Jeffrey D. Holland

Determining the Spatial Scale of Species' Response to Habitat

Abstract Species respond to habitat at different spatial scales, yet many studies have considered this response only at relatively small scales. We developed a technique and accompanying software (Focus) that use a focal patch approach to select multiple sets of spatially independent sites. For each independent set, regressions are conducted between the habitat variable and counts of species abundance at different scales to determine the spatial scale at which species respond most strongly to an environmental or habitat variable of interest. We applied the technique to determine the spatial scales at which 12 different species of cerambycid beetles respond to forest cover. The beetles responded at different scales, from 20 to 2000 meters. We expect this technique and the accompanying software to be useful for a wide range of studies, including the analysis of existing data sets to answer questions related to the large-scale response of organisms to their environment.

Fecundity determines the extinction threshold in a Canadian assemblage of longhorned beetles (Coleoptera: Cerambycidae)

Reproductive rate has been suggested to have a positive effect on the amount of habitat loss a species can tolerate while emigration from habitat patches has been suggested to have both positive and negative effects. Forest fragmentation has been suggested to have negative effects on forest species. We determined the extinction threshold for 12 species of saproxylic (dead wood dependent) longhorned beetles (Coleoptera: Cerambycidae) using trap catch data from Ontario, Canada. We also determined the maximum egg production of each species and whether they were likely to move outside of forest patches. We found a strong negative relationship between reproductive rate and the minimum habitat amount required for species presence. This relationship is obscured if the scale of investigation is not appropriate for the study organism. As well, species caught moving outside forest habitat had lower extinction thresholds than species not caught moving outside forest but this was not significant after accounting for reproductive rate. Fragmentation did not have an effect on the minimum habitat requirements. These relationships can inform predictions of which species will be most affected by habitat loss.

Sensitivity of Cerambycid Biodiversity Indicators to Definition of High Diversity

The cutoff used to determine sites of high biological diversity has the potential to influence which species are identified as relevant biological indicators. I␣used data on longhorned beetles and the IndVal program to conduct a sensitivity analysis by varying the definition of high diversity sites from the upper 50% of sites to the upper 5% of sites. The analysis was carried out at all levels of a site typology based on the tree species present at the forested sites. Three species emerged as strong indicators of high diversity sites. Although the indicator values for these species were almost always statistically significant within the upper level of the site typology (all forested sites) the definition of high diversity had a large impact on these values. All three species showed an increase in their indicator values with higher cutoffs for high diversity sites suggesting a relatively nested set of species.

Habitat connectivity for pollinator beetles using surface metrics

Measuring habitat connectivity in complex landscapes is a major focus of landscape ecology and conservation research. Most studies use a binary landscape or patch mosaic model for describing spatial heterogeneity and understanding pattern-process relationships. While the value of landscape gradient approaches proposed by McGarigal and Cushman are recognized, applications of these newly proposed three dimensional surface metrics remain under-used. We created a gradient map of habitat quality from several GIS layers and applied three dimensional surface metrics to measure connectivity between 67 locations in Indiana, USA surveyed for one group of ecosystem service providers, flower longicorn beetles (Cerambycidae: Lepturinae). The three dimensional surface metrics applied to the landscape gradient model showed great potential to explain the differences of lepturine assemblages among the 2,211 studied landscapes (between site pairs). Surface kurtosis and its interaction with geographic distance were among the most important metrics. This approach provided unique information about the landscape through four configuration metrics. There were some uniform trends of the responses of many species to some of surface metrics, however some species responded differently to other metrics. We suggest that three dimensional surface metrics applied to a habitat surface map created with insight into species requirements is a valuable approach to understanding the spatial dynamics of species, guilds, and ecosystem services.

Cerambycidae Larval Host Condition Predicts Trap Efficiency

Abstract Insect traps of different designs should sample some species more effectively than others. I used three different traps to survey longhorned beetles (Coleoptera: Cerambycidae) at 43 locations throughout the state of Indiana to test the prediction that these traps would sample different assemblages of cerambycids. Nonmetric multidimensional scaling revealed that, while there was little difference between the assemblages sampled by Lindgren multiple funnel traps and Intercept panel traps, window traps caught quite different assemblages. Several species of cerambycids that showed differences in trap efficiencies seem to be differentially caught by different trap designs according to the nature of the larval host. These results can be used to plan monitoring according to the guild of the target beetles.

Graph and circuit theory connectivity models of conservation biological control agents

The control of agricultural pests is an important ecosystem service provided by predacious insects. In Midwestern USA, areas of remnant tallgrass prairie and prairie restorations may serve as relatively undisturbed sources of natural predators, and smaller areas of non-crop habitats such as seminatural areas and conservation plantings (CP) may serve as stepping stones across landscapes dominated by intensive agriculture. However, little is known about the flow of beneficial insects across large habitat networks. We measured abundance of soybean aphids and predators in 15 CP and adjacent soybean fields. We tested two hypotheses: (1) landscape connectivity enhances the flow of beneficial insects; and (2) prairies act as a source of sustaining populations of beneficial insects in well-connected habitats, by using adaptations of graph and circuit theory, respectively. For graph connectivity, incoming fluxes to the 15 CP from connected habitats were measured using an area- and distance-weighted flux metric with a range of negative exponential dispersal kernels. Distance was weighted by the percentage of seminatural area within ellipse-shaped landscapes, the shape of which was determined with correlated random walks. For circuit connectivity, effective conductance from the prairie to the individual 15 CP was measured by regarding the flux as conductance in a circuit. We used these two connectivity measures to predict the abundance of natural enemies in the selected sites. The most abundant predators were Anthocoridae, followed by exotic Coccinellidae, and native Coccinellidae. Predator abundances were explained well by aphid abundance. However, only native Coccinellidae were influenced by the flux and conductance. Interestingly, exotic Coccinellidae were negatively related to the flux, and native Coccinellidae were highly influenced by the interaction between exotic Coccinellidae and aphids. Our area- and distance-weighted flux and the conductance variables showed better fit to field data than area-weighted flux or Euclidean distance from the prairie. These results indicate that the network of seminatural areas has greater influence on the flow of native predators than that of exotic predators, and that the prairie acts as a source for native Coccinellidae. Managers can enhance conservation biocontrol and sustain the diversity of natural enemies by optimizing habitat networks.

