Complexities in the Implementation and Maintenance of Integrated Pest Management in Potato.

Integrated pest management (IPM) is an educated and systematic effort to use multiple control techniques to reduce pest damage to economically acceptable levels while minimizing negative environmental impacts. Although its benefits are widely acknowledged, IPM is not universally practiced by farmers. Potato farming, which produces one of the most important staple crops in the world, provides a good illustration of the issues surrounding IPM adoption. Potatoes are attacked by a complex of insect pests that can inflict catastrophic crop losses. Potato production has gone through the processes of consolidation and intensification, which are linked to increased pest problems, particularly selection for insecticide-resistant pest populations. While use of insecticides remains the most common method of pest control in potatoes, other techniques, including crop rotation and natural enemies, are also available. In addition, there are effective monitoring techniques for many potato pests. However, reliable economic thresholds are often lacking. Potato ecosystems are complex and diverse; therefore, the knowledge necessary for developing ecologically based pest management is not easily obtained or transferable. Furthermore, potato systems change with the arrival of new pest species and the evolution of existing pests. Modern technological advances, such as remote sensing and molecular biotechnology, are likely to improve potato IPM. However, these tools are not going to solve all problems. IPM is not just about integrating different techniques; it is also about integrating the efforts and concerns of all stakeholders. The collaboration of farmers and scientists in agricultural research is needed to foster the development of IPM systems that are appropriate for grower implementation and thus more likely to be adopted. Additional emphasis also needs to be placed on the fact that not only does IPM decrease degradation of the environment, but it also improves the economic well-being of its practitioners.

Invasion Biology, Ecology, and Management of Western Flower Thrips.

Western flower thrips, Frankliniella occidentalis, first arose as an important invasive pest of many crops during the 1970s-1980s. The tremendous growth in international agricultural trade that developed then fostered the invasiveness of western flower thrips. We examine current knowledge regarding the biology of western flower thrips, with an emphasis on characteristics that contribute to its invasiveness and pest status. Efforts to control this pest and the tospoviruses that it vectors with intensive insecticide applications have been unsuccessful and have created significant problems because of the development of resistance to numerous insecticides and associated outbreaks of secondary pests. We synthesize information on effective integrated management approaches for western flower thrips that have developed through research on its biology, behavior, and ecology. We further highlight emerging topics regarding the species status of western flower thrips, as well as its genetics, biology, and ecology that facilitate its use as a model study organism and will guide development of appropriate management practices.

Emerging Themes in Our Understanding of Species Displacements.

The displacement of a species from a habitat by actions of another is the most severe outcome of interspecific interactions. This review focuses on recent developments in the understanding of (a) ecological mechanisms that lead to displacements, (b) how outcomes of interspecific interactions are affected by the context of where and when they occur, and (c) impacts of displacements. Displacements are likely to escalate as their primary initiating factors-the spread of non-native species and environmental change-continue at unprecedented rates. Displacements typically result from interactions of multiple mechanisms, not all of which involve direct competition. Various biotic and abiotic factors mediate these mechanisms, so variable outcomes occur when the same species interact in different environments. Though replacement of one species by another has particular relevance to pest management and conservation biology, the cascading effects that displacements have in managed and natural systems are critical to understand.

Emergence of Groundnut ringspot virus and Tomato chlorotic spot virus in Vegetables in Florida and the Southeastern United States.

Groundnut ringspot virus (GRSV) and Tomato chlorotic spot virus (TCSV) are two emerging tospoviruses in Florida. In a survey of the southeastern United States, GRSV and TCSV were frequently detected in solanaceous crops and weeds with tospovirus-like symptoms in south Florida, and occurred sympatrically with Tomato spotted wilt virus (TSWV) in tomato and pepper in south Florida. TSWV was the only tospovirus detected in other survey locations, with the exceptions of GRSV from tomato (Solanum lycopersicum) in South Carolina and New York, both of which are first reports. Impatiens (Impatiens walleriana) and lettuce (Lactuca sativa) were the only non-solanaceous GRSV and/or TCSV hosts identified in experimental host range studies. Little genetic diversity was observed in GRSV and TCSV sequences, likely due to the recent introductions of both viruses. All GRSV isolates characterized were reassortants with the TCSV M RNA. In laboratory transmission studies, Frankliniella schultzei was a more efficient vector of GRSV than F. occidentalis. TCSV was acquired more efficiently than GRSV by F. occidentalis but upon acquisition, transmission frequencies were similar. Further spread of GRSV and TCSV in the United States is possible and detection of mixed infections highlights the opportunity for additional reassortment of tospovirus genomic RNAs.

