Diorhabda carinulata
Encyclopedia
Diorhabda carinulata is a species of leaf beetle
known as the northern tamarisk beetle (NTB) which feeds on tamarisk trees from southern Russia and Iran to Mongolia and western China. The NTB is used in North America as a biological pest control
agent against saltcedar or tamarisk (Tamarix
spp.), an invasive species
in arid and semi-arid ecosystems (where the NTB and its closely related sibling species
are also less accurately referred to as the 'saltcedar beetle', 'saltcedar leaf beetle', 'salt cedar leaf beetle', or 'tamarisk leaf beetle') (Tracy and Robbins 2009).
(Brullé). Chen (1961) described the NTB in western China as a new subspecies Diorhabda elongata deserticola Chen. Yu et al. (1996) proposed the species D. deserticola. Berti and Rapillly (1973) recognized the NTB as a separate species Diorhabda carinulata (Desbrochers) based on detailed morphology of the endophallus of the male genitalia. Tracy and Robbins (2009) confirmed the findings of Berti and Rapilly (1973), established D. e. deserticola as a junior synonym to D. carinulata, and provided illustrated taxonomic keys separating the NTB from the four other sibling species of the D. elongata (Brullé) species group: Diorhabda elongata
, Diorhabda carinata
(Faldermann), Diorhabda sublineata
(Lucas), and Diorhabda meridionalis
Berti and Rapilly. In literature prior to 2009, D. carinulata was usually referred to as D. elongata, a China/Kazakhstan ecotype of D. elongata (in the U.S.), or D. elongata deserticola. (For additional information, see
Wikispecies: Diorhabda carinulata.)
(Tracy and Robbins 2009). Extensive laboratory host range studies verified that NTB is a specialist feeder on tamarisks, feeding only on plants of the tamarisk family. In North America, NTB prefer T. ramosissima to T. parviflora in the field (Dudley et al. 2006) and this preference is also seen in laboratory studies (Dalin et al. 2009). In laboratory and field cage studies, the NTB will also feed and complete development on Frankenia shrubs of the family Frankeniaceae
, distant relatives of tamarisks in the same plant order Tamaricales
, but NTB greatly prefer to lay eggs upon tamarisk (DeLoach et al. 2003, Lewis et al. 2003a, Milbrath and DeLoach 2006). Field studies in Nevada confirm that the NTB will not significantly attack Frankenia (Dudley and Kazmer 2005).
Wikimedia Commons: Diorhabda carinulata.) From two to four generations of tamarisk beetles occur through spring and fall in central Asia. In the late summer and early fall adults begin to enter diapause in which they cease reproduction and feed to build fat bodies before seeking a protected place to overwinter beneath the tamarisk (Lewis et al. 2003b). Larvae and adults are sensitive to shorter daylengths as the summer progresses that signal the coming of winter and induce diapause (Bean et al. 2007a, 2007b). Cossé et al. (2005) identified an aggregation pheromone
that adult male NTB can emit to attract both males and females to certain tamarisk trees.
in 2001. Since its release, the NTB has defoliated tens of thousands of acres of tamarisk in Nevada, Utah, Colorado and Wyoming. However, the NTB appears to be poorly adapted to some areas where other species of Old World tamarisk beetles are being introduced, such as the Mediterranean tamarisk beetle, Diorhabda elongata
, in northern California and parts of west Texas, and the larger tamarisk beetle, Diorhabda carinata
(Faldermann), and the subtropical tamarisk beetle, Diorhabda sublineata
(Lucas), in parts of west Texas (Tracy and Robbins 2009).
Tamarisk does not usually die from a single defoliation from tamarisk beetles, and it can resprout within several weeks of defoliation. Repeated defoliation of individual tamarisk trees can lead to severe dieback the next season and death of the tree within several years (DeLoach and Carruthers 2004). Tamarisk beetle defoliation over the course of at least one to several years can severely reduce the nonstructural carbohydrate reserves in the root crowns of tamarisk (Hudgeons et al. 2007). Biological control of tamarisk by the NTB will not eradicate tamarisk but it has the potential to suppress tamarisk populations by 75–85%, after which both NTB and tamarisk populations should reach equilibrium at lower levels (DeLoach and Carruthers 2004, Tracy and DeLoach 1999).
