Silvia I. Rondon

The Potato Tuberworm: A Literature Review of Its Biology, Ecology, and Control

The potato tuberworm, Phthorimaea operculella (Zeller), is a worldwide pest of solanaceous crops especially devastating to potatoes. Adults mate and lay eggs in foliage or tubers throughout the growing season, preferring foliage over tubers. When foliage has naturally or artificially senesced and/or tubers are accessible, they deposit eggs in or near the eye buds. The larvae mine leaves, stems, and petioles causing irregular galleries, and excavate tunnels through tubers. Foliar damage to the potato crop usually does not result in significant yield losses but infested tubers may have reduced marketability and losses in storage may be up to 100% especially in non-refrigerated systems. The greatest risk of tuber damage occurs immediately before harvest while the crop is left in the field prior to digging; additional damage may occur in storage, if conditions are not maintained properly. Potatoes that are left in the field for any length of time can become infested. The pest is difficult to control and growers rely extensively on the use of insecticides and a variety of cultural practices. After harvest, the insect may continue to develop on tubers or volunteer plants remaining in the field as well as on other solanaceous plants. Incorporation of host plant resistance together with insecticides and appropriate biological and cultural practices may provide the best management options. This review addresses P. operculella bionomics, including origins, distribution, host range, life cycle and life stage behavior; seasonal dynamics; abiotic factors; cultural, biological, and chemical control methods; and host plant resistance.ResumenLa palomilla de la papa Phthorimaea operculella (Zeller) es una plaga importante de cultivos de solanáceas en todo el mundo pero especialmente devastadora para la papa. Los adultos se aparean y ponen huevecillos en follaje o en tubérculo a lo largo del ciclo de cultivo, con preferencia de follaje sobre los tubérculos. Cuando el follaje senesce natural o artificialmente y/o los tubérculos están accesibles, las polillas depositan sus huevos en o cerca de los ojos de las yemas. Las larvas hacen minas en las hojas, los tallos y en peciolos causando galerías irregulares, y excavan túneles en los tubérculos. El daño al follaje del cultivo usualmente no resulta en pérdidas significativas de rendimiento, pero los tubérculos infestados pueden tener una reducción en el mercado y las pérdidas en el almacén pueden llegar hasta el 100% especialmente en sistemas no refrigerados. El mayor riesgo de daño en los tubérculos se presenta inmediatamente antes de la cosecha mientras el cultivo está en el campo antes de ser cosechado y transportado. Se puede presentar daño adicional en el almacén si las condiciones no se mantienen apropiadamente. Las papas que se quedan en el campo por tiempo prolongado pueden ser infestados. La plaga es difícil de controlar y los productores confían extensivamente en el uso de insecticidas y en una variedad de prácticas culturales. Después de la cosecha, el insecto puede continuar su desarrollo en tubérculos o en plantas voluntarias que permanecen en el campo, así como en otras solanáceas. La incorporación de resistencia en la planta hospedante junto con insecticidas y prácticas culturales y biológicas apropiadas pudieran proporcionar las mejores opciones de manejo. Esta revisión menciona la bionómica de P. operculella, incluyendo su origen, distribución, hospederos, ciclo de vida y el comportamiento de acuerdo al estadío de su vida; dinámica temporal; factores abióticos; métodos de control cultural, biológico y químico; y resistencia de la planta hospedante.

Comparison of single and combination treatments of Phytoseiulus persimilis, Neoseiulus californicus, and Acramite (bifenazate) for control of twospotted spider mites in strawberries.

Greenhouse and field experiments were conducted from 2003 to 2005 to determine the effectiveness of combining releases of two predatory mite species, Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor), and a reduced-risk miticide, Acramite® (bifenazate), for control of twospotted spider mite (TSSM) (Tetranychus urticae Koch) in strawberries. In the greenhouse experiment, a combination treatment of P. persimilis and N. californicus was compared with single treatments of each species, Acramite application, and untreated control. All treatments significantly reduced TSSM numbers compared with the control. Field studies employed two approaches: one investigating the same five treatments as the greenhouse experiment and a second, comparing combination treatments of P. persimilis/N. californicus, Acramite/N. californicus, and Acramite/P. persimilis to single treatments of each and to control plots. Among the combination treatments, the P. persimilis/N. californicus treatment significantly reduced TSSM numbers compared with the control, but was not as effective as N. californicus alone during the 2003–2004 field season. Also, combination treatments of Acramite/N. californicus, and Acramite/P. persimilis significantly reduced TSSM populations compared with the control. These findings indicate that all three combination treatments are promising options for TSSM control in strawberries for growers in northern Florida and other strawberry producing areas of the world.

