Parasitoid Tamarixia Radiata Research Articles

Control of Diaphorina citri (Hemiptera: Liviidae) using environmentally friendly chemical alternatives

Diaphorina citri poses a serious threat to citrus. Here, the nymphicidal activity of mineral and soybean oils, organosilicon, and citrus-essential-oil-derived adjuvants was evaluated. Additionally, mineral and soybean oils were studied for antifeedant and repellent effects on adults. Residual effect on the parasitoid Tamarixia radiata was also assessed. Nymphicidal activity ranged between 65–83%, with Silwet enhancing mineral and soybean oil efficacy. Evaluated soybean and mineral oil exhibited comparable antifeedant and repellent effects on adults. All products caused <20% mortality in T. radiata, even 24 h after spraying. Overall, tested adjuvants and oils offer promising eco-friendly alternatives for sustainable D. citri management.

Conservation of natural enemies of Diaphorina citri and their impact on Huanglongbing: Analysis and perspectives

Diaphorina citri is the main vector of Candidatus Liberibacter asiaticus (CLas), the causative agent of HLB, the most devastating citrus disease. Although the importance of biological control is recognized, insecticides are the main control tool used. Its use in citrus should be cautious, as it could interfere with the biocontrol of exotic pests already present. Diaphorina citri has a wide range of natural enemies; however, only the parasitoid Tamarixia radiata and some species of entomopathogenic fungi are used inundatively. Although the main predators of the vector occur naturally, few studies address their conservation in situ. This review supports the idea that the conservation of natural enemies should be the basis of the integrated management of D. citri and CLas. The conservation of alternate hosts, the inclusion of nectar plants, in situ conservation of parasitoids, and the autodissemination of entomopathogenic fungi are proposed. Studies carried out on conservation of natural enemies of D. citri and related pests, their probable impact on the disease, and prospects for implementation in Mexico are analyzed and discussed. The proposed strategies could enhance not only the biological control of D. citri-CLas, but also the autoregulation of citrus pests in general.

Native, naturalized and commercial predators evaluated for use against Diaphorina citri

Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a key pest of citrus associated with the yet uncurable Huanglongbing (HLB) disease, that is threatening worldwide citrus production. Control of D. citri has hitherto relied on chemical insecticides and on the use of the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). However, use of insecticides is problematic due to environmental and social issues, especially where D. citri is mostly spread in residential areas, and use of T. radiata has resulted in mixed success. Therefore, there is an urgent need to find sustainable and complementary practices to control this pest. Generalist predators, including green lacewings and coccinellids, have been frequently associated to D. citri in field surveys, yet they have rarely been tested. We have tested the predation capability under laboratory, greenhouse and semi-field conditions, of five predators: the green lacewings Chrysoperla comanche (Banks) and C. rufilabris Burmeister (Neuroptera: Chrysopidae), the coccinellids Diomus pumilio Weise and Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) and the brown lacewing Sympherobius barberi Banks (Neuroptera: Hemerobiidae). All of them were capable of feeding on D. citri and reduce its populations under laboratory conditions, but critical differences emerged in greenhouse and field cages, with some predators (the green lacewings and D. pumilio) being the most effective. We discuss possible ways of utilizing these predators as an additional biological control tool to address current limitations of D. citri control in commercial groves, in residential areas and at the urban-agricultural interface.

'Candidatus Liberibacter' Pathosystems at the Forefront of Agricultural and Biological Research Challenges.

'Candidatus Liberibacter' Pathosystems at the Forefront of Agricultural and Biological Research Challenges.

