@article {KNZ001672, title = {Weather affects grasshopper population dynamics in continental grassland over annual and decadal periods}, journal = {Rangeland Ecology and Management}, volume = {68}, year = {2015}, pages = {29 -39}, abstract = {

Understanding the complex dynamics of insect herbivores requires consideration of both exogenous and endogenous factors at multiple temporal scales. This problem is difficult due to differences in population responses among closely related taxa. Increased understanding of dynamic relationships between exogenous and endogenous factors will facilitate forecasting and suggest nodes in the life cycle of economically important species susceptible to intervention by managers. This study uses an information-theoretic approach to examine the contributions of weather and density to model population densities and growth rates of nine common grasshopper species from continental U.S. grassland over 25 years. In general, grass-feeding species and total grass-feeders as a functional group were most closely associated with weather during the year before hatching. Increased variability in prior growing season precipitation was associated with increased densities of Mermiria bivittata, Opeia obscura, Phoetaliotes nebrascensis, and the grass-feeding guild. Melanoplus sanguinipes densities tended to be smaller following warm fall seasons, while Amphitoruns coloradus declined during the positive phase of the North Atlantic Oscillation or after warmer than average winters. Population growth rate dynamics of all grouped species combinations were best explained by models including variability in precipitation during the prior year growing season. Large-scale Pacific Decadal Oscillation (PDO) patterns were also associated with growth rate dynamics of the mixed-feeding species group. Density showed a negative relationship with population growth rates of five species. This study indicates the importance of parental and diapause environmental conditions and the utility of incorporating long-term, readily obtained decadal weather indices for forecasting grasshopper densities and identifying critical years with regard to grasshopper management\—at least to the degree that the past will continue to predict the future as global climates change.

}, keywords = {LTER-KNZ, acrididae, atmospheric oscillations (NAO PDO SOI), density dependence, exogenous and endogenous feedbacks, grasshopper control, insect herbivores, population growth rate (R)}, doi = {10.1016/j.rama.2014.12.011}, url = {https://www.sciencedirect.com/science/article/pii/S1550742414000128?via\%3Dihub}, author = {Jonas, J.L. and Wolesensky, W. and Anthony Joern} } @article {KNZ001618, title = {Dietary selection and nutritional regulation in a common mixed-feeding insect herbivore}, journal = {Experimentalis et Applicata Entomologia}, volume = {148}, year = {2013}, pages = {20 -26}, abstract = {

The geometric framework provides a way for understanding the multi-dimensional nutritional relationships between consumers and their food. We use this approach to further our understanding of the feeding and nutritional ecology of a ubiquitous mixed-feeding insect herbivore that consumes a variety of host plants spanning a wide range of nutritional composition. Our overall objective was to examine feeding decisions, resulting performance, and post-ingestive consequences in a common mixed-feeding insect herbivore, Melanoplus bivittatus (Say) (Orthoptera: Acrididae), when presented with paired diets differing in protein:carbohydrate (p:c) ratio. Intake p:c of M. bivittatus differed among all but two treatments and in many cases was farther than expected from the previously identified p:c intake target for this species. Despite this variability in intake of protein and carbohydrate, we found few effects of the diet treatments on performance or post-ingestive processing. However, our results suggest that when feeding on high-quality diets, nutrients consumed in excess may be stored rather than excreted.

}, keywords = {LTER-KNZ, acrididae, carbohydrate, geometric framework, homeostasis, Melanoplus bivittatus, nutritional ecology, Orthoptera, protein}, doi = {10.1111/eea.12065}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/eea.12065}, author = {Jonas, J.L. and Anthony Joern} } @article {KNZ001458, title = {The invasive Lespedeza cuneata attracts more insect pollinators than native congeners in tallgrass prairie with variable impacts}, journal = {Biological Invasions}, volume = {14}, year = {2012}, pages = {1045 -1059}, abstract = {

Invasive plant species can potentially exert competitive or facilitative effects on insect pollination services of native species. Factors that influence these effects include the degree of shared pollinator species, synchronous flowering phenology, similar flower morphology and color, relatedness of invasive and natives, and showiness and densities of flowers. We investigated such plant-pollinator dynamics by comparing the invasive Lespedeza cuneata and three native congeners, all sympatric with synchronous flowering, using in situ populations over 2 years during peak floral displays. Insect visitation rates of the invasive were significantly higher per plant in both years than on the native species. The invasive exerted a competitive effect on visitation of the two native species with fewer shared pollinators, and a facilitative effect on visitation of the native species with the highest degree of shared insect visitors. Positive correlations were found between floral density and visitation rate per plant in all the native species. Although no such correlation was found for the invasive, floral density in L. cuneata was at least twenty times higher than in the native species and likely saturated the response of the pollinator community. Analyses of insect visitor taxonomic data indicated the insect communities visiting each of the Lespedeza species were generally similar though with species-specific differences. The main exception was that the common honeybee, Apis mellifera, was a primary visitor to the invasive plant species, yet was never observed on the native Lespedeza species.

