The avian vampire fly Philornis downsi (Dodge & Aitken) (Diptera: Muscidae) is native to continental South America and the Caribbean, but invasive in the Galapagos Archipelago. The larvae of P. downsi feed on the blood and tissues of the nestlings of 75% of the small land bird species that are endemic or native to Galapagos, causing high in-nest mortality and severe population declines in some species. Efficient trapping techniques are vital to safeguarding these birds in the short term as well as for monitoring fly populations, but basic information about the ecology of the fly is still needed to help develop a species-appropriate trapping method. In this study, we used a novel trapping regime with a vertical distribution to make inferences about P. downsi's behavioral and spatial ecology and to optimize trap catch. Our results showed that male and female P. downsi were trapped in greater numbers below the canopy (3.1–7.5 m), lower down than other commonly caught insect species (5.1–11.5 m). Notably, the effect of trap height remained consistent across seasons and different weather conditions. These findings suggest that P. downsi tend to move at heights where their hosts nest (at or below the canopy) and do not spend time above the canopy. This also makes it unlikely that strategies such as hill-topping or aerial swarming are being used to locate mates. As such, trapping and control efforts should be focused below the canopy in forests with similar canopy heights to effectively capture P. downsi and reduce bycatch of other insects.

La mosca vampiro aviar Philornis downsi (Dodge & Aitken) (Diptera: Muscidae) es originaria de América del Sur continental y el Caribe, pero invasora en el archipiélago de Galápagos. Las larvas de P. downsi se alimentan de la sangre y los tejidos de los polluelos de 75% de las aves terrestres pequeñas que son endémicas o nativas de Galápagos, lo que provoca una alta mortalidad en los nidos y graves disminuciones en las poblaciones de algunas especies. Las técnicas de captura eficientes son vitales para salvaguardar a estas aves a corto plazo, así como para monitorear las poblaciones de moscas, pero aún se necesita información básica sobre la ecología de P. downsi para ayudar a desarrollar un método de captura apropiado para esta especie. En este estudio utilizamos un nuevo régimen de captura con una distribución vertical para hacer inferencias sobre la ecología espacial y conductual de P. downsi y optimizar la captura con trampas. Nuestros resultados mostraron que los machos y las hembras de P. downsi quedaron atrapados en mayor número debajo del dosel (3,1–7,5 m), más abajo que otras especies de insectos comúnmente capturadas (5,1–11,5 m). En particular, el efecto de la altura de la trampa se mantuvo constante en todas las estaciones y en diferentes condiciones climáticas. Estos hallazgos sugieren que P. downsi tiende a moverse en las alturas donde anidan sus huéspedes (en o debajo del dosel) y no pasa tiempo por encima del dosel. Esto también hace que sea poco probable que se utilicen estrategias como hill topping o el enjambre aéreo para localizar parejas. Como tal, los esfuerzos de captura y control deben centrarse debajo del dosel en bosques con alturas de dosel similares para capturar eficazmente P. downsi y reducir la captura incidental de otros insectos.

It is essential to correctly identify and keep track of the abundance of thrips species on infested host crops to understand their population dynamics and implement control measures promptly. The current study was conducted to evaluate the performance of sticky traps in monitoring thrips species in exporters' eggplant and chili farms and to assess the impact of weather factors on thrips population dynamics. Thrips species were monitored using blue, yellow, and white sticky traps on chili and eggplant farms inTuba, respectively, in 2020 and 2021. Each field was divided into 8 blocks, and in each replicate, all colors representing 3 treatments were randomly tied to stakes at the center of the respective crop. Data loggers were installed to record hourly weather variables. Three thrips species [Thrips parvispinus Karny (Thysanoptera: Thripidae), Franklinella schultzei Trybom (Thysanoptera:Thripidae), and Thrips tabaci Lindeman (Thysanoptera:Thripidae)] were identified from both farms and the different species showed varied attractiveness to trap color for both seasons, with white proving more attractive to T. parvispinus.The population dynamics of the species varied significantly with the season and weather but not with the crop. Optimum temperatures (28–31 °C) and relative humidity (60%–78%) showed a positive linear relationship between the trapped insects with temperature and RH, while extreme temperatures (35 °C) negatively affected their abundance. All sticky trap colors attracted several nontarget organisms; however, yellow colors had higher populations, including the predator, Orius insidiosus. White sticky traps are recommended for inclusion in the country-wide monitoring for thrips, especially T. parvispinus.

