Knowledge on movement and spatial patterns of insect pest populations among preferred hosts aids in the development of effective pest management strategies. In this study, we quantified the ...spatiotemporal dynamics of the invasive brown marmorated stink bug, Halyomorpha halys (Stål 1855), in relation to field corn, Zea mays L., and soybean, Glycine max (L.), crop phenology.We also examined the potential role of corn as a source of stink bugs in adjacent soybean. The highest density of stink bugs in each crop coincided with blister to milk-dough stages in corn (R2–R3/R4), and beginning seed to full seed (R5–R6) stages in soybean. In entire fields of adjacent corn and soybean, H. halys was found in very low density (<0.5/m2) or absent beyond 25m from the field edge. Inverse distance weighted interpolations of H. halys densities suggest potential dispersal of H. halys, particularly adults and large nymphs, from corn into soybean, coinciding with the end of dough stage in corn and beginning of soybean seed development stage. These findings have important implications for managing H. halys through location and timing of scouting efforts, consideration of crop arrangement, and decisions on management interventions. Repeated scouting of field corn to assess H. halys densities, particularly from blister stage onwards, could inform decisions on management interventions for preventing or mitigating H. halys colonization into soybean. Where H. halys is an economic problem, reducing the extent of boundary shared between corn and soybean could reduce dispersal into soybean.
Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural ...insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran's Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs.
Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns.
These results help predicting the pest potential of H. halys and vulnerability of agricultural systems at various regions, given the climatic conditions, and its interaction with resource availability and distance from source populations. Monitoring and control efforts within parts of the United States and Europe with more suitable climate could focus in areas of peri-urban developments with deciduous forests and other host plants, along with efforts to reduce propagule pressure.
Suitability of the local habitat (‘habitat filtering’) and dispersal between stream reaches determines the composition of insect communities, and urban land use may affect both processes. While urban ...streams are often poor habitats for insects and dispersal between them is often hindered, conservation and restoration activities generally focus solely on the local (in‐stream) environment. We determined whether in‐stream habitat filtering (a ‘local’ process) or dispersal between reaches (a ‘regional’ process) controlled assemblage composition in a landscape subject to ongoing urban development (‘urbanizing’). We compared models incorporating geographic distance between sites, environmental dissimilarity, and land‐use/land‐cover attributes of dispersal pathways in an attempt to explain the dissimilarity of stream insect assemblages. Distance and land‐use/land‐cover attributes were characterised along both overland (straight line) and corridor pathways. Both in‐stream habitat filtering and dispersal affected assemblage composition, but habitat had a stronger influence. Overland distance was a better predictor of assemblage dissimilarity than corridor distance, implying stream insect dispersal occurs across catchment boundaries as well as along stream corridors. The best model incorporated land‐use/land‐cover attributes along dispersal pathways, which supported the idea that urban land‐use in the terrestrial environment mediates dispersal. Conservation and restoration strategies for streams in urbanizing landscapes that focus on local habitat quality and ignore dispersal are missing a potentially important mechanism affecting insect assemblage composition. While the primary focus should be on maintaining or improving the local habitat, potential dispersal pathways should also be considered.
1. Spatial synchrony, the tendency for temporal population fluctuations to be correlated across multiple locations at regional scales, is common and contributes to the severity of outbreaks and ...epidemics, but is little studied in agricultural pests.
2. This study analysed spatial synchrony from 1974 to 2008 in 16 lepidopteran agricultural pests in Maryland, U.S.A., and investigated whether pest synchrony is driven by interannual variability in seasonal weather and the areas planted in different crop types.
3. Lepidopteran pests exhibited high degrees of spatial synchrony, which was driven by environmental variation, a phenomenon known as the Moran effect. Region‐wide variation in the areas planted in major crops drove spatially synchronous abundance fluctuations in more than half of studied species. The combination of weather and crop composition explained large fractions of synchrony in black cutworm, corn earworm, European corn borer, and spotted cutworm populations. Other pests, including forage looper and variegated cutworm, displayed a high degree of spatial synchrony, but without dependence on the tested drivers.
4. The study finding that synchronous variation in the area planted in different crop types contributed to synchronous pest abundance fluctuations suggests that strategies to reduce synchrony in changes in crop type across a region could reduce the severity of pest outbreaks and enhance the stability of agricultural systems.
Abundances of 16 lepidopteran agricultural pests in Maryland, U.S.A., exhibited pronounced spatially synchronous fluctuations during 1974–2008.
A combination of weather and synchronous temporal variation in the area planted in major crops drove crop pest spatial synchrony.
Strategies to reduce spatial synchrony in crop type changes could reduce the severity of pest outbreaks and enhance the stability of agricultural systems.