}, keywords = {LTER-KNZ, Apis mellifera, Competition, Facilitation, Invasive, Lespedeza, Pollination}, doi = {10.1007/s10530-011-0138-0}, url = {https://link.springer.com/article/10.1007\%2Fs10530-011-0138-0}, author = {Woods, T.M. and Jonas, J.L. and Ferguson, C.J.} } @article {KNZ001336, title = {Grasshoppers (Orthoptera: Acrididae) select vegetation patches in local-scale responses to foliar nitrogen but not phosphorus in native grassland}, journal = {Insect Science}, volume = {18}, year = {2010}, pages = {533 -540}, abstract = {

Key elements such as nitrogen (N) and phosphorus (P) are often limiting relative to the nutritional needs of herbivores that feed on them. While N often limits insect herbivores in natural terrestrial ecosystems, the effect of P is poorly studied in the field, even though compelling hypotheses from the ecological stoichiometry literature predict its importance. We evaluated small-scale spatial distributions of, and herbivory by, grasshoppers among neighboring plots that vary in foliar-N and -P in tallgrass prairie. Grasshopper densities were 67\% greater in N-fertilized plots but detected no effect to grasshopper densities from P-fertilizer. Leaf damage to the dominant grass Andropogon gerardii was 32\% greater in N-fertilized plots, but no response to foliar-P was detected. Herbivore damage to a common forb, goldenrod (Solidago missouriensis), was not strongly linked by fertilizer treatments, although there was increased leaf damage in N-fertilizer treatments when no P was applied (a significant N \× P interaction). Under field conditions at local scales, we conclude that spatially heterogeneous distributions of grasshoppers are primarily affected by foliar-N in host plants with little evidence that P-levels contribute to the spatial patterns.

}, keywords = {LTER-KNZ, Andropogon gerardii, ecological stoichiometry, insect herbivory, Konza Prairie, N-P fertilization experiment, Solidago missouriensis}, doi = {10.1111/j.1744-7917.2010.01376.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1744-7917.2010.01376.x}, author = {Loaiza, V. and Jonas, J.L. and Anthony Joern} } @article {KNZ001167, title = {Does dietary-P affect feeding and performance in the mixed-feeding grasshopper (Acrididae) Melanoplus bivitattus?}, journal = {Environmental Entomology}, volume = {37}, year = {2008}, pages = {333 -339}, abstract = {

Although consequences of limited dietary protein and carbohydrate to performance are well studied for terrestrial insect herbivores, the importance of phosphorus (P) remains poorly understood. We examined the significance of dietary P to performance in fifth-instar nymphs of the grasshopper Melanoplus bivittatus fed artificial diets. Consumption, digestion, developmental rate, and growth in response to different levels of P nested within standard-Protein and carbohydrate diets were determined. Developmental rate was slowest on high-P diets; protein:carbohydrate concentration and P in diets affected frass production and consumption. Approximate digestibility and conversion of digested food were primarily influenced by the protein:carbohydrate quality of the diet but not P. Mass gain was marginally lower in the low-Protein:high carbohydrate diet used in this study. At the individual level, other than small effects to developmental rate at high concentrations for M. bivittatus, dietary P otherwise seems to have little effect on nymphal performance. To the degree that it is important, effects of dietary P depend on the concentrations of protein and carbohydrate in the diet.

}, keywords = {LTER-KNZ, dietary phosphorus limitation to grasshopper, multiple nutrients, nutritional ecology, nutritional indices, secological stoichiometry}, doi = {10.1093/ee/37.2.333}, url = {https://academic.oup.com/ee/article/37/2/333/498535}, author = {Loaiza, V. and Jonas, J.L. and Anthony Joern} } @article {KNZ001210, title = {Host-plant quality alters grass/forb consumption by a mixed-feeding insect herbivore, Melanoplus bivittauts (Orthoptera: Acrididae)}, journal = {Ecological Entomology}, volume = {33}, year = {2008}, pages = {546 -554}, abstract = {

1.\ Factors affecting the nutritional ecology of mixed-feeding, polyphagous herbivores are poorly understood. Mixed-feeding herbivores do better when they consume both forb and grass species although they typically feed primarily on forbs, which are of relatively higher protein content than grasses. 2.\ In a field experiment, we examined the effects of nitrogen and phosphorus fertilization and associated changes in host-plant C:N:P on proportional grass consumption by a mixed-feeding insect herbivore, Melanoplus bivittatus, using natural abundance stable carbon isotope (12C/13C) methods. We also examined a grass-feeding (Phoetaliotes nebrascensis) and forb-feeding (Hesperotettix viridis) species. 3.\ The C isotope signatures of M. bivittatus collected from plots fertilized with nitrogen (+N), phosphorus (+P), nitrogen and phosphorus (+N+P) and no fertilizer were compared with the C isotope signatures of plants in those plots to determine the proportion of assimilated C derived from C4 grasses and C3 forbs in each plot. We also examined the relationship between M. bivittatus diets and plant C:N:P stoichiometry. 4.\ The proportion of grass assimilated approximately doubled in N-fertilized treatments (39.1 \± 0.1\%) compared with non-fertilized treatments (19 \± \<0.1\%), an increase associated with decreased C:N and increased N:P of grasses. 5.\ These results indicate that mixed-feeding M. bivittatus can selectively feed to balance C:N:P intake even when choosing between two structurally and chemically different groups of plants. 6.\ The strong relationship between diet selection and grass stoichiometry also suggests that plant nutrient composition may be more important than defensive chemistry in food choice.