Graphical Abstract

Stink bugs have become an increasing concern for tree fruit growers due to changing management strategies and the introduction of an invasive species. The use of broad-spectrum insecticides for stink bug control disrupts biological control and leads to secondary pest outbreaks. To seek alternative tactics, we investigated the physical exclusion of native stink bugs with single-wall net barriers at orchard borders. First, stink bug capture on clear sticky panels along orchard edges showed that movement between the native shrub-steppe vegetation and the orchard occurs for much of the growing season instead of the presumed single migration event in August. Most stink bugs were captured between 1 m and 3 m heights, signifying a 4 m exclusion barrier would intercept migrating bugs. We tested large net barriers (4 m × 23 m) constructed of plain netting with or without deltamethrin-infused netting in flaps compared to a no-net control. The capture of target and nontarget arthropods was determined with plastic tarps below the nets or on the open ground of the control. Net barriers did not directly affect stink bug densities in the orchards, although orchard populations were low overall. Barriers did intercept stink bugs, and the addition of deltamethrin flaps enhanced stink bug mortality but at the price of nontarget arthropod mortality. Our results indicate that stink bug management efforts should focus earlier in the growing season and given the long period of migration, barriers are a more sustainable way of slowing movement into the orchard than the current sole reliance on chemical control.

Graphical Abstract

Many insects rely heavily on visual cues in foraging and other life activities. Mantids are insect predators that usually ambush prey. The sophisticated visual system of mantids allows them to spot, track, and strike at prey with high accuracy. Mantids are categorized as diurnal animals in most cases, while our field observations suggested that they were active in foraging both day and night. Therefore, we hypothesize that predation in dim light is possible for mantids, while mantids are unable to capture prey in complete darkness. In this study, we experimentally examined whether different light conditions could affect the predation success and efficiency of mantid nymphs and adults, Hierodula chinensis Werner (Mantodea: Mantidae), through behavioral observations. Individual mantids were placed in individual chambers in complete darkness, simulated moonlight (0.1 lux), or simulated dusk (50 lux) conditions and were allowed to forage for prey items for 10 min. Our observations showed no evidence that H. chinensis could capture any prey in complete deprivation of light. The proportion of nymphs with successful predation in simulated moonlight was 50% higher than that in complete darkness and 45.83% lower than that in simulated dusk. The proportion of adults with successful predation in simulated moonlight was 42.11% higher than that in complete darkness and 57.89% lower than that in simulated dusk. Overall, the results provide new insights into the behavioral ecology of diurnal predators at night, with potential association with moonlight, starlight, and light pollution.

Graphical Abstract

Eucryptorrhynchus scrobiculatus (Motschulsky) (Coleoptera: Curculionidae) is a notorious pest of Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae). E. scrobiculatus adults typically aggregate under leaves and in soil crevices at the base of A. altissima in the field. We hypothesize that the environmental factors and conspecific signals determine their aggregation behavior. To test this, we investigated adult numbers in light-exposed and shaded areas of the sample trees and conducted experiments in both field and lab settings. Results revealed that (i) greater adult distribution in shaded areas; (ii) significant influence of temperature and illumination on aggregation tendency in the field; (iii) no gender-based difference in aggregation degree and maximum aggregation between light and dark; (iv) the host plant triggering the aggregation tendency, negatively affected in the absence; (v) the aggregation tendency of E. scrobiculatus weakened with the temperature gradually changing to ordinary temperature; and (vi) mutual attraction and chemical attraction between males and females. Thus, the aggregation behavior was influenced by factors including temperature, light intensity, host plant, and conspecific signals, but light's role was not obvious in the lab.

