No description available.

No description available.

No description available.

Arthropods were collected at three sites on the Canaveral Peninsula of the east central Florida coast, from May until November, 1975. These sites were old fields dominated by grasses and herbs and one of them (site 1) was located near Launch Complex 41, Kennedy Space Center. A modified drop-trap of 0.5 m2 was used to trap arthropods at approximately 14-day intervals. A vacuum collector removed the arthropods and loose material which was visually inspected for arthropods by the unaided eye and a 7X dissecting scope. A total of 12,296 arthropods was collected during the study. Insects were by far the most numerous group, usually contributing 85 to 95% of the individuals. Ants were very numerous comprising 47% of all individuals and were most numerous at site 1. Arthropod density was greatest on site 1 and increased on all three sites until October and then declined November. A bimodal trend in herbivore density occurred with peaks in June-July and October-November. Predators increased during the study and this significantly correlated with the increase in all other arthropods on the three sites and with herbivores on site 2 and 3. Ants increased in density during the study, while parasites, scavengers, and omnivores remained at low densities. The percentage of predators was roughly constant over most of the study. New species were encountered on site 1 about 1.5 times a fast as on sites 2 and 3. The distribution of individuals among the insect families was similar for the three sites, but site 1 averaged more individuals per family. The average number of individuals per species on site 1 was about double that for sites 2 and 3. Species diversity (Shannon-Weaver) values indicated that arthropods at site 1 were more evenly distributed among the species. Dominance (Simpson) values were not significantly different among the three sites. Community similarity indicated that about 50% of the species on one site were found on one of the other two sites. The different plant communities or habitats surrounding the sites were apparently unrelated to the number of arthropod species present on the study sites. The number of arthropod species present did appear to be related to differences in the number of plant species and their relative abundance on the grids. The launches of two Viking spacecraft appeared to have no detrimental effect on the nearby arthropods.

The resistance status of Tetranychus urticae Koch and Lygus hesperus Knight sourced from California strawberry fields was evaluated in laboratory bioassay experiments. Adult female T. urticae sourced from a miticide naïve population were exposed to a range of miticide active ingredient concentrations mixed with acetone in contact bioassay experiments. LC50 concentrations for the active ingredients fenpyroximate, abamectin, bifenazate, and spiromesifen as well as LC90 concentrations for the active ingredients fenpyroximate, abamectin, and bifenazate were derived from this susceptible population. A total of ten field populations of T. urticae, five from the Santa Maria growing region and five from the Ventura/Oxnard growing region, were exposed to these concentrations and mortality response was compared with the susceptible population to determine the resistance status of T. urticae on a per-field basis. Resistance detection occurred less often in the LC50 concentration groups compared to their respective LC90 concentrations. Resistance to the LC50 concentration of spiromesifen could not be detected in any field population. Resistance to the LC90 concentrations of fenpyroximate and abamectin was detected in three field populations from Santa Maria and four populations from Ventura/Oxnard. Resistance to the LC90 concentration of bifenazate was detected in three populations from Ventura/Oxnard and in no populations from Santa Maria. Lygus hesperus were exposed to formulated products registered in California strawberries after being separated into three groups based on life stage. Instars one through three were considered small, instars four and five were considered large, and winged individuals were considered adults. The small and large groups were exposed to the maximum field labeled rate of Rimon® (a.i. = novaluron). Adults were exposed to the maximum field labeled rate of Actara®, Brigade®, and Sivanto®, the active ingredients of which are thiamethoxam, bifenthrin, and flupyradifurone respectively. A total of 14 field populations were screened for resistance, six collected from the Santa Maria growing region in 2021, and eight collected in 2022, five of which came from the Santa Maria region, and three from the Salinas/Watsonville region. Resistance was detected by comparing the mortality response of an insecticide naïve population of L. hesperus and field collected populations in residual laboratory bioassay experiments. Resistance to Rimon® in the small group was effectively detected in all populations in 2021 and 2022. Resistance to Rimon® in the large group was detected in four populations in 2021 and five populations in 2022. Resistance to Actara® and Brigade® was effectively detected in all populations in 2021 and 2022. Resistance to Sivanto® was effectively detected in four populations in 2021 and two of three populations in 2022. A full submersion assay was utilized for the second half of Sivanto® trials in 2022 since mortality response of the susceptible population was low in the residual group. Five of five populations tested with the modified assay were considered effectively resistant.

Little is known about arthropod communities inhabiting longleaf pines in the southeastern United States. This information is of particular importance because arthropods serve as the food base for the federally endangered red-cockaded woodpecker (RCW). In a recent study, this arthropod community has been suggested to be the mechanism by which RCW reproductive success is linked to the groundcover composition of the forest (which is a reflection of the forest's fire history). This is possible because it has been shown that much of the arthropod community found on longleaf pines originates from the forest floor. If the arthropod community is the link between the ground cover and the RCWs' reproductive success then higher amounts of arthropods should be found in areas with groundcover that is indicative of frequent burning. I conducted a one year study at three sites containing RCWs to determine whether the ground cover of the forest influences the abundance and mass of the arthropod communities on longleaf pines. I focused on impacts of groundcover on arthropods by controlling for tree species, tree age, soil type, hardwood midstory density, and overstory basal area. My results show that arthropod biomass was positively and significantly correlated to the percent coverage of herbaceous and graminoid vegetation and was negatively and significantly correlated to the percent coverage of woody vegetation. Arthropod biomass and abundance was also observed to vary seasonally with a peak occurring during spring and summer. Additionally, prescribed fire was not found to have a negative short-term impact on arthropod biomass. / Master of Science

