“The first sighting of emerald ash borer in North America occurred in 2002, when it was discovered attacking ash trees in Ontario, Canada and what U.S. state?” 

If you answered “Michigan,” as the UC Davis Entomology Team did, you're right. 

Doctoral students Jill Oberski, Zachary Griebenow and Hannah Kahl of the UC Davis Department of Entomology and Nematology teamed to compete in the Entomological Society of America's Virtual Entomology Games, a college-bowl type of competition formerly known as the Linnaean Games. 

Oberski and Griebenow are both fourth-year doctoral students in the Phil Ward lab, while Kahl, a member of the Jay Rosenheim lab, is currently a third-year doctoral student who will begin her fourth year in January. 

The UC Davis team won its preliminary round and then entered the highly competitive finals, placing 11th. Alabama's Auburn University edged the Boiler Bugs of Purdue to win the championship. 

 “This  year's format was significantly different from the past since it was held virtually,” said Joe Rominiecki, manager of communications for the Entomological Society of America (ESA). “A  preliminary round was held in early November online via WikiQuiz, and then the finals, with 14 teams total, took place live, broadcast via Zoom, on Monday night, Nov. 16. But rather than a head-to-head competition as in the past, all 14 teams competed at once, answering the same questions--four rounds of 10 questions, plus a tiebreaker question.” 

The champions, from Auburn University's Department of Entomology and Plant Pathology, answered 27 of the 40 questions correctly, tying with the Boiler Bugs of Purdue, “but Auburn had the closest answer for the tiebreaker question,” Rominiecki said. 

In the Entomology Games, teams of two to four students test their entomological knowledge by answering questions drawn from all disciplines of insect science: behavior and ecology, biological control, entomology in culture, integrated pest management (IPM) and insect/plant interactions, medical and veterinary entomology, biochemistry and toxicology economic entomology, history of entomology, morphology and physiology, and systematics and evolution. 

In this year's event, the games were divided into four rounds of 10 questions each. All teams competed to answer the same sets of questions. Each question was worth one point, with 40 being the best possible score. 

ESA did not record the Games this year, as the event itself “was mostly just a recitation of the questions, without the more lively 'buzzing in' format of the live event,” Rominiecki related.

“All in all, we were pleased with how the Entomology Games went this year, in an entirely new format," he said. "Our organizers worked hard in just a few short months to create a virtual version of the Games, and it was great to have teams from all over the country participating as usual, despite the new circumstances. We look forward to returning to an in-person event in the future, of course, but the 2020 virtual edition will be a memorable one. Congratulations to Auburn on their victory, and kudos to all the teams who participated!”

Some of the questions the UC Davis team answered correctly (answers below):

1. Keye Luke, Jay Chou, and Bruce Lee have all portrayed Kato, the crimefighting partner of what fictional vigilante?
2. What is the full scientific name (genus and species) of the bacterium classified by IRAC as a microbial disruptor of insect midgut membranes?
3. "Yoke-winged" is the literal translation of the name of what insect suborder, which can be distinguished from other members of its order by the presence of caudal gills on the aquatic immatures?
4. A worker honey bee has how many pairs of wax glands on its abdomen?
5. Although this year's festivities were postponed due to COVID-19, the small town of Point Pleasant, West Virginia, normally hosts an annual festival that commemorates the 1966 sightings of what paranormal figure?
6. A widely-publicized 2017 study reported a 75 percent decline in insect biomass over the past 27 years. This study was conducted across 63 protected natural areas in what European country?
7. What striking form of structural coloration involves color changes based on the angle of the observer, and was recently shown to help jewel beetles camouflage in order to avoid bird predation?
8. These specialty loaves of bread are labeled "kuwagata," which is a Japanese word that refers to insects in what family?
9. "Stimulo-deterrent diversion" was one of the earlier names for what IPM strategy that uses volatile cues from both repellent and attractant plants to reduce damage from insect pests?
10. The megalopteran family Corydalidae is divided into two clades: Corydalinae (aka dobsonflies) and what other subfamily, whose members are commonly known as fishflies?
11. Bombykol and bombykal are components of a sex pheromone emitted by certain females in what insect order?
12. What term refers to a parasitoid that halts the development of its host shortly after the initial parasitization?
13. Paederus dermatitis, also known as whiplash dermatitis, is a type of skin irritation caused by contact with the hemolymph of certain species in what insect family?
14. What type of semiochemical benefits the receiver and harms the emitter?
15. What sixteen-letter adjective is most commonly used to describe fungi and nematodes that can potentially act as biological control agents of insect pests?
16. Of the three types of lobes typically found in an insect brain, which lobe innervates the labrum and foregut?
17. A 2020 Ig Nobel Prize was awarded to Richard Vetter for collecting evidence that many entomologists exhibit what psychological condition? This condition is also the title of a movie that won the 1990 Saturn Award for Best Horror Film.
18. What twelve-letter term was coined by entomologist Willi Hennig to refer to a derived character that is shared between multiple species and their most recent common ancestor?

