Research

Research News

2018
Morgan Christman receives a USU Ecology Center Graduate Research Award.
Lori Spears recognized as the 2018 USU New Extension Specialist Award winner.
2017
National Entomological Society of America Conference (Denver, CO) Presentation Award Winner

Kaitlin Rim, 1st place President's Prize (poster session-Biological Control)

Pacific Branch-Entomological Society of America Conference (Portland, OR) Presentation Award Winner

Gunn Gill, 2nd place (PhD poster session)

2016
Lori Spears and Ricardo Ramirez are highlighted in The Western Front, newsletter of the Western IPM Center.
Levi Wilkes highlighted for gaining undergraduate research experience in the lab.
Madeleine Dupuy's research and review on billbug management gets press.

Steve Price pictured in Hay and Forage Grower magazine for an alfalfa stem nematode article.
2015
Alice Ruckert receives a USDA-AFRI Graduate Student Travel Award to attend the National Entomological Society of America Conference and present her research in Minneapolis, MN.

Pacific Branch-Entomological Society of America Conference (Coeur d'Alene, ID) Presentation Award Winners

Houston Judd, 1st place (MS poster session)
Alice Ruckert, 2nd place (PhD talk session)

2014
National Entomological Society of America Conference (Portland, OR) Presentation Award Winner

Steve Price, 1st place (President's Prize, MS poster session)

2013
National Entomological Society of America Conference (Austin, TX) Presentation Award Winner

Madeleine Dupuy, 1st place (President's Prize, PhD poster session)

2012
Erica Stephens is a recipient of a USDA Western-SARE Graduate Student Grant, see project abstract.

Current Research Areas

Effects of abiotic factors on plant-arthropod interactions:

Drought stress effects on plant-arthropod interactions

Sustainable management of agricultural crops and urban landscapes in the Intermountain West is challenging because water resources are limited and the frequency of drought episodes is increasing. Water conservation practices and drought may impact the efficacy of IPM strategies. We examine how drought/water-stress alters plant defenses and impacts arthropod outbreaks. These interactions may be mitigated with drought-tolerant and arthropod-resistant varieties, two strategies that are being investigated. We are focusing on the generalist two-spotted spider mite and the specialist Banks grass mite, two common herbivores that appear to flourish under drought conditions, and their interactions on corn and barley host plants.

Findings

Combinations of drought-stress and neonicotinoids appear to increase spider mite outbreaks.
Drought-stress alone alters plant defense responses and micro-habitat (e.g., increased leaf temperature) that may favor spider mites.
Banks grass mite and two-spotted spider mite appear to alter gene expression in plants and plant defense proteins in unique ways.

Non-target effects of pesticides

Pesticides are an important component of herbivore suppression and improving crop yields. However, the direct and indirect effects of pesticides are not always clear. We examine how pesticide use disrupts (1) predator-prey interactions and the conservation of predators , and (2) bees that provide pollination services.

Broad spectrum insecticides can negatively affect predator species diversity that provide natural pest suppression. There is evidence that species rich predator communities can lead to improved herbivore suppression through mechanisms including resource-partitioning and facilitation. The effects of pesticides may go beyond the impacts on species diversity and alter life-stage diversity of predators. Immature and adult predator life-stages may differ in their foraging behavior, prey preference, mobility, among other factors that affect herbivore suppression. We are examining these interactions in the alfalfa system where pesticides are commonly applied for alfalfa weevil management and that often lead to aphid outbreaks.

Findings

The predatory insect community in alfalfa is made up of several simultaneously occurring species that vary in their abundance of adult and immature life stages.
Early occurring predator species are harmed by early season broad-spectrum insecticide applications, resulting in shifts in the timing of adult and immature life stages during the season.
Predator communities of both adult and immature life stages appear to suppress herbivores more than communities consisting of a single life stage alone.

Pesticides have been implicated as one factor impacting pollinator health and declines. It is clear that bees are sensitive to pesticides but the modes of exposure are not always known. Some bee species use soil and leaves as substrates for nest building where residual pesticides may be present. In addition, pollinators can be exposed to pesticides through pollen but work is needed to determine which type of pollen is being used by different bee species. Bee exposure to sub-lethal doses of pesticides may affect foraging and immunity against pathogens.

Understanding herbivore biology and ecology to improve suppression:

Herbivore phenology and predictive modeling

Improving our knowledge of herbivore emergence from overwintering sites and tracking the timing of each life-stage can provide useful information for management. Through surveys of herbivore activity over time and the development and validation of predictive models, such as degree day models, we can better time management and target the most susceptible life stages. The lab is surveying invasive pests (spotted-wing drosophila), and soil pests in turfgrass (billbugs) and alfalfa (clover root curculio) to determine their phenology in the Intermountain West and develop predictive models to improve the suppression of these pests.

Findings

In our region billbugs are made up of a complex of weevils (3-4 species) whose larvae are the damaging life stage in turfgrass.
Predictive models from the eastern U.S. do not appear to match the activity of billbugs in the West.
A model with an earlier biofix (Jan 1) and cooler temperature threshold (3°C) makes the model more robust and provides better assistance with tracking billbugs.

