Anne Nielsen

Dr. Anne Nielsen


Research Focus & Metrics

Academic Career Length

31Years (1996-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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7 January 2018 in Annual Review of Entomology
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Journal Article
Closed access
TLTracy C. Leskey
Tracy C. Leskey
Anne NielsenAnne Nielsen
Anne Nielsen
The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is an invasive pentatomid introduced from Asia into the United States, Canada, multiple European countries, and Chile. In 2010, BMSB populations in the mid-Atlantic United States reached outbreak levels and subsequent feeding severely damaged tree fruit as well as other crops. Significant nuisance issues from adults overwintering inside homes were common. BMSB is a highly polyphagous species with a strong dispersal capacity and high reproductive output, potentially enabling its spread and success in invaded regions. A greater understanding of BMSB biology and ecology and its natural enemies, the identification of the male-produced aggregation pheromone, and the recognition that BMSB disperses into crops from adjacent wooded habitats have led to the development of behavior-based integrated pest management (IPM) tactics. Much is still unknown about BMSB, and continued long-term collaborative studies are necessary to refine crop-specific IPM programs and enhance biological control across invaded landscapes.

17 July 2013 in Biological Invasions
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Journal Article
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JXJiawu Xu
Jiawu Xu
DFDina M. Fonseca
Dina M. Fonseca
GHGeorge C. Hamilton
George C. Hamilton
KHKim A. Hoelmer
Kim A. Hoelmer
Anne NielsenAnne Nielsen
Anne Nielsen

18 May 2016 in Frontiers in Physiology
Verified
Journal Article
Open access
Anne NielsenAnne Nielsen
Anne Nielsen
SCShi Chen
Shi Chen
SFShelby J. Fleischer
Shelby J. Fleischer
We developed an agent-based stochastic model expressing stage-specific phenology and population dynamics for an insect species across geographic regions. We used the invasive pentatomid, Halyomorpha halys, as the model organism because gaps in knowledge exist regarding its developmental physiology, it is expanding its global distribution, and it is of significant economic importance. Model predictions were compared against field observations over three years, and the parameter set that enables the largest population growth was applied to eight locations over ten years, capturing the variation in temperature and photoperiod profiles of significant horticultural crop production that could be affected by H. halys in the US. As a species that overwinters as adults, critical photoperiod significantly impacted H. halys seasonality and population size through its influence on diapause termination and induction, and this may impact other insects with similar life-histories. Photoperiod and temperature interactions influenced life stage synchrony among years, resulting in an order of magnitude difference, for occurrence of key life stages. At all locations, there was a high degree of overlap among life stages and generation. Although all populations produced F2 adults and thus could be characterized as bivoltine, the size and relative contribution of each generation to the total, or overwintering, adult population also varied dramatically. In about half of the years in two locations (Geneva, NY and Salem, OR), F1 adults comprised half or more of the adult population at the end of the year. Yearly degree-day accumulation was a significant covariate influencing variation in population growth, and average maximum adult population size varied by 10-fold among locations. Average final population growth was positive (Asheville, NC, Homestead, FL, Davis, CA) or marginal (Geneva, NY, Bridgeton, NJ, Salem, OR, Riverside, CA), but was negative in one location (Wenatchee WA) due to cooler temperatures coupled with timing of vitellogenesis of F2 adults. Years of the highest population growth in the mid-Atlantic site coincided with years of highest crop damage reports. We discuss these results with respect to assumptions and critical knowledge gaps, the ability to realistically model phenology of species with strongly overlapping life stage and which diapause as adults.

1 June 2013 in Journal of Economic Entomology
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Journal Article
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PDF file
Anne NielsenAnne Nielsen
Anne Nielsen
KHKristian Holmstrom
Kristian Holmstrom
GHGeorge C. Hamilton
George C. Hamilton
JCJohn Cambridge
John Cambridge
JIJoseph Ingerson-Mahar
Joseph Ingerson-Mahar
Monitoring the distribution and abundance of an invasive species is challenging, especially during the initial years of spread when population densit

21 July 2017 in Ecology and Evolution
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Journal Article
Open access
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Anne NielsenAnne Nielsen
Anne Nielsen
SFShelby Fleischer
Shelby Fleischer
GHGeorge C. Hamilton
George C. Hamilton
THTori Hancock
Tori Hancock
GKGregorz Krawczyk
Gregorz Krawczyk
TLTracy C. Leskey
Tracy C. Leskey
Temperature‐based degree‐day models describe insect seasonality and to predict key phenological events. We expand on the use of a temperature‐based process defining timing of reproduction through the incorporation of female reproductive physiology for the invasive pentatomid species Halyomorpha halys, the brown marmorated stink bug. A five‐stage ranking system based on ovary development was able to distinguish between the reproductive statuses of field‐collected females. Application of this ranking method described aspects of H. halys’ seasonality, overwintering biology, and phenology across geographic locations. Female H. halys were collected in the US from NJ, WV, NC, OR, and two sites in PA in 2006–2008 (Allentown, PA only) and 2012–2014. Results identify that H. halys enters reproductive diapause in temperate locations in the fall and that a delay occurs in developmental maturity after diapause termination in the spring. Modification of the Snyder method to identify biofix determined 12.7‐hr photoperiod as the best fit to define initiation of reproduction in the spring. Applying the biofix, we demonstrated significant differences between locations for the rate at which the overwintering generation transition into reproductive status and the factors contributing to this difference require further study. For example, after including abiotic variables influencing development such as temperature and photoperiod (critical diapause cue), reproduction occurred earlier in OR and for an extended period in NJ. This data describe a method to investigate insect seasonality by incorporating physiological development across multiple regions that can clarify phenology for insects with overlapping generations.

25 February 2016 in Environmental Entomology
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Journal Article
Closed access
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Anne NielsenAnne Nielsen
Anne Nielsen
GDGalen Dively
Galen Dively
JPJohn M. Pote
John M. Pote
GZGladis Zinati
Gladis Zinati
CMClarissa Mathews
Clarissa Mathews
The invasive brown marmorated stink bug, Halyomorpha halys, poses significant risk to organic farming systems because they rely on biological control, nonsynthetic inputs, and cultural tactics for pest management. This study evaluated the potential of five crop plants (sorghum, admiral pea, millet, okra, and sunflower) to be used as trap crops under organic production in four mid-Atlantic states. Stink bug (H. halys and endemic species) densities and host plant phenologies were recorded weekly (mid-June through September). Sorghum attracted significantly more H. halys than the other crops evaluated, followed by sunflower and okra. Seasonal average H. halys density was 1.5–4× higher on sorghum than the other crops (P < 0.05), depending on site. Endemic stink bugs were equally attracted to all crops except admiral pea. A significant effect of time was detected (P < 0.0001), with H. halys densities initially higher on sunflower; as the sunflower senesced, sorghum supported significantly higher average H. halys densities. While sunflower and sorghum phenologies differed, these crops together provided a 5-wk attraction period coinciding with peak H. halys activity. The efficacies of pheromone-baited traps, flaming, applying OMRI-approved insecticides (Azera and Venerate), and vacuuming to removing stink bugs were evaluated as a management tactic. Flaming was the most effective treatment against H. halys and endemic stink bugs. Our results suggest that a trap crop composed of sorghum and sunflower may be an effective management tool for the mid-Atlantic stink bug complex, including H. halys. Future research should address the appropriate size and placement of trap crop within the farm.