  Answers:

1. Green Hornet
2. Bacillus thuringiensis
3. Zygoptera
4. Four
5. Mothman
6. Germany
7. Iridescence
8. Lucanidae
9. Push pull
10. Chauliodinae
11. Lepidoptera
12. Idiobiont
13. Staphylinidae
14. Kairomone
15. Entomopathogenic
16. Tritocerebrum
17. Arachnophobia
18. Synapomorphy

The tiebreaker question? It dealt with the number of Far Side comics referencing insects. The question: "Gary Larson is known for using insects as a source of humor in his acclaimed comic strip 'The Far Side.' A survey of 4,300 'Far Side' comics revealed that exactly how many contained some sort of entomological reference?" Answer: 359. 

Over the last few years, UC Davis teams have won the national championship three times in the fun and lively competitions. (See Bug Squad blog) 

"Hopefully, we can be back onstage in person next year," said Oberski.

• "A Study of Landing Behaviour by the Walnut Twig Beetle, Pityophthorus juglandis, Among Host and Nonhost Hardwood Trees in a Northern California Riparian Forest" (https://doi.org/10.1111/afe.12385). 
• "Walnut Twig Beetle Landing Rates Differ Between Host and Nonhost Hardwood Trees under the Influence of Aggregation Pheromone in a Northern California Riparian Forest" (https://doi.org/10.1111/afe.12410)

The walnut twig beetle, in association with the fungus, Geosmithia morbida, causes the insect-pathogen complex known as "thousand cankers disease," which wreaks havoc on walnut trees. The insect, measuring about 1.5 millimeters long, is smaller than a grain of rice.

"The first study is one of few bark beetle host selection studies conducted without the use of semiochemical lures," Audley said. "Together, both studies provide strong evidence for directed flight host searching and in-flight, host discrimination behaviors by Pityophthorus juglandis. These papers highlight sources of and provide an ecological context for potential non-host, volatile compounds that may be of use in semiochemical repellents to protect walnut trees from attack by P. juglandis." 

• The host selection behaviour of the walnut twig beetle, Pityophthorus juglandis, was assessed by monitoring the landing rates of the beetles with sticky sheet traps on the host and nonhost hardwood branches.
• Sticky sheet traps were deployed for 8 weeks from 6 June to 2 August. 2017 in the Putah Creek Riparian Reserve, Davis, CA. Branches from host northern California black walnut, Juglans hindsii, were paired with branches from six nonhost hardwood species.
• The landing rate of P. juglandis (412 beetles trapped/8 weeks; 389 on host branches, 23 on nonhost branches) was significantly greater on the host branches for all nonhost hardwoods except Populus fremontii. Proportional comparisons of beetle presence also revealed a significant preference for the host branches compared with all but two nonhost species, Acer negundo and P. fremontii.
• Capturing P. juglandis without the use of an aggregation pheromone was a rare event, underscoring the difficulty of studying the initial phases of host selection behaviour in bark beetles. Unbaited funnel traps adjacent to selected host trees in the experiment only captured five individuals over a 19‐week period. None were captured in traps adjacent to nonhost trees.
• This study provided evidence that P. juglandis discriminates between host and nonhost branches while in‐flight. This directed flight behaviour is likely informed by the recognition of both host and nonhost volatile cues.
• This study established an ecological context for the development of a semiochemical‐based repellent system for protecting walnut trees from future attacks from this invasive bark beetle. 