Video Abstract

Implementation of augmentative biological control requires estimates of parasitoid dispersal from the release point to determine appropriate release density, spacing, and timing. This study evaluated the movement patterns of Fopius arisanus Sonan (Hymenoptera: Braconidae) parasitoids, which have historically been used to control invasive tephritid fruit flies. The wasps were released from the central point, and dispersal was monitored over time using parasitism in sentinel fruit and trap captures at 40 points radiating out from the center (15–240 m). The releases were conducted 4 times during June, July, September, and November 2006. The data showed that there were large declines in dispersal by distance. Parasitism was greatest closest to the release point, within 30 m. Parasitism was also greatest within the first 24 h of the release. After 1 wk, parasitism decreased from 41% to 1.5% within 30 m. These data correlated strongly with trap capture data, which also showed that parasitoid movement favored the SE region of our release site, roughly corresponding to the overall prevailing winds. Wind speed, relative humidity, and temperature all affected parasitoid movement during our trial, indicating the complex environmental factors that can affect release success. This is the first report of dispersal metrics for F. arisanus. Our findings are in agreement with other similar studies on braconid movement generally and suggest that frequent, high-density releases are most effective since the dispersal of F. arisanus is limited and retention in the environment is low. We discuss our results in the context of international augmentative biological control release programs.

Graphical Abstract

Alternanthera philoxeroides (Amaranthaceae), commonly known as alligator weed, is a globally invasive and detrimental perennial weed. Agasicles hygrophila serves as an important biocontrol agent for alligator weeds. However, during mid-summer, when temperatures increase, A. hygrophila populations experience a significant decline, leading to ineffective weed control. This study has examined the impact of periodic heat events on the reproduction and survival of A. hygrophila females and males using various mating combinations and durations of temperature treatments. The results demonstrated significant effects on all of the studied parameters across mating combinations when compared with the control. Under the same temperature combination, the fecundity and survival rates of females, as well as the egg-hatching rate, decreased significantly with increasing repeated heat exposure. Furthermore, the egg-hatching rate varied significantly among different temperatures and time-interval combinations. In addition, the females displayed greater sensitivity to heat stress than males in terms of fecundity. These findings enhance our understanding of A. hygrophila population dynamics during summer and provide insights into the release of biocontrol agents in diverse regions with varying climates.

Graphical Abstract

Arthropods are active during the winter in temperate regions. Many use the seasonal snowpack as a buffer against harsh ambient conditions and are active in a refugium known as the subnivium. While the use of the subnivium by arthropods is well established, far less is known about subnivium community composition, abundance, biomass, and diversity and how these characteristics compare with the community in the summer. Understanding subnivium communities is especially important given the observed and anticipated changes in snowpack depth and duration due to the changing climate. We compared subnivium arthropod communities with those active during the summer using pitfall trapping in northern New Hampshire. We found that compositions of ground-active arthropod communities in the subnivium differed from those in the summer. The subnivium arthropod community featured moderate levels of richness and other measures of diversity that tended to be lower than the summer community. More strikingly, the subnivium community was much lower in overall abundance and biomass. Interestingly, some arthropods were dominant in the subnivium but either rare or absent in summer collections. These putative “subnivium specialists” included the spider Cicurina brevis (Emerton 1890) (Araneae: Hahniidae) and 3 rove beetles (Coleoptera: Staphylinidae): Arpedium cribratum Fauvel, 1878, Lesteva pallipes LeConte, 1863, and Porrhodites inflatus (Hatch, 1957). This study provides a detailed account of the subnivium arthropod community, establishes baseline information on arthropod communities in temperate forests of northeastern North America, and explores the idea of subnivium specialist taxa that are highly active in winter and might be especially vulnerable to climate change.

Graphical Abstract

A temperate deciduous forest in winter and summer, including a cross-sectional view of the snowpack and leaf litter.The subnivium, a space between the snowpack and the soil surface that acts as a refuge for winter arthropods (and other taxa), is represented by the thin dark layer in the left panel.The arthropod community differs between seasons in composition, biomass, and abundance.The 5 arthropods presented on each side of the illustration, in winter (left) and in summer (right), are representative of groups commonly captured during their respective collection period. On the winter panel, from left to right, the arthropods shown here are a centipede (family Linotaeniidae), a spider (Cicurina brevis; family Hahniidae), a beetle larva (likely belonging to the family Cantharidae), a rove beetle (family Staphylinidae), and a wingless fly (genus Chionea). In the summer panel from left to right, the arthropods are a rove beetle (family Staphylinidae), a carrion beetle (family Silphidae), a cricket (family Rhaphidophoridae), a fly (family Phoridae), and a ground beetle (family Carabidae). The leaf litter layer and the arthropods depicted are magnified in this illustration for effect.

