Factors that Affect Pupation and Adult Emergence
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 adult emergence which is fundamental to the development and improvement of exclusion and eradication methodologies. In addition, this information can help in predicting whether larvae in cut wood will be able to complete development and emerge to potentially start a new infestation.
Effects of Temperature on Pupation and Adult Emergence
Pupation of ALB from two populations (Ravenswood, Chicago, Illinois, and Worcester, Massachusetts) was evaluated under different constant temperature regimes. The affects of chilling large larvae of different sizes, for different lengths of time, and at different temperatures on pupation were investigated. Temperature affects on how fast new adults could scleritize and chew out of artificial wood chambers was also investigated.
Effects of Dietary Moisture on Pupation
Larval survival, development, and pupation of ALB from two populations (Ravenswood, Chicago, Illinois, and Worcester, Massachusetts) were evaluated using 3 different dietary moisture regimes. Timing of pupation and weight at pupation will be compared.
The responses of ALB to temperature can be used for predicting the potential geographical range of this species and in developing phenological models to predict the timing of adult emergence which is important for management programs. The biological basis for predicting emergence of adults from cut wood so that the potential for spread and infestation of new areas can be better understood.
Effects of Temperature on Pupation
Larvae did not pupate at constant temperatures > 30ºC or < 10ºC. The number of instars larvae went through before pupation varied from a minimum of 5 to more than 9 depending on the temperature regime and larval nutrition. It took about 2 years for larvae to complete development at a constant 15ºC, or if eggs hatched too late to allow larvae to reach the critical weight/instar for pupation before chill in a varying temperature regime.
Larvae from the Illinois population began pupation sooner than those from New York or China and were least affected by the timing of the larval chill period. The Chinese population was the most sensitive to the timing of chill, possibly indicating that larvae from this population tend to pupate at a later instar, more individuals may require a chill to complete development, or that some individuals may require more than one year to complete development under some conditions. A larval chill period was not required by all the larvae, which is consistent with earlier findings. Some larvae that had not reached their critical weight for pupation prior to the chill period required a second chill period before they initiated pupation. The critical weight for pupation appears to vary both within and between populations, which could indicate a high degree of plasticity or genetic variation for this trait. Overall survival decreased when the developmental time decreased before the chill period. Manipulating the timing of the larval chill appeared to be useful for synchronizing adult emergence and increasing pupation.
When larvae were chilled at 15°C they required a longer chill period to cue them to pupate and in general it took them longer to initiate pupation after the chill than those held at lower temperatures. It appears that there are several factors that can interact to affect Asian longhorned beetle pupation.
Keena, MA. 2005. Pourable artificial diet for rearing Anoplophora glabripennis (Coleoptera: Cerambycidae) and methods to optimize larval survival and synchronize development. Ann., Entomol. Soc. Am. 98(4): 536-547.
Keena, MA. 2007. Factors that Influence Asian Longhorned beetle Pupation, pp. 125-126 In Victor Mastro, David Lance, Richard Reardon, and Gregory Parra, compilers. Emerald Ash Borer and Asian Longhorned Beetle Research and Technology Development Meeting; October 29-November 2, 2006; Cincinnati, OH. U.S. Department of Agriculture, Forest Service, Forest Health Technology Enterprise Team FHTET-2007-04.
Effects of Temperature on Adult Emergence
The average depth of wood that the beetles chewed through was 7 mm (range 3-11 mm). Adult weight was positively correlated with exit hole diameter (diam. = 2.2 * weight (g) + 7.9). The rate at which beetles chewed through the wood (136, 178, and 168 mm/d at 20, 25 and 30 °C, respectively) significantly differed between temperatures. Heavier adults did not chew significantly faster than lighter adults although that was the trend. Temperature has a significant effect on the time it takes adults to scleritize and chew through Norway maple wood. On average, it took 7, 5, and 4 d to scleritize and 5, 4, and 4 d to chew out at 20, 25, and 30 °C, respectively, suggesting that beetles spend more than a week in the wood even at summer temperatures.
Keena, MA. and V Sánchez. 2008. How Long does it take teneral adult Anoplophora glabripennis (Coleoptera: Cerambycidae) to scleritize and then chew out of the wood? In Gottschalk KW, ed. Proceedings, 18th U.S. Department of Agriculture Interagency Research Forum on Gypsy Moth and Other Invasive Species 2007; 2007 January 9-12; Annapolis, MD. U.S. Dep. Agric., For. Serv., Northern Res. Sta., Gen. Tech. Rep. NRS-P-28. p 43.
Effects of Dietary Moisture on Pupation
We reared larvae from 2 populations (Worcester, MA and Chicago, IL), on artificial diets with experimentally manipulated moisture contents. Beetles developing within both low moisture and incrementally decreasing moisture environments pupated sooner than beetles reared in the standard, high moisture diet. Earlier pupation resulted in smaller adults, but contrary to expectations, there was no significant treatment effect on total egg production. From an applied perspective, firewood and pallets represent potential host wood with low, and declining moisture contents. A. glabripennis developing within these low moisture environments may develop earlier than existing models predict, thus emerging earlier in the spring and potentially having a longer period of time to reproduce and disperse. This may also increase the risk of establishment associated with movement of firewood as a pathway for human-mediated dispersal.
Whitney, A; Keena, MA. 2009. Asian Longhorned Beetle Phenology: Evaluating the Effects of Host Wood Moisture on Time to Pupation and Adult Eclosion. Published in McManus, KA; Gottschalk KW, eds. Proceedings, 21th U.S. Department of Agriculture Interagency Research Forum on Invasive Species 2010; 2010 January 12-15; Annapolis, MD. U.S. Dep. Agric., For. Serv., Northern. Res. Sta., Gen. Tech. Rep. NRS-P-75, p 142.
- Melody Keena, USDA Forest Service- Northern Research Station Research Entomologist
- Vicente Sanchez, USDA Forest Service – NRS Entomologist
- Paul Moore, USDA-Forest Service- NRS Biological Sciences Technician
- Alexandra Whitney, School of Forestry, Yale University, Master’s Student
Last Modified: 07/13/2017