moderate symptoms, and late symptoms. A declining Sabal palmetto was also available for analysis and examined as well. The findings of this study revealed that regardless of the stage of decline, the highest amount of phytoplasma detected was nearest to the base of the trunk and gradually decreased further up the trunk. Also, in P. sylvestris it was found that with symptoms present, the entire trunk has a systemic infection, resulting in positive reactions for every sample taken. These data are useful to stakeholders because they provide useful sampling recommendations in that only a single sample is needed when sampling a palm suspected to be infected with phytoplasma. Also, based on these results, sampling lower on the trunk is advised.

Barrier cropping plays an essential role in controlling insect pests and insect-transmitted diseases in cultural control. It has been proven efficient in suppressing the spread of nonpersistently transmitted viruses. For suppressing the spread of persistently transmitted viruses, barrier cropping is not considered an effective control strategy because barrier plants cannot act as a virus sink to purge the virus in the vector. However, few successful cases of barrier cropping suppressing the spread of persistently transmitted viruses have been reported. The objectives of the present study were to screen candidates (cucumber, okra, Chinese kale, soybean, and corn) for potential barrier plants to control tomato yellow leaf curl Thailand virus (TYLCTHV) and examine whether prefeeding on these plants can reduce the virus titer in its vector, Bemisia tabaci, thus reducing TYLCTHV transmission. The results revealed that nonviruliferous whiteflies preferred cucumber and okra to tomato, whereas viruliferous whiteflies preferred cucumber to tomato. Although prefeeding on cucumber, okra, and Chinese kale did not reduce the titer of TYLCTHV in viruliferous whiteflies, the vector transmission rate decreased after the whiteflies fed on Chinese kale. It implies that planting Chinese kale as a barrier plant for tomato cultivation may reduce the incidence of TYLCTHV. In addition, the preference to cucumber plants may reduce the incidence of whiteflies acquiring TYLCTHV from virus-infected tomato plants and of viruliferous whiteflies inoculating the virus into healthy tomato plants, thereby reducing the disease incidence. Further field trials of barrier cropping using the candidate plants are warranted.

The 16SrIV-D phytoplasma was first identified in Florida in 2006. Since its discovery, it has spread throughout most of the state. It is most prevalent in the central part of Florida, from Hillsborough County on the west coast to St. Lucie County on the east coast. The 16SrIV-D phytoplasma is the causal agent of lethal bronzing disease (LBD), which is also known as Texas Phoenix palm decline (TPPD). It affects a variety of common and economically important ornamental palm species as well as the native and ecologically important species, Sabal palmetto. It has spread into the southern portions of Florida, where the palm species diversity is higher. The aims of this survey were to document the spread of disease in terms of geographic and host range one decade after its introduction into Florida, and to assess the risk that LBD poses to the nursery and landscaping industries. The survey included samples received from stakeholders throughout the state, covering 18 counties, as well as a systematic sampling of palms at the Fort Lauderdale Research and Education Center (FLREC), where the disease is spreading actively. The findings of this survey resulted in the detection of LBD in eight new counties, including Collier, Hernando, Jefferson, Martin, Miami-Dade, Monroe, Seminole, and St. Johns, and the expansion of LBD into four new host species, Cocos nucifera, Livistona chinensis, Butia capitata, and Carpentaria acuminata. These findings are crucial for stakeholders because they highlight new hosts of 16SrIV-D phytoplasma and the geographic expansion of the disease, indicating that vigilance is needed when surveying declining palms.