Second Paper: Walnut Twig Beetle Landing Rates

The abstract:

1. Host selection behaviour of the walnut twig beetle (WTB) among hardwood trees was investigated in a riparian forest in northern California by monitoring the landing rate of the beetle with sticky traps on branches baited with 3‐methyl‐2‐buten‐1‐ol, the male‐produced aggregation pheromone.
2. The assay was conducted over 7 days (22 May to 29 May 2017) and compared landing rates on branches of six nonhost species paired with northern California black walnut, Juglans hindsii (the host).
3. A total of 2242/1192 WTB were collected on branches of host/nonhost pairs, and more WTB landed on J. hindsii than on nonhosts in 42 of 58 instances. Female landing rate generally exceeded male landing rate, which underscores the influence of the male‐produced synthetic pheromone in this system.
4. Landing rates of WTB males, females, and the combined sexes on boxelder, Acer negundo, and valley oak, Quercus lobata, did not differ significantly from the landing rates on J. hindsii, suggesting that these two nonhost riparian hardwoods do not repel WTB (in the context of the aggregation pheromone).
5. Significantly fewer WTB landed on Oregon ash, Fraxinus latifolia, river red gum, Eucalyptus camaldulensis, Fremont cottonwood, Populus fremontii, and red willow, Salix laevigata, than on J. hindsii, which suggests that these four nonhosts may repel one or both sexes of WTB in the context of the aggregation pheromone. Future analysis of the volatiles from these four hardwood species may lead to the discovery of semiochemical repellents for WTB.

Co-authors (in addition to Audley, Homicz, Seybold and Bostock) are Yigen Chen, Foundation Research, Analytics and Business Applications, E. & J. Gallo Winery, Modesto, Calif.; and scientist Catherine Tauber, UC Davis Department of Entomology and Nematology, and formerly with the Department of Entomology, Cornell University, Ithaca, N.Y.

Jackson Audley

Audley is now a postdoctoral fellow funded by the Oak Ridge Laboratories, and based at the USDA Forest Service, Pacific Southwest Research Station, Davis.  While at UC Davis, Audley investigated behavioral chemicals that repel the walnut twig beetle from landing on English walnut trees. He conducted his research in a commercial orchard near Winters. He received the 2019 Western Forest Insect Work Conference (WFIWC) Memorial Scholarship Award for his research on the chemical ecology of the walnut twig beetle. He holds a master's degree in forestry (2015) from the University of Tennessee, and a bachelor of science degree in wildlife biology and natural resource recreation and tourism (2009) from the University of Georgia. 

Crystal Homicz

Homicz, who joined the UC Davis doctoral program in September 2019, received a bachelor of science degree in animal biology with an emphasis in entomology (2018) from UC Davis. Her practicum: "Landing Behavior of the Walnut Twig Beetle on Host and Non-Host Hardwood Trees Under the Influence of Aggregation Pheromone in a Northern California Riparian Forest."  She holds associate degrees in both biology and natural sciences (2016) from Shasta College.

For more information on the walnut twig beetle and thousand cankers disease, see the UC Statewide Integrated Pest Management Program website.

Newly published UC Davis research, the first of its kind, reveals that pesticide exposure and food scarcity pack a double punch to blue orchard bees, Osmia lignaria, a wild  bee that pollinates early spring bloom, including almonds. 