Haplotypes of the Potato Psyllid, Bactericera cockerelli, on the Wild Host Plant, Solanum dulcamara, in the Pacific Northwestern United States

Abstract‘Candidatus Liberibacter solanacearum’ (Lso) is a bacterium that infects solanaceous crops and causes plant decline and yield losses, especially in potato and tomato. Lso is transmitted to these hosts by the potato psyllid (Bactericera cockerelli Sulc) vector. B. cockerelli host plants are not limited to crop plants, but also include many wild, solanaceous weeds. These wild hosts could potentially impact overwintering and breeding of the psyllids and serve as reservoirs for Lso. In the Pacific Northwestern United States, B. cockerelli was recently reported to overwinter on bittersweet nightshade (Solanum dulcamara L.). The present study utilized high resolution melting analysis of the B. cockerelli mitochondrial cytochrome c oxidase I gene to assess the psyllid populations occurring on S. dulcamara during the summer and winter months in Washington, Oregon, and Idaho. This technique has previously been used to analyze the cytochrome c oxidase I gene of B. cockerelli, and has identified four psyllid haplotypes. Lso infection was also determined for the psyllids collected from S. dulcamara. During both the summer and the winter months in the Pacific Northwest, the Northwestern psyllid haplotype was the predominant population found living on S. dulcamara. However, low levels of the Western psyllid population were also present in Washington and Oregon during the same period. No overwintering psyllids tested were Lso-infected, suggesting that these populations do not pose an imminent threat of Lso transmission to newly emerging potatoes and other solanaceous crops in the region, unless a source of Lso becomes available.Resumen‘Candidatus Liberibacter solanacearum’ (Lso) es una bacteria que infecta a cultivos de solanáceas y causa abatimiento y pérdida de cosechas, especialmente en papa y tomate. Lso se transmite a estos hospedantes por el vector psílido de la papa (Bactericera cockerelli Sulc). Las plantas hospederas de B. cockerelli no se limitan a especies cultivadas, sino que también incluyen muchas malezas silvestres solanáceas. Estas hospedantes silvestres pudieran impactar potencialmente la invernación y apareamiento de los psílidos y servir como reservorios para Lso. En el Noroeste del Pacífico de los Estados Unidos de América se ha reportado recientemente a B. cockerelli invernando en la planta “uva del diablo”, “dulcamara” o “matagallinas” (Solanum dulcamara L.). En el presente estudio se utilizó un análisis de fusión de alta resolución del gen mitocondrial del citocromo c oxidasa de B. cockerelli para analizar las poblaciones del psílido que se presentan en S. dulcamara durante los meses del verano e invierno en Washington, Oregon y Idaho. Se ha utilizado previamente esta técnica para analizar el gen mencionado, y ha identificado cuatro haplotipos del psílido. También se determinó la infección por Lso en psílidos colectados de S. dulcamara. Durante los meses de verano e invierno en el Pacífico del Noroeste, el haplotipo del psílido del Noroeste era la población dominante que se encontraba viviendo en S. dulcamara. No obstante, también se encontraba, aunque en bajos niveles de la población, el psílido del Oeste en Washington y Oregon durante el mismo período. Psílidos no invernantes probados estaban infectados de Lso, sugiriendo que estas poblaciones no representan una amenaza inminente de transmisión de Lso a papas de nueva emergencia y a otros cultivos de solanáceas en la región, a menos que una fuente de Lso estuviera disponible.