A primary objective of tamarisk biological control with the NTB is to reduce competition by exotic tamarisk with a variety of native riparian flora, including trees (willows, cottonwoods, and honey mesquite), shrubs (wolfberry, saltbush, and baccharis), and grasses (alkali sacaton, saltgrass, and creeping and basin wildryes). Unlike expensive chemical and mechanical controls of tamarisk that often must be repeated, tamarisk biological control does not harm native flora and is self-sustaining in the environment. Recovery of native riparian grasses can be quite rapid under the once closed canopy of repeatedly defoliated tamarisk. However, tamarisk beetle defoliation can locally reduce nesting habitat for riparian woodland birds until native woodland flora are able to return. In some areas, tamarisk may be replaced by grasslands or shrublands, resulting in losses of riparian forest habitats for birds (Tracy and DeLoach 1999). Releases of tamarisk beetles in southern California, Arizona, and along the Rio Grande in western New Mexico, are currently delayed until concerns can be resolved regarding safety of tamarisk biological control to nesting habitats of the federally endangered southwestern willow flycatcher, Empidonax traillii Audubon subspecies extimus Phillips, which will nest in tamarisk (see DeLoach et al. 2000, Dudley and DeLoach 2004). The NTB has defoliated some tamarisk nest trees of the southwestern willow flycatcher on the Virgin River in southern Utah, and actions to protect the flycatcher are under consideration. In 2010, the USDA Animal and Plant Health Inspection Service
(APHIS) officially discontinued its program for release of the NTB in 13 northwestern states (USDA APHIS 2005) over concern for the flycatcher (Gruver 2010). The Colorado Department of Agriculture is continuing to redistribute beetles within their state and they are seeing vigorous growth of native vegetation such as willows in response to reductions in tamarisk by the NTB (Johnson 2010).
Leaf beetle
Beetles in the family Chrysomelidae are commonly known as leaf beetles. This is a family of over 35,000 species in more than 2,500 genera, one of the largest and most commonly encountered of all beetle families....
known as the northern tamarisk beetle (NTB) which feeds on tamarisk trees from southern Russia and Iran to Mongolia and western China. The NTB is used in North America as a biological pest control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
agent against saltcedar or tamarisk (Tamarix
Tamarix
The genus Tamarix is composed of about 50-60 species of flowering plants in the family Tamaricaceae, native to drier areas of Eurasia and Africa...
spp.), an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
in arid and semi-arid ecosystems (where the NTB and its closely related sibling species
Sibling species
Sibling species are species that are very similar in appearance, in behavior and in other characteristics, but they are reproductively isolated. In other words, sibling species are pairs or groups of genetically closely related species which are often morphologically indistinguishable, but are...
are also less accurately referred to as the 'saltcedar beetle', 'saltcedar leaf beetle', 'salt cedar leaf beetle', or 'tamarisk leaf beetle') (Tracy and Robbins 2009).
Taxonomy
The NTB was first described from southern Russia as Galeruca carinulata Desbrochers (1870). Weise (1893) created the genus Diorhabda and erroneously placed the NTB as a junior synonym of a sibling species, the Mediterranean tamarisk beetle, Diorhabda elongataDiorhabda elongata
Diorhabda elongata is a species of leaf beetle known as the Mediterranean tamarisk beetle which feeds on tamarisk trees from Portugal and Algeria east to southern Russia...
(Brullé). Chen (1961) described the NTB in western China as a new subspecies Diorhabda elongata deserticola Chen. Yu et al. (1996) proposed the species D. deserticola. Berti and Rapillly (1973) recognized the NTB as a separate species Diorhabda carinulata (Desbrochers) based on detailed morphology of the endophallus of the male genitalia. Tracy and Robbins (2009) confirmed the findings of Berti and Rapilly (1973), established D. e. deserticola as a junior synonym to D. carinulata, and provided illustrated taxonomic keys separating the NTB from the four other sibling species of the D. elongata (Brullé) species group: Diorhabda elongata
Diorhabda elongata
Diorhabda elongata is a species of leaf beetle known as the Mediterranean tamarisk beetle which feeds on tamarisk trees from Portugal and Algeria east to southern Russia...
, Diorhabda carinata
Diorhabda carinata
Diorhabda carinata is a species of leaf beetle known as the larger tamarisk beetle which feeds on tamarisk trees from Ukraine, eastern Turkey and Syria east to northwest China, Kyrgyzstan and Pakistan, extending as far south as southern Iran...
(Faldermann), Diorhabda sublineata
Diorhabda sublineata
Diorhabda sublineata is a species of leaf beetle known as the subtropical tamarisk beetle which feeds on tamarisk trees from Portugal, Spain and France to Morocco, Senegal, Algeria, Tunisia, Egypt, Yemen, and Iraq...