Sublethal Effects of Beauveria bassiana (Ascomycota: Hypocreales) on Life Table Parameters of Frankliniella occidentalis (Thysanoptera: Thripidae).

We assessed effects of parental exposure to Beauveria bassiana on life history traits of subsequent generations of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Progeny from individuals that survived fungal exposure as second instars had significantly shorter egg stages, but longer prepupal development times than corresponding untreated controls. However, survivorship to adulthood of these progeny groups did not differ. Although fecundities of the parental types did not differ, the sex ratio of progeny from fungal-treated parents was male-biased, whereas sex ratio of progeny from untreated control parents was even. We calculated life table parameters for the progeny and found that all parameters, except for generation time, were significantly less for the progeny of fungal-treated parents than for progeny of untreated parents. The intrinsic rate of increase, finite rate of increase, net reproductive rate, mean generation time, and gross reproductive rate were 0.199 d(-1), 1.229 d(-1), 21.84, 15.48 d, and 27.273, respectively, for progeny of treated thrips, and 0.266 d(-1), 1.316 d(-1), 52.540, 14.92 d, and 70.64, respectively, for progeny of control thrips. Consequently, population projections demonstrated that offspring of parents exposed to B. bassiana would increase their population more slowly than those from untreated parents. These results demonstrate that B. bassiana has sublethal effects that reduce the reproductive success of F. occidentalis and these effects should be taken into account when evaluating its use in management programs for F. occidentalis.

Molecular Survey for the Invasive Leafminer Pest Liriomyza huidobrensis (Diptera: Agromyzidae) in California Uncovers Only the Native Pest Liriomyza langei.

Liriomyza huidobrensis (Blanchard) is a highly destructive invasive leafminer pest currently causing extensive damage to vegetable and horticultural crops around the world. Liriomyza langei Frick is a leafminer pest native to California that cannot currently be morphologically distinguished from L. huidobrensis. We used a DNA-barcoding approach, a published PCR-RFLP method, and a new multiplex PCR method to analyze 664 flies matching the morphological description of huidobrensis-langei. We found no evidence for the presence of L. huidobrensis in our extensive samples from California. In addition to the new molecular method, this work is important because it provides definitive data that the California "pea leafminer" is currently, and has probably always been, L. langei. These data will also be important in the event that the highly invasive L. huidobrensis ever becomes established.

Nucleotide and dinucleotide preference of segmented viruses are shaped more by segment: In case study of tomato spotted wilt virus.

Several studies have showed that the nucleotide and dinucleotide composition of viruses possibly follows their host species or protein coding region. Nevertheless, the influence of viral segment on viral nucleotide and dinucleotide composition is still unknown. Here, we explored through tomato spotted wilt virus (TSWV), a segmented virus that seriously threatens the production of tomatoes all over the world. Through nucleotide composition analysis, we found the same over-representation of A across all viral segments at the first and second codon position, but it exhibited distinct in segments at the third codon position. Interestingly, the protein coding regions which encoded by the same or different segments exhibit obvious distinct nucleotide preference. Then, we found that the dinucleotides UpG and CpU were overrepresented and the dinucleotides UpA, CpG and GpU were underrepresented, not only in the complete genomic sequences, but also in different segments, protein coding regions and host species. Notably, 100% of the data investigated here were predicted to the correct viral segment and protein coding region, despite the fact that only 67% of the data analyzed here were predicted to the correct viral host species. In conclusion, in case study of TSWV, nucleotide composition and dinucleotide preference of segment viruses are more strongly dependent on segment and protein coding region than on host species. This research provides a novel perspective on the molecular evolutionary mechanisms of TSWV and provides reference for future research on genetic diversity of segmented viruses.

Irrigation Method Matters: Contamination and Die-off Rates of Escherichia coli on Dry Bulb Onions After Overhead and Drip Irrigation in Washington State (2022-2023).

