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No description available.

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No description available.

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Four closely related species of leaf beetles (Diorhabda spp.; Coleoptera:Chrysomelidae) have been introduced into the western United States as biocontrol agents for the invasive Eurasian shrub tamarisk (Tamarix spp.; Violales:Tamaricaceae). These beetles have since continued to spread and establish throughout the western United States. Another exotic insect, the tamarisk leafhopper (Opsius stactogalus, Fieber;Hemiptera: Cicadellidae), had previously become established in these areas and now shares tamarisk as a host plant with the beetles. To assess more carefully the potential for interactions between leafhoppers and beetles, field censuses and cage studies were conducted to determine the phenologies and potential interactions of O. stactogolus and D. carinulata when attacking Tamarix ramosissima (Ledebour) in western Colorado. The leafhopper underwent development through at least three generations per season, whereas the beetle was shown to develop through two generations per season. Variation in leafhopper abundance was associated with the extent and type of foliar damage to tamarisk trees. Individual trees with greatest D. carinulata abundances and subsequent defoliation had significantly reduced O. stactogalus abundances thereafter. Abundance of O. stactogalus was also shown to vary significantly among tamarisk plants in cage settings where leafhoppers were given the choice of potted tamarisk plants with ~50% damage to foliage from D. carinulata versus undamaged plants. In contrast, D. carinulata abundance was not shown to differ strongly in response to O. stactogalus damage in the field or in cage experiments. Field results across sites, however, showed similar trends of reduced beetle abundance on plants more heavily attacked by leafhoppers, and larval growth tests suggested slight reductions in larval pupation and adult emergence of D. carinulata when grown on O. stactogalus-damaged tamarisk. It is not clear if slight tendencies in D. carinulata abundance along with much stronger responses in O. stactogalus abundance were the result of limited plant material, rather than an induced plant defense. It is clear, however, that these specialist herbivores are interacting in an asymmetric competitive fashion while feeding on the same host plant.

This study investigates the pheromone preference of a bark beetle predator Thanasimus dubius between latent and intermediate phases of southern pine beetle. Two trap treatments were set up in each SPB phase. Standard Lindgren funnel traps were baited with either SPB lures or Ips lures. The number of T. dubius caught in each trap was recorded and data was analyzed using both the Mann Whitney U test and a two-way factorial ANOVA. Thanasimus dubius showed no variation in SPB pheromone preference but did show a slight increase in preference for Ips pheromones in intermediate phase areas. A protocol was developed to identify prey DNA within gut contents of T. dubius to understand prey preference in relation to pheromone preference. Primers were developed to amplify CO1 gene sequences from five different bark beetles. All primers were specific to their own DNA and able to detect at least 0.2 picograms of DNA.

No description available.