Abstract Proof of concept for a continuous environmental sampling methodology that employs common terrestrial arthropods as environmental samplers was tested by analyzing pitfall, malaise and black light captures over a six month period over a replicated urban-suburban-rural gradient in Central Virginia. All arthropods captured at the nine sites were identified and assigned to aquatic, vegetation, or soil groups based on their association with these microhabitats. To offset variability in arthropod life history patterns and species abundance within habitat types, arthropod categories based on presence/absence data over the six month period were constructed to provide for sampling reliability within each microhabitat type. Arthropod categories ranged from single abundant species and families to synthetic groupings based on microhabitat associations (e.g., “soil beetles”), all of which could be easily identified. Mean weekly captures of individuals in each resulting category were compared within and among the nine sites using GLM or ranks analyses. Overall and weekly mean capture rates in the aquatic (two categories), soil (seven categories) and vegetation (11 categories) microhabitats were similar within each habitat type. With the exception of the two aquatic category members (midges and caddisflies), overall, monthly and weekly mean capture rates of all arthropod categories were highest in suburban and lowest in urban habitats. Results demonstrate reliability of the arthropod categories constructed and provide ground truthing for a continuously deployable and user-friendly arthropod-based system for monitoring environmental agents.

Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Nov. 7, 2008). Includes bibliographical references.

Univ Arizona, Dept Mol & Cellular Biol

<p>Environmental changes, such as climate change, can have differential effects on species, with important consequences for community structure and ultimately, for ecosystem functioning. In the Arctic, where ecosystems are experiencing warming at twice the rate as elsewhere, these effects are expected to be particularly strong. A proper characterization of the link between warming and biotic interactions in these particular communities is of global importance because the tundra's permafrost stores a vast amount of carbon that could be released through decomposition as greenhouse gases and alter the global rate of climate change. In this dissertation, I examine how arthropod communities are responding to warming in the Arctic and how these responses might be affecting ecosystem functioning. </p><p>I first address the question of whether and how long-term changes in climate are affecting individual groups and overall community structure in a high-arctic arthropod food web. I find that increasingly warm springs and summers between 1996-2011 differentially affected some arthropod groups and that this led to major changes in the relative abundances of different trophic groups within the arthropod community. Specifically, spring and summer warming are associated with relatively more herbivores and parasitoids and fewer detritivores within the community. These changes are particularly pronounced in heath sites, suggesting that arthropod communities in dry habitats are more responsive to climate change than those in wet habitats. I also show that herbivores and parasitoids are sensitive to conditions at subzero temperatures, even during periods of diapause, and that all trophic groups benefit from a longer transition period between summer and winter. These results suggest that the projected winter and springtime warming in Greenland may have unexpected consequences for northern arthropod communities. Moreover, the relative increase in herbivores and loss of detritivores may be changing the influence of the arthropod community over key ecosystem processes such as decomposition, nutrient cycling, and primary productivity in the tundra. </p><p>Predator-induced trophic cascades have been shown to impact both community structure and ecosystem processes, yet it is unclear how climate change may exacerbate or dampen predator effects on ecosystems. In the second chapter of my dissertation, I investigate the role of one of the dominant tundra predators within the arctic ecosystem, wolf spiders, and how their impact might be changing with warming. Using results from a two-year-long field experiment, I test the influence of wolf spider density over the structure of soil microarthropod communities and decomposition rates under both ambient and artificially warmed temperatures. I find that predator effects on soil microarthropods change in response to warming and that these changes translate into context-specific indirect effects of predators on decomposition. Specifically, while high densities of wolf spiders lead to faster decomposition rates at ambient temperatures, they are associated with slower decomposition rates in experimentally warmed plots. My results suggest that if warming causes an increase in arctic wolf spider densities, these spiders may buffer the rate at which the massive pool of stored carbon is lost from the tundra. </p><p>Wolf spiders in the Arctic are expected to become larger with warming, but it is unclear how this change in body size will affect spider populations or the role of wolf spiders within arctic food webs. In the third chapter of my dissertation, I explore wolf spider population structure and juvenile recruitment at three sites of the Alaskan Arctic that naturally differ in mean spider body size. I find that there are fewer juveniles in sites where female body sizes are larger and that this pattern is likely driven by a size-related increase in the rate of intraspecific cannibalism. These findings suggest that across the tundra landscape, there is substantial variation in the population structure and trophic position of wolf spiders, which is driven by differences in female spider body sizes. </p><p>Overall, this dissertation demonstrates that arctic arthropod communities are changing as a result of warming. In the long-term, warming is causing a shift in arthropod community structure that is likely altering the functional role of these animals within the ecosystem. However even in the short-term, warming can alter species interactions and community structure, with important consequences for ecosystem function. Arthropods are not typically considered to be major players in arctic ecosystems, but I provide evidence that this assumption should be questioned. Considering that they are the largest source of animal biomass across much of the tundra, it is likely that their activities have important consequences for regional and global carbon dynamics.</p> / Dissertation