Two U.S. outbreaks of salmonellosis in 2020 and 2021 were epidemiologically linked to red onions. The 2020 outbreak investigation implicated the production of agricultural water as a likely contamination source. Field trials were designed to investigate the prevalence and survival of Escherichia coli (surrogate for Salmonella) on dry bulb onions after the application of contaminated irrigation water at the end of the growing period. Irrigation water was inoculated at 3 log most probable number (MPN)/100 mL (2022 and 2023) or 5 log MPN/100 mL (2023, drip only) with a cocktail of rifampin-resistant E. coli and applied with the final irrigation (0.4 acre-inch/0.4 ha-cm) to onions. Onion bulbs (40 or 80) were sampled immediately after irrigation and throughout field curing (4 weeks) and E. coli was enumerated using an MPN method. For drip irrigation, at 3 log MPN/100 mL E. coli was detected on 13% of onions at 24 h but not detected at 0 h; at 5 log MPN/100 mL for drip irrigation applied to saturated soil, E. coli was detected in 63% of onions at 0 h. Prevalence significantly (P < 0.05), decreased after 7 d of curing with cell densities of 1-1,400 MPN/onion. At the end of field curing in 2023, 1/80 of onions had detectable E. coli (2.04 MPN/onion). E. coli was detected in a significantly smaller percentage of onions (2022: 13%; 2023: 68%) after a contaminated drip irrigation event compared to overhead irrigation (98-100%; P < 0.05). After overhead irrigation, E. coli was detected in onions (1-1,000 MPN/onion) on day 0. Prevalence decreased significantly (P < 0.05) after 7 d of field curing in both years (2022: 15%; 2023: 7%). E. coli was not detected on Calibra onions (80/year) at the end of field curing in either year but was detected at <12 MPN/onion in 2.5-3.75% of onions (n = 80) for other cultivars. These data confirm limited contamination risk associated with drip irrigation water quality and begin to quantify contamination risks associated with overhead irrigation of dry bulb onions.

Escherichia coli Survival on Dry Bulb Onions Treated with Crop Protection Sprays Prepared using Contaminated Water in the Treasure Valley Growing Region.

Contaminated agricultural water has been implicated in produce-associated outbreaks, including dry bulb onions (Allium cepa). This study was designed to quantify risks associated with t contaminated water used to prepare crop protection sprays applied immediately before the onset of field curing of dry bulb onions. Laboratory experiments determining behavior of Salmonella and Escherichia coli in crop protection chemical solutions were performed to guide selection for field use. Field trials were conducted (2022, 2023) in eastern Oregon (Treasure Valley) using two onion cultivars ('Red Wing' and 'Cometa') inoculated with a rifampicin-resistant E. coli cocktail (3-4 log CFU/100 mL) suspended in fungicide solution or clay suspension, and applied with a backpack sprayer at the end of the growing season. Onions were sampled through the next 4 weeks of field curing and after 1 and 4-5 mos of postharvest storage. In 2022, onions were initially contaminated at a maximum cell density of 48 MPN/onion (Geometric mean (GM): 3.7 MPN/onion). At the end of curing, a single onion (out of 320) tested positive at 2 MPN/onion. In 2022, E. coli was not detected during postharvest storage (n = 160). In 2023, the application of contaminated sprays resulted in a maximum contamination of 275 MPN/onion (GM: 8.6 MPN/onion). At the end of the 2023 curing period, three out of 320 onions (0.9%) had detectable levels of E. coli (1-2 MPN/onion). Three 'Cometa' onions from the same plot that were treated with fungicide were positive for E. coli after 5 months of postharvest storage (2, 11, and 83 MPN/onion). These field trials indicate field curing conditions in the Treasure Valley help mitigate risks associated with contaminated water used for applying crop protection sprays. E. coli was detected on a small percentage of onions at low cell density after curing. The single onion with elevated E. coli populations after postharvest storage had internal damage characteristic of bacterial rot.

Development and reproduction of Scirtothrips dorsalis (Thysanoptera: Thripidae) on six host plant species.