Simple Summary Tomato yellow leaf curl viruses cause disease epidemics in tomato crops in tropical and subtropical areas worldwide. The sweet potato whitefly, Bemisia tabaci, is a vector of this group of viruses. This research studied the transmission biology of tomato yellow leaf curl Thailand virus (TYLCTHV) by B. tabaci, including virus-infected tissues, virus translocation, virus replication, and transovarial transmission (i.e., transmission from mother to progeny via ovaries). We discovered that the virus first infects the alimentary gut, then the hemolymph, and finally the salivary glands of the whitefly. The virus did not replicate in the whitefly during infection. In addition, TYLCTHV was detected in only 10% of infected females’ first-generation progeny, but the progeny was unable to cause viral infection of tomato plants; therefore, there was no evidence of transovarial transmission. When combined with the current literature, our results suggest that B. tabaci transmits TYLCTHV in a persistent-circulative mode. Abstract Viruses that cause tomato yellow leaf curl disease are part of a group of viruses of the genus Begomovirus, family Geminiviridae. Tomato-infecting begomoviruses cause epidemics in tomato crops in tropical, subtropical, and Mediterranean climates, and they are exclusively transmitted by Bemisia tabaci in the field. The objective of the present study was to examine the transmission biology of the tomato yellow leaf curl Thailand virus (TYLCTHV) by B. tabaci, including virus-infected tissues, virus translocation, virus replication, and transovarial transmission. The results demonstrated that the virus translocates from the alimentary gut to the salivary glands via the hemolymph, without apparent replication when acquired by B. tabaci. Furthermore, the virus was detected in 10% of the first-generation progeny of viruliferous females, but the progeny was unable to cause the viral infection of host plants. There was no evidence of transovarial transmission of TYLCTHV in B. tabaci. When combined with the current literature, our results suggest that B. tabaci transmits TYLCTHV in a persistent-circulative mode. The present study enhances our understanding of virus–vector interaction and the transmission biology of TYLCTHV in B. tabaci.

Insect vector feeding preference and behavior play important roles in pathogen transmission, especially for pathogens that solely rely on insect vector transmission. This study aims to examine the effects of the 16SrIV-D phytoplasma, the causal agent of lethal bronzing (LB) disease of palms, on associated auchenorrhynchan insects. The numbers of auchenorrhynchans collected during weekly surveys during a yearlong study using yellow sticky traps were analyzed. The cumulative number of H. crudus was 4.5 times greater on phytoplasma-infected relative to non-infected palms. Other auchenorrhynchans showed no difference between phytoplasma-infected and non-infected palms or were greater on non-infected rather than on infected palms. Furthermore, we examined the effects of LB, palm height, temperature, and the interactive effects of these factors on H. crudus abundance. When the palms were infected with LB, at low temperature, H. crudus was more abundant on shorter than taller palms, however, H. crudus was more abundant on taller than shorter palms at the median and higher temperatures. These results may indicate that H. crudus prefers LB-infected palms over non-infected palms. The interactive effects of LB, palm heights, and temperature further suggest that vector monitoring and disease management should be optimized according to seasonal variation in temperature.

Lethal bronzing disease is caused by the 16SrIV-D phytoplasma and is fatal to many palm species. This disease has caused significant economic losses to nursery and landscaping industries in Florida. As is the phloem-limited nature of phytoplasmas, the lethal bronzing disease phytoplasma is transmitted only by phloem-feeding insect vectors. However, the vector remains unconfirmed and this impedes the development of Integrated Pest Management programs that target vector populations. The primary objective of this study was to identify potential vectors of the 16SrIV-D phytoplasma in Florida by surveying auchenorrhynchans using sticky traps at the area where the disease is actively spreading, and screening the specimens for the presence of the phytoplasma. Cixiidae, Cicadellidae, Derbidae, and Membracidae insects were collected consistently during the 1-yr survey. The total number of a cixiid planthopper, Haplaxius crudus (Van Duzee) (Hemiptera: Cixiidae), was significantly higher than other insects that were collected on the traps. Of 3,734 specimens tested by nested polymerase chain reaction, approximately 0.672% of the H. crudus specimens and 1 unidentified leafhopper (Cicadellidae sp.) tested positive for the16SrIV-D phytoplasma. The 16S sequences amplified from the positive specimens were confirmed by sequencing and phylogenetic analysis. Based on the population survey and the polymerase chain reaction assay results, we suggest that H. crudus is the potential vector of the 16SrIV-D phytoplasma. However, the vector competency of H. crudus needs to be further investigated due to the possibility of feeding residue being detected. The study has important implication for current lethal bronzing disease management by monitoring and controlling vector candidates in disease areas.