Predicting the establishment of Diaphorina citri and Tamarixia radiata on Citrus x\xa0aurantiifolia orchards based on the plant\u2013psyllid\u2013parasitoid interaction on Murraya paniculata

BackgroundThe insect vector of Huanglongbing, Diaphorina citri Kuwayama, 1908 (Hemiptera: Lividae) was detected in Ecuador in 2013 and its main parasitoid Tamarixia radiata (Waterston, 1922) (Hymenoptera: Eulophidae) was reported for the first time in 2017. In the citrus production region of Manabí province, Ecuador, D. citri and T. radiata were reported for the first time on Murraya paniculata L. in 2016 and 2018, respectively. D. citri was first found infesting Citrus x aurantiifolia (Christm.) Swingle in Manabí province at the end of 2018. The present study was conducted between August 2018 and May 2021 to: (1) monitor D. citri populations on M. paniculata and C. x aurantiifolia and determine the parasitism rates of T. radiata on D. citri nymphs on both host plants, (2) establish the occurrence of T. radiata parasitizing D. citri on C. x aurantiifolia, and (3) calculate a predictive model for estimating the number of parasitized nymphs on a planting lot of M. paniculata and a C. aurantiifolia orchard.ResultsDiaphorina citri populations on M. paniculata decreased from 11 nymphs (2018–2019) to approximately 2 nymphs per flush (2020). This was associated with a natural increase in parasitism rates of T. radiata from 20% (2018) to 96% in 2020. The regression equation (Y = 2.049Ln (x) + 5.88) was able to estimate the number of parasitized D. citri nymphs based on parasitism on M. paniculata (R2: 0.8315). Tamarixia radiata was first detected on C. x aurantiifolia in July 2020. Populations of D. citri reached 55 nymphs per flush (no parasitism) and subsequently decreased to the minimum level of 14 nymphs per flush (parasitism rates of up to 31%). The model allowed estimating the number of parasitized nymphs by T. radiata on M. paniculata and C. x aurantiifolia, with a maximum deviation of approximately 2 nymphs.ConclusionsBased on the colonization and establishment of the psyllid–parasitoid interaction on M. paniculata, it is estimated that approximately by the end of 2022, populations of D. citri on C. x aurantiifolia would decline due to the highest percentages of parasitism by T. radiata. High parasitism rates may indicate the potential of T. radiata in conservation biological control and integrated pest management programs.

Field Efficacy of Cordyceps javanica, White Oil and Spinetoram for the Management of the Asian Citrus Psyllid, Diaphorina citri.

Simple SummaryCitrus greening is devastating the citrus industry in Florida, and conventional synthetic pesticide applications are rapidly becoming unsustainable for the control of the vector, the Asian citrus psyllid (AsCP), Diaphorina citri. Laboratory experiments indicate that the entomopathogenic fungus Cordyceps javanica, alone and in combination with horticultural oils, may offer a more sustainable strategy to manage AsCP. The field study in this paper indicated that C. javanica alone, C. javanica mixed with white oil, and spinetoram (the chemical standard) mixed with white oil significantly suppressed AsCP populations by 60–90% and 61–83% 7 and 14 days after treatment, respectively, in 2018, compared to white oil only and the untreated control treatments. Only spinetoram + oil suppressed AsCP 100% up to 7 days after treatment in 2019. AsCP’s natural enemies, mostly lady beetles, were observed on fungal-treated citrus trees and the untreated control. Overall, C. javanica was as effective in suppressing AsCP adults as spinetoram for up to 14 days in field conditions and was compatible with the psyllids’ natural enemies. The use of C. javanica in citrus-integrated pest management is suggested.Citrus greening disease is devastating the citrus industry in Florida, and the conventional synthetic pesticide applications used to control the vector, the Asian citrus psyllid (AsCP), Diaphorina citri, are rapidly becoming unsustainable. Various laboratory experiments indicate that the entomopathogenic fungus Cordyceps javanica, alone and in combination with horticultural oils, may offer a more sustainable strategy for the management of AsCP. Field studies conducted in 2018 and 2019 in mature citrus indicated that C. javanica alone, C. javanica mixed with white oil, and the chemical standard spinetoram mixed with white oil significantly suppressed AsCP adult populations by 61–83% up to 14 days after treatment in 2018, although colony-forming units of C. javanica were still present on the leaves 21 days after treatment (DAT). Only spinetoram + oil significantly suppressed AsCP, by 100%, up to 7 DAT in 2019. Natural enemies of AsCP, including lady beetles, lacewing larvae and the parasitoid Tamarixia radiata, were observed in the fungal treatments and the untreated control. The AsCP suppression by C. javanica and its compatibility with beneficial organisms suggest the potential use of this entomopathogenic fungus in citrus-integrated pest management.

