Bactericera Cockerelli Research Articles

Effects of High-Level Acylsugar-Producing Tomato Lines on the Development of Tomato Psyllids (Hemiptera: Triozidae).

Acylsugars have been shown to provide activity against numerous insect pests of tomatoes. Comparison of acylsugar levels in four tomato plant lines, FA7/AS, FA2/AS, CU071026, and 'Yellow Pear', found that the acylsugar contents in the elevated acylsugar lines were significantly higher than the commercial Yellow Pear (control) tomato plant line. Adult choice tests indicated that the tomato psyllid, Bactericera cockerelli, preferred to settle on the Yellow Pear and FA2/AS lines over the line with the highest content of acylsugars, FA7/AS, and the parental line, CU071026. The no-choice test demonstrated that adults laid fewer eggs on the high acylsugar tomato lines than on the control tomato line, Yellow Pear. For all high acylsugar lines, the relative growth index of the psyllid was significantly lower compared with the commercial line, indicating a reduced potential for population growth. Although some tomato psyllids completed their life cycle on the high acylsugar tomato plant lines, the percent survival of psyllids to the adult stage when developing on the high acylsugar lines was significantly less (range = 43.7-57.1%) than on the commercial tomato line (83.8%). All mortality occurred during the early stages of development (egg stage to third instar), which has implications for acquisition and transmission of Candidatus Liberibacter solanacearum, the causal agent of tomato vein greening disease. Therefore, with reduced attractiveness for tomato psyllids and significantly reduced survival, the high-acylsugar tomato plant lines have the potential to be part of an integrated pest management program for this pest.

Associations of the Potato Psyllid and "Candidatus Liberibacter solanacearum" in Idaho with the Noncrop Host Plants Bittersweet Nightshade and Field Bindweed.

Zebra chip disease (ZC) in potato (Solanum tuberosum L. [Polemoniales: Solanaceae]) can produce unmarketable tubers with striped necrotic patterns. ZC is associated with the bacterium "Candidatus Liberibacter solanacearum" (Lso), which is transmitted by the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). Potato psyllids are associated with numerous noncrop host plants, especially from the Solanaceae and Convolvulaceae; however, the contribution and importance of these hosts to ZC epidemiology in potato is poorly understood. To clarify seasonal phenologies on two such hosts, we sampled potato psyllids from bittersweet nightshade, Solanum dulcamara L. (Polemoniales: Solanaceae), and field bindweed, Convolvulus arvensis L. (Polemoniales: Convolvulaceae), over 2013-2017 and 2014-2016, respectively. Adult psyllids were sampled using yellow sticky traps, vacuum samples, and beat sheets. Each psyllid was tested for the presence of Lso by polymerase chain reaction. Psyllids often were abundant on bittersweet nightshade during May to November, with low numbers observed over each winter. Vacuum samples often captured more psyllids than other methods. Lso incidence was low except during 2016 when vacuum samples showed 23% incidence. Potato psyllids regularly overwinter on bittersweet nightshade in Idaho; however, differences in psyllid populations and Lso incidence from those found on potato suggest that this host plant may only partly contribute to infestations in potato. Observations of psyllids on field bindweed suggest only transient visits to this plant around potato harvest, with no evidence of overwintering and no Lso detected. Further work is needed to clarify how potato psyllid use of other noncrop hosts is related to their abundance in Idaho potato fields.

Quenching autofluorescence in the alimentary canal tissues of Bactericera cockerelli (Hemiptera: Triozidae) for immunofluorescence labeling.