The genus Haplaxius is a large taxon of cixiid planthoppers that is of economic importance due to the ability of Haplaxius crudus to transmit lethal yellowing in coconut palms. Haplaxius dougwalshi sp. n. is established as a new taxon of Cixiidae in the tribe Oecleini collected from native palms in lowland tropical rainforest in Costa Rica. Placement in the genus Haplaxius is supported both by molecular evidence based on the COI and 18S genes as well as by morphological characters. This novel taxon was discovered during survey work in Costa Rica to look for phytoplasmas and document planthopper diversity on palms. Furthermore, Haplaxius skarphion was also collected from coconut palms during survey work and is reported for the first time in Costa Rica.

Lethal bronzing disease (LBD) is a fatal infection in a variety of ornamental palms in Florida caused by the 16SrIV-D phytoplasma. The disease was first found in 2006 in Florida and has since spread to 31 different counties, reaching as far north as Jacksonville and as far south as Key Largo. Stakeholders (nursery personnel, landscaping personnel, and extension agents) from across the state take and send samples for analysis. To provide better sampling recommendations and reduce the time associated with the sampling process, the distribution of the 16SrIV-D phytoplasma was examined by quantitative PCR analysis in various

A new species of the genus Agoo Bahder & Bartlett, Agoo beani sp. n. was found associated with coconut (Cocos nucifera L., Arecaceae) in Jamaica. This species was discovered as part of a survey of the Caribbean basin to document planthopper diversity on palms. Cytochrome c oxidase subunit I (COI) and 18S sequence data strongly support placement of the new species in Agoo. The morphological features of Omolicna cocoana Rodriguez-Leon & Hidalgo-Gato from Cuba are reviewed and this species transferred into the genus Agoo.

Lethal bronzing disease (LBD) is a lethal decline of various palm species caused by the 16SrIV-D phytoplasma. The disease was described in Texas in 2002 but found in Florida in 2006. Since its introduction, the phytoplasma has spread throughout much of the state. Typically, sampling of infected palms involves taking trunk tissue; however, in some instances this is not possible so alternative protocols are needed. In this study, phytoplasma titers were measured in different leaf tissues of infected palm in order to provide stakeholders with more sampling options. In addition, understanding the phytoplasma distribution in the palm canopy can shed light on the pathogen’s biology and aid in vector studies. Three species of palm, Phoenix roebelinii, Sabal palmetto, and Syagrus romanzoffiana, were identified and confirmed positive for infection by qPCR analysis. Leaf tissue from these species that represented different stages of decay were sampled and tested by qPCR and dPCR. For each species, phytoplasma was only detectable in the spear leaf tissue that was connected directly to the apical meristem by both qPCR and dPCR. These data are useful by demonstrating that the 16SrIV-D phytoplasma appears to be restricted to the spear leaf so stakeholders who wish to sample palms but cannot sample trunk tissue due to palm size or lack of permission to drill into the trunk have an alternative tissue type to reliably sample. In addition, this information will help improve vector research by knowing where to collect insects that have a higher probably of possessing the phytoplasma.

Phytoplasmas are an economically important group of plant pathogens that negatively impact a wide variety of plants in agricultural and natural ecosystems. In Florida, palm trees are essential elements in the nursery and landscaping industries that suffer from diseases caused by phytoplasmas that are related to each other but are classified in two different subgroups, 16SrIV-A and 16SrIV-D. In this study, a TaqMan assay was developed for digital polymerase chain reaction (dPCR) to detect both palm-infecting phytoplasmas found in Florida. When compared with real-time PCR assays and nested PCR assays, dPCR was capable of detecting the phytoplasmas at much lower concentrations than was possible by using real-time PCR and nested PCR. Additionally, the assay was capable of detecting 16SrIV-B phytoplasma as well as isolates representing the 16SrI and 16SrIII phytoplasma groups. Due to sequence identity of primer annealing regions across diverse phytoplasmas, the assay is likely to be successful for detection of a wide variety of phytoplasmas. The increased sensitivity of this dPCR assay over real-time PCR will allow for earlier detection of phytoplasma infection in palm trees, as well as for screening of salivary glands of candidate insect vector species. These advantages should aid timely management decisions to reduce disease spread and rapid determination of phytoplasma transmission by vectors.