}, keywords = {LTER-KNZ, C3 photosynthetic pathway, C4 photosynthetic pathway, Carbon (C), grasshopper, nitrogen (N), optimal foraging, Orthoptera: Acrididae, phosphorus (P), stoichiometry, tallgrass prairie}, doi = {10.1111/j.1365-2311.2008.01004.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2311.2008.01004.x}, author = {Jonas, J.L. and Anthony Joern} } @article {KNZ001097, title = {Consumptionof mycorrhizal and saprophytic fungi by Collembola in grassland soils}, journal = {Soil Biology and Biochemistry}, volume = {39}, year = {2007}, pages = {2594 -2602}, abstract = {Although soil-dwelling Collembola can influence plant growth and nutrient cycling, their specific role in soil food webs is poorly understood. Soil-free microcosm studies suggest that Collembola are primarily fungivores where they feed preferentially on saprophytic fungi (SF) over other fungal types. We directly assessed collembolan consumption of arbuscular mycorrhizal fungi (AMF) and SF using plant{\textendash}soil mesocosms and natural abundance stable carbon isotope techniques. Mycorrhizal Andropogon gerardii (C4 grass) seedlings were placed in pots containing Collembola and soil from a C3 plant dominated site, while mycorrhizal Pascopyrum smithii (C3 grass) seedlings were placed in pots with Collembola and soil collected at a C4 plant dominated site. After 6 weeks, collembolans assimilated carbon derived from C3 and C4 sources in both A. gerardii and P. smithii treatments. Comparing Collembola isotope values in AMF vs. AMF-suppressed treatments, our data show that both AMF and SF were consumed in these experimental soil environments.}, keywords = {LTER-KNZ, Andropogon gerardii, Arbuscular mycorrhizal fungi, Collembola, grassland, Natural abundance stable isotopes, Pascopyrum smithii, Saprophytic fungi, δ13C}, doi = {10.1016/j.soilbio.2007.05.004}, author = {Jonas, J.L. and G.T. Wilson and White, P.M. and Anthony Joern} } @article {KNZ001098, title = {Grasshopper (Orthoptera: Acrididae) communities respond to fire, bison grazing and weather in North Americantallgrass prairie: A long-term study}, journal = {Oecologia}, volume = {153}, year = {2007}, pages = {699 -711}, abstract = {

Because both intrinsic and extrinsic factors influence insect population dynamics, operating at a range of temporal and spatial scales, it is difficult to assess their contributions. Long-term studies are ideal for assessing the relative contributions of multiple factors to abundance and community dynamics. Using data spanning 25 years, we investigate the contributions of weather at annual and decadal scales, fire return interval, and grazing by bison to understand the dynamics of abundance and community composition in grasshopper assemblages from North American continental grassland. Each of these three primary drivers of grassland ecosystem dynamics affects grasshopper population and community dynamics. Negative feedbacks in abundances, as expected for regulated populations, were observed for all feeding guilds of grasshoppers. Abundance of grasshoppers did not vary in response to frequency of prescribed burns at the site. Among watersheds that varied with respect to controlled spring burns and grazing by bison, species composition of grasshopper assemblages responded significantly to both after 25 years. However, after more than 20 years of fire and grazing treatments, the number of years since the last fire was more important than the managed long-term fire frequency per se. Yearly shifts in species composition (1983\–2005), examined using non-metric multidimensional scaling and fourth-corner analysis, were best explained by local weather events occurring early in grasshopper life cycles. Large-scale patterns were represented by the Palmer Drought Severity Index and the North Atlantic Oscillation (NAO). The NAO was significantly correlated with annual mean frequencies of grasshoppers, especially for forb- and mixed-feeding species. Primary grassland drivers\—fire, grazing and weather\—contributing both intrinsic and extrinsic influences modulate long-term fluctuations in grasshopper abundances and community taxonomic composition.

}, keywords = {LTER-KNZ, Fire frequency, Insect populations, Konza Prairie, Long-Term Ecological Research Program, Weather}, doi = {10.1007/s00442-007-0761-8}, url = {https://link.springer.com/article/10.1007/s00442-007-0761-8}, author = {Jonas, J.L. and Anthony Joern} } @phdthesis {6324, title = {Nutrient resources and stoichiometry affect the ecology of above- and belowground invertebrate consumers}, volume = {PhD Dissertation}, year = {2007}, school = {Kansas State University}, type = { Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ}, url = {http://hdl.handle.net/2097/404}, author = {Jonas, J.L.} }