Density dependent mortality, climate, and Argentine ants affect population dynamics of an invasive citrus pest, Diaphorina citri, and its specialist parasitoid, Tamarixia radiata, in Southern California, USA

The effects of climate and ants on population regulation of an invasive citrus pest, Diaphorina citri (Hemiptera: Liviidae), by its parasitoid Tamarixia radiata (Hymenoptera: Eulophidae), in southern California were examined over a four-year period. Densities of D. citri eggs, nymphs, and adults, and Argentine ant, Linepithema humile (Hymenoptera: Formicidae), a mutualist which defends psyllid nymphs from natural enemies, citrus flush growth patterns, and parasitism rates of T. radiata, were monitored every four weeks on grapefruit, lemon, lime, orange, and tangerine trees at 28 urban sites across three climate types (coastal, intermediate, and desert). Significant spatial and temporal effects on D. citri abundance and parasitism rates were observed over this four-year period. Highest D. citri densities and parasitism rates were found in the intermediate and coastal regions during peaks of flushing cycles of citrus plants over March-June and September-November each year. Over the course of this study, population densities of D. citri declined by over 75%. Parasitism by T. radiata was identified as a significant mortality factor often exceeding 60% during periods of peak parasitoid activity. Analyses indicated that parasitism resulted in delayed density-dependent mortality and subsequent reductions in D. citri densities lagged by ~ 1 yr. Trends in D. citri densities and parasitism rates over time were similar on grapefruit, lemons, limes, oranges, and tangerines. Presence of L. humile in citrus resulted in a 3-fold increase in D. citri densities and control of this pest ant is needed to maximize biological control of D. citri.

Impact of the Temperature on the Phenology of Diaphorina citri (Hemiptera: Liviidae) and on the Establishment of Tamarixia radiata (Hymenoptera: Eulophidae) in Urban Areas in the Lower Colorado Desert in Arizona.

The invasive pest Diaphorina citri Kuwayama was first detected in Arizona in 2009. Since late 2013, the parasitoid Tamarixia radiata (Waterson), the main biocontrol agent of D. citri, has been released as part of a biological control program on citrus grown in urban areas of two western Arizona counties in the lower Colorado desert environment. Here we report a 3-yr survey aimed at evaluation of T. radiata releases on D. citri populations and assess the impact of the climate conditions on the phenology of D. citri and on the establishment success of T. radiata. We also monitored the phenology of D. citri as part of this assessment on different citrus host species. We show that the high summer temperatures in the Arizona desert halt the development of D. citri for about 3 mo every year which appears to have limited the establishment and impact of T. radiata. At survey sites distant from release areas the parasitism rates over the season ranged from 0 to 75% and on average peaked around 50% in 2016 but it was low or absent in 2015 and 2017, respectively. We discuss the consequences of this phenology of D. citri in the desert areas for the prospects of long-term establishment of T. radiata and the management of this key citrus pest.

Applied Biological Control in Brazil: From Laboratory Assays to Field Application.

Brazil has a long history of the use of biological control (BC) of pests. The first attempt to use parasitoids was reported in the 1930s, and the first successful case dates to 1967. For a long period, chemical products were the most widespread control measure among Brazilian growers. This situation has gradually changed because of the lack of satisfactory control to manage certain pests, a slow change in the culture of growers, and some emblematic cases of the successful use of BC. The use of BC as a component of Integrated Pest Management is increasingly common. The present contribution summarizes the evolution of BC in Brazil, citing as an example the case of successful use of Cotesia flavipes (Cameron) (Hymenoptera: Braconidae), Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) and Trichogramma spp. It presents some data on the utilization of BC in the country, such as the case of sugarcane, for which microorganisms as well as macroorganisms are used; the use of Baculovirus in soybean, produced in mass-reared lepidopteran larvae; and the recent case of the control of Diaphorina citri Kuwayama (Hemiptera: Liviidae) by the parasitoid Tamarixia radiata. Finally, the prospects for wider use of BC in Brazil are discussed, together with the challenges involved in broadening the growers’ use of this technology.

Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae), a small but voracious predator of Diaphorina citri (Kuwayama) (Hemiptera: Liviidae)

Se evaluó el efecto de depredación de Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae) sobre ninfas de Diaphorina citri Kuwayama (Hemiptera: Liviidae) mantenidas en condiciones experimentales para la cría de Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). Se realizó un ensayo empleando jaulas con capacidad para 9 plantas de Murraya paniculata (L.) Jack (Rutaceae) infestadas con un promedio de 600 ninfas de D. citri y 100 adultos de T. radiata por jaula. Tres jaulas fueron expuestas a las hormigas y una sin exposición (Control). En cada jaula se contabilizó el número de ninfas sanas y parasitadas y el número de adultos de D. citri y T. radiata, cada 2 días durante 15 días. La exposición a la depredación por W. auropunctata afectó de forma significativa el número de ninfas que alcanzaron el estado adulto y el número de ninfas parasitadas por T. radiata (prueba exacta de Fisher). En las jaulas expuestas, cerca del 3% de las ninfas sobrevivieron al estado adulto en contraste con 18% en la jaula control. De igual manera se vio afectada la acción del parasitoide, con un 24% de ninfas parasitadas en las jaulas expuestas en contraste con 66% en la jaula control. Wasmannia auropunctata tiene gran potencial como controlador de esta plaga en viveros de cítricos. La hormiga también consume T. radiata de forma indirecta al consumir ninfas de D. citri parasitadas.

Effect of host feeding on life history traits of Tamarixia radiata, parasitoid of the Asian citrus psyllid, Diaphorina citri

The parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) is being used for the biological control of the Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Liviidae). The parasitoid is strongly synovigenic, as it is born with very few mature eggs. Synovigenic insects need to feed on host haemolymph to mature additional eggs, and are able to resorb mature eggs to allocate resources toward maintenance. We investigated the effect of host feeding on parasitism, longevity and egg load dynamics, and estimated egg maturation and resorption rates. Although host feeding does not increase survival or longevity, it results in increased parasitization rates when parasitoids are seven days old, and that a single host meal leads to an average gain of three eggs. We discuss the importance of these data to predict the foraging and parasitization behavior of T. radiata in the field, and to potentially improve current efforts to control ACP.

Residual toxicity of selected organic insecticides to Diaphorina citri (Hemiptera: Liviidae) and non-target effects on Tamarixia radiata (Hymenoptera: Eulophidae) in California

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) threatens California's citrus industry because of its ability to transmit the bacterium, Candidatus Liberibacter asiaticus, associated with huanglongbing (HLB). To reduce the risk of HLB spread, an area-wide management strategy was established to control D. citri in both conventional and organic commercial citrus. In addition, releases of the parasitoid Tamarixia radiata Waterston (Hymenoptera: Eulophidae) as a classical biological control agent have been conducted in certain urban areas of California to improve control of D. citri. The objectives of this study were to document the residual efficacy of organic insecticides against D. citri nymphs, compare the efficacy of multiple applications of the organic spinosad relative to a single application of the non-organic insecticide fenpropathrin, and estimate the non-target effect of selected foliar insecticides on T. radiata. Spinosad + oil showed greater residual control of D. citri nymphs compared to pyrethrins + oil. The effects of organic insecticides were short lived; by 10 d post treatment there was no detectable effect. Fenpropathrin provided significantly longer control of D. citri nymphs and the efficacy of two or more applications of spinosad was comparable to one application of fenpropathrin. Of the organic insecticides, spinosad + oil resulted in the greatest non-target effects on T. radiata and pyrethrins, pyrethrins + oil, and oil alone had the least severe effects on T. radiata. This study provides important information regarding the residual control of D. citri by organic insecticides and their compatibility with the biological control agent T. radiata.

Modeling the Phenology of Asian Citrus Psyllid (Hemiptera: Liviidae) in Urban Southern California: Effects of Environment, Habitat, and Natural Enemies.

