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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
(608) 231-9544 TTY/TDD

Asian Longhorned Beetle

Modeling Phenology

Research Issue

There was a critical need for information on the basic biology of Anoplophora glabripennis (Motschulsky) (ALB).  This information is needed to predict the timing of biological events fundamental to the development and improvement of exclusion and eradication methodologies.  Some attempts using climate data from the countries of origin have been used to predict the potential range of this insect. Simple degree day models have been developed to predict adult emergence, but no previous attempt has been made to fully model the phenology of this insect so that the timing of all stages can be predicted.  Such a model could also be used to predict the potential range and number of years required to complete a generation.

Our Research

We developed a climate-driven phenology model for A. glabripennis that provides simulated life-tables for populations of individual beetles under variable climatic conditions that takes into account the variable number of instars beetles may undergo as larvae.  Phenology parameters in the model are based on a synthesis of published data and studies of A. glabripennis, and the model output was evaluated using a laboratory reared population maintained under varying temperatures mimicking those typical of Central Park in New York City.  The laboratory evaluation of the phenology of this beetle over a 3-year time frame used 31 pairs of laboratory-reared adults from the Chicago, IL strain (emerged end of June to middle of August)  Development and survival was monitored for of about one third of the larvae that hatched from the eggs laid by these adults until they became adults.

The phenology model was then used along with a model of heat transfer in the wood of the host and spatial data describing host species presence/absence data, to produce a map of risk factors across the conterminous United States to define potential for ALB infestation and relative threat of impact.

Expected Outcomes

A phenological model that can be used both to predict the timing of all stages and the potential geographical range of this species.

Research Results

[photo:] ALB Adults and ovioposition boltsIn the experiment that simulated seasonal variations a total of 1,989 eggs were laid by the original 31 adults; 1,193 of these hatched from which the development of 406 larvae placed on artificial diet were followed. The first egg was laid on June 28 and the last on October 30 when the temperature was 12°C during the first year of the study.  Egg hatch continued until the temperature was decreased to 6°C and resumed the following year when temperatures reached 12°C.  The last larval molt in the first year occurred at 13°C on October 19 and the first molt the next year occurred on May 8 at 16°C. Larvae continued to molt through the year until temperatures dropped below 5°C.  During the first simulated  winter, eggs and larvae through the 7th instar over wintered and during the second winter 6 through 13th instars over wintered.  At the onset of the simulated winter, larvae that pupated during the second year weighed 0.568 + 0.037 g and those that pupated in during the third year weighed 1.883 + 0.022 g.  Pupation of 6th-13th instars occurred from July 3 to August 29 in the second year and from June 3 to August 6 in the third year.  Adults emerged from July 22 to September 24 during the second year and from June 27 to August 26 during the third year. 
[photo:] Larva and eggs in boxesALB phenology allows the species to adapt very well to ambient environmental conditions.  If larvae that have not reached the critical weight needed for pupation, either by the beginning of winter or when they resume feeding in the spring (before temperatures approach 25°C), they will not proceed to pupation but instead continue growing and molt until they reach their maximal weight or temperatures drop below about 15°C.  This can force part or all the individuals in a population into a 2-year life cycle, especially larvae that hatch too late to grow large enough the first year or where the growing season is short.  ALB eggs and larvae of all sizes over winter, surviving temperatures of at least as low as 0°C for three weeks and enhancing the ability of this insect to adapt.  This data set was used to validate two phenology models that were developed using previously collected data on the effects of temperature on the development of all the life stages.

Predicted Asian longhorned beetle emergence for a few sites using the phenology model and 30 year climate normals.  The dates in the lower right corner are the first predicted emergence dates.The phenology model that was developed was stable under variations in population size, simulation length, and the Julian dates used to initiate individual beetles within the population.  Comparison of model results with previously published field-based phenology studies in native and invasive populations indicate both this new phenology model, and the previously published heating-degree-day model show good agreement in the prediction of the beginning of the flight season for adults.  However, the phenology model described avoided underpredicting the cumulative emergence of adults through the season, in addition to providing tables of life stages and estimations of voltinism for local populations.  This information can play a key role in evaluating risk by predicting the potential for population growth, and may facilitate the optimization of management and eradication efforts.

Asian longhorned beetle years to maturity for viable host area defined by urban areas and host species at risk.When the model was used to produce a map of risk factors across the conterminous United States to define potential for ALB infestation and relative threat of impact the results showed that the region with greatest risk of ALB infestation is the eastern half of the country, with lower risk across most of the western half due to low abundance of host species, less urban area, and prevalence of cold, high elevations. Risk was high in southeastern states primarily because of temperature, while risk was high in northeastern and northern central states because of high abundance of host species.

Kappel AP, Trotter RT, Keena MA, and Williams CA. 2017. Mapping of the Asian Longhorned Beetle’s time to maturity and risk to invasion at contiguous United States extent.  Biological Invasions 19:1999–2013.

Trotter RT and Keena MA. 2016. A Variable-Instar Climate-Driven Individual Beetle-Based Phenology Model for the Invasive Asian Longhorned Beetle (Anoplophora glabripennis, Coleoptera:Cerambycidae).  Environ. Entomol. 45(6):1360-1370.

Keena, MA. 2009. Phenology of the Asian longhorned beetle under simulated annual environmental fluctuations. In: McManus, Katherine; Gottschalk, Kurt W., eds. Proceedings, 19th U.S. Department of Agriculture interagency research forum on invasive species 2008: 2008 January 8-11; Annapolis, MD. Gen. Tech. Rep. NRS-P-36. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 37. Abstract.


Research Participants

Principal Investigators

  • Melody Keena, USDA Forest Service- Northern Research Station Research Entomologist
  • Talbot Trotter, USDA Forest Service- Northern Research Station Research Ecologist
  • Alexander P. Kappel, Clark University, Graduate School of Geography, former MS student
  • John Rogan, Clark University, Graduate School of Geography
  • Christopher A. Williams, Clark University, Graduate School of Geography

Last Modified: 07/14/2017