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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICAL CONTROL OF INVASIVE PLANTS OF THE NORTHERN GREAT PLAINS

Location: Pest Management Research Unit

Title: Seasonal adaptations to day length in ecotypes of Diorhabda spp. (Coleoptera: Chrysomelidae) inform selection of agents against saltcedars (Tamarix spp.)

Authors
item Dalin, Peter -
item Bean, Daniel -
item Dudley, Tom -
item Carney, Vanessa -
item Eberts, Debra -
item Gardner, Kevin -
item Jones, Erin -
item Kazmer, David
item Michels Jr, G -
item O'Meara, Scott -

Submitted to: Ecological Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 29, 2010
Publication Date: October 1, 2010
Repository URL: http://hdl.handle.net/10113/46261
Citation: Dalin, P., Bean, D.W., Dudley, T., Carney, V.A., Eberts, D., Gardner, K.T., Jones, E.M., Kazmer, D.J., Michels Jr, G.J., O'Meara, S.A. 2010. Seasonal adaptations to day length in ecotypes of Diorhabda spp. (Coleoptera: Chrysomelidae) inform selection of agents against saltcedars (Tamarix spp.). Ecological Entomology. 39(5): 1666-1675.

Interpretive Summary: 1. Seasonal adaptations to day length often limit the effective range of biocontrol insects. The leaf beetle Diorhabda carinulata was introduced into North America from Fukang, China (latitude 44°N) for the biocontrol of saltcedars (Tamarix spp.), but failed to establish below 38° latitude because of a mismatched critical day length response for diapause induction which caused beetles to enter diapause too early in the season to survive the winter at southern latitudes. 2. Using climate chambers, we characterized the critical day length response for diapause induction (CDL) in three ecotypes of Diorhabda beetles originating from 36°, 38° and 43° latitudes in Eurasia. In a field experiment, the timing of reproductive diapause and voltinism was compared among ecotypes by rearing the insects on plants in the field. 3. CDL declined with latitude of origin among Diorhabda ecotypes. Moreover, CDL in southern (<40° latitude) ecotypes was shortened by more than an hour when the insects were reared under a fluctuating 35-15°C thermoperiod than at constant 25°C. In the northern (>40° latitude) ecotypes, however, CDL was relatively insensitive to temperature. 4. The southern ecotypes produced up to four generations when reared on plants in the field at sites below 38°, whereas northern ecotypes produced only one or two generations. 5. The study reveals latitudinal variation in how Diorhabda ecotypes respond to day length for diapause induction and how these responses affect insect voltinism across the introduced range.

Technical Abstract: 1. Seasonal adaptations to day length often limit the effective range of biocontrol insects. The leaf beetle Diorhabda carinulata was introduced into North America from Fukang, China (latitude 44°N) for the biocontrol of saltcedars (Tamarix spp.), but failed to establish below 38° latitude because of a mismatched critical day length response for diapause induction which caused beetles to enter diapause too early in the season to survive the winter at southern latitudes. 2. Using climate chambers, we characterized the critical day length response for diapause induction (CDL) in three ecotypes of Diorhabda beetles originating from 36°, 38° and 43° latitudes in Eurasia. In a field experiment, the timing of reproductive diapause and voltinism was compared among ecotypes by rearing the insects on plants in the field. 3. CDL declined with latitude of origin among Diorhabda ecotypes. Moreover, CDL in southern (<40° latitude) ecotypes was shortened by more than an hour when the insects were reared under a fluctuating 35-15°C thermoperiod than at constant 25°C. In the northern (>40° latitude) ecotypes, however, CDL was relatively insensitive to temperature. 4. The southern ecotypes produced up to four generations when reared on plants in the field at sites below 38°, whereas northern ecotypes produced only one or two generations. 5. The study reveals latitudinal variation in how Diorhabda ecotypes respond to day length for diapause induction and how these responses affect insect voltinism across the introduced range.

Last Modified: 8/22/2014