Publications by authors named "David W Crowder"

Wild bee communities in urban ecosystems are often challenged by habitat fragmentation and low floral diversity. In such settings, marginal land surrounding airports or in power line corridors may support bees, even with small habitat patches. However, temporal surveys of wild bees are lacking for many urban areas such as the Puget Sound region of western Washington State, USA.

View Article and Find Full Text PDF

The emerald ash borer, Agrilus planipennis Fairmire (Coleoptera: Buprestidae), is a notorious invasive pest that can devastate ash trees, Fraxinus spp. L., and embedded communities.

View Article and Find Full Text PDF

Multiple predator species can enhance or disrupt prey suppression based on whether different predators forage in complementary or overlapping niches. Interactions between predator species are primarily evaluated by resulting effects on prey abundance, although alterations of prey behavior also occur. When prey are vectors of plant pathogens, changes in their movement among plants may affect pathogen transmission as strongly as changes in vector abundance.

View Article and Find Full Text PDF

In agricultural systems, insect pest populations are often assessed using traps to survey adults, as adults are mobile and attracted to volatiles. While immature stages of insects (nymphs, larvae) are often most damaging, they can be difficult to sample, and management decisions targeting immatures must be based on adult sampling. For some insect pests, such as the grape mealybug (Pseudococcus maritimus), pheromone trap observations of adults occur too late to warn growers about pest risk, since overwintering first-instar nymphs are the dominant stage that transmits grape leafroll-associated viruses.

View Article and Find Full Text PDF

Successful plant growth requires plants to minimize harm from antagonists and maximize benefit from mutualists. However, these outcomes may be difficult to achieve simultaneously, since plant defenses activated in response to antagonists can compromise mutualism function, and plant resources allocated to defense may trade off with resources allocated to managing mutualists. Here, we investigate how antagonist attack affects plant ability to manage mutualists with sanctions, in which a plant rewards cooperative mutualists and/or punishes uncooperative mutualists.

View Article and Find Full Text PDF
Article Synopsis
  • The Afrotropical region has a rich diversity of endemic bee groups, particularly the Nomiinae subfamily, but their study has often lacked an integrated approach.
  • Researchers used phylogenomics, molecular dating, and distribution modeling to investigate the evolutionary ecology of the genus Trinomia, analyzing data from 59 species, including all six Trinomia species.
  • Findings indicated that Trinomia is monophyletic with unexpected connections to the Asian genus Gnathonomia, and suggests a recent origin of Trinomia around 5.8 million years ago, highlighting the need for further research on African bee biodiversity.
View Article and Find Full Text PDF

Background: Efficacy of insecticides is often determined from apparent yield loses due to a target pest. However, pests can affect yields even when controls work as expected. Further, most pest populations are monitored through adult counts without procedures to assess dynamics of immature stages.

View Article and Find Full Text PDF
Article Synopsis
  • * Research across 2,655 farms in 11 countries shows that diversifying agriculture—through livestock, crops, soils, non-crop plantings, and water conservation—improves both social outcomes like food security and environmental outcomes like biodiversity.
  • * Using multiple diversification strategies together yields better results than using any one strategy alone, highlighting the need for supportive policies to encourage these practices.
View Article and Find Full Text PDF

Soil rhizobia promote nitrogen fixation in legume hosts, maximizing their tolerance to different biotic stressors, plant biomass, crop growth, and yield. While the presence of soil rhizobia is considered beneficial for plants, few studies have assessed whether variation in rhizobia abundance affects the tolerance of legumes to stressors. To address this, we assessed the effects of variable soil rhizobia inoculum concentrations on interactions between a legume host (), a vector insect (), and a virus (, PEMV).

View Article and Find Full Text PDF

Carrion decomposition is fundamental to nutrient cycling in terrestrial ecosystems because it provides a high-quality resource to diverse organisms. A conceptual framework incorporating all phases of carrion decomposition with the full community of scavengers is needed to predict the effects of global change on core ecosystem processes. Because global change can differentially impact scavenger guilds and rates of carrion decomposition, our framework explicitly incorporates complex interactions among microbial, invertebrate, and vertebrate scavenger communities across three distinct phases of carcass decomposition.

View Article and Find Full Text PDF

Plant pathogens that are transmitted by insect vectors cause considerable damage to crops when pests or pathogens are not detected early in the season and populations are not controlled. Knowledge of pathogen prevalence in insect pest populations can aid growers in their insect pest management decisions but requires the timely dissemination of results. This process requires that specimen capture, identification, nucleic acid extraction, and molecular detection of a pathogen(s) occur alongside a platform for sharing results.

View Article and Find Full Text PDF

Vector-borne plant viruses are a diverse and dynamic threat to agriculture with hundreds of economically damaging viruses and insect vector species. Mathematical models have greatly increased our understanding of how alterations of vector life history and host-vector-pathogen interactions can affect virus transmission. However, insect vectors also interact with species such as predators and competitors in food webs, and these interactions affect vector population size and behaviors in ways that mediate virus transmission.