To illustrate the impact of genetically modified (GM) Bt maize on the natural enemy communities in the Huang-Huai-Hai summer maize-growing region in China, the abundance of 7 common predator taxa (Geocoris pallidipennis Costa, Harmonia axyridis (Pallas), lacewings, Orius sauteri (Poppius), Propylea japonica (Thunberg), spiders, and Staphylinidae) was quantitatively evaluated by comparing Bt-Cry1Ab DBN9936 and Bt-Cry1Ab/Cry2Aj Ruifeng 125 events to their near non-Bt isolines during the growing season from 2016 to 2019. A total of 10,302, 19,793, 13,536, and 5,672 individuals were observed during 4 years, and the abundance of each taxa on Bt maize varied between sample dates among those arthropod taxa. Shannon–Wiener diversity index of predator communities from 7 taxa showed very similar temporal dynamics and principal response curve analyses to examine community-level effects showed no significant differences in predator abundance in Bt maize compared with non-Bt maize. We conclude that the 2 Bt maize hybrids did not adversely affect the predator community in the Huang-Huai-Hai summer maize-growing region of China.

Termite hindguts are inhabited by symbionts that help with numerous processes, but changes in the gut microbiome due to season can potentially impact the physiology of termites.This study investigated the impact of seasonal changes on the composition of bacteria and protozoa in the termite gut. Termites were obtained monthly from May to October 2020 at a location in the central United States that typically experiences seasonal air temperatures ranging from < 0 to > 30 °C. The guts of 10 termites per biological replication were dissected and frozen within 1 day after collections. DNA was extracted from the frozen gut tissues and used for termite 16S rRNA mitochondrial gene analysis and bacterial 16S rRNA gene sequence surveys. Phylogenetic analysis of termite 16S rRNA gene sequences verified that the same colony was sampled across all time points. On processing bacterial 16S sequences, we observed alpha (observed features, Pielou's evenness, and Shannon diversity) and beta diversity (unweighted Unifrac, Bray-Curtis, and Jaccard) metrics to vary significantly across months. Based on the analysis of the composition of microbiomes with bias correction (ANCOM-BC) at the genus level, we found several significant bacterial taxa over collection months. In addition, Spearman correlation analysis demonstrated that 41 bacterial taxa were significantly correlated (positively and negatively) with average soil temperature. These results from a single termite colony suggest termite microbial communities go through seasonal changes in relative abundance related to temperature, although other seasonal effects cannot be excluded. Further investigations are required to conclusively define the consistency of microbial variation among different colonies with season.

In a nature reserve in southern Maine, we removed invasive Japanese barberry (Berberis thunbergii de Candolle) along sections of forested recreational trails that ran through dense barberry infestations. Barberry thickets provide questing substrate and a protective microclimate for blacklegged ticks (Ixodes scapularis Say), and trail users could brush up against encroaching barberry and acquire ticks. Trailside barberry removal will reduce or eliminate encroaching tick questing substrate and could reduce trailside questing tick abundance by creating a microclimate more hostile to ticks. The same-day cut-and-spray treatment comprised mechanical cutting of barberry clumps (individual plants with numerous ramets) followed immediately by targeted herbicide application to the resulting root crowns. The treatment created trail shoulders to a lateral width of 1–2 m on both sides of 100-m trail sections, with initial treatment in the fall of 2013 and one retreatment in the summer of 2014. Our aim was to remove 90% of barberry clumps to achieve a 50% or better reduction in questing tick abundance on trail shoulders. However, by the fall of 2015, there were only 41% fewer barberry clumps on treated vs. untreated trail sections and there was no reduction in either adults or nymphs. We concluded that our barberry treatment protocol was not sufficiently aggressive since the resulting ecotone habitat on trail shoulders proved suitable for questing I. scapularis. In principle, cutting back barberry along trails should reduce trail user contact with questing deer ticks, but we were unable to demonstrate a reduction in trailside tick abundance.

