- Author: Kathy Keatley Garvey
Yes, if you use the term “personality” to refer to “intraspecific expression of behaviors that are stable over time and consistent across different situations,” says ecologist Richard “Rick” Karban, an international authority on plant communications and a distinguished professor in the UC Davis Department of Entomology and Nematology.
“Individual plants respond differently to alarm calls, just as individual animals do,” says Karban, a 40-year member of the UC Davis faculty who has studied plant communication in sagebrush (Artemisia tridentata) since 1995 on his research site, located east of the Sierra Nevada mountain range.
In a newly published paper in the international peer-reviewed journal, Oecoogia, the UC Davis professor and two colleagues found that when plants tell their neighbors—via volatile cues—that they are under attack by herbivores, the plants showed consistent individual variation in how they perceived and responded to the cues, that is, how effectively they shored up their defenses.
“The gist of the argument here is that animal behaviorists have found it useful to recognize that individual animals show behavioral tendencies that are consistent under different circumstances and repeatable over time,” Karban explained. “So, for instance, some individuals are bolder or shyer in terms of issuing or responding to alarm calls. They have termed these individual tendencies 'personalities.' We have found similar consistent individual differences among sagebrush plants.”
The paper, titled “Consistent Individual Variation in Plant Communication: Do Plants Have Personalities?,” is co-authored by Patrick Grof-Tisza of the University of Eastern Finland and Charline Couchoux of the University of Quebec. Established in 1968, Oecoogia is one of the most cited ecology journals.
“Just as animal biologists have come to consider consistent individual personalities to be an important factor in shaping animal phenotypes, behaviors, and interactions, so, too, should plant biologists include individual variation in plant communication as a significant individual attribute that influences their evolution and ecology,” they noted.
In their abstract, they explained that “When animals sense danger, some individuals will alert neighbors with alarm calls and both calling and responding vary consistently among individuals. Plants, including sagebrush, emit volatile cues when they are attacked by herbivores and neighbors perceive these cues and reduce their own damage.”
They found that 5 percent of the variance in chewing damage “was attributable to the identity of the emitter that provided the cue. This fraction of variation was statistically significant and could not be attributed to the environmental conditions of the receiver. Effective receivers were also relatively effective emitters, indicating consistency across different situations. Pairs of receivers and emitters that were effective communicators in 2018 were again relatively effective in 2019, indicating consistency over time. These results suggest that plants have repeatable individual personalities with respect to alarm calls.”
In their paper, the scientists pointed out that the goal “in discussing plant personalities is not to insinuate that plants are people or are intelligent in a similar way that we are, but to highlight that animal behavior has much to offer the development of plant biology. Recognizing that plants exhibit consistent behaviors that are repeatable in different situations and stable over time (i.e., personalities) has several important consequences.”
First, they said most plant biologists focus on treatment groups instead of individuals. “The idea that individual plants may show consistent tendencies that can be quantified, independent of other treatments, leads to a different research focus. In addition, the existence of plant personalities means that knowledge of an individual's past provides information that can predict its behavior in the future. In Bayesian jargon, the existence of personalities means that informed priors can be used to improve predictive power.”
Tradeoffs. Second, they wrote, “recognition of correlations among different plant behaviors suggests that there may be tradeoffs among important traits that are not independent of one another. For example, a negative correlation between growth of roots and shoots suggests an allocation tradeoff between above and below ground tissues while a positive correlation between growth of roots and shoots suggests that differential access to resources is more important than such an allocation tradeoff. Life-history tradeoffs of this nature are familiar to evolutionary plant biologists and this framework can be applied to other plant behaviors.”
Third, they wrote, “alarm calls that affect herbivory influence plant growth, survival, and reproduction in the few systems where they have been studied. These demographic effects have the potential to shape plant adaptations, population sizes and distributions, ability to respond to natural and human induced changes, and interactions with other species, although potential effects of variation in plant communication have been largely neglected.”
The trio pointed out that “many of these volatile chemicals dissipate rapidly so that they are present in biologically active concentrations over relatively short distances (often less than 1 m). In many instances, cues may be emitted unintentionally, and this process is probably best described as eavesdropping by the receiving plant. These same plant volatile cues have been found to serve other functions in some instances such as repelling herbivores and attracting the predators and parasites of the herbivores.”