Immunofluorescence has been widely used to localize microbes or specific molecules in insect tissues or cells. However, significant autofluorescence is frequently observed in tissues which can interfere with the fluorescent identification of target antigens, leading to inaccurate or even false positive fluorescent labeling. The alimentary canal of the potato psyllid, Bactericera cockerelli Šulc, exhibits intense autofluorescence, hindering the application of immunolocalization for the detection and localization of the economically important pathogen transmitted by this insect, "Candidatus Liberibacter solanacearum" (Lso). In the present study, we tested the use of irradiation, hydrogen peroxide (H2 O2 ) and Sudan black B (SBB) treatments to reduce the autofluorescence in the B. cockerelli alimentary canal tissues. Furthermore, we assessed the compatibility of the above-mentioned treatments with Lso immunolocalization and actin staining using phalloidin. Our results showed that the autofluorescence in the alimentary canal was reduced by irradiation, H2 O2 , or SBB treatments. The compatibility assays indicated that irradiation and H2 O2 treatment both greatly reduced the fluorescent signal associated with Lso and actin. However, the SBB incubation preserved those target signals, while efficiently eliminating autofluorescence in the psyllid alimentary canal. Therefore, herein we propose a robust method for reducing the autofluorescence in the B. cockerelli alimentary canal with SBB treatment, which may improve the use of immunofluorescence labeling in this organism. This method may also have a wide range of uses by reducing the autofluorescence in other arthropod species.

Captures of Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) Adults Affected by the Presence of Volunteer Potatoes (Solanum tuberosum L.)

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a key potato (Solanum tuberosum L.) pest that has the ability to vector the plant pathogenic bacterium Candidatus Liberibacter solanacearum (Lso), the putative causal agent of zebra chip disease of potato. The insect primarily feeds and completes its life cycle on Solanaceous crops and weeds; however, in the Columbia Basin of Oregon and Washington, B. cockerelli has been found in association with crops such as maize (Zea mays L.) and wheat (Triticum spp), both belonging to the Poaceae family. We hypothesize that this is due to the presence of volunteer potato; in this region, the potato crop is in a 3-yr rotation with either maize or wheat. Consequently, we evaluated potato, maize, wheat, maize + volunteer potato, wheat + volunteer potato on captures of B. cockerelli adults in a 2-year field experiment using an inverted leaf blower and yellow sticky cards. Data collected in this study confirms that B. cockerelli has an affinity for potato, although, B. cockerelli could be found in maize and wheat mainly when volunteer potatoes were present. In addition, B. cockerelli counts varied depending if using inverted leaf blower or yellow sticky cards. Knowing that B. cockerelli is found in fields where volunteer potatoes are present, it should be taken into consideration for large-scale potato psyllid management.

The Weed Link in Zebra Chip Epidemiology: Suitability of Non-crop Solanaceae and Convolvulaceae to Potato Psyllid and “Candidatus Liberibacter Solanacearum”

Potato psyllid (Bactericera cockerelli) is a vector of “Candidatus Liberibacter solanacearum”, the pathogen associated with potato zebra chip disease. While the psyllid apparently colonizes potato from non-crop Solanaceae or Convolvulaceae, the identity of these weed sources is uncertain. We examined susceptibility of ten non-crop species (one Convolvulaceae and nine Solanaceae) to potato psyllid and Liberibacter, with an emphasis on psyllid populations (northwestern and western haplotypes) and plant species that are present in the Pacific Northwest. Psyllids of the western haplotype survived and developed on all plant species, while psyllids of the northwestern haplotype survived on all species except Solanum physalipholium. All species except Lycium barbarum and Convolvulus arvensis were susceptible to Liberibacter. Results of our study provide the most extensive examination of plant suitability to potato psyllid and Liberibacter and will lead to improved capabilities of predicting which potato fields are at risk to arrival of infective psyllids.

Mesh crop covers improve potato yield and inhibit tomato potato psyllid and blight: The roles of mesh pore size and ultraviolet radiation