Habitat manipulation such as intercropping can be used as a simple and common cultural practice in pest management. This method is based on the principle of reducing pest populations by increasing the diversity of an ecosystem. This study has been carried out to evaluate the influence of additive series intercropping common bean with some aromatic plants (AP), and 2 acaricides on the different life stages (egg, immature mobile stages, and adult) of Tetranychus urticae Koch (Trombidiformes: Tetranychidae), over 2 yr of experimentation (2020 and 2021). This experiment was conducted following a randomized complete block design with 7 treatments including common bean monoculture, common bean sprayed by spiromesifen or Dayabon, and common bean + companion plants (coriander, ajwain, basil, or dill). Each treatment was replicated 3 replicates.The lowest and highest number of eggs, immature mobile stages, and adults were observed in common bean + spiromesifen and the common bean monoculture, respectively. Additionally, the common bean + Dayabon supported significantly different T. urticae life stage densities compared to common bean monoculture. Also, among intercropped treatments, common bean + basil showed the lowest number of T. urticae (eggs, immature mobile stages, and adults). The highest yield and land equivalent ratio were recorded in common bean + basil and common bean + spiromesifen, respectively. Finally, it can be concluded that additive intercropping with these AP can effectively decrease the T. urticae population density, which is useful for the safe production of common bean.

Potato leafhopper (PLH), Empoasca fabae Harris (Hemiptera: Cicadellidae), is an economic pest of a variety of crops that migrates between overwintering sites in the southern United States and northern breeding grounds. Since 2005, the Midwest Suction Trap Network (STN) has monitored the magnitude and timing of aerially dispersing aphids' activity, but the potential of the network to monitor other taxa is only beginning to be explored. Here, we use the Midwest STN to examine how the magnitude and timing of PLH activity vary with weather, cropland cover, and time of year. We found that weekly PLH activity increased early in the season (May–June) with increasing degree day accumulation and decreased mid-season (July–August) with increasing occurrence of rain. The first detections occurred earlier in southern latitudes, while the last detections occurred sooner, when there was more surrounding potato land cover, and later over time between 2018 and 2021 and in southern latitudes. PLH activity was thus longer in duration in southern latitudes and has continued to extend later into the year overall. Resolving uncertainty about how well the Midwest STN captures migratory activity and how closely suction trap detections reflect local population densities in crop fields remain important research priorities before the potential of the Midwest STN for PLH monitoring can be realized. Still, observed patterns suggest that PLH could increase in economic importance as insects disperse over larger portions of the growing season in the warming, agriculturally productive US Midwest and that the STN can become a useful tool to monitor these changes.

Chitosan is a naturally derived polymer that has significant potential for use as a bioinsecticide. Despite this, there is a lack of research as to the efficacy of chitosan for many insect pest species. The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is one such pest for which chitosan toxicity has not been explored. In this study, the toxicity of chitosan for R. pomonella adults was tested via no-choice feeding assays. An aging trial was further used to test the mortality of flies provided dried chitosan-sucrose treatments (CST), which were aged for 0 or 3 days in greenhouse conditions. This study found that the CST is toxic for R. pomonella adults when ingested, leading to a significant increase in the rate of mortality compared to control groups. The use of dried chitosan, however, did not change the mortality of flies, suggesting this will not be an effective delivery mechanism. Effective biopesticide delivery systems have not been defined for chitosan use outside of a laboratory, indicating the need for further research testing delivery mechanisms. It is suggested that an effective method of delivery can be as a food-based bait in attract-and-kill traps, as chitosan must be ingested to kill flies. Forming a viscous solution, chitosan may be best suited to these lure systems.

Eastern subterranean termites, Reticulitermes flavipes (Kollar), are widely distributed across North America where they are exposed to a broad range of environmental conditions. However, mechanisms for overwintering are not well understood. Wisconsin is a unique location to study mechanisms of cold tolerance as it represents the northern boundary for persistent R. flavipes populations. In this study, we evaluated seasonal shifts in cold tolerance using critical thermal minimum (CT_min) and supercooling point (SCP) and examined how these measurements correlate to changes in the microbial community of the termite gut. Results showed seasonal acclimatization to cold, which is consistent with the use of behavioral freeze-avoidant mechanisms. However, these insects also demonstrated an increased susceptibility to freezing later in the season, which may be tied to changes in gut microbiota. Our results found shifts in the composition of the gut microbiome in R. flavipes between mid- to late summer and early to late fall. These differences may be suggestive of a change in metabolism to adjust to a period of reduced feeding and increased metabolic stress during overwintering. Specifically, results showed an increased abundance of Methanobrevibacter sp. (Euryarchaeota) associated with cold, which may be indicative of a metabolic shift from acetogenesis to methanogenesis associated with overwintering. Further work is needed focusing on specific contributions of certain gut microbes, particularly their role in metabolic adaptability and in providing protection from oxidative stress associated with changes in environmental conditions.