Landmark Book. Karban is the author of the landmark book, Plant Sensing and Communication (University of Chicago Press, 2015). He is a fellow of the Ecological Society of America (ESA) and the American Association for the Advancement of Science, and the recipient of the 1990 George Mercer Award from ESA for outstanding research.
The UC Davis ecologist is featured in the Dec. 23-30, 2013 edition of The New Yorker in Michael Pollan's piece, The Intelligent Plant: Scientists Debate a New Way of Understanding Plants. Zoe Schlanger featured him in a Nov. 21, 2020 Bloomberg Quint article titled The Botanist Daring to Ask: Do Plants Have Personalities?
Karban, who holds a doctorate in biology from the University of Pennsylvania, Philadelphia, joined the UC Davis faculty in 1982.
- Author: Kathy Keatley Garvey
Yes, according to UC Davis community ecologist and doctoral candidate Danielle Rutkowski and her colleagues in their newly published research in the Royal Entomological Society's Journal of Ecological Entomology.
The research, “Bee-Associated Fungi Mediate Effects of Fungicides on Bumble Bees,” provides direct evidence that fungi can benefit both survival and reproduction in two species of bumble bees, Bombus vosnesenskii, and B. impatiens. The research also suggests that yeast, commonly found in the gut of bumble bees, may be more important than originally thought.
“Bumble bees are important pollinators that face threats from multiple sources, including agrochemical application,” said Rutkowsi, the lead researcher-author. “Declining bumble bee populations have been linked to fungicide application, which could directly affect the fungi often found in the stored food and gastrointestinal (GI) tract of healthy bumble bees.”
“I tested if fungicides commonly applied in orchard systems affected yeasts and the health of their bee hosts, and if feeding those bees their fungi after fungicide exposure could rescue them,” said Rutkowski, who studies with major professors Rachel Vannette and Richard Karban, community ecologists in the Department of Entomology and Nematology.
“Bombus vosnesenskii (commonly known as the yellow-faced bumble bee), is native to California and we reared colonies of it from wild-caught queens,” Rutkowski said. “In this species, we observed strong negative effects of fungicide and the ability of bee-associated fungi to rescue bees from these negative effects. The other species, Bombus impatiens, is native to the eastern United States, but is commonly produced and sold commercially for pollination. In this species, we did not find any negative impacts of fungicide, but the addition of yeasts was very beneficial for bee survival and offspring production.”
“Although most previous work on bee microbiomes has focused on bacteria and their role in bee health, Danielle's work suggests that yeasts --which are commonly found in association with bumble bees--may be more important than previously thought,” Vannette said. “This has been hinted at in the literature but rarely tested directly.”
Rutkowski examined the interactive effects of the fungicide propiconazole and fungal supplementation on the survival, reproduction and microbiome composition of microcolonies (queenless colonies) using the two species.
Both B. vosnesenskii and B. impatiens benefitted from fungal addition but in different ways. fungicide exposure decreased survival in B. vosnesenskii, while fungal supplementation mitigated fungicide effects. For B. impatiens, fungicide application had no effect, but fungal supplementation improved survival and offspring production.
“Because the effect of fungicides on yeasts and bees takes a few weeks to observe, it is not detected in short term LD50 trials,” Vannette said, “and therefore could be an unrecognized threat to bumble bees and their symbionts.”
Other co-authors of the paper are entomologist Eliza Litsey and environmental scientist Isabelle Maalouf.
More research is planned to determine the mechanism by which yeasts can affect bee health, and which fungicides affect bee-associated yeasts.
“I'm currently working on a project to determine the mechanisms behind the positive effects of yeast addition that we observed,” Rutkowski said. “In some bees and other insects, fungi can produce nutritionally important compounds for their host, and I'm currently trying to determine if this is the case for bumble bees as well.”
“Additionally, I'm planning on following up some of the interesting results on differences between bumble bee species by determining how associated microbial communities differ between wild and commercially-reared bumble bees,” Rutkowski said. “In this current paper, we found that the fungal communities associated with the commercially-sourced bees were less diverse and less abundant, and I'm hoping to determine if that's a common pattern.”
