Evaluation of hybridization among three Laricobius species, predators of hemlock woolly adelgid, (Adelgidae)
Fischer, Melissa J
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Hybridization was evaluated among three Laricobius spp. involved in the biological control of hemlock woolly adelgid (Adelges tsugae Annand). Following lab mating studies, there was no evidence that Laricobius osakensis Montgomery and Yu could produce hybrid progeny with either Laricobius nigrinus Fender or Laricobius rubidus LeConte. Interaction between L. osakensis and L. nigrinus did not result in a lower production of progeny as a result of fitness costs associated with interspecific mating attempts. Laricobius nigrinus and L. rubidus hybrids were produced in the lab and collected in the field. Hybrid progeny showed very little evidence of decreased fitness. For example, there was no significant difference in the number of days it took for hybrids and pure parental species to develop from egg hatch to the prepupal stage, there was no difference among hybrids and pure parental species in the head capsule widths and larval lengths for the first through third instar, and there was evidence of an F2 generation from field collected specimens. Hybrids produced in the lab had intermediate shaped genital paramere angles compared with parental species, and had elytra coloration similar to that of L. rubidus. Hybrids showed no host preference in the lab, but a preference for Adelges tsugae in the field. Of 12 site factors examined, only the number of years that L. nigrinus was present at the site was found to be associated with percent hybrids. Contamination of the L. osakensis colony with Laricobius naganoensis Leschen resulted in the need to develop molecular methods to differentiate L. osakensis from L. naganoensis. Three restriction enzymes were found that correctly differentiated the two species.
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Prey-mediated effects of imidacloprid on Laricobius nigrinus (Coleoptera: Derodontidae) and Sasajiscymnus tsugae (Coleoptera: Coccinellidae), two predators of hemlock woolly adelgid Eisenback, Brian Matthew (Virginia Tech, 2008-06-27)Prey-mediated effects of imidacloprid were evaluated for Laricobius nigrinus Fender and Sasajiscymnus tsugae Sasaji and McClure after feeding on hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae). ...
Evaluating the suitability of Laricobius nigrinus Fender (Coleoptera: Derodontidae), a biological control agent for hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae) Lamb, Ashley B. (Virginia Tech, 2005-04-20)Hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), is an introduced pest injurious to hemlock trees (Tsuga spp.) in the eastern United States. HWA currently infests hemlock in over 50% of its ...
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