Lead author Clara Stuligross, a doctoral student in the lab of pollination ecologist Neal Williams, a professor in the Department of Entomology and Nematology, teamed with Williams to study the results of food scarcity and pesticide exposure. 

They exposed the bees to the neonicotinoid insecticide imidacloprid, widely used in agriculture, and found that the combined threats—imidacloprid exposure and the loss of flowering plants—reduced the bee's reproduction by 57 percent, resulting in fewer female offspring. 

Of the two stressors—food scarcity and pesticide exposure—pesticide exposure showed the great impact on nesting activity and the number of offspring produced, they said. 

The study, Pesticide and Resource Stressors Additively Impair Wild Bee Reproduction, accomplished in the spring of 2018 on the grounds of the UC Davis Harry H. Laidlaw Jr. Facility, is published in the journal Proceedings of the Royal Society B. 

Other scientists have conducted similar research on honey bees, but this is the first comparable research on wild bees in field or semi-field conditions. 

The blue orchard bee, nicknamed BOB, is a dark metallic mason bee, smaller than a honey bee. It is prized for pollinating almond, apple, plum, pear, and peach trees. California almond growers often set up bee boxes or bee condos for them in their orchards to aid in the honey bee pollination. In the wild, the bees nest in reeds or natural holes. 

“Bees and other beneficial insects experience multiple stressors within agricultural landscapes that act together to impact their health and diminish their ability to deliver the ecosystem services on which human food supplies depend,” they wrote in their abstract. “Disentangling the effects of coupled stressors is a primary challenge for understanding how to promote their populations and ensure robust pollination and other ecosystem services.” 

To study the survival, nesting and reproduction of the blue orchard bee, they set up nesting females in large flight cages, some with high densities of wildflowers and others with low densities that were treated “with or without the common insecticide, imidacloprid.” Bees are commonly exposed to insecticides when they forage on treated flowers.   

“Pesticides and resource limitation acted additively to dramatically reduce reproduction in free-flying bees,” they wrote in their abstract. “Our results emphasize the importance of considering multiple drivers to inform population persistence, management, and risk assessment for the long-term sustainability of food production and natural ecosystems.” 

"Understanding how multiple stressors interplay is really important, especially for bee populations in agricultural systems, where wild bees are commonly exposed to pesticides and food can be scarce,” said Stuligross, who holds a bachelor of arts degree in environmental studies (2014) from Earlham College, Richmond, Ind. She joined the UC Davis ecology doctoral program in 2016.

Onset of Nesting Delayed
Key factors in affecting bee reproduction are the probability that females will nest and the total number of offspring they have. The UC Davis research found that pesticide-exposed and resource-deprived female bees delayed the onset of nesting by 3.6 days and spent five fewer days nesting than unexposed bees.

Professor Williams pointed out that this is a substantial delay because bees nest only for a few weeks, and it's crucial to reproduce female offspring to carry on the future generations. “Fewer females will reduce the reproductive potential of subsequent generations," said Williams, a UC Davis Chancellor's Fellow and a newly elected fellow of the California Academy of Sciences.

They found that only 62 percent of pesticide-exposed bees produced at least one daughter compared to 92 percent of bees not exposed to pesticides.

The study drew support from a UC Davis Jastro Research Award, a UC Davis Ecology Graduate Research Fellowship, a National Science Foundation Graduate Research Fellowship, and the UC Davis bee biology facility

The blue orchard bee bee is one of the few native pollinators that is managed in agriculture. North America has 140 species of Osmia, according to a Pollinator Partnership (PP) article in a U. S. Forest Service publication, authored by entomologist and PP member Beatriz Moisset and PP director Vicki Wojcik. “Mason bees use clay to make partitions and to seal the entrance,” they wrote. “This unique mud-building behavior leads to their common designation as mason bees. Honey bees are very important to commercial agriculture, but native bees like the blue orchard bees are better and more efficient pollinators of native crops.”