(Lucas), and Diorhabda meridionalis
Diorhabda meridionalis
Diorhabda meridionalis is a species of leaf beetle known as the southern tamarisk beetle which feeds on tamarisk trees from Syria to western and southern Iran and southern Pakistan...
Berti and Rapilly. In literature prior to 2009, D. carinulata was usually referred to as D. elongata, a China/Kazakhstan ecotype of D. elongata (in the U.S.), or D. elongata deserticola. (For additional information, see
Wikispecies: Diorhabda carinulata.)Host plants
Extensive literature on the biology and host range of the NTB in Kazakhstan, China, and Mongolia are found under the names of Diorhabda elongata and Diorhabda elongata deserticola. The NTB is a well known pest of tamarisk in western China where in certain years large outbreaks of the beetle can defoliate thousands of acres of tamarisk trees. The NTB is controlled in western China to protect plantings of tamarisk for windbreaks and soil stabilization. In nature, the NTB feeds on at least 14 species of tamarisk and the closely related genus Myricaria, and all these food plants are restricted to the tamarisk plant family TamaricaceaeTamaricaceae
Tamaricaceae is a flowering plant family containing four genera. In the 1980s, the family was classified in the Violales under the Cronquist system; more modern classifications place them in the Caryophyllales.The family is native to drier areas of Europe, Asia and Africa...
(Tracy and Robbins 2009). Extensive laboratory host range studies verified that NTB is a specialist feeder on tamarisks, feeding only on plants of the tamarisk family. In North America, NTB prefer T. ramosissima to T. parviflora in the field (Dudley et al. 2006) and this preference is also seen in laboratory studies (Dalin et al. 2009). In laboratory and field cage studies, the NTB will also feed and complete development on Frankenia shrubs of the family Frankeniaceae
Frankeniaceae
Frankeniaceae is the botanical name for a family of flowering plants. Such a family has been widely recognized by many taxonomists; it has commonly been assumed to be closely related to family Tamaricaceae....
, distant relatives of tamarisks in the same plant order Tamaricales
Tamaricales
The Tamaricales are an order of dicotyledons. This order has been abandoned by the most recent systems, and the three families in the order have been distributed to other orders:* family Tamaricaceae, now in the Caryophyllales;...
, but NTB greatly prefer to lay eggs upon tamarisk (DeLoach et al. 2003, Lewis et al. 2003a, Milbrath and DeLoach 2006). Field studies in Nevada confirm that the NTB will not significantly attack Frankenia (Dudley and Kazmer 2005).
Life cycle
The NTB overwinters as adults on the ground in leaf litter beneath tamarisk trees. Adults become active and begin feeding and mating in the early spring when tamarisk leaves are budding. Eggs are laid on tamarisk leaves and hatch in about a week in warm weather. Three larval stages feed on tamarisk leaves for about two and a half weeks when they crawl to the ground and spend about 5 days as a “C”-shaped inactive prepupa before pupating about one week. Adults emerge from pupae to complete the life cycle in about 4–5 weeks in the summer. (For images of various life stages, see Wikimedia Commons: Diorhabda carinulata.) From two to four generations of tamarisk beetles occur through spring and fall in central Asia. In the late summer and early fall adults begin to enter diapause in which they cease reproduction and feed to build fat bodies before seeking a protected place to overwinter beneath the tamarisk (Lewis et al. 2003b). Larvae and adults are sensitive to shorter daylengths as the summer progresses that signal the coming of winter and induce diapause (Bean et al. 2007a, 2007b). Cossé et al. (2005) identified an aggregation pheromonePheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
that adult male NTB can emit to attract both males and females to certain tamarisk trees.
Biological control agent
The NTB is currently the most successful biological control agent for tamarisk in North America. Populations of NTB from around 44°N latitude at Fukang, China and Chilik, Kazakhstan were initially released by the USDA Agricultural Research ServiceAgricultural Research Service
The Agricultural Research Service is the principal in-house research agency of the United States Department of Agriculture . ARS is one of four agencies in USDA's Research, Education and Economics mission area...
in 2001. Since its release, the NTB has defoliated tens of thousands of acres of tamarisk in Nevada, Utah, Colorado and Wyoming. However, the NTB appears to be poorly adapted to some areas where other species of Old World tamarisk beetles are being introduced, such as the Mediterranean tamarisk beetle, Diorhabda elongata
Diorhabda elongata
Diorhabda elongata is a species of leaf beetle known as the Mediterranean tamarisk beetle which feeds on tamarisk trees from Portugal and Algeria east to southern Russia...
