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. La 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.

Overwintering success is an important determinant of arthropod populations that must be considered as climate change continues to influence the spatiotemporal population dynamics of agricultural pests. Using a long-term monitoring database and biologically relevant overwintering zones, we modeled the annual and seasonal population dynamics of a common pest, Helicoverpa zea (Boddie), based on three overwintering suitability zones throughout North America using four decades of soil temperatures: the southern range (able to persist through winter), transitional zone (uncertain overwintering survivorship), and northern limits (unable to survive winter). Our model indicates H. zea population dynamics are hierarchically structured with continental-level effects that are partitioned into three geographic zones. Seasonal populations were initially detected in the southern range, where they experienced multiple large population peaks. All three zones experienced a final peak between late July (southern range) and mid-August to mid-September (transitional zone and northern limits). The southern range expanded by 3% since 1981 and is projected to increase by twofold by 2099 but the areas of other zones are expected to decrease in the future. These changes suggest larger populations may persist at higher latitudes in the future due to reduced low-temperature lethal events during winter. Because H. zea is a highly migratory pest, predicting when populations accumulate in one region can inform synchronous or lagged population development in other regions. We show the value of combining long-term datasets, remotely sensed data, and laboratory findings to inform forecasting of insect pests.

The larvae of click beetles (Coleoptera: Elateridae), known as “wireworms,” are agricultural pests that pose a substantial economic threat worldwide. We produced one of the first wireworm genome assemblies (Limonius californicus), and investigated population structure and phylogenetic relationships of three species (L. californicus, L. infuscatus, L. canus) across the northwest US and southwest Canada using genome-wide markers (RADseq) and genome skimming. We found two species (L. californicus and L. infuscatus) are comprised of multiple genetically distinct groups that diverged in the Pleistocene but have no known distinguishing morphological characters, and therefore could be considered cryptic species complexes. We also found within-species population structure across relatively short geographic distances. Genome scans for selection provided preliminary evidence for signatures of adaptation associated with different pesticide treatments in an agricultural field trial for L. canus. We demonstrate that genomic tools can be a strong asset in developing effective wireworm control strategies.

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.

Characterizing factors affecting insect pest populations across variable landscapes is a major challenge for agriculture. In natural ecosystems, insect populations are strongly mediated by landscape and climatic factors. However, it has proven difficult to evaluate if similar factors predict pest dynamics in agroecosystems because control tactics exert strong confounding effects. We addressed this by assessing whether species distribution models could effectively characterize dynamics of an insect pest in intensely managed agroecosystems. Our study used a regional multi‐year data set to assess landscape and climatic drivers of potato psyllid (Bactericera cockerelli) populations, which are often subjected to calendar‐based insecticide treatments because they transmit pathogens to crops. Despite this, we show that psyllid populations were strongly affected by landscape and climatic factors. Psyllids were more abundant in landscapes with high connectivity, low crop diversity, and large natural areas. Psyllid population dynamics were also mediated by climatic factors, particularly precipitation and humidity. Our results show that many of the same factors that drive insect population dynamics in natural ecosystems can have similar effects in an intensive agroecosystem. More broadly, our study shows that models incorporating landscape and climatic factors can describe pest populations in agroecosystems and may thus promote more sustainable pest management.