Rutkowski, who joined the UC Davis doctoral program in 2018, won the President's Prize (first-place) in her category for her graduate student research presentations at the 2017 and 2021 Entomological Society of America meetings. A 2018 graduate of Cornell University, summa cum laude, she holds a bachelor of science degree in entomology and biological sciences, with a concentration in ecology and evolution.
Rutkowski's research drew support from her three-year USDA National Institute of Food and Agriculture grant.
- Author: Kathy Keatley Garvey
Squirm, maggots, squirm!
If you look behind the scenes of the entomological activities at the 108th annual UC Davis Picnic Day on Saturday, April 23 at Briggs Hall, you'll see a Department of Entomology and Nematology doctoral candidate coordinating everything from Roach Races to Maggot Art.
“I'm really excited to get our events up and running again after two years," said Danielle Rutkowski, the UC Davis Graduate Student Association (EGSA) coordinator of the department's Picnic Day activities at Briggs Hall (with forensic entomologist and faculty member Robert Kimsey).
COVID-19 pandemic cancelled the in-person UC Davis Picnic Day in both 2020 and 2021, but not 2022, nor the renewed enthusiasm.
“Coordinating events has been challenging, mostly because I've only been to one in-person Picnic Day myself!" said Rutkowski, who enrolled in the doctoral program in 2018, and is advised by associate professor Rachel Vannette and UC Davis distinguished professor Richard Karban.
"But it's been fun to work with other graduate students and the entomology club to get our exhibits from previous years back together. This is the first Picnic Day for many students in the department, so I want to make sure it's a fun experience for volunteers as well as visitors.”
Entomological activities at Briggs Hall will include Bug Doctor and Doctor Death booths; displays featuring honey bees, ants, mosquitoes, integrated pest management, forest entomology, medical entomology and agricultural entomology; and EGSA's insect-themed t-shirt sales, as well as the crowd-pleasing Roach Races and Maggot Art. And more. (See schedule at Briggs and Bohart Museum of Entomology.)
“The Roach Races are a definite favorite of the public; they're really high energy and a lot of fun," Rutkowski said. "And the (American) roaches are from a colony that the entomology club cares for, so they can return home after a hard day of racing. Maggot Art is another popular event among visitors, and we order the maggots from a bait supplier.”
Rutkowski says there are plenty of events “that I haven't seen before, and I'm looking forward to being a part of them this year. We'll have a lot of displays set up in Briggs 122, which I'm excited to see. We'll be bringing back some previous displays on forest entomology and medical entomology, as well as some new displays on agricultural entomology and caterpillar biology.”
Her research is funded by a three-year USDA National Institute of Food and Agriculture (NIFA) pre-doctoral fellowship of $180,000; it provides tuition stipends and research funding to study the impacts and mechanisms of fungicide and bee-associated fungi on bumble bee health. Her other grants or scholarships include a 2020 Academic Senate grant of $25,000 to research the effects of fungicide on the health and microbiome composition of bumble bees; three George H. Vansell Scholarships (2019, 2020 and 2021 totaling $8950) to study the effects of fungicide on the health and microbiome composition of bumble bees; and a 2018-2020 UC Davis Eugene Cota-Robles Fellowship of $95,200.
Danielle holds a bachelor of science degree from Cornell University in entomology and biological sciences, with a concentration in ecology and evolutionary biology. She graduated in May 2018 summa cum laude with distinction in research.
At Cornell, Rutkowski worked with Professor Richard Lindroth on multiple projects investigating how genotype and environmental conditions interact to affect the growth, defense, and insect community of aspen trees. She did independent research with Professor Jennifer Thaler, carrying out an independent honor's thesis research project on ecological interactions between insect herbivores, plants, and arbuscular mycorrhizal fungi. Rutkowski also worked with Thaler on numerous other projects, studying interactions between potato plants, Colorado potato beetles, and their predators, as well as projects studying the interactions between arbuscular mycorrhizal fungi, tomato plants, and insect herbivores.