Spatial and Temporal Dynamics of Potato Tuberworm (Lepidoptera: Gelechiidae) in the Columbia Basin of the Pacific Northwest

ABSTRACT A landscape-scale study from 2004 to 2006 investigated the spatial and temporal dynamics of a new pest to the Columbia Basin of the Pacific Northwest, the potato tuberworm, Phthorimaea operculella (Zeller). Male P. operculella were monitored in spring, summer, and fall each year with a pheromone-baited trapping network in Oregon and Washington. The objectives of the study were to (1) describe the temporal and spatial dynamics of the recent outbreak of P. operculella in the region and (2) examine the relationship of the spatial and temporal distribution of the outbreak and weather (air temperature, precipitation, and dew point) and geographic variables (elevation and latitude). Weather data during the P. operculella outbreak were compared with a reference period (1993–1999) that occurred before the outbreak. The outbreak in 2004, which caused the first widespread tuber damage in the region, was positively associated with warmer temperatures in the preceding fall and in the spring, summer, and fall of the growing season. October and November 2003 and March 2004 were also drier than the reference period. However, the winter of 2003/2004 was colder than the reference period and thus mild winter conditions did not explain the outbreak. The importance of environmental variables on the seasonal spatial distribution of the pest each year was examined using nonparametric multiplicative regression. Locations with higher spring, summer, or fall temperatures were associated with increased trapping rates in most seasons. Elevation and latitude seemed to play a constraining role, because low trapping rates of P. operculella were associated with higher elevations and latitudes.

POPULATION DYNAMICS OF THE COTTON APHID, APHIS GOSSYPII (HOMOPTERA: APHIDIDAE), ON STRAWBERRIES GROWN UNDER PROTECTED STRUCTURE

Abstract A well developed management plan is in place for control of pests such as the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), in field and greenhouse grown strawberry, Fragaria ananassa Duchesne; however, an integrated pest management approach to control the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), is not available. In order to initiate an effective program for the cotton aphid, the population dynamics of the aphid and the effectiveness of the pink spotted lady beetle, Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae), to control aphids were studied on greenhouse strawberry. Results from this experiment established peaks of aphid infestation throughout the growing season and location of different cotton aphid life forms on the plant. The greatest positive response of the pink spotted lady beetle to cotton aphid occurred at high prey density. This characteristic indicates that the pink spotted lady beetle may be a good candidate for augmentative biological control of cotton aphid on strawberry in the greenhouse. This study provides a basis for developing a biological control of cotton aphid component for an integrated strawberry pest management program.

ANASA TRISTIS (HETEROPTERA: COREIDAE) DEVELOPMENT, SURVIVAL AND EGG DISTRIBUTION ON BEIT ALPHA CUCUMBER AND AS PREY FOR COLEOMEGILLA MACULATA (COLEOPTERA: COCCINELLIDAE) AND GEOCORIS PUNCTIPES (HETEROPTERA: LYGAEIDAE)

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. ANASA TRISTIS (HETEROPTERA: COREIDAE) DEVELOPMENT, SURVIVAL AND EGG DISTRIBUTION ON BEIT ALPHA CUCUMBER AND AS PREY FOR COLEOMEGILLA MACULATA (COLEOPTERA: COCCINELLIDAE) AND GEOCORIS PUNCTIPES (HETEROPTERA: LYGAEIDAE)

Resistance of potato germplasm to the potato tuberworm (Lepidoptera: Gelechiidae).

ABSTRACT The evaluation of potato germplasm for resistance to potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a valuable component of integrated pest management; however, few attempts have been made to identify natural genetic tuber resistance to tuberworm on potato germplasm. The objective of this study was to screen potato germplasm with potential tuberworm resistance for tuber resistance under field and laboratory conditions. Experiments were conducted over a 2-yr period at the Hermiston Agricultural Research and Extension Center, Hermiston, OR. Of 125 germplasm that were tested in 2006, q13 were selected for further screening in 2007. These germplasm were: A0008-1TE, A97066LB, NY123, PA00N10-5, PA99N2, PA99N82, Paciencia, Q174-2, Russet Burbank, Rubi, Ranger Russet, Spunta G2, and T88-4. Tuber resistance of potato germplasm was determined based on the number of mines per tuber and the number of live larvae. Tubers of transgenic clone Spunta G2 were resistant to tuberworm damage. All other germplasm tested in this study, including Russet Burbank and Ranger Russet, were susceptible to tuberworm in the field and laboratory experiments. Incorporation of host plant resistance to tuber penetration by larvae together with appropriate cultural practices including limiting exposure time of tubers in the field may provide the best management option in the future.