, in northern California and parts of west Texas, and the larger tamarisk beetle, Diorhabda carinata
Diorhabda carinata
Diorhabda carinata is a species of leaf beetle known as the larger tamarisk beetle which feeds on tamarisk trees from Ukraine, eastern Turkey and Syria east to northwest China, Kyrgyzstan and Pakistan, extending as far south as southern Iran...
(Faldermann), and the subtropical tamarisk beetle, Diorhabda sublineata
Diorhabda sublineata
Diorhabda sublineata is a species of leaf beetle known as the subtropical tamarisk beetle which feeds on tamarisk trees from Portugal, Spain and France to Morocco, Senegal, Algeria, Tunisia, Egypt, Yemen, and Iraq...
(Lucas), in parts of west Texas (Tracy and Robbins 2009).
Tamarisk does not usually die from a single defoliation from tamarisk beetles, and it can resprout within several weeks of defoliation. Repeated defoliation of individual tamarisk trees can lead to severe dieback the next season and death of the tree within several years (DeLoach and Carruthers 2004). Tamarisk beetle defoliation over the course of at least one to several years can severely reduce the nonstructural carbohydrate reserves in the root crowns of tamarisk (Hudgeons et al. 2007). Biological control of tamarisk by the NTB will not eradicate tamarisk but it has the potential to suppress tamarisk populations by 75–85%, after which both NTB and tamarisk populations should reach equilibrium at lower levels (DeLoach and Carruthers 2004, Tracy and DeLoach 1999).
A primary objective of tamarisk biological control with the NTB is to reduce competition by exotic tamarisk with a variety of native riparian flora, including trees (willows, cottonwoods, and honey mesquite), shrubs (wolfberry, saltbush, and baccharis), and grasses (alkali sacaton, saltgrass, and creeping and basin wildryes). Unlike expensive chemical and mechanical controls of tamarisk that often must be repeated, tamarisk biological control does not harm native flora and is self-sustaining in the environment. Recovery of native riparian grasses can be quite rapid under the once closed canopy of repeatedly defoliated tamarisk. However, tamarisk beetle defoliation can locally reduce nesting habitat for riparian woodland birds until native woodland flora are able to return. In some areas, tamarisk may be replaced by grasslands or shrublands, resulting in losses of riparian forest habitats for birds (Tracy and DeLoach 1999). Releases of tamarisk beetles in southern California, Arizona, and along the Rio Grande in western New Mexico, are currently delayed until concerns can be resolved regarding safety of tamarisk biological control to nesting habitats of the federally endangered southwestern willow flycatcher, Empidonax traillii Audubon subspecies extimus Phillips, which will nest in tamarisk (see DeLoach et al. 2000, Dudley and DeLoach 2004). The NTB has defoliated some tamarisk nest trees of the southwestern willow flycatcher on the Virgin River in southern Utah, and actions to protect the flycatcher are under consideration. In 2010, the USDA Animal and Plant Health Inspection Service
Animal and Plant Health Inspection Service
Animal and Plant Health Inspection Service is an agency of the United States Department of Agriculture responsible for protecting animal health, animal welfare, and plant health. APHIS is the lead agency for collaboration with other agencies to protect U.S. agriculture from invasive pests and...
(APHIS) officially discontinued its program for release of the NTB in 13 northwestern states (USDA APHIS 2005) over concern for the flycatcher (Gruver 2010). The Colorado Department of Agriculture is continuing to redistribute beetles within their state and they are seeing vigorous growth of native vegetation such as willows in response to reductions in tamarisk by the NTB (Johnson 2010).
External links
- Center for Biological Diversity 17 June 2009 press release regarding lawsuit to protect the southwestern willow flycatcher in view of defoliation of tamarisk nesting habitat by D. carinulata. http://www.biologicaldiversity.org/news/press_releases/2009/southwestern-willow-flycatcher-06-17-2009.html
- Montana War on Weeds information on D. carinulata (not D. elongata) for tamarisk biocontrol. http://mtwow.org/Diorhabda-elongata.htm
- Tamarisk Coalition information on tamarisk biocontrol (China and Kazakhstan source tamarisk beetles are D. carinulata).http://www.tamariskcoalition.org/tamariskcoalition/BioControl.html
- University of California Berkeley Campus News article on initial 2001 release of D. carinulata (not D. elongata).
- USDA/ARS research with D. carinulata (not D. elongata) for tamarisk biocontrol in Wyoming and Montana. http://www.ars.usda.gov/Research/docs.htm?docid=10524
- USDA/ARS and Texas Agri-Life Research and Extension Service Report of Information to the Public; Progress on Biological Control of Saltcedar in the Western U.S.: Emphasis—Texas 2004-2009. PDF