Crop losses caused by the tomato potato psyllid (TPP; Bactericera cockerelli) and blight (Alternaria solani; Phytophthora infestans) continue to be major concerns for potato (Solanum tuberosum) growers worldwide, and commercial crops often require frequent use of agrichemicals to maintain tuber yield and quality. Nevertheless, a paradigm shift is unfolding in crop protection where new tools, such as physical barriers and light‐modifying filters, are being used to develop chemical‐free approaches for pest and disease control. In this study, we examined the use of crop covers as a non‐chemical method for controlling TPP and reducing blight in field potatoes. Our study demonstrated that those plants grown under mesh covers exhibited reduced levels of blight, TPP and associated psyllid yellows. Additionally, potatoes grown under mesh covers exhibited increased yield (91.4 ± 6.9 SD t/ha) compared with both uncovered control plants (75.0 ± 11.8 t/ha) and plants grown using agrichemical pest control (84.5 ± 10.8 t/ha). The plants grown under mesh produced fewer smaller tubers, with increased average and maximum tuber size, so that marketable yield (tubers ≥60 g) was also increased (83.5 ± 7.5 t/ha), compared with that achieved for uncovered control plants (60.0 ± 8.3 t/ha) and plants grown using agrichemicals (69.6 ± 9.2 t/ha). A second field experiment suggested that the incidence of TPP foliage damage and the development of blight were lowest when the passage of ambient ultraviolet (UV) radiation through the crop cover was reduced. This hypothesis was supported by a third trial where potatoes grown outdoors in pots exhibited reduced TPP foliage damage and fewer resident TPP when grown under UV‐blocking plastic screens. The results of these experiments suggest that the use of mesh covers offers new opportunities to sustainably protect potato crops both by acting as a physical barrier and by modifying the wavelength of light incident on the crop.

Tri-partite complexity: odour from a psyllid's mutualist ant increased predation by a predatory mite on the psyllid.

Predator-prey interactions consist of direct consumption of prey by predators and indirect non-consumptive effects on prey. Predator cues can induce predation stress in prey that negatively influences the survival, development, reproduction, and feeding behaviour of the prey. This study evaluated the effects of hemipteran-tending ant (Technomyrmex albipes) odour on the development, survival, reproduction, and predation rates of the predatory mite Amblydromalus limonicus when feeding on an invasive pest of solanaceous crops, Bactericera cockerelli. The age-stage, two-sex life table theory was used to compare the demographic characteristics and predation rates of A. limonicus in the presence and absence of ant odour. We show that exposure to ant odour did not alter the development, survival rate, and fecundity of A. limonicus, but induced a sexually dimorphic response in its longevity; consumption rates also showed that dimorphic response-predation rates increased in female A. limonicus, but not in males. To our knowledge, this is the first report indicating increased consumption rates by natural enemies exposed to odour from a mutualist of pest (ant). This finding may provide new insights into understanding tri-partite interaction involving a pest, its predator, and a mutulist of the pest. © 2018 Society of Chemical Industry.

Impact of the zoophytophagous predator Engytatus varians (Hemiptera: Miridae) on Bactericera cockerelli (Hemiptera: Triozidae) control

Engytatus varians (Distant) (Hemiptera: Miridae), a polyphagous predator that is widely distributed, has recently been documented for the first time in Mexico, feeding on nymphs of the very detrimental pest of several solanaceous crops Bactericera cockerelli (Sulc.) (Hemiptera: Triozidae). The predation of this mirid was evaluated in a greenhouse in 7 m2 cages containing tomato (Solanum lycopersicum Miller) plants for 12 weeks. Two release rates, 1 and 4 adults of E. varians (Ev)/plant, were studied and compared to the control (0 Ev/plant). An 80 to 90% reduction in both nymphs and adults of B. cockerelli occurred when 1 or 4 adults of Ev/plant were released irrespective of the pest life stage. The cumulative number of E. varians nymphs and adults per day was significantly higher in the treatments than in the control (30 and 3, respectively). On the other hand, due to its zoophytophagous habits, E. varians can feed on tomato plants and cause necrotic rings on the leaves; therefore, this type of injury was also recorded. The number of necrotic rings/leaf was inversely proportional to prey presence, but no significant differences were observed between the treatments. Our results point to E. varians being able to establish and control B. cockerelli populations under greenhouse conditions, without causing significant damage to tomato plants. The potential use of this predator as a biological control agent of B. cockerelli is discussed.

