If you were a sand field cricket, you would not like horsehair worms.

"The horsehair worm (Paragordius varius) is a long-lived parasite that infects arthropods, including the sand field cricket, Gryllus firmus," says biologist Amy Worthington, assistant professor, Creighton University, Omaha, Neb. "This parasite lives inside its host for upwards of 28 days and can grow as long as 30 cm, presenting a significant challenge for its host's own growth, survival, and reproduction."

You can learn more about Worthington's work when she delivers a UC Davis Department of Entomology and Nematology seminar--it will be both in-person and virtual--on "A Host of Hardships: The Costs of Harboring a Long-Lived Parasite."

Worthington will speak at 4:10 p.m., Wednesday, March 8 in 122 Briggs Hall. Her seminar also will be virtual. The Zoom link:
https://ucdavis.zoom.us/j/95882849672.

"Parasites often manipulate their hosts'  behavior and physiology, resulting in detrimental effects on host fitness," Worthington says in her abstract. In her research, "we tested the ability of infected male crickets to invest in immunity, somatic growth, and reproductive structures. We also compared courtship behaviors, calling abilities, and mating success rates between infected and healthy males to identify how host reproductive fitness is affected by this large, long-lived parasite. Our results demonstrate surprisingly few physiological trade-offs, yet preliminary research suggests a reproductive burden on infected males, where even when host male crickets are able to survive horsehair worm infection, they will likely suffer from significantly reduced lifetime reproductive fitness."

UC Davis doctoral candidate Lindsey Mack, who studies with major professor Geoffrey Attardo, medical entomologist-geneticist, is the seminar host. "Dr. Worthington was my undergraduate research advisor," said Mack, adding. "She studies reproduction/immune trade-offs in crickets. Currently, her work focuses on the reproductive costs of high parasitic loads in field crickets, but she has experience with stalk=eyed flies, rhinoceros beetles, horsehair worms, and many other organisms. Generally, she is interested in wild sexually selected morphologies and behaviors."

"Additionally, she teaches at a religiously affiliated, primarily undergraduate institution (Creighton is a private Jesuit research university) and would be a great person to talk to about this type of career," Mack said.  A pre-seminar coffee takes place from 3:30 to 4:10 p.m. in 158 Briggs. 

Worthington, who joined Creighton's Department of Biology in the fall of 2016, holds a bachelor's degree in biology from the University of South Dakota (USD), and also received her master's degree at USD, studying the anti-predator behaviors of stalk-eyed flies and managing a long-term project dedicated to conserving the federally endangered Hine's Emerald dragonfly. 

Worthington completed her doctorate in ecology and evolutionary biology at Iowa State University, researching mating behavior in field crickets. She then transitioned into a postdoctoral fellowship at Washington State University where she worked on the development of sexually selected weapons in rhinoceros beetles and the hormonal mechanisms mediating wing polymorphism in crickets.

"Broadly, I am fascinated by bizarre morphologies and behaviors that are the result of sexual selection," Worthington says on her website. "Specifically, I am interested in the functional and physiological costs of these traits. I focus on trade-offs between reproduction and immunity, but also investigate topics such as sperm competition, the benefits of polyandry, and the molecular/hormonal mechanisms responsible for life-history tradeoffs. I have worked with a diverse array of invertebrate taxa (stalk-eyed flies, jumping spiders, dragonflies, crayfish, snails, and rhinoceros beetles), but currently focus my research on Gryllus firmus crickets. One particular interest is how individuals respond to long-term parasitic infections by the horsehair worm Paragordius varius, and how this infection impacts life-long fitness in its host."

The UC Davis Department of Entomology and Nematology's winter seminars are held on Wednesdays at 4:10 p.m. in 122 Briggs Hall. All are virtual. Urban landscape entomologist Emily Meineke, assistant professor, coordinates the seminars. (See schedule.) She may be reached at ekmeineke@ucdavis.edu for technical issues.