White-Tailed Deer (Odocoileus virginianus) as a Potential Sentinel for Human Lyme Disease in Indiana

We assessed the potential of white‐tailed deer (WTD) (Odocoileus virginianus) to be a sentinel for human cases of Lyme disease (LD) in Indiana using location data from a 3‐year survey of approximately 3400 hunted deer with associated tick Ixodes scapularis and Borrelia burgdorferi (Bb) data. Data on human LD cases at the county level were obtained from the Indiana Department of Health. All data were assigned to county centroids to match the resolution of the LD data before creating optimized trend surfaces for LD incidence, hunted deer count, Ixodes scapularis and Bb prevalence. To determine whether LD was spatially associated with the areas of high densities of deer, deer with Ixodes scapularis and deer with ticks infected with Bb, we used spatial analysis with distance indices (SADIE). The SADIE analysis found significant spatial association between LD and the distribution of three organismal predictor variables, that is, WTD, Ixodes ticks and Bb. Lyme disease incident rate varied between 0.08 cases per 10 000 habitants (Johnson county) and 5.9 cases per 10 000 habitants (Warren county). In conclusion, WTD can be used as an accurate and cost‐effective sentinel for human LD. This method will permit public health workers to identify potentially endemic areas independently of human case reports.

Optimizing Fishing Time: One vs. Two-Night Fyke Net Sets in Great Lakes Coastal Systems

ABSTRACT Synoptic surveys of fish assemblages captured using fyke nets typically use a soak time of one night. We questioned whether enough information was gained from maintaining the nets for a second night to justify both the additional effort and the resulting reduction in sites sampled per field season. We compared fyke net catches from one-night and two-night sets at Great Lakes coastal margin ecosystems. Re-setting nets for a second night increased species richness by an average (± SE) of 12 ± 0.06%. This translated to an average of 2.5 ± 0.25 additional species captured. Ordinations of the assemblage data revealed that one-night and two-night catches from the same site (catch pairs) were much more similar to each other than were catches from different sites: the Kendalls kappa concordance values between one-night catches and their two-night pairs measured along the first three ordination axes were 80%, 88%, and 87%, respectively. Catch pairs plotted more closely, Sorensens distances were smaller, and assemblages were much more concordant than were pairs of catches randomly selected from different sites. Bootstrap analyses of catch species richness indicated that there was little difference between adding effort by increasing soak time versus adding effort by increasing the number of nets. Our data indicate that one- and two-night sets generally produce comparable assemblage data. For synoptic studies, the increase in statistical power gained by increasing the number of sites sampled will typically be more important than the moderate amount of additional information acquired by fishing sites for a second night.

Evidence for the stratification of hydrocarbons in the epicuticular wax layer of female Megacyllene robiniae (Coleoptera: Cerambycidae)

Contact pheromones mediate mate recognition and play important roles in mating systems of longhorned beetles (Coleoptera: Cerambycidae). One common bioassay of contact chemoreception in cerambycids involves presenting a freeze-killed female to a male in a Petri dish arena. If the male attempts to mate with the female carcass, it confirms that mate recognition signals are present and intact and behavior is not involved. Cuticular hydrocarbons are then stripped from the female with successive solvent washes, rendering her unattractive to males and also resulting in a crude extract containing the cuticular hydrocarbons. To test the bioactivity of the crude extract, the same female is then treated with the extract and presented again to the male. Males of some species, including Megacyllene robiniae (Förster), respond less readily to reconstituted females than to those same beetles before they were solvent-extracted. In the present study, we test the hypothesis that the contact pheromone of M. robiniae, Z9:C25, exists as a layer on the surface of the epicuticle. We used solid phase microextraction (SPME) to sample cuticular hydrocarbons of female beetles after they were freeze-killed, solvent washed, and treated with crude cuticular extracts. We found that extracting cuticular hydrocarbons from females and applying the resulting crude extract back onto the solvent-washed cadaver scrambles the wax layer and decreases the abundance of the contact pheromone presented on the surface of the insect.

Isolating spatial effects on beta diversity to inform forest landscape planning

Understanding the effects of landscapes on pest and non-pest species is necessary if regional landscape planning is to both control pests and conserve biodiversity. A first step is understanding of how both pests and non-pest species interact with the landscape configuration to determine the density of the two groups. While it is impossible to examine the occurrence and dispersal behavior of all species, different turnover rates in different species assemblages may offer general insights into responses of species assemblages. In this study I examine the distance decay of similarity of longhorned beetle assemblages in a large forest area in Indiana, USA, with minimal differences in habitat and few barriers to dispersal. Differences in beta diversity between groups are therefore likely due to dispersal distances. I found differences in turnover rates between species that decompose dead wood and those that attack living trees, and between species with different adult feeding habits. This suggests that management for simultaneous conservation and pest control is possible.