Building a better Psylloidea (Hemiptera) trap? A field-look at a prototype trap constructed using three-dimensional printer technology

AbstractAn insect trap constructed using three-dimensional (3D) printing technology was tested in potato (Solanum tuberosum Linnaeus; Solanaceae) fields to determine whether it could substitute for the standard yellow sticky card used to monitor Bactericera cockerelli (Šulc) (Hemiptera: Psylloidea: Triozidae). Sticky cards have shortcomings that prompted search for a replacement: cards are messy, require weekly replacement, are expensive to purchase, and accumulate large numbers of nontarget insects. Bactericera cockerelli on sticky cards also deteriorate enough that specimens cannot be tested reliably for the presence of vectored plant pathogens. A prototype trap constructed using 3D printing technology for monitoring Diaphorina citri Kuwayama (Hemiptera: Psylloidea: Liviidae) was tested for monitoring B. cockerelli. The trap was designed to attract B. cockerelli visually to the trap and then funnel specimens into preservative-filled vials at the trap bottom. Prototype traps were paired against yellow sticky cards at multiple fields to compare the captures of B. cockerelli between cards and traps. The prototype trap was competitive with sticky cards early in the growing season when B. cockerelli numbers were low. We estimated that two or three prototype traps would collect as many B. cockerelli as one sticky card under these conditions. Efficacy of the prototype declined as B. cockerelli numbers increased seasonally. The prototype trap accumulated nontarget taxa that are common on sticky cards (especially Thysanoptera and Diptera), and was also found to capture taxa of possible interest in integrated pest management research, including predatory insects, parasitic Hymenoptera, and winged Aphididae (Hemiptera), suggesting that the traps could be useful outside of the purpose targeted here. We believe that 3D printing technology has substantial promise for developing monitoring tools that exploit behavioural traits of the targeted insect. Ongoing work includes the use of this technology to modify the prototype, with a focus on making it more effective at capturing psyllids and less susceptible to capture of nontarget species.

Bactericera cockerelliSulc Oviposition Preference and Development on Three Tomato Varieties

Interactions between plants and insects have been widely studied. Plants develop numerous strategies to avoid establishment and/or feeding by insects. The aim of this research was to evaluate oviposition preference, nymphal development, and survival of Bactericera cockerelli Sulc on ‘Floradade’, ‘Micro-Tom’, and ‘Wild’ varieties of tomato (Solanum lycopersicum L.). Free-choice assays showed B. cockerelli oviposited twice more on ‘Floradade’ than ‘Micro-Tom’ with 1,000 and 479 eggs, respectively. Nymphal stages as well as adults of the pest developed much better on Floradade’ variety to emerge 3 days earlier than in ‘Micro-Tom’ and ‘Wild’ varieties. Adult emergence percentage was 52, 36, and 18% for ‘Floradade’, ‘Micro-Tom’, and ‘Wild’. Results in a greenhouse showed the degree of domestication of tomato varieties affected oviposition preference and survival of the insect.

Differences in Zebra Chip Severity between ‘Candidatus Liberibacter Solanacearum’ Haplotypes in Texas

‘Candidatus Liberibacter solanacearum’ (Lso) is a phloem-restricted plant pathogen that is vectored between host plants by the potato psyllid, Bactericera cockerelli. Lso infects solanaceous crops whithin North America and New Zealand and is responsible for causing zebra chip (ZC) in potato. Two Lso haplotypes (A and B) have been identified infecting potato (Solanum tuberosum). Previously, we identified differences in disease severity associated with each Lso haplotype in tomato (Solanum lycopersicum). In this study, the severity of ZC symptoms was evaluated for Lso haplotypes A and B independently or in co-infection in Atlantic variety potato tubers grown in Texas fields. Discolorations in tuber vascular tissues were measured in potato chips using a published 6-point visual scale and compared among plants submitted to five treatments: no psyllids (control), psyllids not infected with Lso (LsoFree), psyllids infected with Lso haplotype A (LsoA), psyllids infected with Lso haplotype B (LsoB), and psyllids infected with both haplotypes (LsoAB). These experiments were performed a total of three times, twice in the Lower Rio Grande Valley (Weslaco, TX) during the winters 2014 and 2018 and once during the spring 2015 in the Texas Panhandle (Springlake, TX). This study showed that significantly lower ZC symptom severity was associated with plants treated with LsoA-infected psyllids compared to plants treated with either LsoB- or LsoAB-infected psyllids; however, this difference was marginal. This difference might be relevant for the disease biology; it has no impact on the tuber suitability for the market. This study also showed that average tuber mass was significantly lower in plants infected with Lso compared with uninfected plants and that this reduction in mass was similar among Lso haplotype treatments. Overall, this study demonstrates that Lso haplotypes A and B cause slightly different ZC symptom severity and that ZC symptom severity in plants treated with psyllids co-infected with both haplotypes is similar to the symptoms associated with Lso haplotype B.