Although copper is an essential element for any organism's well-being, it becomes toxic if present in excess. In the present study, copper was provisioned at 25, 50, and 75 mg/kg in an artificial diet and fed to juvenile larvae of cotton bollworm, Helicoverpa armigera (Lepidoptera; Noctuidae), for 4 generations.The results of this investigation exhibited shortening of larval life in the first 2 generations, but extended duration was observed in third and fourth generations compared to controls, and dietary copper caused reduced total hemocyte counts in all treatments. The number of immunocytes (i.e., granulocytes and plasmatocytes) were also significantly reduced. The changes in activities of certain important enzymes, including catalase, superoxide dismutase, and peroxidases, were seen. Furthermore, after treatment, an increase in the activity of 2 detoxifying enzymes, glutathione s-transferase and acetylcholinesterase, was observed. It is clear that metallothioneins are important in maintaining essential and nonessential metal ion homeostasis. While copper is typically regarded as an important essential metal in an organism's life, excessive amounts can have deteriorating effects. This heavy metal is being used as a nano-based pesticide. Therefore, the present investigation aims to determine the fate of Cu in insects receiving them in new formulations.

Graphical Abstract

Duponchelia fovealis (Zeller) (Lepidoptera: Crambidae) is a polyphagous pest that feeds on a variety of ornamental and crop plants. At least 47 plant families have been identified as hosts for D. fovealis in literature based on empirical data and observations. This list is surely incomplete based on the broad feeding habits of D. fovealis. We sought to expand the list of known D. fovealis host plants and to identify species that may be less preferred or not fed upon by D. fovealis. We used laboratory feeding assays to measure D. fovealis consumption rate of leaf disks from 32 herbaceous plant species and 32 woody species grown outdoors throughout the Southeastern United States, and 24 tropical species typically grown as house plants. These plants were from 65 genera and 36 families. Between the 3 ornamental plant groups, we tested (herbaceous, woody, and tropical) that, after 24 h, plants in the tropical group were the least consumed by D. fovealis. After 24 h, the average proportion of leaf disks eaten by D. fovealis was 0.80 or higher for 5 herbaceous and 12 woody species. Proportions of leaf disks eaten varied at the family and genus level in many cases. Our research can improve integrated pest management of D. fovealis by informing growers that plants may be at more or less risk of infestation and damage by larvae.

Spotted lanternfly, Lycorma delicatula (White), is an invasive planthopper from China, which was first detected in Berks County, PA, in 2014 and has since spread to adjacent states including New Jersey in 2018. Lycorma delicatula is a polyphagous species that gregariously feeds on over 172 known hosts. We investigated development on key host plants Ailanthus altissima (Miller) (Sapindales: Simaroubaceae), Juglans nigra (L.) (Fagales: Juglandaceae), Acer rubrum (L.) (Sapindales: Sapindaceae), and Vitis vinifera (L.) (Vitales: Vitaceae) for each instar to elucidate potential host use throughout the season and target monitoring efforts. Our study indicated significant differences in survivorship and time spent in each nymphal life stage between host plants. We applied a host suitability index as a function of survivorship and development for each host plant and instar, which indicated A. altissima and J. nigra as suitable hosts for all 4 nymphal instars. Vitis vinifera was highly suitable for first and second instars but had low indices for the third and fourth instars, although suitability of V. vinifera may have varied based on variety and age of the vine. Lycorma delicatula nymphs had the lowest survivorship and longest development time on A. rubrum across all 4 life stages, despite this being a preferred oviposition host. Host had a significant effect on the morphometrics we measured within the first and second instars.