Modeling can be used to characterize the effects of environmental drivers and biotic factors on the phenology of arthropod pests. From a biological control perspective, population dynamics models may provide insights as to when the most vulnerable pest life stages are available for natural enemies to attack. Analyses presented here used temperature and habitat dependent, instar-specific, discrete models to investigate the population dynamics of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). This pest is the target of a classical biological control program with the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). The population trends of D. citri eggs, nymphs, and adults, citrus flush growth patterns, and T. radiata activity were monitored monthly on orange and lemon trees at 10 urban sites in southern California for a 2-yr period. Cumulative D. citri egg, nymph, and adult days recorded at each site, were regressed against accumulated degree-days (DDs) to model the population dynamics of each development stage in relation to temperature. Using a biofix point of 1 January, the model predicted that 10% and 90% of eggs were laid by 198 and 2,255 DD, respectively. Populations of small and large D. citri nymphs increased slowly with 90% of the population recorded by 2,389 and 2,436 DD, respectively. D. citri adults were present year round with 10 and 90% of the population recorded by 95 and 2,687 DD, respectively. The potential implications of using DD models for optimizing inoculative releases of natural enemies, such as T. radiata into citrus habitat infested with D. citri, are discussed.

Drought stress affects response of phytopathogen vectors and their parasitoids to infection‐ and damage‐induced plant volatile cues

Abstract1. The response of a phytopathogen vector to pathogen‐induced plant volatiles was investigated, as well as the response of the phytopathogen vector's parasitoid to herbivore‐induced plant volatiles released from plants with and without drought stress.2. These experiments were performed with Asian citrus psyllid (Diaphorina citri), vector of the plant pathogen Candidatus Liberibacter asiaticus (CLas) and its parasitoid Tamarixia radiata as models. Candidatus Liberibacter asiaticus is the presumed causal pathogen of huanglongbing (HLB), also called citrus greening disease.3. Diaphorina citri vectors were attracted to headspace volatiles of CLas‐infected citrus plants at 95% of their water‐holding capacity (WHC); such attraction to infected plants was much lower under drought stress. Attraction of the vector to infected and non‐stressed plants was correlated with greater release of methyl salicylate (MeSA) as compared with uninfected and non‐stressed control citrus plants. Drought stress decreased MeSA release from CLas‐infected plants as compared with non‐stressed and infected plants.4. Similarly, T. radiata was attracted to headspace volatiles released from D. citri‐infested citrus plants at 95% of their WHC. However, wasps did not show preference between headspace volatiles of psyllid‐infested and uninfested plants when they were at 35% WHC, suggesting that herbivore‐induced defences did not activate to recruit this natural enemy under drought stress.5. Our results demonstrate that herbivore‐ and pathogen‐induced responses are environmentally dependent and do not occur systematically following damage. Drought stress affected both pathogen‐ and herbivore‐induced plant volatile release, resulting in concomitant decreases in behavioural response of both the pathogen's vector and the vector's primary parasitoid.

Susceptibility of Diaphorina citri (Hemiptera: Liviidae) and Its Parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) to Entomopathogenic Fungi under Laboratory Conditions.

Diaphorina citri (Kuwayama) is a global pest of citrus that transmits the bacteria associated with the disease, Huanglongbing. Entomopathogenic fungi and the parasitoid Tamarixia radiata (Waterston) are important biological control agents of this pest and likely to interact in D. citri populations. As a basis for interaction studies, we determined the susceptibility of nymphs and adults of D. citri and adults of the parasitoid T. radiata to six fungal isolates from the species Beauveria bassiana s.l. (Bals.-Criv.) Vuill. (isolates B1 and B3), Metarhizium anisopliae s.s. (Metsch.) (Ma129 and Ma65) and Isaria fumosorosea Wize (I2 and Pae). We conducted experiments evaluating infection levels in all three insect groups following inoculation with a series of conidial concentrations (1×104-1×108 conidia mL-1). Results showed that D. citri nymphs and T. radiata were more susceptible to fungal isolates than D. citri adults. Overall, B. bassiana and M. anisopliae isolates caused the greatest infection compared with I. fumosorosea isolates in all three groups of insects. Isolates B1 (B. bassiana) and Ma129 (M. anisopliae) infected a greater proportion of adults and nymphs of D. citri, respectively. Both isolates of B. bassiana caused greater infection in T. radiata compared with isolates of the other fungal species. We propose that isolates B1 and Ma129 are the strongest candidates for control of D. citri. Our results represent the first report of entomopathogenic fungi infecting T. radiata, and the basis for future studies to design a biological control programme that uses both agents more efficiently against D. citri populations.