Imidacloprid, a systemic insecticide that acts as an insect neurotoxin, is used to control sucking insects, termites, some soil insects and fleas on pets, according to National Pesticide Information Center. It mimics nicotine, toxic to insects, which is naturally found in many plants, including tobacco.  More than 400 products for sale in the United States contain imidacloprid.

Newly published UC Davis research analyzing modern-day and museum collections of monarch butterflies over a 200-year period indicates that the loss of migration and range expansion leads to smaller and shorter wings. 

The research, “Two Centuries of Monarch Butterfly Collections Reveal Contrasting Effects of Range Expansion and Migration Loss on Wing Traits,” appears this week in  the Proceedings of the National Academy of Sciences. 

“We measured the wings of 6,000 museum specimens of monarch butterflies collected from 1856 to the present, as well as contemporary wild-caught monarchs from around the world,” said lead author Micah Freedman, a former UC Davis doctoral candidate in population biology and now a postdoctoral fellow at the University of Chicago. 

“The major implications of the research,” Freedman said, “are that it shows (1) loss of migration can affect the evolution of monarch butterflies over contemporary time scales--dozens to hundreds of years; and (2) monarchs with large forewings are better-suited for long distance movement, and this likely contributed to their global expansion over the past 200 years.” 

Co-Authors of PNAS Paper
Freedman works closely with noted migratory animal authority and co-author Hugh Dingle, emeritus professor, UC Davis Department of Entomology and Nematology, who received a 2014 UC Davis Edward A. Dickson Professorship Award to research “Monarchs in the Pacific: Is Contemporary Evolution Occurring on Isolated Islands?” They co-authored the research with Sharon Strauss, professor and Santiago Ramirez, associate professor, Center for Population Biology and the Department of Evolution and Ecology. 

“We used the monarchs' recent global range expansion to test the hypotheses about how dispersal traits evolve,” said Freedman, who received his doctorate from UC Davis in February after earning a degree in entomology and plant sciences at Cornell University. “We found that early monarch founders have large and elongated forewings, but post-establishment loss of migration repeatedly leads to smaller wings, a pattern detectable in both time series with historical specimens and experimentally reared monarchs.” 

Their research documents how migration-associated traits may be favored during range expansion but disfavored when species cease seasonal migration. “Furthermore, it highlights the value of museum collections by combining historical specimens with experimental rearing to demonstrate contemporary evolution of migration-associated traits in natural monarch populations,” Freedman said. 

Said Dingle: “At a time when museum collections are under pressure from a scarcity of funding, the results also show just how valuable such collections can be to evolutionary research and to the understanding of ongoing biological processes in the face of anthropogenic change.”

In their abstract, they pointed out that “migratory animals exhibit traits that allow them to exploit seasonally variable habitats. In environments where migration is no longer beneficial, such as oceanic islands, migration-association traits may be selected against or be under relaxed selection.” 

“Monarch butterflies are best known for their continent-scale migration in North America but have repeatedly become established as non-migrants in the tropical Americas and on Atlantic and Pacific Islands,” they wrote. “These replicated non-migratory populations provide natural laboratories for understanding the rate of evolution of migration-associated traits.” 

What They Determined
They determined (1) how wing morphology varies across the monarch's global range, (2) whether initial long-distance founders were particularly suited for migration and (3) whether recently-established non-migrants show evidence for contemporary phenotypic evolution. 

Under controlled conditions in a UC Davis lab, they also reared more than 1000 monarchs from six populations around the world and measured migration-associated traits. 

“Historical specimens show that initial founders are (1) well-suited for long-distance movement and (2) loss of seasonal migration is associated with reductions in forewing size and elongation,” they related. “Monarch butterflies raised in a common garden from four derived non-migratory populations exhibit genetically based reductions in forewing size, consistent with a previous study.” 

Dingle said the findings “provide a compelling example of how migration-associated traits may be favored during the early stages of range expansion, and also the rate of reductions in those same traits upon loss of migration.” 

