- Author: Kathy Keatley Garvey
She will speak at 4:10 p.m. 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. "The horsehair worm (Paragordius varius) is a long-lived parasite that infects arthropods, including the sand field cricket, Gryllus firmus. 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."
"Here, we tested the ability of infected male crickets to invest in immunity, somatic growth, and reproductive structures," she noted. "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."
Seminar host is doctoral candidate Lindsey Mack of the laboratory of medical entomologist-geneticist Geoffrey Attardo. "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.
- Author: Kathy Keatley Garvey
Link to PLOS ONE research article is at http://dx.plos.org/10.1371/journal.pone.0118785)
Crickets, known to pack a protein punch, are often touted as “the sustainable food of the future,” but the issue is far more complex than that, say University of California Cooperative Extension agronomist Mark Lundy and horticultural entomologist Michael Parrella, professor and chair of the UC Davis Department of Entomology and Nematology, in research published April 15 in the Public Library of Science (PLOS ONE). The research is titled "Crickets Are Not a Free Lunch: Protein Capture from Scalable Organic Side-Streams via High-Density Populations of Acheta domesticus."
"While there is potential for insect cultivation to augment the global supply of dietary protein, some of the sustainability claims on this topic have been overstated,” said Lundy, who headed the research at UC Davis while seeking his doctorate in agronomy. “Our study demonstrates that the sustainability gains associated with cultivating crickets as an alternative source of protein will depend, in large part, on what the crickets are fed and which systems of livestock production they are compared to.”
“Insect cultivation is more likely to contribute to human nutrition at a scale of economic and ecological significance if it does not rely on a diet that competes with conventional livestock, but more innovation is needed for this to become a reality,” Lundy said. “Moving forward, the imperative will be to design cost-effective processes that enable large populations of insects to capture protein from underutilized organic waste and side streams."
For the study, the researchers modified a UC Davis greenhouse into replicated cells. They measured the biomass output and feed conversion ratios of populations of crickets (Acheta domestics) reared on food that ranged from grain-based to highly cellulosic diets.They found that the biomass accumulation was “strongly influenced by the quality of the diet.”
“The measurements were made at a much greater population scale and density than any previously reported in the scientific literature,” they wrote. “The biomass accumulation was strongly influenced by the quality of the diet, with the nitrogen concentration, the ratio of N to acid detergent fiber content, and the crude fat explaining most of the variability between feed treatments. In addition, for populations of crickets that were able to survive to a harvestable size, the feed conversion ratios (FCR) measured were higher (less efficient) than those reported from studies conducted at smaller scales and lower population densities. Compared to the industrial-scale production of broiler chickens, crickets fed a poultry feed diet showed little improvement in protein conversion efficiency (PCE), a key metric in determining the ecological footprint of grain-based livestock protein.”
“Crickets fed solid filtrate from food waste processed at an industrial scale via enzymatic digestion were able to reach a harvestable size and achieve an FCR and PCE similar to that of broiler chickens,” they wrote. “However, cricket populations fed minimally-processed, municipal-scale food waste and diets composed largely of straw experienced more than a 99% mortality before reaching a harvestable size.”
The researchers concluded that the potential for “Acheta domesticus to sustainably supplement the global protein supply, beyond what is currently produced via grain-fed chickens, will depend on capturing regionally scalable organic side-streams of relatively high-quality that are not currently being used for livestock production.”
Worldwide, statistics show that crickets are the most widely cultivated insects for the human diet, and are considered the “gateway bug” to entomophagy. They are touted as highly nutritious, and much better for the planet—environmentally and financially--than livestock due to their comparatively efficient feed conversion.
Lundy, who received his doctorate in agronomy from UC Davis in 2013, and his master's degree in international agricultural development from UC Davis, in 2010, has engaged in entomophagy. Crickets? Yes. “I ate some of my experimental subjects, after weighing them for the research,” he said. He dusted them with cornmeal and Cajun seasoning and fried them in olive oil. He has also snacked on protein bars made with cricket flour.
“I'm all for exploring alternatives, and I am impressed by the amount of innovation that has sprung up around insect cultivation and cuisine in the last few years,” Lundy said. “However, I also think we need to be clear-eyed about what the sustainability gains are and aren't, and focus our innovative efforts and limited resources to where they will have the most lasting impact.”
Crickets are readily available in pet stores as food for turtles, frogs and other pets. Part of many human diets, they are considered delicacies or snacks in many countries. Cricket flour is now commonly found in protein bars, baked goods and protein powders.
Related Links:
PLOS ONE article
Insects: The Food of the Future (Beer and Bugs event at the Mondavi Institute for Wine and Food Science, UC Davis)
