Development of a novel repellant compound for the potential management of the northern tamarisk beetle (Diorhabda carinulata). Repellant has been shown to be effective on reproductive adults and alter the behaviors of 1st and 2nd instar larvae. Continued development and field deployment of this repellent compound may provide a new tool for the management of D. carinulata.
Stahlke et al. developed a reference genome for tamarisk beetles (Diorhabda spp.) and reference panel of all four introduced parental species to monitor range expansion and hybridization across North America. They found a substantial genetic bottleneck among D. carinulata in N. America, although populations continue to establish and spread, possibly due to aggregation behavior. Among hybrids, they found that D. carinata, D. elongata, and D.
To what extent has invasive riparian vegetation (IRV) treatment reversed channel narrowing and reduced dynamism trends? Paired treated and untreated reaches at 15 sites along 13 rivers were compared before and after treatment using repeat aerial imagery to assess long-term (~10 year) channel change due to treatment on a regional scale across the Southwest U.S. Wieting et al. found that IRV treatment significantly increased channel width and floodplain destruction.
Clark et al. evaluated theoretical predictions for evolution of reproductive life-history and dispersal traits in the range expansion of the tamarisk biological control agent, Diorhabda carinulata, or northern tamarisk beetle. With experiments run on field-collected populations, they found that females at the expansion front had increased fecundity and body mass, and reduced age at first reproduction; and that dispersal increased at the expansion front in males, especially when unmated and reared at low density.
Does hybridization among tamarisk beetles change the risk of non-target attack in the field? Clark et al. study the consequences of hybridization in tamarisk beetles (Diorhabda). They paired laboratory phenotyping with genomics to assess changes in risk of non-target attack and body size and fecundity. Body size and early fecundity were similar in pure and hybrid females, indicating that hybridization is not detrimental to insect fitness or the biocontrol program and may provide variation that allows populations to become locally adapted.
What site conditions are associated with greater recovery and overall higher cover of willows? Goetz et al. performed a meta-analysis of tamarisk removal and willow (Salix) recovery across the southwest, compiling data from 260 sites where tamarisk was subject to active removal and/or biocontrol and 132 reference sures. Cut-stump method with biological control was the most effective method to improve native species dominance. Willow cover was generally highest in locations with low drought stress, as reflected by soil properties, distance to water, and climate.
A study subjecting tamarisk from two distinct populations originating from areas with greatly varying soil salinities to a range of different salinities. Results showed dramatic differences between growth with the low salinity population accumulating 72% more biomass when grown at 4 ppt compared to 16 ppt, while the high salinity population produced 50% more biomass when grown at 16 ppt. Additionally, the high salinity population had a lower turgor loss point and exhibited greater stomatal control relative to the low salinity population.
The northern tamarisk beetle Diorhabda carinulata (Desbrochers) was approved for release in the United States for classical biological control of a complex of invasive saltcedar species and their hybrids (Tamarix spp.). An aggregation pheromone used by D. carinulata to locate conspecifics is fundamental to colonization and reproductive success.
Riverine ecosystems are known to provide important habitat for avian communities, but information on responses of birds to differing levels of Tamarix is not known. Past research on birds along the Colorado River has shown that avian abundance in general is greater in native than in non-native habitat.
In this chapter, Carothers et al have three objectives: first, they document the value of nonnative Tamarix as summer habitat for birds compared to native riparian habitats of mesquite bosques and cottonwood/willow, and mixed deciduous gallery woodlands; second, they specifically focus on the unintended consequences to native avifauna of dam construction, Tamarix invasion, native vertebrate colonization of the Tamarix-dominated riparian habitat, and subsequent biocontrol along approximately 300 miles of the Colorado River in Grand and Glen Canyons; and, third, the