Taxonomic revision and biogeography of the Tamarix-feeding Diorhabda elongata (Brullé, 1832) species group (Coleoptera: Chrysomelidae: Galerucinae: Galerucini) and analysis of their potential in biological control of Tamarisk

Abstract

The primarily Palearctic Diorhabda elongata species group is established for five Tamarix-feeding sibling species(tamarisk beetles): D. elongata (Brullé, 1832), D. carinata (Faldermann, 1837), D. sublineata (Lucas, 1849) REVISEDSTATUS, D. carinulata (Desbrochers, 1870), and D. meridionalis Berti & Rapilly, 1973 NEW STATUS. Diorhabdakoltzei ab. basicornis Laboissière, 1935 and D. e. deserticola Chen, 1961 are synonymized under D. carinulata NEWSYNONYMY. Illustrated keys utilize genitalia, including male endophallic sclerites and female vaginal palpi andinternal sternite VIII. Distribution, comparative biogeography, biology, and potential in biological control of Tamarix inNorth America are reviewed. Diorhabda elongata is circummediterranean, favoring Mediterranean and temperate forestsof Italy to western Turkey. Diorhabda carinata resides in warm temperate grasslands, deserts, and forests of southernUkraine south to Iraq and east to western China. Diorhabda sublineata occupies Mediterranean woodlands from Franceto North Africa and subtropical deserts east to Iraq. Diorhabda carinulata primarily inhabits cold temperate deserts ofMongolia and China west to Russia and south to montane grasslands and warm deserts in southern Iran. Diorhabdameridionalis primarily occupies maritime subtropical deserts of southern Pakistan and Iran to Syria. Northern climatypesof D. carinulata are effective in Tamarix biological control, especially in the Great Basin desert. Diorhabda elongata isprobably best suited to Mediterranean woodlands of northern California. Northern climatypes of D. carinata may be bestsuited for central U.S. grasslands. Diorhabda sublineata, D. meridionalis, and southern climatypes of D. carinata and D. carinulata may each be uniquely suited to areas of the southwestern U.S.

Host Plant Quality ofTamarix ramosissimaandT. parviflorafor Three Sibling Species of the Biocontrol InsectDiorhabda elongata(Coleoptera: Chrysomelidae)

“…Neither did we Þnd any strong support for our alternative hypothesis that beetles should show the highest preference for, and the best performance on, the host species that predominate in the beetlesÕ areas of origin. For example, we did not Þnd an increased preference for or greater performance on T. parviflora in D. elongata, although the beetleÕs distribution range overlaps with T. parviflora in the Mediterranean region where T. ramosissima is absent (Baum 1978, Tracy andRobbins 2009). Similar results were found for D. carinata, although the distribution ranges of the two Tamarix species suggest that this subspecies should be better adapted to feed on T. ramosissima (Baum 1978, Gaskin andSchaal 2002).…”

“…The beetles were originally collected in central Asia and released at many sites across nine states starting in 2001 (Dudley et al 2001, Lewis et al 2003. The beetles were referred to as a subspecies of D. elongata (D. e. deserticola), but the taxonomy has recently been updated, and the central Asia beetles should currently be referred to as D. carinulata (Desbrochers) (Tracy and Robbins 2009). In this paper, we will follow this new taxonomy of Diorhabda species group.…”

“…These beetles differ in several ecological aspects, especially in their response to temperature and daylength for diapause induction (Dudley et al 2006). The beetles are considered to be different Diorhabda sibling species and colonies currently maintained under quarantine in the United States include D. carinulata from central Asia, D. elongata (Brullé ) from the eastern Mediterranean area, and D. carinata (Faldermann) from western Asia (Tracy and Robbins 2009). All are specialized to feed on Tamarix spp.…”

“…(Milbrath and DeLoach 2006), but there is limited information about what species of Tamarix the different sibling species feed on in their native ranges. The Mediterranean D. elongata may be adapted to feed on T. parviflora because its distribution range overlaps with the plant T. parviflora in the Mediterranean basin (Tracy and Robbins 2009). However, because of a lack of knowledge about the beetlesÕ host ranges, it is currently difÞcult to predict the success of the beetles in the control of T. parviflora.…”

Temperature-dependent development, diapause and cold tolerance of Gratiana graminea, a potential biological control agent of Solanum viarum in Florida, USA

“…Tauber and Tauber 1976;Gomi and Takeda 1992), which may affect agent establishment. For example, the Tamarix-feeding beetle Diorhabda carinulata (Desbrochers) (Chrysomelidae) initially failed to establish in some areas in North America south of 38°N latitude probably due to the premature diapause during the summer rather than the fall, resulting in inadequate food reserves for overwintering (Bean et al 2007;Tracy and Robbins 2009). According to Diaz et al (2011), adults of G. boliviana enter diapause when exposed to short photoperiods (10:14 L:D h) and 22°C or 25°C.…”