Incidence of resistance to neonicotinoid insecticides in Bactericera cockerelli across Southwest U.S.

The potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) is a vector of the pathogen (Candidatus Liberibacter solanacearum) that causes zebra chip in potato. The insect and the disease are managed solely through insecticide applications. One of the primary insecticide chemistries used to suppress the psyllid includes various formulations of neonicotinoid (group 4A) insecticides and their frequent use across Southwest U.S., where potato psyllids and zebra chip are prevalent, has raised concerns of widespread insecticide resistance. Potato psyllids collected from California and the Lower Rio Grande Valley (LRGV) of Texas have been previously shown to be resistant to these insecticides, but the psyllid susceptibility to neonicotinoid insecticides across Southwest U.S. has not been established. To test the extent of neonicotinoid resistance, we collected potato psyllids from Colorado, New Mexico, and from two major potato-producing regions of Texas. We exposed immature progeny of these field-collected potato psyllids to several doses of two neonicotinoids, imidacloprid and thiamethoxam. Survival of the psyllids was compared to a control colony of B. cockerelli, which was collected prior to widespread use of neonicotinoid insecticides and was known to be susceptible to them. Our results indicated that the psyllids were resistant to both insecticides. The degree of resistance depended on the geographic location of each psyllid population and on the insecticide, with imidacloprid resistance most prominent in psyllids from LRGV. These outcomes emphasize the need to diversify and integrate tactics used to suppress the psyllids and lessen dependence on insecticides to manage the insect and the disease.

Spatial Distribution of Eggs of Bactericera cockerelli (Hemiptera: Trizoidae) in Tomatillo Using Geostatistical Techniques

Abstract The tomatillo, Physalis ixocarpa Brotero, is an important vegetable in central Mexico but production is limited by the psyllid pest Bactericera cockerelli (Sulc) (Hemiptera: Trizoidae). This study was undertaken in 2016 to generate maps of the spatial distribution of B. cockerelli in the municipalities of Luvianos, Jocotitlan, and Ixtlahuaca in the State of Mexico to support implementation of integrated pest management strategies to improve tomatillo production. Geostatistical analysis was performed to estimate the experimental semivariogram and fitted to a theoretical model with the program Variowin 2.2. All generated models were validated. It was determined that for the three municipalities evaluated, 29 semivariograms were the adjusted spherical model, four were the Gaussian model, and three were the exponential model. Aggregation maps of the pest were evaluated in all plots, and areas were identified with the highest incidence of the pest, thus allowing initiation of control measures at sele...

Host plant influences establishment and performance of Amblydromalus limonicus, a predator for Bactericera cockerelli.

Management of tomato potato psyllid (TPP; Bactericera cockerelli (Šulc)) predominantly relies on insecticides. However, biological control agents (BCAs) could provide viable alternatives to suppress TPP populations. In this laboratory experiment, we assessed the predatory mite Amblydromalus limonicus (Garman & McGregor) as a BCA of TPP on whole plants of two tomato and two pepper cultivars over a 5-week period. Plant species and cultivar had a significant effect on the ability of A. limonicus to suppress populations of TPP. Numbers of TPP were suppressed by A. limonicus on four pepper treatments, but on only one tomato treatment. Amblydromalus limonicus could survive and reproduce on pepper and tomato, but more were found on pepper at the end of the 5-week period. Amblydromalus limonicus has the potential to suppress TPP populations on pepper but not tomato cultivars, based on the present study. Possible reasons for these results include the difference in leaf morphology between species, and higher predator:prey ratios on pepper than tomato because of the longer TPP generation time on pepper. © 2018 Society of Chemical Industry.