Host plants can strongly influence the population performance of insects. Here, we investigated the development, survival, and oviposition of Scirtothrips dorsalis Hood on 6 host plants-Camellia sinensis ( L.) Kuntze (Ericales: Theaceae), Rosa chinensis Jacq. (Rosales: Rosaceae), Capsicum annuum L. (Solanales: Solanaceae), Eustoma grandiflorum (Hook.) G.Don (Gentianales: Gentianaceae), Glycine max (L.) Merr. (Fabales: Fabaceae), and Cucumis sativus L. (Cucurbitales: Cucurbitaceae), and constructed life tables for S. dorsalis on each plant. Significant differences in S. dorsalis development on the host species were observed. The mean developmental period from egg to adult was 11.45 ±â€…0.12 days, 11.24 ±â€…0.13 days, 12.08 ±â€…0.15 days, 12.28 ±â€…0.12 days, 12.67 ±â€…0.10 days, and 13.03 ±â€…0.11 days on C. sinensis, R. chinensis, C. annuum, E. grandiflorum, G. max, and C. sativus, respectively. Significant differences in survival of S. dorsalis were observed, namely, C. sinensis ≈ R. chinensis > E. grandiflorum ≈ C. annuum > G. max > C. sativus. The highest and lowest fecundities of S. dorsalis were recorded on R. chinensis (60.44 ±â€…1.53) and C. sativus (28.64 ±â€…1.02), respectively. Both of the net reproductive rate (R0) and intrinsic rate of increase (rm) of S. dorsalis were the highest on R. chinensis, with the values of 27.63 ±â€…0.58 and 0.142 ±â€…0.002, respectively; while the lowest on C. sativus, with the values of 8.81 ±â€…0.12 and 0.092 ±â€…0.003, respectively. Thus, R. chinensis was found to be the most suitable host, but C. sativus was the least suitable, for population development of S. dorsalis. Our results provide important information for the key control of S. dorsalis among different host plants.

Establishment of Beauveria bassiana as a fungal endophyte in potato plants and its virulence against potato tuber moth, Phthorimaea operculella (Lepidoptera: Gelechiidae).

The potato tuber moth, Phthorimaea operculella, is the most damaging potato pest in the world and is difficult to control as the larvae are internal feeders in the foliage and tubers. Entomopathogenic fungi that colonize plants as endophytes have lethal and sublethal pathological effects on insect pests. We show that Beauveria bassiana colonizes the aerial parts of potato plants endophytically after inoculation through soil drenching. Endophytic B. bassiana persisted in potato foliage for more than 50 days postinoculation. Bioassays indicated that foliage of B. bassiana-inoculated potato plants were pathogenic against larvae of P. operculella. Sublethal experiments indicated that B. bassiana negatively affected the growth, development, and reproduction of P. operculella. Development experiments showed that the weight of P. operculella pupae reared on B. bassiana-colonized potato plants (4.25 mg) was significantly less than that of those reared on uninoculated control plants (8.89 mg). Compared with newly eclosed larvae fed on control plants, those fed on B. bassiana-inoculated plants had significantly lower survivorship, with only 17.8% developing to the adult stage. Oviposition of P. operculella females reared on B. bassiana endophytically colonized plants was significantly lower (35 eggs/female) than of those reared on uninoculated plants (115 eggs/female). This study demonstrates that endophytic B. bassiana can be a potential biological control agent for the control and management of P. operculella. Comparing pupal weights of P. operculella reared on potato plants inoculated with the B. bassiana strain GZGY-1-3 and on untreated control plants, pupae from the control plants were significantly heavier than those from treated plants.

Population performance and detoxifying and protective enzyme activities of four thrips species feeding on flowers of Magnolia grandiflora (Ranunculales: Magnolia).

BACKGROUND: Different thrips species can co-occur on the same flowers with different dominance degrees. To accurately evaluate the population performance on different thrips species on Magnolia grandiflora flowers, we investigated the diversity of thrips species and their population dynamics both in the field and laboratory. In addition, the activities of detoxifying and protective enzymes in thrips were also measured. RESULTS: Field investigations revealed that four thrips species (Thrips hawaiiensis, Thrips flavidulus, Frankliniella occidentalis, and Thrips coloratus) coexisted on M. grandiflora flowers. They were ranked, from highest population density to lowest, as follows: T. hawaiiensis > T. flavidulus > F. occidentalis > T. coloratus. In laboratory investigations, the species were ranked, from fastest developmental rates to slowest, as follows: F. occidentalis > T. hawaiiensis > T. flavidulus > T. coloratus; and from largest population size to smallest, as follows: T. hawaiiensis > F. occidentalis > T. flavidulus > T. coloratus. Biochemistry assays showed that the four species differed in their activities of detoxifying enzymes (carboxylesterase, glutathione-S-transferase, and cytochrome P450) and protective enzymes (superoxide dismutase, peroxidase) in both laboratory and field strains. CONCLUSION: Differences in population performance among these four thrips on M. grandiflora may be related to their activity levels of physiological enzymes. The variations in thrips population performance between the field and the laboratory could be due to differences in environmental conditions. T. hawaiiensis showed a strong host preference for M. grandiflora, and thus it has the potential to be a dangerous pest in horticultural plants. © 2023 Society of Chemical Industry.