Thrips and thrips-transmitted tospoviruses cause significant losses in crop yields worldwide. The melon thrips (Thrips palmi) is not only a pest of cucurbit crops, but also a vector that transmits tospoviruses, such as the watermelon silver mottle virus (WSMoV). Vector transmission of tospoviruses has been well studied in the tomato spotted wilt virus (TSWV)–Frankliniella occidentalis model system; however, until now the transmission mode of WSMoV by T. palmi has not been sufficiently examined. The results of the transmission assays suggest that T. palmi transmits WSMoV in a persistent manner, and that the virus is mainly transmitted by adults, having been ingested at the first-instar larval stage. Complementary RNAs corresponding to the NSm and NSs genes of WSMoV were detected in viruliferous thrips by reverse transcription-polymerase chain reaction; NSs protein was also detected in viruliferous thrips by western blotting, verifying the replication of WSMoV in T. palmi. Furthermore, we demonstrated that in thrips infected with WSMoV at the first-instar larval stage, the virus eventually infected various tissues of the adult thrips, including the primary salivary glands. Taken together, these results suggest that T. palmi transmits WSMoV in a persistent-propagative mode. The results of this study make a significant contribution to the understanding of the transmission biology of tospoviruses in general.

Life table parameters and predation rate of the coccinellid predator Harmonia dimidiata F. fed on Aphis gossypii Glover were determined at 25°C using the age-stage, two-sex life table. When the total number of eggs were included in our calculations, the intrinsic rate of increase (r), finite rate (λ), net reproductive rate (R0) and mean generation time (T) for H. dimidiata were 0.1354/day, 1.1450/day, 280.8 offspring and 41.6 day, respectively. These values were significantly different, however, only when viable (=hatchable) H. dimidiata eggs were counted (0.0909/day, 1.0952/day, 67.6 offspring and 46.3 day, respectively). The values obtained using all eggs did not realistically reflect the effect of variable hatch rate and true population parameters of H. dimidiata. We therefore excluded unhatched eggs from our data and demonstrated mathematically that in future demographic studies, it should be a standard procedure to exclude all unhatched eggs when analysing hatch rates that vary with maternal age. A mathematical proof was derived in this study to substantiate this. To observe and quantify variations that occur in the predation rate due to the age and stage of the predator, the daily number of A. gossypii consumed by individual H. dimidiata was analysed using the age-stage, two-sex life table. The net predation rate of H. dimidiata on A. gossypii was 14 804 aphids. The transformation rate Qp showed that the predator needs to consume an average of 219.1 aphids to produce one viable egg. The finite predation rate of H. dimidiata was 125.7 when only hatchable eggs were included in the analysis. Because the age-stage, two-sex life table takes both of the sexes and the variable predation rate occurring among stages into consideration, it becomes possible to use the population projection to quantify and time biological control procedures.

The sea grape flatid, Petrusa epilepsis (Kirkaldy) (Hemiptera: Flatidae) is a polyphagous, widespread planthopper in the Caribbean that infests common ornamental plants, as well as some of agricultural importance. In 2015, P. epilepsis was found in Florida for the first time, and was confirmed to be established in 2017 by the detection of eggs and nymphs on various ornamental plants located at the University of Florida's Fort Lauderdale Research and Education Center in Davie, Florida, USA. In this study, 9 new host plants are reported with 1 representing a new host family (Araliaceae). Additionally, the presence of adults, eggs, and nymphs of various sizes suggests that there are overlapping generations. Molecular analysis reveals no genetic variation of the COI gene. This study records establishment of another invasive species that has the potential to become a pest due to the large number of ornamental plants that are grown in South Florida that could serve as hosts of P. epilepsis elsewhere in Florida and the Caribbean.

Demography and population growth are the most important subjects of population ecology and economics. Finite and intrinsic growth rates have been used as standard parameters for describing and comparing growth potentials of populations. The predation potentials of predator populations or consumption potentials of consumer populations cannot be properly described using these growth rates alone. A standard parameter is needed for the description of the predation or consumption potential, as well as for the quantitative evaluation of a predator population in an ecosystem or biological control program. We show that the finite predation rate can be the standard parameter by linking the finite rate, the stable age-stage distribution, and the age-stage specific predation rate. The finite predation rate can be used to describe and compare the predation potentials of natural enemies used in biological control and in predicting the damage potential of different pest populations to crops.