Survival and development of potato psyllid (Hemiptera: Triozidae) on Convolvulaceae: Effects of a plant-fungus symbiosis (Periglandula).

Plant species in the family Solanaceae are the usual hosts of potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Psylloidea: Triozidae). However, the psyllid has also been shown to develop on some species of Convolvulaceae (bindweeds and morning glories). Developmental success on Convolvulaceae is surprising given the rarity of psyllid species worldwide associated with this plant family. We assayed 14 species of Convolvulaceae across four genera (Convolvulus, Calystegia, Ipomoea, Turbina) to identify species that allow development of potato psyllid. Two populations of psyllids were assayed (Texas, Washington). The Texas population overlaps extensively with native Convolvulaceae, whereas Washington State is noticeably lacking in Convolvulaceae. Results of assays were overlain on a phylogenetic analysis of plant species to examine whether Convolvulaceae distantly related to the typical host (potato) were less likely to allow development than species of Convolvulaceae more closely related. Survival was independent of psyllid population and location of the plant species on our phylogenetic tree. We then examined whether presence of a fungal symbiont of Convolvulaceae (Periglandula spp.) affected psyllid survival. These fungi associate with Convolvulaceae and produce a class of mycotoxins (ergot alkaloids) that may confer protection against plant-feeding arthropods. Periglandula was found in 11 of our 14 species, including in two genera (Convolvulus, Calystegia) not previously known to host the symbiont. Of these 11 species, leaf tissues from five contained large quantities of two classes of ergot alkaloids (clavines, amides of lysergic acid) when evaluated by LC-MS/MS. All five species also harbored Periglandula. No ergot alkaloids were detected in species free of the fungal symbiont. Potato psyllid rapidly died on the five species that harbored Periglandula and contained ergot alkaloids, but survived to adulthood on seven of the nine species in which ergot alkaloids were not detected. These results support the hypothesis that a plant-fungus symbiotic relationship affects the suitability of certain Convolvulaceae to potato psyllid.

Asian citrus psyllid stylet morphology and applicability to the model for inter-instar stylet replacement in the potato psyllid

In Hemiptera, presumptive stylets for each consecutive postembryonic instar are manufactured prior to ecdysis to replace the ecdysial stylets discarded with the exuviae. With the discovery that the bacterium “Candidatus” Liberibacter solanacearum accesses the tissues involved in the stylet replacement process of the potato psyllid, a hypothesis was formed that the bacterium could adhere to the stylets of freshly emerged instars and hence gain access to the host plant when feeding is resumed. Although unproven, it was imperative that a model for stylet replacement be built. Stylet morphology and the stylet replacement process of the Asian citrus psyllid (ACP), vector of “C.” L. asiaticus, causal pathogen of citrus greening disease, are comparable to the potato psyllid model system. Morphology consists of a basal terminus with its tab-shaped auricle, a base, shaft, and an apical terminus. Each of the four auricles act as a platform for the replacement apparatus, which is compacted into a tight aggregate of cells, the ‘end-cap’. As modeled, on apolysis of larval instar hypodermis, the aggregate ‘deconstructs’ and expands into a snail shell-shaped tube, the ‘atrium’, that houses the presumptive stylet as it is synthesized. Completed stylets then despool from the atrium and are fitted into their functional positions as the next instar emerges from its exuviae.

Role of ‘Candidatus Liberibacter solanacearum’ and Bactericera cockerelli Haplotypes in Zebra Chip Incidence and Symptom Severity

Two haplotypes of the pathogen, ‘Candidatus Liberibacter solanacearum,’ (Lso) and four haplotypes of the insect vector, Bactericera cockerelli, are associated with zebra chip disease of potato. Whether disease severity or incidence is influenced by pathogen or insect haplotype is poorly understood. The role of Lso ‘A’ and ‘B,’ transmitted by three haplotypes of B. cockerelli, on disease severity and incidence in eight potato cultivars was analyzed. Both haplotypes of Lso induced tuber symptoms. In general, Lso B caused higher incidence of symptoms, and greater reduction in tubers compared with Lso A. Lso B was associated with more severe tuber symptoms, producing fewer mild or moderate tuber symptoms. Lso A was associated with less severe tuber symptoms, despite being able to induce severe symptoms. Disease incidence, tuber yield, and symptom severity ratings were not dependent upon the psyllid haplotype transmitting the pathogen, suggesting that pathogen, not insect haplotype affects Lso transmission.