Semipersistent Whitefly Transmission of Squash vein yellowing virus, Causal Agent of Viral Watermelon Vine Decline.

Squash vein yellowing virus (SqVYV), a recently described Ipomovirus sp. in the family Potyviridae, is the cause of viral watermelon vine decline, a devastating disease in Florida. SqVYV is known to be transmitted by the whitefly, Bemisia tabaci (Gennadius) B strain, but details of the transmission process have not previously been investigated. We completed a series of experiments to determine efficiency of transmission, effects of different acquisition and inoculation access periods, the length of time that whiteflies retained transmissible virus, and the minimum time needed to complete a cycle of acquisition and inoculation. Efficiency was low, with at least 30 whiteflies per plant needed for consistent transmission. Acquisition leading to later transmission peaked at 4 h, and inoculation access periods longer than 4 to 8 h led to no increase in infection rates. Whiteflies retained virus only a short time, with no transmission by 24 h after removal from infected plants. A minimum of 3 h was needed to complete a cycle of transmission under laboratory conditions. These results demonstrate semipersistent transmission of SqVYV and will help refine models of the epidemiology of this virus and the disease it causes.

Rosa chinensis Cultivars Affect Fitness-Related Characteristics and Digestive Physiology of the Western Flower Thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae).

Host plant species will influence the population and physiological performance of insects. Frankliniella occidentalis is a well-known invasive pest commonly found on flowering plants. Herein, the population development of F. occidentalis was investigated on the flowers of different Rosa chinensis cultivars (Ruby, Love, Parade, Pink Peace, and Mohana), and the digestive enzyme activities in thrips were measured after feeding on these flowers. The developmental times of F. occidentalis from egg to adult were 10.07, 10.37, 11.64, 10.66, and 10.90 d on Ruby, Love, Parade, Pink Peace, and Mohana, respectively. Significant differences in fecundity were also observed, with the greatest fecundity levels of F. occidentalis on Ruby (82.96) and the lowest on Mohana (63.40). F. occidentalis showed the greatest R0 on Ruby (43.57), followed by Love (36.46), Parade (33.00), Pink Peace (27.97), and Mohana (23.21). The rm showed a similar trend, with values of 0.156, 0.145, 0.141, 0.134, and 0.130, respectively. There were significant differences in digestive enzyme activities in F. occidentalis on different flowers, and different digestive enzymes showed different performance among these plants. The highest amylase and lipase activities in F. occidentalis were on Ruby, on which F. occidentalis had the fastest development rate and the highest R0, whereas the highest trypsin activity was on Pink Peace. All three digestive enzymes in thrips showed the lowest activities on Mohana. The varied population development of F. occidentalis associated with R. chinensis cultivars may be related to their digestive enzyme performance, which plays important roles in nutrient metabolism and insect growth.

Species displacements are common to two invasive species of leafminer fly in China, Japan, and the United States.