Population Structure of Phthorimaea operculella (Lepidoptera: Gelechiidae) in the United States

ABSTRACT The potato tuberworm, Phthorimaea operculella Zeller, is one of the most damaging pests of potatoes worldwide. Although tuberworm was recorded in California as early as 1856, it was first reported in damaging numbers in Oregon and Washington in the early 2000s. The objective of this study was to provide baseline information on the population structure of potato tuberworm in the United States. Potato tuberworm adults were collected from potato fields in the major production regions in the United States. Amplified fragment length polymorphisms (AFLP) were used to determine the genetic population structure of potato tuberworm. We used 219 individuals and 335 polymorphic AFLP bands to infer the geographic population structure of potato tuberworm. Posterior probabilities calculated using the model-based clustering method implemented in STRUCTURE, and Fst values calculated using AFLP-SURV confirmed the existence of two distinct populations in the United States (one mostly associated to the western United States and the other one mostly associated to the eastern United States). This study provides baseline data for the molecular characterization of potato tuberworm populations, which will aid in tracking the origin of future invasions within the United States.

Reducing Tuber Damage by Potato Tuberworm (Lepidoptera: Gelechiidae) with Cultural Practices and Insecticides

ABSTRACT Cultural practices and insecticide treatments and combinations were evaluated for effect on tuber damage by potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) in the Columbia basin of eastern Oregon and Washington. A range of intervals between initial application of several insecticides and vine-kill were tested to determine how early to implement a program to control potato tuberworm tuber damage. Esfenvalerate, methamidophos, and methomyl were applied at recommended intervals, with programs beginning from 28 to 5 d before vine-kill, All insecticide treatments significantly reduced tuber damage compared with the untreated control, but there was no apparent advantage to beginning control efforts earlier than later in the season. Esfenvalerate and indoxacarb at two rates and a combination of the two insecticides were applied weekly beginning 4 wk before and at vine-kill, and indoxacarb was applied at and 1 wk postvine-kill as chemigation treatments. Application of insecticides at and after vine-kill also reduced tuberworm infestation. ‘Russet Norkotah’ and ‘Russet Burbank’ plants were allowed to naturally senesce or were chemically defoliated. They received either no irrigation or were irrigated by center-pivot with 0.25 cm water daily from vine-kill until harvest 2 wk later. Daily irrigation after vine-kill reduced tuber damage, and chemical vine-kill tended to reduce tuber damage compared with natural senescence. Covering hills with soil provides good protection but must be done by vine-kill. Data from these trials indicate that the most critical time for initiation of control methods is immediately before and at vine-kill.

Chaetosiphon fragaefolii (Homoptera: Aphididae): a potential new pest in Florida?

During the spring of 2003-2004, the strawberry aphid, Chaetosiphon fragaefolii (Cockerell) (Homoptera: Aphididae), was found infesting ten different strawberry cultivars, Fragaria ananassa Duchesne, grown under protected culture in a greenhouse in Marion County, FL. The cultivars were ‘Treasure’, ‘Earlibrite’, ‘Strawberry Festival’, ‘Sweet Charlie’, FL 97-39, ‘Camarosa’, ‘Carmine’, ‘Camino Real’, ‘Diamante’, and ‘Ventana’. This is the first report of the presence of C. fragaefolii in cultivated strawberry in Florida (Division of Plant Industry, DPI E2004-278-201). In December 2003, the strawberry aphid was observed on a strawberry cultivar trial at the University of Florida Plant and Science Research Unit at Citra. The susceptibility of ten strawberry cultivars to natural infestations to the cotton aphid, Aphis gossypii Glover, was being evaluated. ‘Treasure’, ‘Earlibrite’, ‘Strawberry Festival’, ‘Sweet Charlie’, FL 97-39, ‘Camarosa’, and ‘Carmine’ plugs were grown at UF facilities as described by Paranjpe et al. (2003); ‘Camino Real’, ‘Diamante’, and ‘Ventana’ plugs came from a Canadian nursery. Two months after the beginning of the trial, samples of an “unknown” aphid in the cotton aphid trial were taken to the Division of Plant Industry in Gainesville, FL, for identification. On 22 January, samples were identified as C. fragaefolii , the true strawberry aphid. Since the strawberry aphid was detected relatively early in the season, two applications of insecticidal soap (10%) (28 January and 12 February) were required to effect control. Two days after the second soap application, 10 Chrysoperla rufilabris L. and Aphidoletes aphidimyza L. per m 2