Statistics show that the population of monarch butterflies in the United States has declined by 90 percent over the past 20 years.

Undergoing Contemporary Evolution
The monarch butterflies established just 200 years ago in remote Pacific Islands are undergoing contemporary evolution through differences in their wing span and other changes, Dingle said. He and Freedman studied monarchs in the Pacific Islands for a week in 2016 in a project funded by Dingle's UC Davis emeritus faculty grant, the Edward A. Dickson Professorship Award. The research involved measuring the wingspans of Guam monarchs to determine whether there has been an evolutionary decrease in size or shape due to their migration-free lifestyle on the island. They also measured the wings of monarchs in the University of Guam's museum collection.

An analysis of a monarch population in Hawaii shows that resident monarchs have shorter, broader wings than the long-distance migrants, Dingle noted. The Hawaii butterfly wings were shorter than the eastern U.S. long-distance migrants, but “not so short-winged as the residents in the Caribbean or Costa Rica, which have been present in those locations for eons, rather than the 200 years for Hawaii.”

Dingle, author of two editions of  Migration: The Biology of Life on the Move (Oxford University Press), a fellow of the American Association for the Advancement of Science and a past president of the Animal Behavior Society, said previous studies by various authors revealed that migrant and long-resident monarchs exhibit different wing shapes. "Thus, it was desirable to examine populations with only short residency to see if the same phenomenon was evident.”

Dingle, who served as a UC Davis entomology professor from 1982 to 2002, achieving emeritus status in 2003, has engaged in research throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia. National Geographic featured Dingle in its cover story on “Great Migrations”  in November 2010.  LiveScience interviewed him for its November 2010 piece on“Why Do Animals Migrate?”

The Bohart Museum of Entomology at UC Davis was among the 22 global museum collections studied. The research also included private collections and online databases. Freedman and assistant Christopher Jason reared some of the butterflies included in the PNAS paper in a UC Davis greenhouse. 

The project drew funding from the National Science Foundation (NSF) Graduate Research Fellowship Program, the NSF East Asia and Pacific Summer Institute Program, the UC Davis Center for Population Biology, and the National Geographic Society to Freedman, as well as the Dickson Emeritus Professor Award to Dingle, a California Agricultural Experiment Station grant to Strauss, and a David and Lucille Packard Fellowship to Ramirez. 

The abstract:

“Migratory animals exhibit traits that allow them to exploit seasonally variable habitats. In environments where migration is no longer beneficial, such as oceanic islands, migration-association traits may be selected against or be under relaxed selection. Monarch butterflies are best known for their continent-scale migration in North America but have repeatedly become established as non-migrants in the tropical Americas and on Atlantic and Pacific Islands. These replicated non-migratory populations provide natural laboratories for understanding the rate of evolution of migration-associated traits. We measured more than 6,000 museum specimens of monarch butterflies collected from 1856 to the present, as well as contemporary wild-caught monarchs from around the world. We determined (1) how wing morphology varies across the monarch's global range, (2) whether initial long-distance founders were particularly suited for migration and (3) whether recently-established non-migrants show evidence for contemporary phenotypic evolution. We further reared more than 1,000 monarchs from six populations around the world under controlled conditions and measured migration-associated traits. Historical specimens show that (1) initial founders are well-suited for long-distance movement and (2) loss of seasonal migration is associated with reductions in forewing size and elongation. Monarch butterflies raised in a common garden from four derived non-migratory populations exhibit genetically-based reductions in forewing size, consistent with a previous study. Our findings provide a compelling example of how migration-associated traits may be favored during the early stages of range expansion, and also the rate of reductions in those same traits upon loss of migration.”

As a postdoctoral fellow at the University of Chicago, Freedman said he is "currently using breeding experiments and DNA sequencing trying to figure out which genes affect migratory traits and behaviors in monarchs. This includes wing traits (shapes and size) discussed in the PNAS paper.”