Insect migrations have ecological and economic impacts, particularly in agriculture. However, there is limited knowledge about the migratory movements of pests at the continental scale, which is an important factor influencing the spread of resistance genes. Understanding the migratory patterns of economic pests, like Helicoverpa zea (Boddie), is essential for improving Integrated Pest Management (IPM) and Insect Resistance Management (IRM) strategies. In this study, we used stable hydrogen isotopic ratios in wing tissue as a biogeochemical marker to examine migratory patterns and estimate the native origins of H. zea individuals collected across a wide latitudinal gradient in North America. Samples collected at higher latitudes (Ontario, Canada and Minnesota, USA) exhibited a greater proportion (60%–96%) of nonlocal individuals, with an increased probability of origin from the southeastern United States. Populations from mid-latitudes (Florida, North Carolina, and South Carolina) showed a blend of local and nonlocal (40%–60%) individuals. Finally, 15% of the southernmost population individuals (Puerto Rico) were classified as migratory, with some having a probability of origin at higher latitudes (>30°). Overall, our results provide evidence of a northward spring/summer migration of H. zea in North America and underscore the significance of the southeastern United States as a hub for genetic flow. In addition, based on stable hydrogen isotopic ratios, there is strong evidence of reverse (southward) migration of H. zea from the continental United States to Puerto Rico. Our study highlights the implications for IPM and IRM programs and the need for management strategies that account for both northward and southward migration patterns.

Migrações de insetos têm impactos ecológicos e econômicos significativos, especialmente na agricultura. No entanto, existe um conhecimento limitado sobre os movimentos migratórios de pragas em escala continental, o que é um fator determinante na disseminação de genes de resistência. Entender os padrões migratórios de pragas econômicas, e.g., Helicoverpa zea (Boddie), é essencial para o aprimoramento das estratégias de Manejo Integrado de Pragas (MIP) e da Resistência de Insetos (MRI). Neste estudo, utilizamos isótopos estáveis de hidrogênio presentes nas asas das mariposas como marcador biogeoquímico para examinar os padrões migratórios e estimar a origem de indivíduos de H. zea coletados em um amplo gradiente latitudinal na América do Norte. Amostras coletadas em latitudes mais altas (Canadá e Minnesota, EUA) exibiram uma proporção maior (60-96%) de indivíduos não locais, com uma alta probabilidade de origem na região sudeste dos EUA. Populações de latitudes médias (Flórida, Carolina do Norte e Carolina do Sul) mostraram uma mistura de indivíduos locais e não locais (40-60%). Finalmente, 15% dos indivíduos da população mais ao sul (Porto Rico) foram classificados como migratórios, com alguns tendo alta probabilidade de origem em latitudes mais altas (> 30°). No geral, nossos resultados fornecem evidências de uma migração durante primavera/verão de H. zea para o norte na América do Norte, e também destacam a importância do sudeste dos EUA como um ‘hub’ de fluxo genético. Além disso, com base nas proporções dos isótopos estáveis de hidrogênio, existem fortes evidências de uma migração reversa (em direção ao sul) de H. zea do continente dos EUA para Porto Rico. Nosso estudo destaca as implicações para os programas de MIP e MRI, enfatizando a necessidade de estratégias abrangentes que considerem tanto os padrões de migração para o norte quanto para o sul.

It is important to have reliable information on the presence/absence, population structure, and density of animals across their natural range. Detecting small organisms, however, such as the Nearctic tree trunk sheetweaver spider Drapetisca alteranda Chamberlin 1909 (Araneae: Linyphiidae), presents challenges due to its diminutive size and cryptic nature. We used a capture/recapture study to determine the detection and recapture probabilities of this spider using a standard beat sheet technique adopted for surveying tree trunks. Spiders were released on 3 different tree species that provided a range of microhabitats, including variable bark surface area and furrow depth/width. Microhabitat features played a small role in the timing of spider recapture (i.e., slower rate of recapture as furrowing increased). However, our results demonstrated 100% detection across replicate experiments and individual recapture probabilities exceeding 90% in most situations, with no significant differences in recapture observed among tree species and with respect to tree circumference. Furthermore, we show that most spiders could be recaptured within 2 sampling revolutions around the tree trunk, and there was no difference in the probability of collecting male and female spiders (although they differ markedly in size). Finally, we found no difference among brushers, supporting the idea that this method is replicable across collectors and studies. Collectively, we establish confidence in the ecological knowledge obtained with this technique and encourage its application with similar species and systems.