Effects of sticky trap colour, UV illumination and within-trap variation on tomato potato psyllid captures in glasshouses

ABSTRACTThe tomato potato psyllid (TPP) is a serious pest of New Zealand glasshouse crops. This study examined the use of sticky traps in a glasshouse tomato crop to identify factors that influence TPP catches, with a view to developing a more consistent TPP monitoring system for use in IPM decision models. TPP catches were highest on yellow traps compared with black traps and white traps, and were greatest when traps were set near the glasshouse roof (2.1 m). Ultraviolet (UV) illumination substantially increased TPP catches on traps of all colours. There was considerable variation in TPP catch density within traps, especially near the edges. The results suggest that yellow sticky traps have good potential as TPP monitoring tools in glasshouse tomato crops. Consistency in TPP counts could be enhanced if traps were placed at constant height, were illuminated by UV, and assessments were limited to the trap centres.

Morfometría de inmaduros y tablas de vida de Bactericera cockerelli (Hemiptera: Triozidae) de poblaciones del noreste de México

Se han reportado diferentes parámetros de la biología de Bactericera cockerelli, los cuales están influenciados por el manejo, hospederos y condiciones ambientales en las que se desarrolla. Por lo anterior, el presente estudio tuvo como objetivo determinar los parámetros poblacionales de B. cockerelli de tres poblaciones de campo del noreste de México y una de laboratorio. Para ello se recolectaron especímenes en zonas productoras de San Luis Potosí, Aguascalientes y Coahuila-Nuevo León; posteriormente se establecieron en invernadero y laboratorio para la lectura de datos. Los resultados muestran que la población San Luis Potosí fue la que registró mayor número de oviposturas con una media de 178,5 huevos en el tiempo de evaluación, siendo la más longeva para completar su estadio inmaduro al requerir 31,75 días y por lo tanto es la que mayor tiempo necesita para duplicar la población con una media de 11,07 días; la población Aguascalientes presentó los valores más altos de supervivencia con un 13 % del total de individuos que llegan a la etapa adulta, así como en los parámetros Σmx: 405, Ro: 10,53, rm: 0,089 y λ: 1,093; por último, respecto a la fecundidad y el periodo de pre-oviposición no se registraron diferencias significativas entre poblaciones. Con lo anterior, se demuestra que poblaciones expuestas a presión de selección por plaguicidas, cambian sus parámetros poblacionales.

Assessments of Temporal Variations in Haplotypes of 'Candidatus Liberibacter solanacearum' and Its Vector, the Potato Psyllid, in Potato Fields and Native Vegetation.

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), had been known for nearly a century to cause psyllid yellows of solanaceous crops. However, it has only been a decade since the insect was discovered to transmit the bacterium 'Candidatus Liberibacter solanacearum' (Lso), which putatively causes potato zebra chip disease. This project was initiated to quantify temporal incidences of haplotypes of the psyllid (Central, Southwestern, and Western) and Lso (A, B) in potato fields and in native vegetation. Psyllids were collected from native vegetation in Texas (2011-2014), and from potato fields in Texas and New Mexico (2014-2017). Psyllids were tested for Lso and haplotypes of both psyllid and Lso. In Texas, the Central psyllid haplotype was overwhelmingly dominant both in potato fields and in native vegetation regardless of location and time of collection. However, in New Mexico potato fields, although the Southwestern haplotype was overall dominant, the ratios of individual haplotypes varied among years and within a season. The Southwestern psyllid haplotype was greater in incidence than the Central early but declined later in the season in each of the 4 yr, while the Central haplotype was low in incidence early but increased over time. Lso was detected in all three psyllid haplotypes representing the first report in Southwestern psyllid haplotype. In Texas, Lso haplotype A was more frequently detected than B, but in New Mexico the incidence of positive psyllids was not high enough to make definitive conclusions regarding predominant Lso haplotype.