Publications by authors named "Ricardo A Ramirez"

Plants are attacked by diverse herbivorous pests with different host specializations. While host plant resistance influences pest pressure, how resistance impacts the behaviors of generalist and specialist herbivores, and the relationship to resistance, is less well known. Here, we investigated the short-term (< 1 h) behavioral changes of a generalist herbivore, the two-spotted spider mite (TSM), and a specialist herbivore, the Banks grass mite (BGM), after introduction to no-choice Tanglefoot leaf-arenas (2 × 2 cm) of three maize inbred lines (B73, B75, and B96).

View Article and Find Full Text PDF

Bumble bees are integral pollinators of native and cultivated plant communities, but species are undergoing significant changes in range and abundance on a global scale. Climate change and land cover alteration are key drivers in pollinator declines; however, limited research has evaluated the cumulative effects of these factors on bumble bee assemblages. This study tests bumble bee assemblage (calculated as richness and abundance) responses to climate and land use by modeling species-specific habitat requirements, and assemblage-level responses across geographic regions.

View Article and Find Full Text PDF

Melittobia acasta Walker is one among other hymenopterous parasitoids of Megachile rotundata F. Commercial M. rotundata populations are employed to pollinate North American alfalfa for seed production.

View Article and Find Full Text PDF

Commercialized bumble bees (Bombus) are primary pollinators of several crops within open field and greenhouse settings. However, the common eastern bumble bee (Bombus impatiens Cresson, 1863) is the only species widely available for purchase in North America. As an eastern species, concerns have been expressed over their transportation outside of their native range.

View Article and Find Full Text PDF

In maize (Zea mays ssp. mays), agriculturally damaging herbivores include lepidopteran insects, such as the European corn borer (Ostrinia nubilalis), and distantly related arthropods, like the two-spotted spider mite (Tetranychus urticae). A small number of maize lines, including B96 and B75, are highly resistant to both herbivores, and B96 is also resistant to thrips.

View Article and Find Full Text PDF

Wild and managed bee populations are in decline, and one of many environmental causes is the impact of pesticides on developing bees. For solitary bees, delayed larval development could lead to asynchronous adult emergence, unhealthy and inefficient adult pollinators, and decreased brood production and survival. We examined a methodology for testing Osmia lignaria Say (Hymenoptera: Megachilidae) larval responses to pesticide exposure using a laboratory bioassay.

View Article and Find Full Text PDF

Billbugs ( spp.) are a complex of grass-feeding weevil species that reduce the aesthetic and functional qualities of turfgrass. Effective billbug monitoring and management programs rely on a clear understanding of their seasonal biology.

View Article and Find Full Text PDF

Since the cancellation of broad-spectrum soil-active insecticides in alfalfa ( L.) production, clover root curculio ( F.) (CRC) larval root damage has increased.

View Article and Find Full Text PDF

Maize ( subsp. ) yield loss from arthropod herbivory is substantial. While the basis of resistance to major insect herbivores has been comparatively well-studied in maize, less is known about resistance to spider mite herbivores, which are distantly related to insects and feed by a different mechanism.

View Article and Find Full Text PDF

Spider mite (Acari: Tetranychidae) outbreaks are common on corn grown in the arid West. Hot and dry conditions reduce mite development time, increase fecundity, and accelerate egg hatch. Climate change is predicted to increase drought incidents and produce more intense temperature patterns.

View Article and Find Full Text PDF

While substantial progress has been made in understanding defense responses of cereals to insect herbivores, comparatively little is known about responses to feeding by spider mites. Nevertheless, several spider mite species, including the generalist and the grass specialist , cause damage on cereals such as maize and wheat, especially during drought stress. To understand defense responses of cereals to spider mites, we characterized the transcriptomic responses of maize and barley to herbivory by both mite species, and included a wounding control against which modulation of defenses could be tested.

View Article and Find Full Text PDF

Spider mites, a cosmopolitan pest of agricultural and landscape plants, thrive under hot and dry conditions, which could become more frequent and extreme due to climate change. Recent work has shown that neonicotinoids, a widely used class of systemic insecticides that have come under scrutiny for non-target effects, can elevate spider mite populations. Both water-stress and neonicotinoids independently alter plant resistance against herbivores.

View Article and Find Full Text PDF

Billbugs are native pests of turfgrass throughout North America, primarily managed with preventive, calendar-based insecticide applications. An existing degree-day model (lower development threshold of 10°C, biofix 1 March) developed in the eastern United States for bluegrass billbug, Sphenophorus parvulus (Gyllenhal; Coleoptera: Curculionidae), may not accurately predict adult billbug activity in the western United States, where billbugs occur as a species complex. The objectives of this study were 1) to track billbug phenology and species composition in managed Utah and Idaho turfgrass and 2) to evaluate model parameters that best predict billbug activity, including those of the existing bluegrass billbug model.

View Article and Find Full Text PDF

Aerial traps, using combinations of color and attractive lures, are a critical tool for detecting and managing insect pest populations. Yet, despite improvements in trap efficacy, collection of nontarget species ("bycatch") plagues many insect pest surveys. Bycatch can influence survey effectiveness by reducing the available space for target species and increasing trap screening time, especially in areas where thousands of insects are captured as bycatch in a given season.

View Article and Find Full Text PDF

Billbugs (Coleoptera: Curculionidae: spp.) are a complex of weevil pests affecting turfgrass throughout the United States. Billbug larvae cause damage by feeding in stems, on roots, and on the crowns of turf, causing severe discoloration and eventual plant death.

View Article and Find Full Text PDF

Knowledge about the distribution and abundance of the western black-legged tick, Ixodes pacificus Cooley and Kohls, in Utah is limited. Recent concerns over tick-borne diseases in Utah, primarily Lyme disease, have reinvigorated the need to understand the distribution and habitats favored by this tick species. We surveyed 157 sites throughout Utah to examine the distribution, abundance, and habitat of I.

View Article and Find Full Text PDF

Plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. Generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. As plants are selected for resistance to one phytophagous organism type (insect vs.

View Article and Find Full Text PDF

Resource use generally increases with greater consumer diversity, an effect often attributed to resource partitioning. Pathogens and predators are two classes of consumer that exhibit differences in ecologically important traits (e.g.

View Article and Find Full Text PDF