Interactions between entomopathogenic fungi and Tamarixia radiata (Hymenoptera: Eulophidae) in Diaphorina citri (Hemiptera: Liviidae) populations under laboratory conditions

Biological control of Diaphorina citri (Kuwayama) using the parasitoid Tamarixia radiata (Waterston) or entomopathogenic fungi has been attempted, but there have been few published studies on their potential interactions when used together. We studied the effect of prior residency time on the outcomes of interactions between T. radiata and the fungal pathogens Beauveria bassiana and Metarhizium anisopliae in D. citri nymphs. In the first experiment, nymphs infected with fungi were exposed to the parasitoid after 0, 24 and 72 h. Next, nymphs with parasitoids at different developmental stages (eggs, larvae or pupae) were exposed to fungal inoculation. The greatest proportion of fungus-infected nymphs occurred when they were inoculated 72 h prior to parasitoid exposure. The lowest parasitism rate occurred in nymphs that had been infected by fungi 72 h prior to parasitoid exposure. The number of nymphs used for host-feeding by the parasitoid was similar, regardless of how advanced the fungal infection was. When fungal inoculations were made to parasitized nymphs with different developmental stages of the parasitoid, the greatest proportion becoming infected occurred in nymphs with parasitoid eggs. The overall longevity of adult parasitoids emerging from control and fungal-infected treatments was similar; however, the longevity of adult parasitoids emerging from nymphs which had been inoculated with parasitoid larvae were lowest, with the greatest effect observed for the M. anisopliae isolate. The ecological importance and practical recommendations derived from our results are discussed.

Effect of host deprivation on the foraging behavior of the Asian citrus psyllid parasitoid Tamarixia radiata: observations from the laboratory and the field

AbstractThe Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a significant citrus pest and the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) has been released in various citrus‐producing areas in classical biological control programs targeting D. citri. We investigated the effect of host deprivation on the foraging behavior and patch utilization by T. radiata. In the laboratory, females deprived of hosts for 3 days tended to leave patches of 12 nymphs without parasitizing hosts during the ca. 30 min they spent in the patch before leaving. Moreover, half of these females failed to host feed, and those that did host feed, on average, needed more than 15 min to complete feeding. Conversely, non‐host‐deprived females parasitized on average three nymphs before leaving patches without host feeding during the ca. 39 min they spent in the patch. These laboratory observations were compared to mass‐reared female T. radiata that were released onto colonies of D. citri nymphs infesting citrus in the field. Release vials were provisioned with honey and these females had no opportunities to host feed over the 1‐ to 2‐day containment period prior to release. When introduced onto D. citri colonies, 68% T. radiata females abandoned D. citri patches prior to probing hosts, in part, because Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), tending colonies disturbed searching parasitoids. These results from laboratory and field studies are discussed in the context of classical biological control, with the aim of understanding how to manipulate host availability and ant activity so establishment rates and impact of T. radiata can be improved.