View Article and Find Full Text PDF

The Japanese beetle, Popillia japonica (Newman, 1841) (Coleoptera: Scarabaeidae), was first detected in southern Washington State in 2020. Widespread trapping efforts ensued, and over 23,000 individuals were collected in both 2021 and 2022 in this region known for specialty crop production. The invasion of Japanese beetle is of major concern as it feeds on over 300 plant species and has shown an ability to spread across landscapes.

View Article and Find Full Text PDF

Transmission of insect-borne pathogens is mediated by interactions between insects and plants across variable environments. Water stress, for example, affects the physiology, defense, chemistry, and nutritional balance of plants in ways that alter their tolerance to herbivores and pathogens. However, few studies have explored interactions between water stress and insect-borne pathogens as well as the molecular mechanisms mediating these interactions.

View Article and Find Full Text PDF

Background: Invasive species threaten the productivity and stability of natural and managed ecosystems. Predicting the spread of invaders, which can aid in early mitigation efforts, is a major challenge, especially in the face of climate change. While ecological niche models are effective tools to assess habitat suitability for invaders, such models have rarely been created for invasive pest species with rapidly expanding ranges.

View Article and Find Full Text PDF
Article Synopsis
  • Generalist predators can disrupt biological control by preying on other natural enemies, but their behavior may change based on prey availability.
  • Higher densities of herbivores like aphids and thrips lead to more frequent encounters with intraguild predation, indicating that predator interactions are influenced by prey abundance.
  • As predator competition increases, Geocoris may switch to feeding on detritivores, highlighting how prey diversity can alter predator interactions and foraging strategies.
View Article and Find Full Text PDF

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions.

View Article and Find Full Text PDF

Global efforts to assess honey bee health show viruses are major stressors that undermine colony performance. Identifying factors that affect virus incidence, such as management practices and landscape context, could aid in slowing virus transmission. Here we surveyed viruses in honey bees from 86 sites in the Pacific Northwest, USA, and tested effects of regional bee density, movement associated with commercial pollination, julian date, and hive management on virus prevalence.

View Article and Find Full Text PDF

The abundance and diversity of pollinator populations are in global decline. Managed pollinator species, like honey bees, and wild species are key ecosystem service providers in both natural and managed agroecosystems. However, relatively few studies have exhaustively characterized pollinator populations in diverse agroecosystems over multiple years, while also thoroughly documenting plant-pollinator interactions.

View Article and Find Full Text PDF

Plants are often attacked by multiple antagonists and traits of the attacking organisms and their order of arrival onto hosts may affect plant defences. However, few studies have assessed how multiple antagonists, and varying attack order, affect plant defence or nutrition. To address this, we assessed defensive and nutritional responses of Pisum sativum plants after attack by a vector herbivore (Acrythosiphon pisum), a nonvector herbivore (Sitona lineatus), and a pathogen (Pea enation mosaic virus, PEMV).

View Article and Find Full Text PDF

Ecological theory predicts that host-plant traits affect herbivore population growth rates, which in turn modulates predator-prey interactions. However, while vector-borne plant pathogens often alter traits of both host plants and vectors, a few studies have assessed how pathogens may act as interaction modifiers within tri-trophic food webs. By applying a food web motif framework, we assessed how a vector-borne plant pathogen (Pea-enation mosaic virus, PEMV) modified both bottom-up (plant-herbivore) and top-down (predator-prey) interactions.

View Article and Find Full Text PDF

Herbivores assess predation risk in their environment by identifying visual, chemical, and tactile predator cues. Detection of predator cues can induce risk-avoidance behaviors in herbivores that affect feeding, dispersal, and host selection in ways that minimize mortality and reproductive costs. For herbivores that transmit plant pathogens, including many aphids, changes in herbivore behavior in response to predator cues may also affect pathogen spread.

View Article and Find Full Text PDF
Article Synopsis
  • The study examined how different prey populations affect the ability of generalist predators, specifically Nabis sp. and Geocoris sp., to control the Colorado potato beetle in organic versus conventional potato fields.
  • In organic fields, higher biodiversity led to decreased predation of the beetles by Nabis, suggesting these predators switched to more abundant alternative prey; in contrast, predation increased with arthropod richness in conventional fields.
  • Geocoris predation was more effective in organic fields but decreased when alternative prey like detritus-feeding flies were abundant, indicating that the presence of other prey can significantly disrupt beetle feeding.
View Article and Find Full Text PDF

Wireworms are the larval stage of click beetles (Coleoptera: Elateridae), and some of their species are serious pests of many crops. In the present study, we evaluated the efficacy of naturally occurring and commercial entomopathogenic nematode species against the sugar beet wireworm, Limonius californicus (Mannerheim), in the laboratory. First, efficacies of Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) collected from an irrigated (S.

View Article and Find Full Text PDF

Crop-associated microbiota are a key factor affecting host health and productivity. Most crops are grown within heterogeneous landscapes, and interactions between management practices and landscape context often affect plant and animal biodiversity in agroecosystems. However, whether these same factors typically affect crop-associated microbiota is less clear.

View Article and Find Full Text PDF