Browsing by Author "Niemeyer, Hermann M."
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Item Demographic and performance effects of alternative host use in a Neotropical treehopper (Hemiptera: Membracidae)(2019) Pinto, Carlos F.; Torrico-Bazoberry, Daniel; Flores-Prado, Luis; Bustamante, Ramiro O.; Niemeyer, Hermann M.The mechanisms which promote divergence in populations of phytophagous insects using alternative hosts depend on the characterization of hosts as different selective scenarios and the modeling of the demographic dynamics of the insect on those hosts. In the Bolivian Yungas forests, the treehopper Alchisme grossa (Hemiptera: Membracidae) utilizes two sympatric Solanaceae hosts, Brugmansia suaveolens and Solanum ursinum. On both hosts, females take care of nymphs during their development and adults use almost exclusively their natal host species. We characterized: 1) the performance of families (mother and nymphs) on both hosts, 2) maternal care across families and hosts, 3) biotic (herbivory, predators and parasites) and abiotic (temperature, relative humidity and luminosity) conditions across hosts and 4) demographic parameters of cohorts living under natural conditions on both hosts using matrix population modelling. The life cycle was longer on B. suaveolens than on S. ursinum. Microenvironmental abiotic and biotic traits differed between hosts. Nevertheless, performance did not differ between hosts and no differences between hosts were found in demographic parameters. None of the environmental variables explained the demographic parameters. Females performed maternal care with the same intensity on both hosts. Taken together with published data on the system, these results suggest that individuals of A. grossa in this study belong to a single population. Colonization of one of these hosts might be a recent event and evolutionary processes that promote ecological adaptation and hence demographic or performance differences have not yet become noticeable.Item Response to selected ecological parameters by Leptus hringuri Haitlinger, 2000 larvae (Trombidiformes: Erythraeidae) parasitizing treehoppers (Hemiptera: Membracidae) from Bolivia on two host-plant species(2020) Torrico-Bazoberry, Daniel; Pinto, Carlos F.; Davyt-Colo, Joselina; Niemeyer, Hermann M.Larvae of Leptus hringuri parasitizing families (adult female + offspring) of the treehopper Alchisme grossa on two host-plants, Brugmansia suaveolens (BS) and Solanum ursinum (SU), were studied. The effect of microenvironmental abiotic conditions (luminosity, temperature and relative humidity) and biotic conditions (distance from the soil to a treehopper host and host-plant phenological stage) on this tritrophic interaction was examined. Overall, the results suggest i) intensity of mite infestation (mean number of mites per infested female or family) of treehoppers (insect hosts) was twice on SU than on BS, ii) a preference of L. hringuri larvae for places with more luminosity (on both host-plants) and relative humidity (on SU), iii) a negative correlation between larval infestation and distance of the host colony to the ground, and iv) that larvae of L. hringuri could detect cues (i.e. chemical) emitted by their insect hosts or the host-plant of the insect host. Results indicate that luminosity, humidity and distance to the ground of the insect-host microenvironment affect both parasitization and prevalence of Leptus larvae mites; however, further research will be needed to understand the ecological mechanisms and consequences of these interactions and to test the hypotheses proposed herein under a chemical ecology perspective.