Indirect interactions between herbivores

Herbivore species interactions tend to occur indirectly, through their shared host plants and predators. Recently, we have focused on the indirect effects of herbivores through plants and changes in plant responses to herbivory. Feeding by one herbivore has been shown to prime plant defenses, resulting in plants that are less susceptible to subsequent herbivore species. However, it has also been shown that herbivory from one species may improve nutrient availability, resulting in a plant host that is more favorable to subsequent herbivore species.

Findings

Alfalfa plants infected by stem nematodes, which infect above ground, were more susceptible to aphid infestations than plants without nematodes.
Varieties resistant to stem nematode, regardless of aphid resistance, had lower aphid abundances suggesting possible cross-resistance.

Evaluating alternative IPM strategies for herbivore suppression:

Entomopathogens as a biological control tactic

Traditional management of many herbivorous pests has consisted of synthetic chemical pesticide applications. Some of these pesticides are broad-spectrum, and others have been taken off of the market and have come under scrutiny because of their harmful non-target effects on humans, the environment, and other organisms. Insect pathogens (entomopathogens) and formulations as a bio-pesticide provide one option for targeted and sustainable management of herbivores. Much work is needed to determine and improve entomopathogen effectiveness against herbivores in the field. A focus in the lab has been on using entomopathogens for suppression of soil pest larvae in turfgrass and alfalfa against billbugs and clover root curculio, respectively.

EPN emergence from waxworm.

Beauveria covered clover root curculio.

Soil amendments and host-plant resistance

Plants can be used in a variety of ways to suppress herbivores. Some of the well-know pesticides were derived from plants, for example pyrethroids. We can use attributes of plant defense to expand on pest management. One way is through the use of bio-fumigant crops like mustard plants (Brassica and Sinapis spp.). Incorporation of these plants, which contain glucosinolates and produce isothiocyanate compounds, into the soil before planting of a focal crop has been shown to play a role in the suppression of weeds, plant pathogens, and some insects. We are evaluating this strategy against soil pests in alfalfa for the clover root curculio. The other way in which the lab is looking at utilizing plants for suppression is through host-plant resistance. We evaluate plants that have higher levels of plant defenses, or other mechanisms that reduce herbivore fitness and preference for the plant. The lab is investigating a number of plants for host-resistance toward spider mites (corn and barley) and clover root curculio (alfalfa).

Re-evaluating pest thresholds for management

One component of an IPM strategy is the use of economic thresholds when available to make informed decisions on whether treatment of pests is necessary and cost effective. Changes in climate, development of pest strains, introductions of new pests, and pesticide resistance are some of the factors driving a need to re-evaluate thresholds in the Intermountain West where little research has taken place to determine whether current thresholds are meaningful in the region. Currently we are evaluating these effects in alfalfa for alfalfa weevil and aphids.

Current Research Funding and Collaborations

NSF

PGRP (2015-2019; $1,069,975) Genomics of resistance in cereals to mite herbivores associated with plant drought stress. (R. Clark (Univ. of Utah), R.A. Ramirez)

USDA-NIFA

CPPM (2017-2020; $321,957) Developing innovative IPM tactics for billbug control in urban environments through early detection and non-chemical approaches. (X. Xiong (Univ. of Missouri), D. Richmond (Purdue), R.A. Ramirez, B. Barrett (Univ. Missouri), L. Enders (Purdue))
AFRP (2017-2020; $250,000) Developing an attractant for Lygus hesperus derived from host plant volatile compounds. (Z. Syed (Notre Dame), J. Brunet (USDA/Univ. of Wisconsin), S. Schoville (Univ. of Wisconsin), R.A. Ramirez)
AFRP (2016-2019; $250,000) Increasing preventive and curative options for clover root curculio management in western alfalfa. (R.A. Ramirez, L. Godfrey (Univ. California Davis), J. Barbour (Univ. of Idaho))
AFRP (2016-2019; $246,000) Overhauling alfalfa weevil management in irrigated southwest desert alfalfa. (A. Mostafa (Univ. of Arizona), E. Natwick (Univ. of California Davis), R.A. Ramirez)
AFRP (2015-2018; $206,000) Re-establishing IPM recommendations for aphids in alfalfa hay in the low desert. (A. Mostafa, E. Natwick, R.A. Ramirez)
WRIPM (2012-2015; $125,697) Insect-attacking nematodes and water conservation practices as alternatives to insecticides for billbug control in Intermountain West turfgrass. (R.A. Ramirez, P. Johnson (USU), K. Kopp (USU), E. Bechinski (Univ. of Idaho))
AFRI (2012-2015; $496,126) The causes and consequences of secondary pest outbreaks: direct effects of pesticides on plant defenses against herbivores. (M.D. Eubanks (Texas A&M Univ.), A. Szczepaniec (South Dakota State Univ.), R.A. Ramirez, D. Kerns (Louisiana State Univ.), E. Bynum (Texas A&M), C. Tamborindeguy (Texas A&M))

USDA-ARS

SCA (2014-2017; $136,373) The interaction of pesticides with pollinator health and behavior in fruit production systems in the United States (R.A. Ramirez, J.P. Strange (USDA-ARS Logan, UT), T. Pitts-Singer (USDA-ARS Logan-UT))