Congratulations to four outstanding young entomologists from the UC Davis Department of Entomology and Nematology--all PhDs to be.

They did UC Davis proud at the annual Entomological Society of America (ESA) meeting, which this year was a Joint Meeting of the Entomological Societies of America, Canada, and British Columbia. It took place Nov. 13-16 in Vancouver, British Columbia.

Doctoral candidates Danielle Rutkowski and Zachary Griebenow won the President's Prize or first-place honors for their individual research presentations. This was Rutkowski's second consecutive President's Prize. 

Doctoral candidate Lindsey Mack and doctoral student Adelaine “Addie” Abrams scored runner-up or second-place for their research presentations in the highly competitive program. 

Their topics ranged from bumble bees (Rutkowski) and ants (Griebenow) to mosquitoes (Mack) and thrips and aphids (Abrams). 

At the ESA annual meetings, students are offered the opportunity to present their research and win prizes. They can compete in 10-minute papers (oral), posters, or infographics. The President's Prize winners receive a one-year paid membership in ESA, a $75 cash prize, and a certificate. Second-winners score a one-year free membership in ESA and a certificate. 

Danielle Rutkowski 
Danielle Rutkowski, who studies with community ecologists Rachel Vannette, associate professor, and distinguished professor Richard “Rick” Karban, spoke on “The Mechanism Behind Beneficial Effects of Bee-Associated Fungi on Bumble Bee Health,” at her presentation in the category, Graduate School Plant-Insect Ecosytems: Pollinators.

Her abstract: "Bees often interact with fungi, including at flowers and within bee nests. We have previously found that supplementing bumble bee colonies with these bee-associated fungi improves bee survival and increases reproductive output, but the mechanisms behind these effects are unclear. This research aimed to determine the mechanisms underlying positive impacts of fungal supplementation in the bumble bee, Bombus impatiens. We tested two hypotheses regarding possible nutritional benefits provided by bee-associated fungi. These included the role of fungi as a direct food source to bees, and the production of nutritionally important metabolites by fungi. To test these mechanisms, we created microcolonies bumble bees and exposed each microcolony to one of four treatment groups. These four treatments were created based on the presence of fungal cells and the presence of fungal metabolites. We found that bee survival and reproduction were unaffected by treatment, with trends of decreased survival and reproduction when fungi were present. This contradicts previous results we've found using this bumble bee species, where fungi had a positive impact. It is possible that this disparity in results is due to differences in pathogen pressure between the two experiments, as bees in the first experiment were exposed to large amounts of pathogen through provided pollen, including Ascosphaera and Aspergillus. This pollen was sterilized for subsequent experiments, reducing pathogen load. Therefore, it is possible that bee-associated fungi benefit bees through pathogen inhibition, and future work exploring this hypothesis is necessary to fully understand the role of these fungi in bumble bee health."

Zachary Griebenow
Zach Griebenow, who studies with major professor and ant specialist Phil Ward, (Griebenow also captained the UC Davis Entomology Games Team in its national championship win at the Entomology Games or Bug Bowl) explained  “Systematic Revision of the Obscure Ant Subfamily Leptanillinae (Hymenoptera: Formicidae), Reciprocally Informed by Phylogenomic Inference and Morphological Data.” His category: Graduate School Systematics, Evolution and Biodiversity: Evolution 1. 

His abstract: "Ants belonging to the subfamily Leptanillinae (Hymenoptera: Formicidae) are sister to nearly all other extant ants. Miniscule and subterranean, little is known of their behavior. Contrary to the collecting bias observed in most ants, male leptanilline specimens are acquired more easily than workers or queens. The sexes are almost never collected in association, and many subclades within the Leptanillinae are known from male specimens only. Our comprehension of evolutionary relationships among the Leptanillinae is further obstructed by oft-bizarre derivation in male phenotypes that are too disparate for phylogeny to be intuited from morphology alone. These restrictions plague our understanding of the Leptanillinae with probable taxonomic redundancy. My thesis aims at leptanilline taxonomy that reflects phylogeny, inferred from both genotype and phenotype, and integrates morphological data from both sexes. Here I present the results of (1) phylogenomic inference from ultra-conserved elements (UCEs), compensating for potential systematic biases in these data, representing 63 terminals; and (2) Bayesian total-evidence inferences from a handful of loci, jointly with discrete male morphological characters coded in binary non-additive or multistate fashion. Notably, these analyses identify worker specimens belonging to the genera Noonilla and Yavnella, which were heretofore known only from males. Given such discoveries across the Leptanillinae, the number of valid leptanilline genera is reduced from seven to three in order to create a genus-level classification that upholds monophyly along with diagnostic utility." 