Under field conditions, species displacements have occurred in different directions between the same invasive species of leafminers (Diptera: Agromyzidae). Liriomyza sativae (Blanchard) was displaced by L. trifolii (Burgess) in the western United States, with evidence suggesting that lower insecticide susceptibility of L. trifolii is a factor. However, in Japan, the opposite has occurred, as L. trifolii was recently displaced by L. sativae. This displacement is probably because of the higher fecundity of L. sativae and differential effects of parasitoids on the two leafminer species. Here, we carried out long-term surveys of these same two invasive leafminer species during January through March in 1999, 2007, and 2011, as well as June through July in 2011, in eight locations (Sanya, Dongfang, Haikou, Leidong, Lingshui, Wuzhisan, Qionghai, and Danzhou) across Hainan Island of southern China. Our results indicate that, between 2007 and 2011, L. trifolii rapidly replaced L. sativae as the predominant leafminer of vegetables on Hainan Island, similar to the situation in the western United States. Further surveys of growers revealed that avermectins and cyromazine are the two most frequently used insecticides against leafminers on Hainan Island. Dose-mortality tests showed that L. trifolii populations from Hainan Island are less susceptible to avermectins and cyromazine compared with L. sativae populations. This lower insecticide susceptibility of L. trifolii may be associated with the displacement of L. sativae by L. trifolii, although additional ecological or environmental factors cannot be ruled out.

Variation within and between Frankliniella thrips species in host plant utilization.

Anthophilous flower thrips in the genus Frankliniella (Thysanoptera: Thripidae) exploit ephemeral plant resources and therefore must be capable of successfully locating appropriate hosts on a repeated basis, yet little is known of interspecific and intraspecific variation in responses to host plant type and nutritional quality. Field trials were conducted over two seasons to determine if the abundance of males and females of three common Frankliniella species, F. occidentalis (Pergande), F. tritici (Fitch) and F. bispinosa (Morgan), their larvae, and a key predator, Orius insidiosus (Say) (Hemiptera: Anthocoridae) were affected by host plant type and plant nutritional quality. Two host plants, pepper, Capsicum annuum L. (Solanales: Solanaceae) and tomato, Solanum lycopersicum L. that vary in suitability for these species were examined, and their nutritional quality was manipulated by applying three levels of nitrogen fertilization (101 kg/ha, 202 kg/ha, 404 kg/ha). F. occidentalis females were more abundant in pepper than in tomato, but males did not show a differential response. Both sexes of F. tritici and F. bispinosa were more abundant in tomato than in pepper. Larval thrips were more abundant in pepper than in tomato. Likewise, O. insidiosus females and nymphs were more abundant in pepper than in tomato. Only F. occidentalis females showed a distinct response to nitrogen fertilization, with abundance increasing with fertilization. These results show that host plant utilization patterns vary among Frankliniella spp. and should not be generalized from results of the intensively studied F. occidentalis. Given the different pest status of these species and their differential abundance in pepper and tomato, it is critical that scouting programs include species identifications for proper management.

Lethal and Sublethal Effects of Two Commercial Insecticides on Egg Parasitoids (Hymenoptera: Scelionidae) of Green Stink Bugs (Hem: Pentatomidae).

Pistacia vera L. is one of the most important horticultural crops in Iran. The stink bugs Acrosternum arabicum and Brachynema germari are two of the key pests that cause significant direct and indirect damage on Pistacia vera. Egg parasitoids have been considered as potential biological control agents of pistachio green stink bugs. Among them, Trissolcus semistriatus and Psix saccharicola are the most abundant and efficient parasitoid for A. arabicum in pistachio orchards. In this study, we assessed lethal and sublethal effects of two commonly used insecticide products (fenitrothion and a binary mixture of lambda-cyhalothrin + thiamethoxam) on these two parasitoid wasps under laboratory conditions. The median lethal concentration (LC50) values for fenitrothion and thiamethoxam + lambda-cyhalothrin in P. saccharicola and T. semistriatus were estimated as 1.03, 0.48 and 0.87, 0.98 mg a.i./liter, respectively. In terms of sublethal effects, insecticide treatments altered the type of functional response from type III to type II in T. semistriatus. However, P. saccharicola exhibited a type II functional to density of A. arabicum for all treatments, although attack rates were lower for insecticide-exposed wasps while handling times increased. Our results show that sublethal effects of insecticides further reduce the efficacy of biological control agents. Effective integrated pest management programs should avoid antagonistic interactions between chemical and biological control methods. The results of this study provide useful information to develop comprehensive integrated pest management programs for stink bugs in pistachio orchards.

Assessment of Toxicity Risk of Selected Insecticides Used in Pistachio Ecosystem on Two Egg Parasitoids (Hymenoptera: Scelionidae) of Stink Bugs (Hemiptera: Pentatomidae).