Tamarixia radiata(Hymenoptera: Eulophidae) ×Diaphorina citri(Hemiptera: Liviidae): Mass Rearing and Potential Use of the Parasitoid in Brazil

Huanglongbing (HLB) is the most serious disease affecting citriculture worldwide. Its vector in the main producing regions is the Asian citrus psyllid, Diaphorina citri Kuwayama, 1908 (Hemiptera: Liviidae). Brazil has the largest orange-growing area and is also the largest exporter of processed juice in the world. Since the first detection of the disease in this country, >38 million plants have been destroyed and pesticide consumption has increased considerably. During early research on control methods, the parasitoid Tamarixia radiata (Waterston, 1922) (Hymenoptera: Eulophidae) was found in Brazil. Subsequent studies focused on its bio-ecological aspects and distribution in citrus-producing regions. Based on successful preliminary results for biological control with T. radiata in small areas, mass rearing was initiated for mass releases in Brazilian conditions. Here, we review the Brazilian experience using T. radiata in D. citri control, with releases at sites of HLB outbreaks, adjacent to commercial areas, in abandoned groves, areas with orange jessamine (a psyllid host), and backyards.

Lethal and Sublethal Effects of Insecticides Used on Citrus, on the Ectoparasitoid Tamarixia radiata.

Huanglongbing (HLB) is a disease associated with the bacteria “Candidatus Liberibacter spp.” and has been devastating citrus orchards around the world. Its management involves control of the insect vector, the Asian citrus psyllid Diaphorina citri Kuwayama. However, the indiscriminate use of chemicals has caused pest outbreaks and eliminated the natural enemies of the vector, such as the parasitoid Tamarixia radiata (Waterston), the main agent for biological control of D. citri. This study assessed the lethal and sublethal effects of insecticides recommended for integrated production of citrus on the parasitoid T. radiata. When adult parasitoids were exposed to residues of 25 insecticides, 20% of them, i.e., gamma-cyhalothrin, etofenprox, azadirachtin, tebufenozide and pyriproxyfen, were considered as harmless (Class 1), 12% as slightly harmful (Class 2), 12% as moderately harmful (Class 3) and 56% as harmful (Class 4), according to the classification proposed by the IOBC/WPRS. Afterward, 14 insecticides (5 harmless and 9 harmful) were sprayed on the parasitoid pupae. Of the 14 insecticides tested, only the organophosphates dimethoate and chlorpyrifos affected the parasitoid emergence. The effects of insecticides on the parasitism capacity of adults exposed to residues of azadirachtin, etofenprox, gamma-cyhalothrin, pyriproxyfen and tebufenozide (harmless) were also evaluated. Tebufenozide and gamma-cyhalothrin affected the parasitism of the F0 generation, but did not affect the emergence of the F1 and F2 generations. Therefore, for an effective IPM program, selective insecticides or harmful pesticides to adult parasitoids could be used in the field, provided that the adults do not occur naturally and the chemical applications do not coincide with parasitoid releases.

Bionomics of Asian Citrus Psyllid (Hemiptera: Liviidae) Associated with Orange Jasmine Hedges in Southeast Central Florida, with Special Reference to Biological Control by Tamarixia radiata.

The Asian citrus psyllid, Diaphorina citri Kuwayama, is an important pest in Florida because it transmits bacteria responsible for citrus huanglongbing disease. In addition to infesting citrus, orange jasmine (Murraya exotica L.) is one of Asian citrus psyllid's preferred host plants and is widely grown as an ornamental hedge. We report on Asian citrus psyllid bionomics over three years at five urban plantings of orange jasmine and on biological control of Asian citrus psyllid by a parasitoid Tamarixia radiata (Waterston). T. radiata had been released in Florida shortly after Asian citrus psyllid was first found, and the parasitoid was known to be established at each planting. Additionally, three new T. radiata haplotypes were released every 3 wk at three plantings during the first study year (one haplotype per planting, over all releases an average of 17 parasitoids per linear meter of hedge); all three haplotypes were released at a fourth planting beginning midway through the study (over all releases, an average combined total of 202 parasitoids per linear meter of hedge). Asian citrus psyllid populations were present year-round at each planting, often at large levels. Such plantings may pose risk to commercial citrus as Asian citrus psyllid reservoirs. Releases of the new haplotypes did not cause any measurable reduction in Asian citrus psyllid population levels during the study, and ironically percentage parasitism was generally highest at a planting where no releases were made. Higher release rates might have been more effective. The probability is discussed that repetitive pruning of orange jasmine reduced the full potential of T. radiata against Asian citrus psyllid in this study.