Lindsey Mack
Mack, who studies with medical entomologist-geneticist Geoffrey Attardo, assistant professor, covered “Three Dimensional Analysis of Vitellogenesis in Aedes aegypi Using Synchrotron X-Ray MicroCT” in the category, Graduate School Physiology, Biochemistry and Toxicology: Physiology. 

Her abstract: "Traditional methods of viewing the internal anatomy of insects require some degree of tissue manipulation and/or destruction. Using synchrotron-based x-ray phase contrast microCT (pcMicroCT) avoids this issue and has the capability to produce high contrast, three dimensional images. Our lab is using this technique to study the morphological changes occurring in the mosquito Aedes aegypti during its reproductive cycle. Ae. aegypti is the primary global arbovirus vector, present on all continents except Antarctica. Their ability to spread these viruses is tightly linked with their ability to reproduce, as the production of eggs in this species is initiated by blood feeding. Amazingly, this species produces a full cohort of eggs (typically 50-100) in just 3 days' time following a blood meal. This rapid development represents dramatic shifts in physiological processes that result in massive volumetric changes to internal anatomy over time. To explore these changes thoroughly, a time course of microCT scans were completed over the vitellogenic period. This dataset provides a virtual representation of the volumetric, conformational, and positional changes occurring in tissues important for reproduction across the vitellogenic period. This dataset provides the field of vector biology with a detailed three-dimensional internal atlas of the processes of vitellogenesis in Ae. aegypti."

Addie Abrams
Abrams, who studies with Extension agricultural entomologist and assistant professor Ian Grettenberger (she is a member of the Horticulture and Agronomy Graduate Group), titled her research, “Hitting the Mark: Precision Pesticide Applications for the Control of Aphids in California Lettuce" in the category, Graduate School Physiology, Biochemistry and Toxicology: Integrated Pest Management. 

Her abstract: "Commercial lettuce production in California's central coast represents 70 percent of the production in the United States. Recent discoveries of some chemistries in ground and surface water in the Salinas valley region have placed the insecticidal chemistries used by the industry at risk of increased regulation. Automated thinner-sprayers use plant-detection sensors to apply chemical sprays directly to individual lettuce plants, so that the same amount of product to plants as a standard broadcast sprayer while potentially reducing the amount of pesticide applied per acre by up to 90 percent. Field experiments testing this technology for the control of western flower thrips (Frankliniella occidentalis) and aphids, lettuce-currant aphid (Nasovonia ribisnigri) and others, were conducted to compare the efficacy of automated sprays to a conventional broadcast application system. Experiments were conducted in conventionally managed organic romaine lettuce fields using a complete randomized block design. Prior to and at regular intervals after treatment, heads were sampled from experimental and control plots to assess pest pressure. Results from this experiment validate the use of the automated sprayers to apply insecticides for the control of aphid and thrips pests in lettuce and will be discussed in the context of developing best-use-practices for this technology."

The 7000-member ESA, founded in 1889, is the largest organization in the world serving the professional and scientific needs of entomologists and individuals in related disciplines. Its members,  affiliated with educational institutions, health agencies, private industry, and government, are researchers, teachers, extension service personnel, administrators, marketing representatives, research technicians, consultants, students, pest management professionals, and hobbyists.

(See all of student competition winners on ESA site)