Increased temperature anomaly during the twenty-first century coincides with the proliferation of transgenic crops containing the bacterium Bacillus thuringiensis (Berliner) (Bt) to express ...insecticidal Cry proteins. Increasing temperatures profoundly affect insect life histories and agricultural pest management. However, the implications of climate change on Bt crop–pest interactions and insect resistance to Bt crops remains unexamined. We analysed the relationship of temperature anomaly and Bt adoption with field-evolved resistance to Cry1Ab Bt sweet corn in a major pest, Helicoverpa zea (Boddie). Increased Bt adoption during 1996–2016 suppressed H. zea populations, but increased temperature anomaly buffers population reduction. Temperature anomaly and its interaction with elevated selection pressure from high Bt acreage probably accelerated the Bt-resistance development. Helicoverpa zea damage to corn ears, kernel area consumed, mean instars and proportion of late instars in Bt varieties increased with Bt adoption and temperature anomaly, through additive or interactive effects. Risk of Bt-resistant H. zea spreading is high given extensive Bt adoption, and the expected increase in overwintering and migration. Our study highlights the challenges posed by climate change for Bt biotechnology-based agricultural pest management, and the need to incorporate evolutionary processes affected by climate change into Bt-resistance management programmes.
Since the initial detection of the invasive Halyomorpha halys (Stål) in the United States in the late 1990s, this insect has emerged as a severe agricultural and nuisance pest. Nuisance problems are ...due to adult dispersal to overwintering sites in the fall at which time they alight onto and eventually settle within human-made structures in addition to natural harborage. This study examined how three factors, elevation, light, and moisture affected overwintering site selection by H. halys in the mid-Atlantic. Observational counts performed along elevational transects revealed elevation was significant predictor of H. halys abundance during both years of the study in 2014 and 2015 with more adults observed at higher elevations. Choice tests examining effects of moisture and light on settling behavior demonstrated H. halys settled within overwintering shelter boxes in significantly greater numbers when shelters were dry compared with those having moist conditions, and in darkened shelters compared with those augmented with LED lights. Our findings indicate that H. halys use cues at both landscape and very localized levels when seeking and selecting overwintering sites.
Objectives: Toxic pollutants leaching from littered cigarette butts (CB) raise environmental impact concerns. The US Food and Drug Administration (FDA) is required to assess the environmental impacts ...of its tobacco regulatory actions per the US National Environmental Policy Act
(NEPA). Methods: We determined the chemical constituents in CB leachate through analyses of 109 field-collected CB and literature compilation and characterized their ecotoxicity to aquatic organisms. Results: One-third of the 98 identified CB leachate chemicals were very toxic
and 10% were toxic to aquatic organisms due to acute and chronic toxicity. Polycyclic aromatic hydrocarbons, metals, phthalates, nicotine and volatile organic compounds were the most hazardous CB leachate chemicals for aquatic organisms. Of the 98 CB leachate chemicals, 25 are included in
FDA's list of harmful or potentially harmful constituents in tobacco products and tobacco smoke. Conclusions: Our study quantifies CB leachate constituents, characterizes their ecological hazard and identifies chemicals of concern. Thus, it aids in evaluating the environmental impacts
of tobacco products per NEPA requirements. These results provide important information for strategies to prevent and reduce CB litter (eg, awareness programs, litter laws enforcement), thereby reducing environmental hazards from CB toxicants.
The invasive brown marmorated stink bug, Halyomorpha halys (Stål), has caused severe economic losses in the United States and is also a major nuisance pest invading homes. In diverse woody plant ...nurseries, favored host plants may be attacked at different times of the season and in different locations in the field. Knowledge of factors influencing H. halys abundance and simple methods to predict where H. halys are found and cause damage are needed to develop effective management strategies. In this study, we examined H. halys abundance on plants in tree nurseries as a function of distance from field edges (edge and core samples) and documented the abundance in tree nurseries adjoining different habitat types (corn, soybean, residential areas, and production sod). We conducted timed counts for H. halys on 2,016 individual trees belonging to 146 unique woody plant cultivars at two commercial tree nurseries in Maryland. Across three years of sampling, we found that H. halys nymphs and adults were more abundant at field edges (0–5mfrom edges) than in the core of fields (15–20mfrom edges). Proximity of soybean fields was associated with high nymph and adult abundance. Results indicate that monitoring efforts and intervention tactics for this invasive pest could be restricted to field edges, especially those close to soybean fields. We show clearly that spatial factors, especially distance from edge, strongly influence H. halys abundance in nurseries. This information may greatly simplify the development of any future management strategies.
Invasive plant-feeding insects cause billions of dollars in economics losses annually around the world. Understanding how they utilize different host plants directly informs their management. The ...highly invasive brown marmorated stink bug,
Halyomorpha halys
(Stål) (Hemiptera: Pentatomidae), has destroyed crops and invaded homes since its discovery in the U.S. in the mid-1990s. In this study, we test the hypothesis that in diverse resource environments, the presence and maturity of fruits on trees influences the abundance of
H. halys
. Observational surveys of the abundance of
H. halys
life stages (egg masses, nymphs, and adults) on 3884 trees of 223 cultivars in woody plant nurseries revealed that fruit maturity was a strong predictor of the seasonal abundance and within-tree distribution of
H. halys
. We next explicitly tested whether fruits themselves were the key resource for
H. halys
through a manipulative field experiment. Removal of fruits from trees suppressed stink bug abundance throughout the season. Despite being considered a broad feeding generalist, our results highlight that in landscapes with highly heterogeneous and ephemeral resources,
H. halys
specializes on finding mature fruits. Therefore,
H. halys
can be controlled by designing landscapes with fruitless varieties of popular trees, exploiting phenological mismatches between the pest and its host plants, and through targeted management of
H. halys
on fruiting trees in the landscape.
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