Psix saccharicola (Mani) and Trissolcus semistriatus (Nees) are the most abundant eggs parasitoids of the stink bug, Acrosternum arabicum Wagner, in pistachio orchards and have the potential to contribute to their suppression. However, treatment of orchards with broad-spectrum insecticides may greatly reduce populations of these beneficial natural enemies. Therefore, we conducted risk assessments and evaluated sublethal impacts of two insecticides routinely used in pistachio orchards: the organophosphate fenitrothion and a formulated mixture of the neonicotinoid thiamethoxam and the pyrethroid lambda-cyhalothrin on parasitism success, emergence and sex ratio of P. saccharicola and T. semistriatus. Based on the values of their risk quotients (RQ), which are derived from toxicity data, the two insecticide products would be classified as slightly-to-moderately toxic although an alternative metric, the safety factor (SF), showed them to be highly risky. Assessments of sublethal effects on adult wasps showed that insecticide exposure significantly reduced their ability to successfully parasitize stink bug eggs, and exposure of adult females reduced the emergence, survival, and proportion of females of their progeny, which could disrupt biological control for an extended period of time. Analysis of the decreased emergence and parasitism for P. saccharicola and T. semistriatus in accordance with the standards of the International Organization for Biological Control (IOBC) indicate that fenitrothion is slightly harmful to both parasitoid species whereas the mixture of thiamethoxam + lambda-cyhalothrin is moderately harmful. These findings will be useful for integrating insecticides and egg parasitoids into a comprehensive integrated pest management program for managing stink bugs populations in pistachio orchards.

A global invasion by the thrip, Frankliniella occidentalis: Current virus vector status and its management.

Western flower thrip, Frankliniella occidentalis (Pergande), is among the most economically important agricultural pests globally, attacking a wide range of vegetable and horticultural crops. In addition to causing extensive crop damage, the species is notorious for vectoring destructive plant viruses, mainly belonging to the genera Orthotospovirus, Ilarvirus, Alphacarmovirus and Machlomovirus. Once infected by orthotospoviruses, thrips can remain virulent throughout their lifespan and continue transmitting viruses to host plants when and wherever they feed. These irruptive viral outbreaks in crops will permanently disrupt functional integrated pest management systems, and typically require a remedial treatment involving insecticides, contributing to further development of insecticide resistance. To mitigate against this continuing cycle, the most effective management is early and comprehensive surveillance of the pest species and recognition of plant viruses in the field. This review provides information on the pest status of F. occidentalis, discusses the current global status of the viruses vectored by this thrip species, examines the mechanisms involved in transmitting virus-induced diseases by thrips, and reviews different management strategies, highlighting the potential management tactics developed for various cropping systems. The early surveillance and the utilization of potential methods for control of both F. occidentalis and viruses are proposed.

Host plants and Wolbachia shape the population genetics of sympatric herbivore populations.

Changing climate and land-use practices have the potential to bring previously isolated populations of pest insects into new sympatry. This heightens the need to better understand how differing patterns of host-plant association, and unique endosymbionts, serve to promote genetic isolation or integration. We addressed these factors in populations of potato psyllid, Bactericera cockerelli (Sulc), a generalist herbivore that vectors a bacterial pathogen (Candidatus Liberibacter solanacearum, causal pathogen of zebra chip disease) of potato (Solanum tuberosum L.). Genome-wide SNP data revealed two major genetic clusters-psyllids collected from potato crops were genetically similar to psyllids found on a common weed, Lycium spp., but dissimilar from those found on another common non-crop host, Solanum dulcamara L. Most psyllids found on Lycium spp. and potato represented a single mitochondrial cytochrome oxidase I (COI) haplotype that has been suggested to not be native to the region, and whose arrival may have been concurrent with zebra chip disease first emerging. The putatively introduced COI haplotype usually co-occurred with endosymbiotic Wolbachia, while the putatively resident COI haplotype generally did not. Genetic intermediates between the two genetic populations of insects were rare, consistent with recent sympatry or reproductive isolation, although admixture patterns of apparent hybrids were consistent with introgression of genes from introduced into resident populations. Our results suggest that both host-plant associations and endosymbionts are shaping the population genetic structure of sympatric psyllid populations associated with different non-crop hosts. It is of future interest to explicitly examine vectorial capacity of the two populations and their potential hybrids, as population structure and hybridization might alter regional vector capacity and disease outbreaks.