Active in the Entomological Society of America (ESA), Rutkowski presented her research at the annual meetings in 2017, 2018 and 2021, and received the President's Prize (first place) in both 2017 and 2021. Rutkowski has also served as a member of the UC Davis graduate student group, Equity in Science, Technology, Engineering, Math, and Entrepreneurship (ESTEME), planning activities and lessons for middle school students in the Davis area.
But for now, Danielle Rutkowski is juggling (1) her research on bumble bees (2) her dedication to her academic studies and (3) her mentoring and student teaching with (4) her commitment to public service: coordinating the highly popular Roach Races, Maggot Art and other entomological activities at the UC Davis Picnic Day's campuswide open house.
- Author: Kathy Keatley Garvey
She and other recipients of the prestigious President's Prize, (the first-place award), each held up an empty picture frame lettered with "Student Competition Winner."
Images from the ESA meeting are online on Flickr at https://www.flickr.com/photos/
Rutkowski delivered her 10-minute presentation on "Fungicide Impacts on Bumble Bees are Mediated via Effects on Bee-Associated Fungi" in the category, Plant-Insect Ecosystems: Ecology 3." She studies with community ecologist Rachel Vannette, associate professor, and is also advised by community ecologist and professor Rick Karban.
At the ESA's 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. First-place winners receive a one-year free membership in ESA, a $75 cash prize, and a certificate. Second-winners score a one-year free membership in ESA and a certificate.
Rutkowski's abstract:
"Native bees including bumble bees are important pollinators but face threats from multiple sources, including agrochemical application. Declining bumble bee populations have been linked to fungicide application, which could directly affect the fungi often found in the stored food and GI tract of healthy bumble bees. Here, we test the hypothesis that fungicides impact bee health by disrupting bumble bee -fungi interactions. Using two species, Bombus vosnesenskii and B. impatiens, we test the interactive effect of the fungicide propiconazole and fungal supplementation on the survival, reproduction, and microbiome composition of microcolonies (queenless colonies). We found that both bee species benefitted from fungi, but were differentially affected by fungicides. In B. vosnesenskii, fungicide exposure decreased survival while fungal supplementation mitigated fungicide effects. For B. impatiens, fungicide application had no effect, but fungal supplementation improved survival and offspring production. Fungicides altered fungal microbiome composition in both species, and reduced fungal abundance in B. vosnesenskii microcolonies, but not in B. impatiens, where instead fungal addition actually decreased fungal abundance. Our results highlight species-specific differences in both response to fungicides and the nature of fungal associations with bees, and caution the use of results obtained using one species to predict the responses of other species. These results suggest that fungicides can alter bee- fungi interactions with consequences for bee survival and reproduction, and suggest that exploring the mechanisms of such interactions, including interactions within bee-associated fungal communities, may offer insights into bumble bee biology and bumble bee conservation strategies. (Paper co-authors are associate professor Rachel Vannette, Eliza Litsey and Isabelle Maalouf)
Rutkowski completed her bachelor's degree at Cornell University, where she studied how the relationship between mycorrhizal fungi and their host plants impacts insect herbivores. On the Vannette lab website, she specifies that she studies "how bumble bees interact with the microbes, particularly fungi, in their environment, and how these relationships impact bee health."
Vannette describes her lab as "a team of entomologists, microbiologists, chemical ecologists, and community ecologists trying to understand how microbial communities affect plants and insects (sometimes other organisms too). We often study microbial communities in flowers, on insects or in soil. We rely on natural history observations, and use techniques from chemical ecology, microbial ecology and community ecology. In some cases, we study applied problems with an immediate application including pathogen control or how to support pollinators. Other questions may not have an immediate application but are nonetheless grounded in theory and will contribute to basic knowledge and conservation (e.g. how can dispersal differences among organisms affect patterns of abundance or biodiversity?)"
Related Information:
- Three UC Davis Graduate Students Win Top Awards at ESA Competition (Danielle Rutkowski, President's Prize; Maureen Page, second-place; and Kyle Lewald, second-place)
- UC Davis Graduate Students Present Their Research in ESA Competitions (Jill Oberski, Zachary Griebenow, Lacie Newton, Lindsey Mack, Danielle Rutkowski, Maureen Page, Xavier Zahnle, Erin Taylor Kelly, Jasmin Ramirez Bonilla, Madison Hendrick, Mia Lippey, and Gabriel Foote)
- Author: Kathy Keatley Garvey
The honor is awarded to those scholars “whose work has been internationally recognized and acclaimed and whose teaching performance is excellent.”
The UC Davis Department of Entomology now has a total of nine distinguished professors: six current faculty--Bruce Hammock, Frank Zalom, Lynn Kimsey, James R. Carey, Jay Rosenheim, and Richard Karban--and three emeriti faculty--Harry Kaya, Howard Ferris and Thomas Scott. (In addition, emeritus professor/chair Robert E. Page Jr. is a UC Davis distinguished emeritus professor, as was the late Robbin Thorp, who died in 2019.)
Karban, whose research interests include the population regulation of animal species and the interactions between herbivores and their host plants, currently focuses his research on two main projects: volatile communication between sagebrush plants that affects resistance to herbivory and factors that control the abundance and spatial distribution of wooly bear caterpillars.
Karban has researched plant communication in sagebrush (Artemisia tridentata) on the east side of the Sierra since 1995. His groundbreaking research on plant communication among kin, published in February 2013 in the Proceedings of the Royal Society B: Biological Sciences, drew international attention. In that study, Karban and his co-researchers found that kin have distinct advantages when it comes to plant communication, just as “the ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors.”
On his website, he explains his research on volatile communication: “When sagebrush is experimentally clipped, it releases volatile cues that undamaged branches on the same plant, on different sagebrush plants, and on some other plant species respond to. These volatile cues cause many changes in neighboring plants and some of these changes make the undamaged neighbors better defended against their herbivores. We currently know little about the nature of these cues.
“Blocking air contact between branches makes responses undetectable, indicating the involvement of airborne cues. Methyl jasmonate has the ability to serve as the signal although it remains unclear if it acts in this capacity in nature. I would like to understand the costs and benefits of releasing volatiles cues and of responding to them. I am examining the multiple consequences of emitting cues. For example, cues affect neighboring plants, nearby herbivores, as well as predators and parasites of those herbivores. I am currently examining the long-term fitness consequences for sagebrush of responding to volatile cues.”
On his research on the abundance and distribution of caterpillars, Karban writes: “Many workers define ecology as the science that explains the abundance and distribution of species. Despite a century of work on these questions, our field has only a rudimentary grasp on the factors that are important. I have been censusing populations of wooly bear caterpillars at Bodega Bay for 30 years and have relatively little understanding of the factors that produce patterns in abundance and distribution. The ‘usual suspects' all have relatively little explanatory power: weather, food limitation, and parasitoids all fail to provide much insight. Indeed, caterpillars often recover from the attacks of their tachinid parasitoids and alter their diets when parasitized to increase their chances of surviving. Including a more complete food web in our analysis does not appear to provide more resolution although ants may be unappreciated as predators and food quality may also be important. I am collaborating with Perry de Valpine to attempt to develop new analytical techniques that will account for more of the variance in abundance data. I am collaborating as well with Marcel Holyoak to examine spatial patterns of abundance.”
Karban is the author of landmark book, Plant Sensing and Communication. He is a fellow of the Ecological Society of America (ESA) and the American Association for the Advancement of Science, and the recipient of the 1990 George Mercer Award from ESA for outstanding research.
The UC Davis ecologist is featured in the Dec. 23-30, 2013 edition of The New Yorker in Michael Pollan's piece, The Intelligent Plant: Scientists Debate a New Way of Understanding Plants. Zoe Schlanger featured him in a Nov. 21, 2020 Bloomberg Quint article titled The Botanist Daring to Ask: Do Plants Have Personalities?
Karban received his bachelor's degree in environmental studies from Haverford (Penn.) College in 1977 and his doctorate in biology from the University of Pennsylvania, Philadelphia, in 1982. He served as a lecturer at Haverford College for six months before joining the UC Davis faculty in May 1982 as an assistant professor. He advanced to associate professor in 1988 and to full professor in 1994.
